JP4715494B2 - Brushless motor control method and control apparatus - Google Patents

Description

  The present invention relates to a control method for driving a brushless motor including a rotor having a field magnet and a stator having an armature coil composed of a three-phase coil, and a control device used for carrying out this control method. In particular, the present invention relates to a control method and a control apparatus suitable for controlling a brushless motor used in a high temperature environment.

  As is well known, a brushless motor includes a rotor having a permanent magnet attached to a rotor yoke to form a magnet field, a stator having an armature coil composed of a three-phase coil, and a three-phase coil from a DC power source. An inverter circuit disposed between the DC power supply and the armature coil to switch the energization pattern of the current to be passed through, a position sensor for detecting the position of the rotor (rotational angle position) with respect to each phase coil, In order to rotate the rotor in a predetermined direction, a controller that controls the inverter circuit so as to switch the energization pattern to the three-phase coil in accordance with a change in the position of the rotor detected by the position sensor. .

  Conventionally, as a position sensor for detecting the position of a rotor of a brushless motor, as shown in Patent Document 1, a magnetic sensor composed of a Hall element is often used. However, the magnetic sensor uses a semiconductor. Therefore, it has the property of being vulnerable to heat. Therefore, it is not appropriate to use a magnetic sensor as a position sensor for detecting the position of the rotor of a brushless motor used in a high temperature environment.

  As a brushless motor used in a high temperature environment, for example, there is a motor used for starting an engine. Conventionally, a motor for starting an engine has been provided separately from a generator attached to the engine. Recently, however, a magnet generator attached to an engine can be driven as a brushless motor when starting the engine to start the engine. It is being considered. Magnet generators for engines use a magnetic sensor that is sensitive to heat, such as a hall element, as a position sensor used when operating the generator as a brushless motor because the rotor is directly attached to the crankshaft of the engine. It is inevitable that the reliability will deteriorate.

  Therefore, as disclosed in Patent Document 2, a rotor is provided with a reluctor, and a signal generator that detects the edge of the reluctor and generates a pulse is provided, and the rotor is generated from the output pulse of the signal generator. It has been proposed to detect the position of.

  As is well known, a signal generator for detecting the edge of a reluctator and generating a pulse includes an iron core having a magnetic pole portion facing the reluctator, a signal coil wound around the iron core, and a magnetic coupling to the iron core. In order to induce a pulse signal in the signal coil by causing a change in the magnetic flux interlinking with the signal coil when the edge of the reluctator passes through the position of the magnetic pole part of the iron core. It is configured.

  As a magnetic flux change type signal generator that detects a change in magnetic flux and generates a pulse, in addition to the above type, a pulse generating magnet and a signal coil are provided on the rotor side and the stator side, respectively, to generate a pulse. There is also a type in which a pulse is induced in the signal coil by a change in magnetic flux generated when the working magnet passes the position of the signal coil.

  Since these magnetic flux change detection type signal generators do not use semiconductor elements, they are resistant to heat, but because they obtain pulses using the temporal change of magnetic flux generated as the rotor rotates, There is a problem that it is impossible to generate a pulse that can be recognized that the rotor is not rotating at a rotation speed of a certain level or more.

  Further, as a method for detecting the position of the rotor of the brushless motor, as shown in Patent Document 3, without using a position sensor such as a Hall element, the change of the rotor is detected from the change in the reverse induced voltage of the armature coil. A method for detecting the position is also known. In the method disclosed in Patent Document 3, a three-phase coil connected in a star shape is connected in parallel with a resistor circuit composed of three resistors connected in a star shape, and the neutral point of the armature coil is determined. From the potential difference from the neutral point of the resistance circuit, the sum of the reverse induced voltages of the three-phase coils is detected, and the position of the rotor is detected based on the change in the sum of the reverse induced voltages.

It is also known to detect the position of the rotor of a brushless motor using a resolver as a position sensor instead of a Hall element.
JP 2004-80931 A JP 2004-173482 A JP 60-194782 A

  As described above, since a magnetic sensor such as a Hall element has low heat resistance, if the magnetic sensor is used as a position sensor for detecting the position of the rotor of the brushless motor, the brushless motor is used in a high-temperature environment. The sensor may be damaged. On the other hand, as shown in Patent Document 2, if a magnetic flux change detection type signal generator is used as a position sensor, there is a risk that the sensor may be damaged when the brushless motor is used in a high temperature environment. Can be eliminated.

  However, since the magnetic flux change detection type signal generator cannot generate a pulse that can be recognized that the rotor is not rotating at a certain rotational speed or more, it detects a position for switching the energization pattern of the brushless motor. When such a signal generator is used, a pulse for detecting the switching position of the energization pattern is obtained when the load on the motor becomes heavy and the motor enters a locked state or a state close to the locked state. Cannot be performed, and the locked state continues.

  Similarly, as shown in Patent Document 3, the method of detecting the rotor position from the change in the reverse induction voltage of the armature coil is also applied to the reverse induction exceeding the threshold value in the armature coil when the brushless motor is rotating. Since this method can be applied only when voltage is generated, the purpose of detecting the switching position of the energization pattern at the start of the brushless motor, and the energization pattern when the motor is close to the lock or locked It cannot be used for the purpose of detecting the switching position.

  Further, when a resolver is used as a sensor for detecting the position of the rotor for switching the energization pattern, the resolver itself is expensive and a detection circuit for detecting the phase difference of the output voltage with respect to the excitation voltage is required. Therefore, the problem that cost becomes high arises.

  The object of the present invention is to accurately determine the switching position of the energization pattern to the armature coil when the motor current is limited without using a position sensor with low heat resistance such as a hall element or an expensive position sensor such as a resolver. It is another object of the present invention to provide a brushless motor control method capable of satisfactorily operating a brushless motor from an extremely low speed rotation region to a steady rotation speed region, and a control device used to implement this control method. .

  The present invention rotates a rotor of a brushless motor including a stator having an armature coil composed of a three-phase coil connected so as to have a neutral point and a rotor having a field in a predetermined direction. Therefore, the present invention is applied to a brushless motor control method for controlling an armature current that flows from a DC power source to an armature coil.

  In the present invention, when the armature current reaches the set upper limit value, the supply of current from the DC power source to the armature coil is stopped, and the two-phase coils of the three-phase coils are placed in the middle. A drive stop process in which a circulating current is passed through the armature coil in such a way that a current flows in the same direction with respect to the sex point and a current that is the sum of the currents flowing through the two-phase coils flows through the other one-phase coil. And current limiting control for alternately performing a driving process of supplying current from the DC power source to the armature coil.

  In the driving stop process of the current limiting control, the two phases of the armature coil in which the current flows in the same direction with respect to the neutral point is set as the determination target phase, and the attenuation of the current flowing through the coil of the determination target phase is reduced. A current limit rotor position determination process for determining the rotor position from the state, and a current limit control driving process based on the rotor position determined in the current limit rotor position determination process. Current limit energization pattern determination process that determines the energization pattern when current is passed through the coil of the phase and the position at which energization starts in that energization pattern, and the current limit energization pattern in the drive process of current limit control The inverter circuit is controlled so that current flows from the DC power source to the three-phase coil with the energization pattern determined in the determination process.

  The upper limit value of the armature current is set to a value close to the value of the armature current (lock current) that flows when the motor is locked (a value lower than the lock current value). That is, by detecting that the armature current has reached the upper limit value, it is possible to detect that the motor has become close to the lock state.

  When the load on the motor becomes heavy and the motor is close to the lock state, the rotor hardly rotates and no induced voltage is generated in the armature coil, so that a large current flows through the armature coil. In the present invention, when the armature current increases and reaches the set upper limit value, the driving stop process for stopping the supply of current from the DC power source to the armature coil, and the current supply from the DC power source to the armature coil Current limit control is performed to limit the armature current to the upper limit or less by alternately performing the driving process for resuming the supply, so that excessive current continues to flow when the state close to the lock and the armature coil Burnout can be prevented.

  As a result of various experiments, the present inventor has found that a neutral point is applied to the two-phase coil of the three-phase coils in the current limit control in a state where the supply of current from the DC power supply to the armature coil is stopped. When the circulating current is passed through the armature coil in such a way that the current flows in the same direction to the other and the current of the sum of the currents flowing through the two-phase coils flows through the other one-phase coil. There is a correlation between the decay state of the current flowing through the two-phase coils of the child coil and the position of the rotor (rotational angle position), and the current flowing through the two-phase coils that are disconnected from the power It was found that the position of the rotor can be determined from the attenuation state of the rotor. If the position of the rotor can be determined, the energization pattern necessary to continue generating sufficient output torque from the motor and the energization with the energization pattern are started in the subsequent driving process based on the determination result. The position (switching position of the energization pattern) can be determined, and the output torque can be continuously generated from the motor by energizing the three-phase coils with the determined energization pattern.

  As described above, according to the method of the present invention, when the driven brushless motor is close to the lock state and the armature current reaches the set upper limit value, the DC power supply to the armature coil is The armature current is limited by alternating the process of stopping the current supply and the process of supplying the current from the DC power supply to the armature coil, and the armature is in a state where no current is supplied from the power supply. The position of the rotor is determined from the attenuation state of the circulating current flowing in the same direction in the two-phase coil of the coil, and current is supplied from the DC power source to the three-phase coil in the next driving process based on the determined position. Since the energization pattern at the time of flowing and the start position of energization with the energization pattern are determined, a position sensor with low heat resistance such as a hall element or an expensive position sensor such as a resolver must be used. , Continue to generate an output torque at the time of current limitation control of the brushless motor, it is possible to maintain the rotation. As described above, if the rotation of the motor can be maintained even when the current is limited, the rotational speed can be increased and the steady operation can be resumed when the load is eventually reduced.

  When the load of the driven brushless motor temporarily increases, for example, when the rotary electric machine having a rotor attached to the crankshaft of the engine is driven as a brushless motor and the engine is started, the piston is compressed. It occurs in the process of rising from the bottom dead center to the top dead center. In particular, when starting the engine in a very cold region, if the engine lubricating oil is frozen and the crankshaft is difficult to rotate, the load on the motor will cause the piston to move from the bottom dead center to the top dead center. It becomes very heavy in the process of ascending toward, and the motor becomes close to the lock. Also in an electric vehicle, the load of the driven brushless motor may become heavy just before climbing a steep slope, and the motor may be in a state just before locking. According to the present invention, when the brushless motor whose load is lighter or heavier becomes locked or close to the locked state, the output torque is continuously generated and the motor remains locked. You can prevent falling. As a position sensor for detecting the position of the rotor, a magnetic flux change detection type signal generator having heat resistance can be used, so that a brushless motor used in a high temperature environment can be driven without any problem. it can.

  In a preferred aspect of the present invention, in the current limit rotor position determination process performed in the current stop control drive stop process, the attenuation ratios of the currents flowing through one and the other of the two phases to be determined are respectively As the attenuation ratio of 2, the position of the rotor is determined from the difference between the first and second attenuation ratios.

  In the control for switching the energization pattern to the armature coil of the brushless motor, the phase for switching the energization pattern is usually determined based on the phase of the no-load induced voltage of the armature coil. In general, in a brushless motor, the output torque can be adjusted by the switching phase of the energization pattern. In the driving process at the time of current limitation, it is preferable that the switching position to the energization pattern when the current flows from the power source to the three-phase coil is a position that maximizes the output torque of the motor.

  In the current limit control, after the supply of current from the power source to the armature coil is stopped, the drive process is performed after a certain time has elapsed (after the drive stop process has reached the set value). The driving process may be started after it is detected that the armature current has decreased to the limit release value set lower than the upper limit value.

  In the driving stop process of the current limit control, the attenuation ratio of the current flowing in one and the other of the two phases to be determined is defined as the first and second attenuation ratios, respectively. From the DC power source in the current limit control driving process based on the rotor position determination process at the time of current limit for determining the position of the rotor from the difference and the rotor position determined in the rotor position determination process at the time of current limit It is preferable to perform an energization pattern determination process at the time of current limitation that determines an energization pattern when a current is passed through a phase coil and a position where energization is started in the energization pattern.

  In the above control method, the energization pattern when the current flows from the DC power source to the three-phase coil in the current limit control driving process is the same direction with respect to the neutral point in the two-phase coil of the three-phase coils. It is preferable that the current pattern is such that a current equal to the sum of the currents flowing through the two-phase coils is supplied to the other one-phase coil.

  The present invention also provides an armature coil of a brushless motor including a stator having an armature coil formed of a three-phase coil connected to have a neutral point and a rotor having a field, and a DC power source. The present invention is applied to a brushless motor control device including a bridge-type inverter circuit provided therebetween and a controller that controls the inverter circuit to rotate the rotor in a predetermined direction.

  In the control device according to the present invention, the controller controls the inverter circuit during steady operation of the brushless motor, and the steady-state inverter control unit when the armature current reaches a set upper limit value. The inverter circuit is controlled so that the driving stop process for stopping the current supply to the coil and the driving process for supplying current from the DC power supply to the armature coil are alternately performed, and the armature current is set to the upper limit value. And a current limiting inverter control unit that performs current limiting control to be limited to the following.

  The inverter control unit at the time of current limit stops the supply of current from the DC power source to the armature coil when the armature current reaches a set upper limit value. A current is passed in the same direction with respect to the neutral point in the phase coil, and a circulating current is passed through the armature coil in the manner of flowing the current that is the sum of the currents flowing in the two-phase coils in the other one-phase coil. Inverter control means at the time of driving stop that controls the inverter circuit so that the current flows, and the driving stop process of current limit control is performed, and the neutral point while the supply of current from the DC power supply to the armature coil is stopped Current-limiting rotor position determination means for determining the position of the rotor from the state of attenuation of the current flowing in the determination target phase, with two phases of the armature coil in which current flows in the same direction as the determination target phase And DC power supply in the drive process An energization pattern in which a current in the same direction as a neutral point is supplied to a two-phase coil of three-phase coils and a sum of currents flowing through the two-phase coils is supplied to the other one-phase coil. Assuming that an armature current flows from the DC power source to the armature coil, a current is supplied from the DC power source to the three-phase coil in the current limit control driving process with respect to the rotor position determined by the rotor position determination means at the time of current limitation. Current-limiting energization pattern determining means for determining an energization pattern when flowing current and a position at which energization is started in the energization pattern, and a three-phase from the DC power source with the energization pattern determined by the current-limiting energization pattern determining means And a current limiting motor driving inverter control means for controlling the inverter circuit so as to cause a current to flow through the coil so as to drive the current limiting control.

  In a preferred aspect of the present invention, the inverter control unit at the time of current limitation stops the supply of current from the DC power source to the armature coil when the armature current reaches the set upper limit value. The electric current flows in the same direction with respect to the neutral point in the two-phase coil of the coils of the coil, and the current flowing in the other one-phase coil is the sum of the currents flowing in the two-phase coils. Inverter control means at the time of driving stop that controls the inverter circuit so that the circulating current flows through the child coil to perform the driving stop process of current limiting control, and while the supply of current from the DC power supply to the armature coil is stopped The two phases of the armature coil in which the current flows in the same direction with respect to the neutral point are defined as the determination target phases, and the attenuation ratio of the current flowing in one and the other of the two phases of the determination target phase is set to the first, respectively. And as the second decay rate Current limiting attenuation rate calculating means, current limiting rotor position determining means for determining the position of the rotor from the difference between the first and second attenuation ratios, and current limiting rotor position determining means. Current limit energization pattern that determines the energization pattern when a current flows from a DC power source to a three-phase coil in the drive process of current limit control with respect to the position of the rotor and the position at which energization starts in that energization pattern A current limiting motor for controlling the inverter circuit so that a current limiting control and a driving process of the current limiting control are performed by causing a current to flow from the DC power source to the three-phase coil with the energization pattern determined by the current limiting energizing pattern determining unit Drive inverter control means.

  The inverter control unit at the time of current limit is configured to resume the supply of current from the DC power supply to the armature coil after a certain time has elapsed after stopping the supply of current from the DC power supply to the armature coil. After the supply of current from the DC power supply to the armature coil is stopped, the armature coil is detected from the DC power supply after it is detected that the armature current has decreased to the limit release value set lower than the upper limit value. You may comprise so that supply of the electric current to may be restarted.

  In another preferred aspect of the present invention, a startup inverter control unit is further provided for controlling the inverter circuit when the brushless motor is started. In this case, the configurations of the steady-state inverter control unit and the current limiting inverter control unit may be the same as those described above.

  The start-up inverter control unit performs a transient current energization process for applying a transient voltage to each phase coil by temporarily applying a DC voltage to each phase coil of the stator for each of the three phase coils. A current energizing means, a starting rotor position determining means for detecting a transient current flowing in each of the three-phase coils during the transient current energizing process, and determining a position of the rotor from the detected transient current; A starting energization pattern determining means for determining an energization pattern necessary for rotating the rotor in a predetermined direction with respect to the rotor position determined by the starting rotor position determining means; and a starting energization pattern determination It can be constituted by a start-up inverter control means for controlling the inverter circuit so that the armature coil is energized with the energization pattern determined by the means.

  The starting rotor position determining means can be configured to determine the position of the rotor relative to the three-phase coil from the peak value of the transient current.

  The starting rotor position determining means can also be configured to determine the position of the rotor relative to the three-phase coil from the peak value and waveform of the transient current.

  In a brushless motor, the magnetic flux that flows through the armature core when no current flows through the armature coil is determined by the relative positional relationship between the position of the magnet field and the coil of each phase (the electric motor of each phase of the rotor). Since the inductance of the armature coil of each phase differs depending on the rotor position, the transient current that flows when voltage is applied to the armature coil of each phase of the brushless motor depends on the position of the rotor. It depends on. Therefore, a process of passing a transient current through each phase armature coil by temporarily applying a DC voltage to each phase armature coil of the stator of the brushless motor is performed on each of the three phase coils. Determine the position of the rotor relative to the armature coil of each phase by comparing the peak values of the transient currents that flow through the phase coils and by comparing the waveforms of the transient currents. Can do.

In order to determine the position of the rotor from the waveform of the transient current, it is only necessary to perform a process for extracting the characteristics of the waveform of the transient current flowing in each of the three-phase armature coils and compare the extracted features. . Extraction of the characteristics of the waveform of the transient current can be performed, for example, as follows (a) to (c).
(A) After applying a DC voltage to the armature coil, the current value at the time when a certain time τ has elapsed is measured and compared.
(B) Measure and compare the time required to reach a constant current value after the transient current starts to flow.
(C) The waveform is determined from the temporal change rate at the rise of the transient current.
(D) The first half time change rate Δi 1 / Δt and the second half time change rate Δi 2 / Δt of the transient current waveform having the time width 2Δt are obtained, and the first half change rate Δi 1 / Δt and the second half change rate Δi 2 / It is determined whether or not the difference from Δt is greater than or equal to a set value.

  As described above, according to the present invention, when the armature current of the motor reaches the upper limit value, the drive stop process for stopping the supply of current from the power supply to the armature coil, and the power supply to the armature coil, Since current limiting control is performed to limit the armature current to the upper limit value or less by alternately performing the driving process for supplying current, the armature current becomes excessive when the motor is close to lock. Thus, the armature coil can be prevented from being burned out.

  According to the present invention, the position of the rotor is determined from the decay state of the circulating current flowing through the armature coil in the driving stop process, and the next driving process is started based on the determined rotor position. The armature coil when the motor is close to the lock without using a position sensor with low heat resistance such as a hall element or an expensive position sensor such as a resolver. The energization pattern can be accurately determined. Therefore, according to the present invention, without using a position sensor such as a Hall element with low heat resistance, or an expensive position sensor such as a resolver, from a very low speed rotation region where the motor is close to a lock to a steady rotation speed region, The brushless motor can be operated satisfactorily.

  Further, in the brushless motor according to the present invention, when the motor is started, a transient current is passed through the armature coil, and the energization pattern switching position is determined based on the position of the rotor determined from the transient current. Since the brushless motor can be started without using a position sensor with low heat resistance such as a Hall element or using an expensive position sensor such as a resolver, from the start to the steady rotation range The brushless motor can be operated satisfactorily in all areas.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment to which the present invention is applied when a brushless motor is attached to an engine and operated as a brushless motor when the engine is started, and is operated as a magnet generator after the engine is started. In the figure, 1 is a brushless motor that is also operated as a magnet generator, 2 is a DC power source comprising a battery, 3 is an inverter circuit provided between the brushless motor 1 and the DC power source 2, and 4 is provided with a microprocessor. , A controller for controlling the inverter circuit 3, a signal generator for generating a pulse signal when the position of the rotor of the brushless motor 1 coincides with a predetermined position, and a transient current that is closed when a transient current is passed. The energizing switches 7u to 7w are U, V and W 3-phase coils that constitute the armature coil of the brushless motor. A current detecting means for detecting a current flowing through, respectively.

  More specifically, in FIG. 1, reference numeral 10 denotes a rotor yoke configured to have a substantially cup shape with a ferromagnetic material such as iron, and this rotor yoke is attached to the central portion of the bottom wall portion thereof. The boss portion is fitted and attached to a crankshaft of an engine (not shown). A permanent magnet is attached to the inner periphery of the peripheral wall portion 10a of the rotor yoke 10 to form an even pole field. In the present embodiment, two arc-shaped permanent magnets M1 and M2 arranged at an interval of 180 ° are attached to the inner periphery of the peripheral wall portion 10a of the rotor yoke 10 by adhesion or the like, and these permanent magnets are magnetized. By magnetizing in the radial direction in different directions, a two-pole magnet field is formed on the inner periphery of the rotor yoke. The rotor yoke 10 and the permanent magnets M1 and M2 constitute a rotor 1A. In this example, it is assumed that the magnet rotor 1A is rotated counterclockwise (arrow CCW direction) in FIG. 1 when the engine rotates forward.

  A stator 1B is arranged inside the magnet rotor 1A. The stator 1B includes a known star-shaped annular armature core (not shown) having a structure in which three salient pole portions are radially projected from the outer peripheral portion of the annularly formed yoke portion, and this electric machine. It consists of three-phase coils Lu to Lw wound around three salient pole portions of the core. The three-phase coils Lu to Lw are star-connected, and the three-phase terminals 1u, 1v, and 1w are drawn from the terminal portion on the opposite side to the neutral point of these armature coils.

  The stator 1B is fixed to a stator mounting portion formed in a part of the engine case, and the magnetic pole portions formed at the tips of the three salient pole portions of the armature core are magnets of the magnet rotor 1A. It is made to oppose the magnetic pole of a field through a predetermined gap.

  On the outer periphery of the peripheral wall portion 10a of the rotor yoke 10, three relaxors 11 to 13 made of arc-shaped protrusions extending in the circumferential direction of the peripheral wall portion are formed at intervals of 120 °. The yoke 10 constitutes a signal generating rotor 5A. Further, a pulser 5B that generates a pulse signal having a different polarity when the front end side edge and the rear end side edge in the respective rotation directions of the reluctors 11 to 13 are detected is disposed in the vicinity of the rotor 5A. The pulse generator 5B constitutes a magnetic flux change detection type signal generator 5. In this specification, the magnetic flux change detection type signal generator means a signal generator of a type that induces a signal voltage in the coil by causing a change in the magnetic flux linked to the coil as the rotor rotates. Means.

  The pulsar 5B is fixed to the engine case or the like, and generates a pulse signal of the first polarity when the front end side edge in the rotational direction of each of the reluctors 11 to 13 is detected. When a rear end edge in the rotational direction is detected, a pulse signal having the second polarity is generated. In the present embodiment, each reluctator has a polar arc angle of 60 °, and the three reluctors 11 to 13 are provided at intervals of 120 °. Therefore, the pulsar 5B is rotated during one rotation of the rotor 1A. Six pulse signals are generated at intervals of 60 °. The timings at which these six pulse signals are generated respectively coincide with the six switching timings (excitation phase switching timings) of the energization pattern when driving the brushless motor by 180 ° switching driving, and the pulsers 11 to 13 and the pulser. 5B is provided.

  The pulse signal generated by the pulsar 5B is input to the pulse signal input terminal 4a of the controller 4. The pulse signal input to the pulse signal input terminal 4 a is converted into a signal that can be recognized by the microprocessor by a waveform shaping circuit provided in the controller 4, and input to the microprocessor in the controller 4.

  The inverter circuit 3 includes a known circuit in which each side of the three-phase bridge circuit is configured by an element configured by connecting a switching element that can be controlled on and off and a feedback diode in antiparallel. In the illustrated example, three upper arms of the bridge are configured by switch elements Qu, Qv, and Qw that are commonly connected at one end and feedback diodes Du, Dv, and Dw that are connected in reverse parallel to these switch elements, respectively. Switch elements Qx, Qy, and Qz having one end connected to the other end of each of the switch elements Qu, Qv, and Qw and the other end connected in common, and feedback diodes Dx, Dy and Dz constitute the three lower arms of the bridge. In the present embodiment, a MOSFET is used as a switch element constituting each arm of the bridge of the inverter circuit 3, and a parasitic diode formed between the drain and source of the MOSFET is used as a feedback diode.

  Drive signals Su to Sw and Sx to Sz are supplied from the controller 4 to the control terminals (MOSFET gates in the illustrated example) of the switch elements Qu to Qw and Qx to Qz, respectively. The switch elements Qu to Qw and Qx to Qz are kept on while the drive signals Su to Sw and Sx to Sz are applied, and are turned off when the drive signals Su to Sw and Sx to Sz are removed. Become.

  In the illustrated inverter circuit 3, the common connection point at one end of the switch elements Qu, Qv, Qw constituting the upper arm of the bridge and the common connection point at the other end of the switch elements Qx, Qy, Qz constituting the lower arm are respectively shown. Positive side and negative side DC side terminals 3a and 3b are provided, and connection points between the other ends of the switch elements Qu, Qv, Qw and one end of the switch elements Qx, Qy, Qz are respectively AC side terminals 3u, 3v, 3w. A DC power source 2 is connected between the DC side terminals 3a and 3b, and non-neutral point terminals (terminals opposite to the neutral point) of the armature coils Lu, Lv and Lw are respectively connected to the AC side terminals 3u, 3v and 3w. The three-phase terminals 1u, 1v, and 1w drawn from are connected through shunt resistors Riu to Riw constituting current detectors 7u to 7w.

  In the illustrated inverter circuit 3, a full-wave rectifier circuit is configured by the diodes Du, Dv, Dw, Dx, Dy, and Dz, and when the brushless motor 1 is driven from the outside and operated as a magnet generator, the armature A three-phase AC voltage induced in the coils Lu to Lw is converted into a DC voltage by the full-wave rectifier circuit and applied to the battery constituting the DC power supply 2 as a charging voltage.

  In this embodiment, in order to determine the position of the rotor 1A (positional relationship between the rotor field and each phase coil of the armature coil) while the brushless motor 1 is stopped. A transient current energizing switch 6 is inserted between the neutral point of the armature coils Lu to Lw and the ground.

  The switch for energizing the transient current 6 is composed of an NPN transistor whose emitter is grounded, the collector of the transistor is connected to the neutral point of the coils Lu to Lw, and the base is a switch control signal output terminal provided in the controller 4 4b.

  Detection signals obtained at both ends of the shunt resistors Riu to Riw constituting the current detectors 7u to 7w are input to the current detection signal input terminal 4c of the controller 4 through operational amplifiers OPu to OPw.

  As described above, in the control method according to the present invention, at the time of starting the motor, a process in which a DC voltage is temporarily applied to the armature coils of each phase of the stator 1B and a transient current is caused to flow through the armature coils of each phase. Determine the position of the rotor with respect to the three-phase coil from the transient current energization process for each of the three-phase coils and the transient currents flowing in the three-phase coils during the transient current energization process. The position of the rotor 1A is determined by performing the rotor position determination process. Based on the position of the rotor thus determined, an energization pattern necessary for rotating the rotor in a predetermined direction is determined, and the inverter circuit 3 is set so that a current flows through the armature coil with the determined energization pattern. Control.

  In order to configure the control device according to the present invention, various means shown in FIG. 2 are configured by causing the microprocessor of the controller 4 to execute a predetermined program. In FIG. 2, 20 is an overcurrent energizing means, and this overcurrent energizing means applied a voltage between the terminal opposite to the neutral point of the armature coil of each phase of the stator 1B and the ground potential portion. In this state, the transient current energizing switch 6 is turned on for a short time, and the neutral point is temporarily connected to the ground potential portion, whereby the transient current is temporarily passed through the three-phase coils Lu to Lw of the armature coil. Perform a transient current conduction process.

  Reference numeral 21 denotes a starting rotor position determining means which detects the transient currents that the transient current energizing means 20 has passed through the three-phase coils from the outputs of the current detecting means 7u to 7w, and detects the detected transients. Processing for determining the position of the field of the rotor 1A with respect to the three-phase coils Lu to Lw from the current is performed.

  In the present embodiment, the transient current energizing means 20 and the starting rotor position determining means 21 detect the transient currents respectively flowing in the three-phase coils Lu to Lw during the transient current energizing process, and from the detected transient currents A starting rotor position determining means 22 for determining the position of the rotor is configured.

  Reference numeral 23 denotes a start-time energization pattern determining means, and reference numeral 24 denotes a start-time inverter control means. In the present invention, a current in the same direction with respect to the neutral point is supplied from the DC power source 2 to the two-phase coil among the three-phase coils Lu to Lw, and the two-phase coil is supplied to the other one-phase coil. Assuming that an armature current is passed by an energization pattern that passes a current of the sum of currents, a two-phase current that passes a current in the same direction to rotate the rotor in a predetermined direction (in the present embodiment, the direction of the arrow CCW in FIG. 1). Control to switch the energization pattern by switching the combination.

  The start-time energization pattern determination means 23 determines an energization pattern to the armature coil necessary for rotating the rotor in a predetermined direction based on the position of the rotor determined by the start-time rotor position determination means 22. decide. In addition, the start-time inverter control means 24 causes the three switch elements Qu to the upper arm of the inverter circuit 3 to flow current to the three-phase coils Lu to Lw in accordance with the energization pattern determined by the start-time energization pattern determination means 23. One of Qw and two of the three switching elements Qx to Qz of the lower arm are simultaneously turned on, or one of the three switching elements Qx to Qz of the lower arm of the inverter circuit 3 and the upper The switch elements of the inverter circuit 3 are controlled so that two of the three switch elements Qu to Qw of the arm are simultaneously turned on.

  In this example, a transient current energizing means 20 that performs a transient current energization process for applying a transient voltage to each phase coil by temporarily applying a DC voltage to each phase coil of the stator for each of the three phase coils. And a starting rotor position determining means 21 for detecting a transient current flowing in each of the three-phase coils during the transient current application process and determining the position of the rotor 1A from the detected transient current, and a starting rotor position Based on the position of the rotor determined by the determining means 21, the energization pattern determining means 23 for starting that determines the energization pattern necessary for rotating the rotor in a predetermined direction and the energizing pattern determining means 23 for starting are determined. Inverter circuit at the start of the brushless motor by the start-up inverter control means 24 for controlling the inverter circuit 3 so as to energize the armature coil in the energized pattern. It is constructed the starting inverter control unit 25 for controlling.

  Reference numeral 26 denotes a position where the rotor 1A is located with respect to the three-phase coils Lu to Lw of the stator 1B based on the position information of the rotor 1A obtained from the pulse signal generated by the signal generator 5. The steady-state rotor position determining means 27 for determining the energization pattern required for rotating the rotor in a predetermined direction based on the position determined by the steady-state rotor position determining means 26. The determining means 28 is a steady-state inverter control means for controlling the switching elements of the inverter circuit 3 so that current flows through the three-phase coils Lu to Lw with the energization pattern determined by the steady-state energization pattern determining means 27. .

  In this embodiment, during steady operation of the motor, current flows in the same direction with respect to the neutral point through the two-phase coils of the three-phase coils, and the two-phase coils are connected to the other one-phase coils. Assuming that an armature current is passed by an energization pattern that causes the sum of the currents to flow, control for switching the energization pattern (180 ° switching control) is performed in order to rotate the rotor in a predetermined direction. Therefore, during steady operation, the two switch elements of the upper arm or lower arm of the bridge of the inverter circuit 3 and the two switch elements of the lower arm or upper arm connected in series to these two switch elements are excluded. The switch element of the inverter circuit is on / off controlled by a switch pattern that simultaneously turns on the lower arm or one switch element of the upper arm.

  In this example, the steady-state rotor position determining means 26, the steady-state energization pattern determining means 27, and the steady-state inverter control means 28 are used to control the inverter circuit 3 during steady operation of the brushless motor. Is configured.

  Further, reference numeral 30 denotes a current limit signal SL when the largest current among the currents detected by the current detection means 7u to 7w that detect currents flowing through the three-phase coils reaches a set upper limit value. Current limiting signal generating means 31 for generating a three-phase in a state where the supply of current from the DC power source to the armature coil is stopped when the armature current reaches the upper limit value and the current limiting signal SL is generated. The electric current flows in the same direction with respect to the neutral point in the two-phase coil of the coils of the coil, and the current flowing in the other one-phase coil is the sum of the currents flowing in the two-phase coils. This is a drive stop time inverter control means for controlling the inverter circuit so that the circulating current flows through the child coil and performing the drive stop process of the current limiting control.

  When the armature current reaches the upper limit value, the supply of current from the DC power source to the armature coil is stopped and the circulating current is caused to flow in the pattern as described above. While maintaining the on / off state of the switch element, one or two of the three switch elements of the upper arm are turned off, or the three arms of the upper arm of the bridge of the inverter circuit are switched off. One or two switch elements in the on state may be turned off among the three switch elements constituting the lower arm while keeping the on / off state of the switch element as it is. That is, when the armature current reaches the upper limit value, two switch elements Qu to Qw of the upper arm of the inverter circuit are in the on state, and the three switch elements Qx to Qz of the lower arm are turned on. When one of the switch elements is turned on, whether one switch element that is on in the lower arm is turned on and two switch elements that are on in the upper arm are turned off simultaneously Alternatively, by turning on one switch element in the on state in the lower arm while keeping the two switch elements in the on state in the upper arm in the on state, the circulating current can flow in the above pattern. it can. When the armature current reaches the upper limit value, one of the three switch elements Qu to Qw of the upper arm of the inverter circuit is in the on state, and the three switch elements Qx to Qz of the lower arm are turned on. When two of the switch elements are in the on state, the two switch elements that are in the on state in the lower arm are turned off at the same time while the one switch element that is in the on state in the upper arm is in the on state, Alternatively, by turning on one switch element that is on in the upper arm while the two switch elements that are on in the lower arm are on, the circulating current can flow in the above pattern. .

  As described above, in the present embodiment, the 180 ° switching control is performed during the steady operation of the motor. Therefore, during the steady operation, the two switch elements of the upper arm or the lower arm of the bridge of the inverter circuit and the two switches The switch elements of the inverter circuit are on / off controlled by a switch pattern that simultaneously turns on the lower arm or one switch element of the upper arm excluding two switch elements connected in series to the elements. In this case, when the armature current reaches the upper limit value, the two switch elements of the upper arm or the lower arm that are in the on state are kept in the on state and the other switch elements are in the off state or are turned on. By holding one switch element of the upper arm or the lower arm in the state as it is and turning off the other switch element, the circulating current can flow in the above pattern.

  Reference numeral 32 denotes a current limiting attenuation rate calculating means which is operated in the same direction with respect to the neutral point while the supply of current from the DC power source (battery in the illustrated example) to the armature coil is stopped. Using the two phases of the armature coil through which the current is flowing as the determination target phase, the attenuation ratio of the current flowing through one of the two phases of the determination target phase and the other is calculated as the first and second attenuation ratios, respectively. .

  Reference numeral 33 denotes a current limit rotor position determination means, which determines the position of the rotor 1A from the difference between the first and second attenuation ratios.

  Reference numeral 34 denotes a current limiting energization pattern determining means. This pattern determining means 34 is a current in the same direction with respect to the neutral point from the DC power source to the two-phase coils Lu to Lw in the driving process. Current-limiting rotor position determination means that the armature current flows from the DC power source to the armature coil in a current-carrying pattern in which the current of the sum of the currents flowing through the two-phase coils flows through the other one-phase coil An energization pattern suitable for maintaining the rotation of the rotor with respect to the position of the rotor determined by 33 is determined.

  Reference numeral 35 denotes inverter control means for driving the motor at the time of current limit. This control means drives the current limit control by flowing current from the DC power source to the armature coil with the energization pattern determined by the energization pattern determination means 34 at the time of current limit. The inverter circuit 3 is controlled so as to perform the process.

  In this example, the current limit signal generating means 30, the drive stop time inverter control means 31, the current limit time attenuation ratio calculating means 32, the current limit time rotor position determining means 33, and the current limit time energization pattern determining means 34 are shown. The current limiting inverter control means 35 constitutes a current limiting inverter control unit 36 for controlling the inverter circuit 3 when the current of the brushless motor is limited.

  Reference numeral 37 denotes control switching means. The control switching means controls the inverter circuit 3 by the start-time inverter control unit 25 when the motor is started, and the signal generator 5 generates a pulse signal having a level equal to or higher than a threshold value. After the rotation speed of the brushless motor has increased to the rotation speed, the inverter circuit 3 is controlled by the steady-state inverter control unit 29, and the motor is close to the lock state at the start of the motor or the steady operation, so that the current limit control is performed. When the current is limited, the control is switched so that the inverter control unit 36 controls the inverter circuit 3 when the current is limited.

  When a start command is given from a start / stop command generating means 38 such as a start switch, the illustrated control switching means starts control of the inverter circuit 3 by the start time inverter control unit 25 to start the motor, When the pulse signal generated by the generator 5 is recognized, control of the inverter circuit 3 by the steady-state inverter control unit 29 is started. Further, when the motor is in a locked state or close to a locked state at the time of starting or steady operation, and the current limit signal generating means 30 generates the current limit signal SL, the inverter circuit 3 by the inverter control means 31 at the time of driving stop. The two switching elements that are simultaneously turned on in the upper arm or the lower arm of the inverter circuit are kept in the on state, and another one switch in the lower arm or the upper arm that is in the on state is controlled. By turning off the element, the supply of current from the DC power supply to the armature coil is stopped, and the current flows in the same direction with respect to the neutral point through the two-phase coils of the three-phase coils, The other one-phase coil is driven by circulating current through the armature coil in the manner of flowing the current that is the sum of the currents flowing through the two-phase coils. Let the process take place.

  The control switching means 37 also causes the current limit-time rotor position determination means 33 after the power-supply-limit-time attenuation ratio calculation means 32 calculates the attenuation ratio of the current flowing through the two-phase coil of the determination target phase. The determination of the rotor position by the above and the determination of the energization pattern by the current limit energization pattern determination means 34 are performed. The control switching means 37 also starts control of the inverter circuit 3 by the current-limiting motor drive inverter control means 35 when a fixed time has elapsed after stopping the supply of current from the DC power supply to the armature coil. When the driving process is started or the supply of current from the DC power supply to the armature coil is stopped, it is detected that the armature current has decreased to a limit release value set lower than the upper limit value. Then, the control of the inverter circuit 3 by the motor control inverter control means 35 at the time of current limitation is started to start the driving process. Then, when it is detected that the locked state of the motor is released and its rotational speed is increased and the signal generator 5 generates a pulse signal that is equal to or greater than the threshold value, the control of the inverter circuit 3 is controlled by the inverter control in the steady state The control is switched to the control by the unit 29.

  Here, the principle of the method for detecting the position of the rotor when the motor is started in the present invention will be described. In the brushless motor 1 shown in FIG. 1, when current flows from a terminal opposite to the neutral point of each phase armature coil, the polarity of the coil becomes N pole when viewed from the outside. Phase armature coils are wound.

  Assuming that no current flows through the three-phase coils Lu to Lw, the magnitude of the magnetic flux flowing through the armature core of the stator varies depending on the positional relationship between the magnet field and the armature coils of each phase. Here, assuming that the rotor 1A is rotated stepwise by 30 ° counterclockwise from the state of FIG. 1, positions P1 to P12 whose positions are different by 30 ° as shown in FIGS. 3 (A) to 3 (L). When the magnetic flux φ flowing through the U-phase armature core at the positions P1 to P12 is illustrated with respect to the magnetomotive force by the magnet, it is as shown in FIG. At the positions P6 and P8, since the rotor is in a line-symmetrical positional relationship, the magnetic flux flowing through the U-phase armature core is the same. Similarly, the position of the rotor at each of the positions P9 to P12 is in a line-symmetric relationship with the position of the rotor at each of the positions P5 to P2, and therefore U at each of the positions P9, P10, P11 and P12. The magnitude of the magnetic flux flowing through the phase armature core is the same as the magnitude of the magnetic flux flowing through the U-phase armature core at the positions P5, P4, P3, and P2, respectively. The position P13 shown in FIG. 4 is the same position as the position P1, and the magnetic flux flowing in the U-phase armature core at this position P13 is the same as the magnetic flux flowing in the U-phase armature core at the position P1. .

  As described above, in a brushless motor including a rotor having a field magnet and a stator having a three-phase armature coil, the magnetic flux flowing through the armature core when no current flows through the armature coil is Because the position of the armature coil of each phase differs depending on the relative positional relationship (position of the rotor with respect to the armature coil of each phase), and the inductance of the armature coil of each phase varies with the position of the rotor. Depending on the position of the rotor, the transient currents flowing through the armature coils of each phase are different. Therefore, a process of applying a DC voltage temporarily to the armature coils of each phase of the stator and causing a transient current to flow through the armature coils of each phase is performed for each of the three-phase armature coils, When the characteristics of the transient currents flowing through the armature coils are extracted and compared, the position of the rotor with respect to the armature coils of each phase can be determined.

As shown in FIG. 5, when a circuit for applying the voltage E of the DC power source 2 through the transistor TR1 is configured in a series circuit of the resistor r and the inductance L and the transistor TR1 is turned on, the following (1 The transient current i given by
i = (E / r) [1-exp {-(r / L) t}] (1)

  Here, assuming that the resistance r is constant and the inductance L takes the values of La, Lb and Lc (La <Lb <Lc), the relationship r / La> r / Lb> r / Lc holds. FIG. 6 shows the transient currents ia, ib, and ic that flow when the inductance values are La, Lb, and Lc, respectively, with respect to time t.

In the example shown in FIG. 1, when the position of the rotor is P1 shown in FIG. 3A, the switch element Qu of the inverter circuit 3 is turned on and the transient current energizing switch 6 is turned on. To do. At this time, as shown in FIG. 4, the current ΔI flowing through the armature coil Lu generates a magnetomotive force ΔF, and the magnetic flux of the U-phase armature core changes by Δφ1, so that a reverse induced voltage is generated in the coil. When the inductance of the U-phase armature coil when the rotor is at the position P1 is L1, and the number of turns of the U-phase armature coil is n, there is a relationship of L1 × ΔI = nΔφ1, and therefore the rotor is positioned at the position P1. The inductance L1 of the U-phase armature coil is given by the following equation.
L1 = nΔφ1 / ΔI (2)

On the other hand, when the rotor is at the position P5 shown in FIG. 3E, if the switching element Qu of the inverter circuit 3 is turned on and the transient current energizing switch 6 is turned on, the current ΔI flows. The magnetic flux change Δφ5 is generated by the magnetomotive force ΔF generated by. At this time, the inductance L5 of the U-phase armature coil is given by the following equation.
L5 = nΔφ5 / ΔI (3)
Here, since Δφ1 <Δφ5, L1 <L5, and the transient currents i1 and i5 flowing when the rotor position is P1 and P5, respectively, are as shown in FIG.

  When the rotor position is P1, the rotor position with respect to the V-phase and W-phase armature coils corresponds to the position P5 position with respect to the U-phase armature coil. When the switch element Qv of the inverter circuit 3 is turned on and the transient current energizing switch 6 is turned on, and when the switch element Qw of the inverter circuit 3 is turned on, When the switch 6 is turned on, a transient current equivalent to i5 flows.

  As described above, the peak value and waveform of the transient current that flows when a DC voltage is temporarily applied to the armature coil of each phase vary depending on the position of the rotor 1A. Temporarily applying a DC voltage and passing a transient current through the armature coil of each phase is performed for each of the three-phase coils, and the peak values of the transient currents flowing through the three-phase coils are measured. By comparing the characteristics of the waveforms of the transient currents flowing in the three-phase coils and comparing the crest values, the rotor magnet field is positioned in any position with respect to the three-phase coils. It can be determined whether there is.

  In the present invention, whether to determine the position of the rotor only from the peak value of the transient current or whether to determine using both the peak value and waveform of the transient current is necessary to determine the switching position of the switch pattern. It is determined by whether or not the rotor position can be obtained. That is, if the information on the rotor position necessary to determine the switching position of the switch pattern can be obtained simply by comparing the peak values of the transient currents flowing through the three-phase coils, the peak value of the transient current is obtained. The position of the rotor is determined using only If the information on the rotor position necessary for determining the switching position of the switch pattern cannot be obtained only by comparing the peak values of the transient currents flowing through the three-phase coils, the peak value of the transient current is obtained. And the waveform (features extracted from the waveform) are used to determine the position of the rotor.

When determining the position of the rotor using the transient current waveform as one condition for determination, the characteristics of the waveform of the transient current respectively flowing in the m-phase armature coil are extracted, and the extracted characteristics are compared. The feature extraction of the transient current waveform can be performed, for example, as follows.
(A) After applying a DC voltage to the armature coil, as shown in FIG. 8A, current values iaτ and ibτ at the time when a certain time τ has elapsed are measured and compared.
(B) As shown in FIG. 8B, after the transient currents ia and ib begin to flow, the time ta and tb required to reach a constant current value is are measured and compared.
(C) As shown in FIG. 8C, the waveform is determined from the temporal change rate when the transient current i rises. For example, ib1 / t1 is compared with ia1 / t1, or ib2 / t2 is compared with ia2 / t2.

  As described above, when the brushless motor is stopped, the switch 6 is closed, and the switch elements Qu, Qv and Qw on the upper side of the bridge of the inverter circuit connected to the three-phase coils Lu, Lv and Lw are sequentially turned on. By performing a process of turning on the state for a short time, a transient current is caused to flow in each of the armature coils Lu, Lv and Lw, and a peak value or a peak value and a waveform of the transient current respectively flowing in the three-phase coils Lu to Lw are obtained. By comparing, the position of the rotor 1A can be determined.

  If it is possible to determine the positional relationship of the rotor 1A with respect to the armature coils of each phase while the brushless motor is stopped, the rotor 1A is moved in a predetermined direction based on the determination result. Since the energization pattern necessary for rotating the rotor in a predetermined direction can be determined, by controlling the switch element of the inverter circuit so that the armature coil is energized with the determined energization pattern, the rotor is moved in a predetermined direction. Can be rotated.

  If the brushless motor can be rotated, thereafter, the control switching means 36 switches the control of the inverter circuit 3 from the control by the start-time inverter control unit 25 to the control by the steady-state inverter control unit 29, and the signal generator 5 Is determined by the steady-state energization pattern determining means 27 based on the rotor position information determined by the steady-state rotor position determining means 26 from the pulse signal output by the steady-state rotor pattern determining means 27 and determined by the steady-state energization pattern determining means 27. The brushless motor can be rotated by controlling the switch element of the inverter circuit 3 so that the armature coil is energized with the energized pattern.

  When the brushless motor starts and the rotor 1A reaches the position P1 shown in FIG. 3 (A), the control of the inverter circuit is switched to the control by the steady-state inverter control unit 29, and the motor is switched by 180 ° switching. When the inverter circuit 3 is controlled so that current flows through the child coils Lu to Lw, the switch pattern determined based on the output pulse signal of the signal generator 5 is shown in FIG. 9 together with the waveform of the output pulse signal of the signal generator 5. Indicated. FIG. 9A shows the waveform of the pulse signal output from the signal generator 5. Vf11 and Vr11 are the rotation of the reluctator 11 when the rotor is at the position P1 and the position P3, respectively. The pulse signals generated by detecting the front end side edge f11 and the rear end side edge r11 in the direction are respectively shown, and Vf12 and Vr12 indicate that the pulser 5B has The pulse signals generated by detecting the front end side edge f12 and the rear end side edge r12 in the rotation direction are shown. Vf13 and Vr13 are pulse signals generated when the pulsar 5B detects the front end side edge f13 and the rear end side edge r13 in the rotation direction of the reluctator 13 when the rotor is at the position of P9 and P11, respectively. Show.

  The table shown in FIG. 9B shows combinations (switch patterns) of switch elements of the inverter circuit that are turned on to obtain the energization pattern at each position of the rotor. , V, and W indicate that the switch elements Qu, Qv, and Qw are turned on, respectively, and sections indicated by the symbols X, Y, and Z indicate the switch elements Qx, Qy, and Qz, respectively. Is turned on. For example, when the switching elements Qu, Qy and Qz are turned on, the rotor reaches the position P5 from the energization pattern in which the exciting current flowing into the armature coil Lu flows out through the armature coils Lv and Lw. When the pulse signal Vf12 is generated, the switch pattern is switched from (Qu, Qy, Qz) to (Qu, Qv, Qz), and the currents flowing in the armature coils Lu and Lv are passed through the armature coil Lw. Switch to the energization pattern. When the position of the rotor reaches the position P7, the switch pattern is switched from (Qu, Qv, Qz) to (Qx, Qv, Qz), and the excitation currents flowing into the armature coils Lu and Lv, respectively. The energizing pattern flowing out through the armature coil Lw is switched to the energizing pattern flowing out through the armature coils Lu and Lw from the energizing pattern flowing into the armature coil Lv.

  In the present embodiment, since the reluctator and the pulser are provided so that the pulse signal is generated at the position where the energization pattern is switched, the position of the rotor when switching the control (position P1 in the example shown in FIG. 9). If it is determined, the excitation phase can be easily determined.

  If the rotor can be rotated only slightly because the load is heavy at the start of the brushless motor, it will be driven for the first energization pattern for the duration of the first energization pattern. Then, the process for determining the position of the rotor is performed again, a new energization pattern is determined based on the determination result, and the inverter circuit is controlled so that the armature coil is energized with the determined energization pattern. By continuing this control while the rotation speed is too low to generate a pulse signal that can be identified by the pulser 5B, the brushless motor can be continuously rotated.

  In particular, when starting the engine with a brushless motor, it is considered that the rotational speed cannot be sufficiently increased during the compression stroke of the engine, and it is possible that a pulse signal that can be identified from the pulser cannot be generated. If the control continues, the rotational speed increases when the load passes the peak at the position before the top dead center of the compression stroke of the engine, so a pulse signal that can be identified from the pulsar is generated, and the inverter control at normal time The control can be shifted to the control by the unit 29, and in the next compression stroke, a sufficient torque can be generated from the motor to function as a starting motor.

  As described above, in the control device of the present embodiment, when the brushless motor is stopped and the signal generator cannot generate a pulse signal, the rotor of the rotor determined from the transient current passed through the armature coil is determined. Since the brushless motor is started by controlling the inverter circuit so that the armature coil is energized with the energization pattern determined based on the position, a sensor with low heat resistance such as a hall element or an expensive sensor such as a resolver is used. The brushless motor can be started by determining the energization pattern at the start without using it. In addition, after the brushless motor is started, the rotation speed is increased and a pulse signal having a level that can be identified by the signal generator 5 is generated. Then, the rotation obtained from the pulse signal output from the signal generator 5 is obtained. Since the energization pattern can be determined based on the position of the rotor determined using the angle information and the armature coil can be energized, the brushless motor can be rotated in the same manner as a normal brushless motor.

  Next, a method for actually determining the energization pattern at the start will be described. In FIG. 4, Δφ1, Δφ2,... Is when the switch 6 in FIG. 1 is turned on and a transient current flows when the rotor is in the position of P1, P2, P3,. Shows the change of the magnetic flux φ flowing in the U-phase iron core. Further, the table of FIG. 10 shows that the U phase to W when the transient is passed through the U-phase to W-phase armature coils with the switch 6 turned on in the state where the rotor is in the respective positions P1 to P12. The change of the magnetic flux which flows into the iron core of a phase is shown collectively. When the change of the magnetic flux flowing through the U-phase or W-phase iron core is shown by a curve, it is as shown in FIG. 11A, and the detected peak values Δiu, Δiv and Δiw of the transient current are as shown in FIG. Become. The initial energization pattern is determined from the transient current shown in FIG. 11 (B), and a drive signal is applied to a predetermined switch element of the inverter circuit so that the armature coil is energized with the determined energization pattern. Can be rotated.

  FIG. 11C shows a combination (switch pattern) of switch elements of the inverter circuit that is turned on at the start-up when the rotor is in the position of P1 to P13, for controlling the inverter circuit by 180 ° switching. It was. In the switch pattern shown in FIG. 11C, symbols U, V, W, X, Y, and Z mean that the switch elements Qu, Qv, Qw, Qx, Qy, and Qz are turned on, respectively. For example, the switch pattern (U, Y, W) means that the switch elements Qu, Qy, and Qw are turned on.

  Depending on the position of the rotor, the switch pattern at the start is uniquely determined by the order of the peak values Δiu, Δiv, and Δiw of the transient current shown in FIG. 11B, but depending on the position, the transient current In some cases, the switch pattern cannot be determined only by the order of the sizes. For example, the order of the magnitudes of the transient current peak values Δiu, Δiv, Δiw at the respective positions P1, P5 and P9 is the magnitude of the transient current peak values Δiu, Δiv and Δiw at the positions P7, P11 and P3, respectively. Therefore, at these positions, it is impossible to determine the switch pattern of the inverter circuit at the start only by looking at the order of the peak values of the transient currents.

  Therefore, looking at the waveforms of the transient currents Δiu to Δiw, for example, the waveforms of the transient currents Δiu to Δiw at the position of P1 are as shown in FIGS. 12A to 12C, respectively. The waveforms of the transient currents Δiu to Δiw are as shown in FIGS. 13A to 13C, respectively, and the waveform of the U-phase transient current Δiu differs between the position P1 and the position P7. At P1, the flux change Δφ1 occurs due to the transient current flowing in the direction of demagnetizing the saturated U-phase core. Therefore, the transient current waveform is more convex than the triangular waveform. The transient current flowing through the U-phase armature coil is the largest. Accordingly, when the largest transient current is a U-phase transient current, it is determined whether or not the waveform is more convex than the triangular waveform. If the waveform is convex, the rotor position is P1. Can be determined.

  When the waveform of the transient current is convex, as shown in FIG. 14A, the current increase rate Δi2 / Δt in the latter half is smaller than the current increase rate Δi1 / Δt in the first half of the waveform. In the case of a triangular waveform, as shown in FIG. 14B, the difference between the current increase rate Δi 1 / Δt in the first half of the waveform and the current increase rate Δi 2 / Δt in the second half becomes small. Accordingly, assuming that the time width of the transient current is 2Δt, the temporal change rate Δi1 / Δt in the first half of the transient current waveform and the temporal change rate Δi2 / Δt in the second half are obtained, and the change rate Δi1 / Δt in the first half and the change in the second half are obtained. By determining whether or not the difference from the rate Δi 2 / Δt is greater than or equal to the set value, it is possible to determine whether the waveform of the transient current is a convex shape or a triangular waveform. Whether the position is P1 or P7 can be determined.

  Starting energization pattern determining means for determining an energization pattern for starting a brushless motor from the order of the peak values of the transient current obtained as a result of the transient current energizing process and the waveform of the maximum transient current FIG. 15 shows an example of a program algorithm executed by the microprocessor in order to configure the program 23.

  In the case of the algorithm shown in FIG. 15, the starting energization pattern at each position of the rotor is determined in the form of a combination (switch pattern) of switch elements of the inverter circuit to be turned on. When the process of determining the energization pattern at the start is started, first, the maximum Δimax among Δiu, Δiv and Δiw is found in step S1. As a result, when Δimax is determined to be Δiu as shown in step S2, Δiv is compared with Δiw, and when Δiv> Δiw as shown in step S3, the process proceeds to step S4, and Δiu It is determined whether or not the waveform is convex. As a result, when it is determined that the waveform of Δiu is not convex, the switch pattern at the start is set to UVZ in step S5, and when it is determined that the waveform of Δiu is convex, the switch pattern at the start is set to XYW in step S6. To do.

  Further, as a result of comparing Δiv and Δiw in step S3, as shown in step S7, when Δiv <Δiw, the process proceeds to step S8 to determine whether or not the waveform of Δiu is convex. As a result, when it is determined that the waveform of Δiu is not convex, the switch pattern at the start is XVZ in step S9, and when it is determined that the waveform of Δiu is convex, the switch pattern at the start is UYW in step S10. To do.

  As shown in step S11, when it is determined that the peak value of the maximum transient current found in step S1 is Δiv, Δiw and Δiu are then compared, and Δiw> Δiu as shown in step S12. If there is, the process proceeds to step S13 to determine whether or not the waveform of Δiv is convex. As a result, when it is determined that the waveform of Δiv is not convex, the switch pattern is set to XVW in step S14, and when it is determined that the waveform of Δiv is convex, the switch pattern is set to UYZ in step S15.

  Further, as a result of comparing Δiw and Δiu, as shown in step S16, when Δiw <Δiu, the process proceeds to step S17 to determine whether or not the waveform of Δiv is convex. As a result, when it is determined that the waveform of Δiv is not convex, the switch pattern is set to XYW at step S18, and when it is determined that the waveform of Δiv is convex, the switch pattern is set to UVZ at step S19.

  As shown in step S20, when it is determined that the peak value of the maximum transient current found in step S1 is Δiw, Δiu and Δiv are then compared, and Δiu> Δiv as shown in step S21. If there is, the process proceeds to step S22 to determine whether or not the waveform of Δiw is convex. As a result, when it is determined that the waveform of Δiw is not convex, the switch pattern is set to UYW in step S23, and when it is determined that the waveform of Δiw is convex, the switch pattern is set to XVZ in step S24.

  As a result of comparing Δiu and Δiv, as shown in step S25, when Δiu <Δiv, the process proceeds to step S26 to determine whether the waveform of Δiw is convex. As a result, when it is determined that the waveform of Δiw is not convex, the switch pattern is set to UYZ in step S27, and when the waveform of Δiw is determined to be convex, the switch pattern is set to XVW in step S28.

  Instead of checking whether or not the waveform of the transient current is convex as described above, as shown in FIG. 11, the transient currents flowing through the armature coils of all phases at specific positions P1, P5 and P9 as shown in FIG. It is also possible to determine the position of the rotor by using the fact that the peak values Δiu, Δiv, and Δiw of each indicate a value larger than a certain determination value Δis. As described above, the peak value of the transient current flowing through the armature coils of all phases at a specific position becomes larger than the determination value Δis, but the position is determined by using a relationship that does not occur at other positions. FIG. 16 is a flowchart showing an algorithm of a program executed by the microprocessor in order to configure the start-time energization pattern determining means 23 in this case. In the flowchart shown in FIG. 16, in steps S4 ′, S8 ′, S13 ′, S17 ′, S22 ′ and S26 ′, the peak values Δiu, Δiv and Δiw of the transient currents of all phases are larger than the determination value Δis. Since it is the same as the flowchart shown in FIG. 15 except that it is determined whether or not, detailed description thereof will be omitted.

  When the brushless motor 1 is started, the control switching means 36 controls the inverter circuit 3 by the start-time inverter control unit 25, and after the signal generating device 5 is in a state of generating a pulse signal having a level equal to or higher than a threshold value. Then, the control is switched so that the inverter circuit 3 is controlled by the inverter control unit 29 in the steady state. Therefore, after the brushless motor is started, the energization pattern is switched based on the position of the rotor determined by the pulse generated by the signal generator 5, and the armature coil is energized.

  In the present invention, since it is necessary to perform switching control of the inverter circuit by 180 ° switching in the current limiting control described later, in the above embodiment, the inverter is also switched by 180 ° switching at the time of starting and steady operation. The switching control of the circuit is performed. However, in the control method and the control apparatus according to the present invention, the inverter circuit 3 can be controlled by 120 ° switching at the time of starting and during steady operation.

  Magnetic flux Δφ flowing in the U-phase to W-phase iron core when a transient current is passed through the U-phase or W-phase armature coil while the rotor is in the respective positions P1 to P12, and the detected transient current FIG. 17 shows the crest values Δiu, Δiv and Δiw of FIG. 16 and the change in the switch pattern when the inverter circuit 3 is controlled by 120 ° switching.

  When the inverter circuit is controlled by 120 ° switching, the peak value of the transient current indicating an intermediate value among the peak values Δiu, Δiv, and Δiw of the transient currents respectively flowing in the three-phase coils during the transient current application process is The initial switch pattern is switched depending on whether the peak value of the transient current indicating the intermediate value is equal to or lower than the determination value Is at a position where the determination value ΔIs passes. For example, the switch pattern is switched to (U, Y) at position P2 where Δiu indicating an intermediate value among Δiu, Δiv, and Δiw is equal to or less than the determination value ΔIs, and Δiv indicating the intermediate value among Δiu, Δiv, and Δiw is The switch pattern is switched to (U, Z) at a position P4 where the determination value Is is greater than or equal to. Further, the switch pattern is switched to (V, Z) at a position P6 where Δiv indicating an intermediate value among Δiu, Δiv, and Δiw is equal to or less than the determination value ΔIs.

  In the embodiment described above, the rotation after the motor is started based on the output of the signal generator 5 in which the steady-state rotor position determination means 26 shown in FIG. Although the position of the child is determined, it is also possible to determine the position of the rotor after startup from the change in the reverse induced voltage of the armature coil, as in the method disclosed in Patent Document 3. .

Next, the control when the motor is in a state close to the lock will be described.
In the present invention, the supply of current from the DC power source 2 to the armature coils Lu to Lw is stopped when the motor is close to the lock and the armature current reaches the set upper limit value. Current flows in the same direction with respect to the neutral point through the two-phase coils of the three-phase coils Lu to Lw, and the sum of the currents flowing through the two-phase coils flows through the other one-phase coil. Current limiting control is performed to alternately perform a driving stop process in which circulating current flows through the armature coil and a driving process in which current is supplied from the direct current power source to the armature coil.

  In the drive stop process of the current limit control, the two phases of the armature coil in which the current flows in the same direction with respect to the neutral point is set as the determination target phase, and the current flowing through one and the other of the two phases of the determination target phase Current-limiting rotor position determination process for determining the position of the rotor from the difference between the first and second attenuation ratios, and the next driving process performed. The current in the same direction flows from the DC power source 2 to the two-phase coils of the three-phase coils Lu to Lw with respect to the neutral point, and the sum of the currents flowing through the two-phase coils to the other one-phase coil. Based on the rotor position determined in the current limit rotor position determination process, output from the motor in the next drive process, assuming that an armature current flows from the DC power supply to the armature coil in the energization pattern of In order to continue generating torque, Energizing pattern when supplying a current to the three-phase coil, performs a current limiting during energization pattern determination process of determining the start position of current in the energization pattern (switch position of the energization pattern). In the drive process of the current limit control, the supply of current from the DC power supply to the three-phase coil is started with the energization pattern determined in the current limit energization pattern determination process.

  The normal energization start position of the energization pattern determined in the current limit energization pattern determination process and the position where the driving process is started do not always coincide with each other. When performing the current limiting control driving process, the position where the driving process is started (rotor position) is delayed from the normal energization starting position in the energization pattern determined in the current limiting energization pattern determination process. In the case of the position, at the same time as the driving process is started, energization with the energization pattern determined in the current limiting energization pattern determination process is started halfway, and while the driving process is being performed, the energization pattern is Energize at. In addition, when the position where the driving process is started is ahead of the normal energization start position in the energization pattern determined in the current limiting energization pattern determination process, the current limiting is performed after the drive start process is started. When a normal energization start position is detected in the energization pattern determined in the current energization pattern determination process, energization from the DC power source to the three-phase coil is started, and the energization pattern is performed during the drive process. Energize at.

  In this embodiment, in order to identify the position of the rotor, the center of the tooth portion around which the U-phase coil Lu is wound faces the center of the N pole of the rotor as shown in FIG. The position is defined as a reference position P1 (0 ° position), and P2, P3,... Are added to the positions that appear each time the rotor rotates 30 ° counterclockwise from the reference position P1. The magnetic flux flowing through the U-phase iron core when the rotor is at the positions P1, P2,... Is as shown in FIG. As shown in FIG. 4, the magnetic flux flowing through the iron core on which the U-phase coil is wound is the same when the rotor is at the positions P2 and P12, and the rotor is at the positions P3 and P11. It is the same when it is in the position. The magnetic flux flowing through the iron core on which the U-phase coil is wound is also the same when the rotor is at the positions P5 and P9, and is the same when the rotor is at the positions P6 and P8.

  As shown in FIG. 19A, the position of the rotor P5 rotated 120 ° from the reference position P1, the position P6 rotated 150 ° from the reference position, and the position P7 rotated 180 ° from the reference position P1. Consider the case where When the rotor reaches the position P5, the switch pattern of the inverter circuit 3 is switched to a switch pattern that turns on the two switch elements Qu and Qv of the upper arm and the switch element Qz of the lower arm. The inverter circuits are controlled so that the switch elements Qu and Qv and the switch element Qz are turned on, and the three-phase coils Lu, Lv, and Lw are respectively shown in the leftmost diagrams of FIGS. 18 and 19A. The currents iu, iv, and iw are supplied from the DC power source to the three-phase coils Lu, Lv, and Lw in the energization pattern as described above. At the position P6 of the rotor, the control of the inverter circuit with the above switch pattern is continued, and current is supplied to the three-phase coil in the energization pattern as shown in the center diagram of FIG. ing. When the rotor reaches the position P7, the switch pattern of the inverter circuit 3 is switched to the switch pattern that turns on the switch element Qv of the upper arm and the switches Qu and Qw of the lower arm. Currents iu, iv and iw are supplied to the three-phase coils Lu, Lv and Lw, respectively, in the energization pattern as shown in the rightmost diagram of FIG.

  The table in FIG. 19B shows that the magnetic flux that flows through the iron core of each phase when the rotor is at 120 °, 150 °, and 180 ° is the same as the magnetic flux that flows through the iron core of each phase. It shows the position of the rotor when it flows through the wound iron core. That is, the magnetic flux flowing through the iron core around which the U-phase coil is wound when the rotor is at 120 °, 150 ° and 180 ° positions is as shown in FIG. The magnetic flux that flows through the iron core wound with the V-phase coil when it is at 180 ° is the same as the magnetic flux that flows through the iron core wound with the U-phase coil when the rotor is at the positions P1, P2, and P3. It is. The magnetic flux flowing through the iron core wound with the W-phase coil when the rotor is at 120 °, 150 °, and 180 ° is the U-phase coil when the rotor is at the P9, P10, and P11 positions, respectively. It is the same as the magnetic flux flowing through the iron core wound with.

  Assume that the upper arm switch elements Qu and Qv of the inverter circuit 3 and the lower arm switch element Qz are in an ON state, the load is heavy, and the motor is in a state close to locking. At this time, since the rotor hardly rotates and no induced voltage is generated in the armature coil, the currents iu, iv and iw have very large values, and the current iw which is the sum of the two-phase currents iu and iv is the upper limit value. IL is reached. In the present invention, current limit control is performed when the armature current reaches the set upper limit value.

  In this current limit control, when the largest current iw among the currents iu, iv and iw flowing through the three-phase coils reaches the upper limit value, for example, the switch element Qz of the lower arm that is in the on state is turned off. Then, the supply of current from the DC power source 1 to the three-phase coils Lu to Lw is stopped, and the coil Lu-coil Lw-diode Dw-switching element Qu-coil Lu circuit, coil Lv-coil Lw-diode Dw A circulating current energizing circuit composed of a switch element Qv and a coil Lv circuit is configured, and the currents iu, iv and iw are passed through the feedback diode Dw as a circulating current to the armature coil. These circulating currents decay with time due to the internal resistance of the circuit. In order to start the driving process when a certain time T has elapsed after the switch element Qz is turned off, to turn the switch element Qz on again, and to generate output torque from the DC power supply to the three-phase coil. The supply of current is resumed with a required predetermined energization pattern. As a result, the currents iu, iv and iw increase. Accordingly, when the current iw reaches the upper limit again, the switch element Qz of the lower arm that is in the on state is turned off, and the supply of current from the DC power source 1 to the three-phase coils Lu to Lw is stopped. At the same time, circulating currents iu, iv and iw are supplied. By repeating these operations, the armature current is limited to the upper limit value or less and the motor output torque is continuously generated. The predetermined time T is compared with the switching interval [for example (1/36) sec] of the energization pattern at a rotational speed (for example 60 rpm) at which the signal generator 5 can generate a pulse signal at a level that can be recognized. And sufficiently short (for example, about 100 μsec).

  FIG. 20 shows an example of temporal changes in the currents iu, iv and iw flowing through the three-phase coils Lu to Lw when the current limiting control is performed. In the current limiting control, when a current is supplied from the DC power source to the three-phase coil in the driving process, in order to generate a sufficient output torque from the motor, the three-phase coils Lu to Lw from the DC power source 2 in the driving process. The energization pattern when the current is passed through and the position at which energization is started in the energization pattern (the position of the rotor with respect to the three-phase coil) are accurately determined according to the position of the rotor with respect to the three-phase coil. There is a need. However, when the magnetic flux change detection type signal generator 5 is used in place of the Hall element as a position sensor for detecting the position of the rotor as in the present embodiment, when current limit control is performed (rotation of the rotor) Since a pulse of a level that can be recognized from the signal generator 5 cannot be obtained when the speed is extremely low), the position of the rotor is determined from the output pulse of the signal generator 5 and the energization pattern to the armature coil is determined. I can't do it.

  Therefore, in the present invention, in the driving stop process of the current limiting control, the two phases of the armature coil in which the circulating current flows in the same direction with respect to the neutral point are determined as the determination target phases (in the above example, the U phase and the V phase). Phase), the attenuation ratios of the attenuation currents (iu and iv) flowing in one and the other of the two phases to be determined are obtained as first and second attenuation ratios, respectively, and these first and second attenuation ratios are obtained. The current limit rotor position determination process for determining the rotor position from the difference is performed.

In the above example, the U-phase and V-phase currents when the current limiting control is started are respectively Iu and Iv, the resistances of the coils Lu and Lv are r, and the inductances of the U-phase and V-phase coils Lu and Lv are respectively Assuming that Lu and Lv and the elapsed time from the start of the current limiting control are t, the currents iu and iv flowing in the U-phase and V-phase, which are the determination target phases, are given by the following equations.
iu = Iu.exp {-(r / Lu) .t} (4)
iv = Iv.exp {-(r / Lv) .t} (5)
When the current values iu (0) and iv (0) when t = 0 and the current values iu (Δt) and iv (Δt) when t = Δt are obtained for the above-described attenuation currents iu and iv,
iu (0) = Iu (6)
iu (Δt) = Iu · exp {− (r / Lu) · Δt} (7)
iv (0) = Iv (8)
iv (Δt) = Iv · exp {− (r / Lv) · Δt} (9)
Here, when the ratio iu (Δt) / iu (0) between the current iu (Δt) and iu (0) and the ratio iv (Δt) / iv (0) between iv (Δt) and iv (0) are taken, ,
iu (Δt) / iu (0) = exp {− (r / Lu) · Δt} (10)
iv (Δt) / iv (0) = exp {− (r / Lv) · Δt} (11)
Here, exp {− (r / Lu) · Δt} and exp {− (r / Lv) · Δt} are referred to as attenuation ratios of the currents iu and iv, and exp {− (r / Lu) · Δt}. And exp {− (r / Lv) · Δt} are defined as a first attenuation ratio and a second attenuation ratio, respectively.

When r and Δt are constant, the first and second attenuation ratios exp {− (r / Lu) · Δt} and exp {− (r / Lv) · Δt} are related to the inductances Lu and Lv of the coil. Value. Since the inductance L of the coil is given by L = n ² (Δφ / ΔF), and Δφ / ΔF is determined by the position of the rotor as shown in FIG. 4, the damping ratio exp {− (r / Lu) · Δt} And exp {− (r / Lv) · Δt} is a value related to the position of the rotor. exp {− (r / Lu) · Δt} = expA and exp {− (r / Lv) · Δt} = expB, between the position of the rotor and the first and second damping ratios expA and expB The relationship is shown in FIG. In particular, in FIG. 21, expB-expA increases in proportion to the angle θ indicating the position of the rotor, so that the position of the rotor can be determined from this, and in the driving process based on the determined position of the rotor. The switching position of the energization pattern can be determined. When it is desired to advance the switching position of the energization pattern in the driving process, the energization pattern may be switched to the next pattern when expB-expA is small, and the advance angle of the switching position of the energization pattern is set to 0 °. In this case, the energization pattern may be switched to the next pattern when expB-expA is maximum (position P7). Since the switching order of the energization pattern when performing 180 ° switching control is determined, the energization pattern can be automatically determined if the switching position of the energization pattern is determined.

  An energization pattern in 180 ° switching control is shown in FIG. 22 as a switch pattern of switch elements constituting the inverter circuit. In FIG. 22, U, V, W, X, Y and W correspond to the switching elements Qu, Qv, Qw, Qx, Qy and Qw of the inverter circuit, respectively, and U, V, W, X, Y and W Each of the ON period switching elements Qu, Qv, Qw, Qx, Qy and Qw are turned on. In this case, since the switch pattern changes in a predetermined order such as UYW, UYZ, UVZ, XVZ, XVW,... With the change of the rotor position θ, from the current switch pattern (energization pattern). The next switch pattern can be determined.

FIG. 23 shows an operation when the current flowing through the determination target phase is actually detected in the drive stop process. Now, it is assumed that the W-phase current iw reaches the upper limit value IL and the driving stop process of the current limit control is started. At this time, an interrupt executed by the microprocessor is applied to try to read the value of the current iu, but since there is a delay of Δt [msec] before the value of the current value iu is actually read, the current value of iu that is read iu (Δt) is
iu (Δt) = Iu · exp {− (r / Lu) · Δt} (12)
It becomes. After reading iu (Δt), it takes a conversion time tc [msec] for A / D conversion of iu (Δt) until iv can be read. iv (Δt + tc) is
iv (Δt + tc) = Iv · exp {− (r / Lv) · (Δt + tc)} (13)
It becomes.

Further, the value iu (Δt + t1) of iu read after t1 [msec] after reading iu (Δt) is
iu (Δt + t1) = Iu · exp {− (r / Lu) · (Δt + t1)} (14)
It becomes. After reading iu (Δt + t1), iv can be read after the time tc required for A / D conversion of iu (Δt + t1) has elapsed. (Δt + tc + t1) is
iv (Δt + tc + t1) = Iv · exp {− (r / Lv) · (Δt + tc + t1)} (15)
It becomes.

Here, in order to obtain the attenuation ratio of iu and iv, the ratio of the values of iu and iv read at t1 [msec] intervals (value after t1 seconds) / (value before t1 seconds)
iu (Δt + t1) / iu (Δt) = exp {− (r / Lu) · t1} (16)
iv (Δt + tc + t1) / iv (Δt + tc) = exp {− (r / Lv) · t1} (17)
Thus, the current values of iu and iv are not affected by the time difference of reading. Therefore, the actual detection operation of the attenuation ratio of the two-phase current of the determination target phase can be handled in the same manner as the principle detection operation.

Next, an example of a task algorithm executed by the microprocessor to configure the control device shown in FIG. 2 will be described with reference to the flowcharts of FIGS.
FIG. 24 is a flowchart showing an algorithm of a task that is repeatedly executed at a minute time interval for controlling the brushless motor. In this task, first, in step S101, when the current limit control is performed, the inverter circuit 3 “OFF release timer” that determines the time (the time for which the drive stop process is performed) from when the switch element of the lower arm or the upper arm (the arm in which only one switch element is turned on) is turned off to release the off state. ”Is set to a predetermined time T.

  Next, in step S102, a process of detecting the position of the rotor when starting the motor by applying a transient current to the armature coil is performed, and in step S103, an energization pattern at the time of starting is output. The inverter circuit 3 is controlled so that a current flows through the coil. Next, in step S104, it is determined whether or not the current limit signal is input (the armature current has reached the upper limit value). If the current limit signal is not input, the process proceeds to step S105 to generate a signal. It is determined whether or not a pulse signal generated by the pulsar 5B of the device 5 is input. As a result, if no pulse signal is input, the process returns to step S104. When it is determined in step S105 that the pulse signal output from the pulser has been input, the rotor position is determined from the pulse signal in step S106, and the energization pattern during steady operation at the rotor position is determined. Next, in step S107, the energization pattern is output, and the inverter circuit 3 is controlled so that current flows from the DC power source 2 to the three-phase coils Lu to Lw with this energization pattern.

  When it is determined in step S104 that a current limiting signal has been input (the largest current among the three-phase coil currents has reached the upper limit value), the process proceeds to step S108, where the lower arm of the inverter circuit and In the upper arm, the switch element in the on state of the arm in which only one switch element is in the on state is turned off. As a result, the supply of current from the DC power source 2 to the three-phase coils Lu to Lw is stopped to start the drive stop process of the current limiting control, and the circulating current energizing circuit is configured to generate circulating currents iu, iv and iw. Shed. Next, in step S109, processing is performed to detect the attenuation ratios expA and expB of the two-phase current of the determination target phase in which current flows in the same direction with respect to the neutral point. A process for determining an energization pattern when current is supplied from the power source to the three-phase coils Lu to Lw and a position at which energization is started in the energization pattern (switching position of the energization pattern) is performed.

  Next, in step S111, the time T for which the OFF release timer is set is measured and an OFF release signal is generated (T time has elapsed since the drive stop process was started). When the OFF release signal is generated, the process proceeds to step S112, and the energization pattern determined in step S110 and the position at which energization is started in the energization pattern are output to start the driving process. When the position of the rotor has already passed the position to start energization with the energization pattern determined in step S110 when step S112 is executed, energization with the energization pattern is immediately started. Further, when the position of the rotor when the driving process is started is ahead of the position where the energization pattern determined in step S110 is started, the energization pattern is energized after the driving process is started. When the starting position is detected, energization with the energization pattern is started.

  After energization in the driving process is started, the process proceeds to step S105, and it is determined whether or not an output signal of the pulser is input. As a result, when the rotation speed of the rotor is low and no pulsar output signal is input, the process returns to step S104 to determine whether or not a current limiting signal is generated. When the largest current among the currents flowing through the three-phase coils in the driving process reaches the upper limit value, a current limit signal is generated again, so steps S108 to S112 are executed. When the rotation speed of the rotor increases and a pulse that can be recognized by the pulser is generated, the output signal of the pulser is recognized in step S105, so steps S106 and S107 are executed, The inverter circuit is controlled to energize the three-phase coil.

  The processing algorithm performed in steps S109 and S110 of FIG. 24 is shown in FIGS. FIG. 25 shows a task for performing a process of detecting a two-phase attenuation current of the determination target phase and converting it into a digital value. FIG. 26 shows a two-phase current of the determination target phase obtained by the processing of FIG. A task for performing a process of calculating an attenuation ratio using a digital value, determining a position of the rotor from the attenuation ratio, and determining an energization pattern based on the determination result is shown.

  In the task shown in FIG. 25, the value of one phase of the currents flowing in the same direction in the two phases of the determination target phase is converted into a digital value a1 in step S201, and this digital value is converted in step 202. Set a1 in the register. Next, in step S203, the value of the current of the other phase among the currents flowing in the same direction in the two phases to be determined is converted into a digital value b1, and in step S204, the digital value b1 is set in a register. Next, in step S205, a timer in the microprocessor that performs the operation of measuring the time t1 is started, and when the timer measures the time t1, step 206 is executed to interrupt the processing performed by the microprocessor. In this interrupt process, first, step S207 is executed to convert the value of one phase of the currents flowing in the same direction in the two phases to be judged into a digital value a2, and in step 208, this digital value a2 is converted. Set to register. Next, in step S209, the current value of the other phase among the currents flowing in the same direction in the two phases to be determined is converted into a digital value b2, and in step S210, the digital value b2 is set in a register.

  In the task shown in FIG. 26, in step S301, the ratio a2 / a1 between the digital value a2 and a1 of the detected value of the attenuation current flowing through the one-phase coil of the two phases to be judged is obtained, and the judgment target is obtained. The attenuation ratio expA of the attenuation current flowing through one phase is calculated as the first attenuation ratio. In step S302, the ratio b2 / b1 of the detected value b2 and b1 of the attenuation current flowing through the other phase coil of the two phases to be determined is obtained, and the attenuation current flowing in the other phase of the determination target phase. Is calculated as the second attenuation ratio. In step S303, an attenuation ratio difference expB-expA is calculated, and a map is searched for the attenuation ratio difference to determine the current position of the rotor. Next, in step S304, an inverter switch pattern that provides the next energization pattern is determined from the switch pattern of the inverter that provides the current energization pattern, and the position at which energization is started in the determined energization pattern is determined in step S303. Determine based on the position of.

  In the case of the algorithm shown in FIG. 24, the starting rotor position determining means 21 shown in FIG. 2 is configured in step S102, and the starting energization pattern determining means 23 shown in FIG. Further, the starting inverter control means 24 is constituted by the process of outputting the starting energization pattern in step S103 and the means for supplying a drive signal to the inverter circuit so as to energize the three-phase coil with this energization pattern. Further, step S106 constitutes the steady-state energization pattern determining means 27 in FIG. 2, and the process of outputting the steady-state energization pattern in step S107 and the drive signal to the inverter circuit to energize the three-phase coil with this energization pattern. The steady-state inverter control means 28 is constituted by the means for providing. Furthermore, the current limiting time decay rate calculating means 32 is configured by step S109, and the current limiting time energization pattern determining means 34 is configured by step S110. Further, the process of outputting the energization pattern and the switching position in step S112 and the means for driving the motor at the time of current limitation by means of giving a drive signal to the switch element of the inverter circuit so that the current flows through the three-phase coil with the output energization pattern. Inverter control means 35 is configured. Furthermore, the control switching means 37 is comprised by step S104, S105, and S111.

  In the example shown in FIG. 24, in the process of stopping the current limit control, the calculation of the attenuation ratio at the time of the current limit control, the determination of the rotor position, and the determination of the energization pattern at the time of the current limit are performed. However, when all of these processes cannot be performed in the drive stop process (the calculation processing time is insufficient), the process of calculating the decay rate and determining the energization pattern at the time of current limitation is performed in the drive process. It may be. FIG. 27 shows an example of a task algorithm executed by the microprocessor when the calculation of the attenuation ratio and the determination of the energization pattern at the time of the current limit are performed in the current limit control driving process.

  In the case of the algorithm shown in FIG. 27, first, in step S401, a predetermined time T is set in the “OFF release timer”. Next, in step S402, a process of detecting the position of the rotor when starting the motor by applying a transient current to the armature coil is performed, and in step S403, an energization pattern at the time of start is output. The inverter circuit 3 is controlled so that a current flows through the coil. Next, in step S404, it is determined whether or not the current limit signal is input (whether the largest current among the currents of the three-phase coils has reached the upper limit value). If the current limit signal is not input, In step S405, it is determined whether a pulse signal generated by the pulser 5B of the signal generator 5 is input. As a result, if no pulse signal is input, the process returns to step S404. If it is determined in step S405 that the pulse signal output by the pulser has been input, the rotor position is determined from the pulse signal in step S406, and the energization pattern during steady operation at the rotor position is determined. Next, in step S407, the energization pattern is output, and the inverter circuit 3 is controlled so that current flows from the DC power supply 2 to the three-phase coils Lu to Lw with this energization pattern.

  When it is determined in step S404 that the current limit signal is input, the process proceeds to step S408, and the arm in which only one switch element is on in the lower arm and the upper arm of the inverter circuit is turned on. The switch element in the state is turned off. As a result, the supply of current from the DC power source 2 to the three-phase coils Lu to Lw is stopped to start the drive stop process of the current limiting control, and the circulating current energizing circuit is configured to generate circulating currents iu, iv and iw. Shed. In step S409, the current value of the two-phase current of the determination target phase in which current flows in the same direction with respect to the neutral point is detected, and the current value detected in step S410 is set in the register. Next, in step S411, the time T at which the OFF release timer is set is measured, and an OFF release signal is generated (T time elapses after the drive stop process is started). When the OFF release signal is generated, the process proceeds to step S412 to read the current value set in the register, and in step S413, the two-phase current attenuation ratios expA and expB are calculated. Next, in step S414, a process for determining an energization pattern for supplying current from the DC power source to the three-phase coils Lu to Lw in the driving process and a position at which energization is started in the energization pattern (energization pattern switching position) is performed. Do. Next, in step S415, the determined energization pattern and the position at which energization is started with the energization pattern are output to start the driving process. When the position of the rotor has already passed the position to start energization with the energization pattern determined in step S414 at the time when step S415 is executed, energization with the energization pattern is immediately started. Further, when the position of the rotor when the driving process is started is advanced from the position where the energization pattern determined in step S414 is started, energization is performed with the energization pattern after the driving process is started. When the starting position is detected, energization with the energization pattern is started.

  After energization in the driving process is started, the process proceeds to step S405, and it is determined whether an output signal of the pulser is input. As a result, when the rotation speed of the rotor is low and no pulser output signal is input, the process returns to step S404 to determine whether or not a current limiting signal is generated. When the largest current among the currents flowing through the three-phase coils in the driving process reaches the upper limit value, the current limit signal is generated again, so steps S408 to S415 are executed. When the rotation speed of the rotor is increased and a pulse that can be recognized by the pulsar is generated, the output signal of the pulsar is recognized in step S405. Therefore, steps S406 and S407 are executed. The inverter circuit is controlled to energize the three-phase coil.

  In the example shown in FIG. 24, the switching between the driving stop process and the driving process of the current limiting control is performed by software. However, the switching between the driving stop process and the driving process may be performed using a hardware circuit. it can. FIG. 28 shows a configuration example of a circuit connected to control terminals (gates in the case of MOSFETs) of the switch elements Qx, Qy and Qz of the lower arm of the inverter circuit in order to switch between the driving process and the driving stop process. In the figure, ANDx and ANDz are AND circuits in which output terminals are connected to the control terminals of the switch elements Qx, Qy and Qz, respectively, and drive signals Sx 'to Sz' are given to one input terminal, and R is an AND circuit. This is a latch circuit in which the output terminal is connected to the other input terminal of the circuits ANDx to ANDz. As shown in FIG. 29, the latch circuit R sets the potential of the output terminal to the L level when a current limit signal that changes from the high level (H level) to the low level (L level) is applied, and the current limit signal is When an OFF release signal that rises from the L level to the H level is given after a given time T has passed, the potential of the output terminal is set to the H level.

  In the circuit shown in FIG. 28, when the armature current reaches the upper limit value and the current limit signal is given to the latch circuit R, the output of the latch circuit R becomes L level, so that the outputs of the AND circuits ANDx to ANDz It becomes “0” and the supply of the drive signals Sx to Sz to the switch elements Qx to Qz of the lower arm of the inverter circuit is stopped. Thereby, the drive stop process of the current limiting control is started. When the OFF release signal is given to the latch circuit R after the time T has elapsed after the driving stop process is started, the output of the latch circuit R becomes H level, so that the switch elements Qx to Qz of the lower arm of the inverter circuit The drive signals Sx to Sz are supplied to the signal.

  Although not shown in FIG. 28, a similar circuit is provided for the switch elements Qu to Qw, and is provided for the switch elements Qu to Qw when the switch element of the upper arm of the inverter circuit is turned off. A current limit signal is applied to a latch circuit of a similar circuit.

In the above example, the position of the rotor is determined using the difference between the attenuation ratios expA and expB of the current flowing in the two phases of the determination target phase in the drive stop process of the current limit control. When the time tc (see FIG. 23) required for the A / D conversion is short, the rotor position is determined using the relationship between the slope D of the current attenuation ratio obtained by the following equation and the rotor position. It can also be determined.
D = I · [exp {− (r / L) (Δt + tc)} − exp {− (r / L) (Δt + tc + t1)}] / t1 (18)

  In the above embodiment, 180 ° switching control is performed at the time of start-up, steady state, and current limit control (when close to a lock state). However, in the present invention, it is necessary to always perform 180 ° switching control. There is only at the time of current limit control in which current needs to flow in the same direction with respect to the neutral point in the two phases to be judged. In practicing the present invention, the 180 ° switching control may be performed only during the current limiting control, and the 120 ° switching control may be performed during start-up and in a steady state.

It is the circuit diagram which showed the structure of the hardware of one Embodiment of this invention. It is the block diagram which showed the structure of the control apparatus containing the various means comprised by the microprocessor of the controller in embodiment of FIG. (A) thru | or (L) is explanatory drawing which showed the change of the positional relationship between an armature coil and a rotor. It is a graph which shows the relationship between the change of the position of the magnetic field of a rotor, and the magnetic flux which flows through an armature core. It is the circuit diagram which showed the circuit which sends a transient current to an armature coil in embodiment of this invention. It is the wave form diagram which showed the waveform of the transient electric current which flows when the inductance of an armature coil differs. It is the wave form diagram which showed the waveform of the transient electric current which flows when the position of a rotor differs. (A) thru | or (C) is a figure for demonstrating the different method for recognizing the difference of a transient current. It is the figure which showed the waveform of the pulse signal which the pulser of a signal generator generates after a brushless motor starts as a motor, and the change of a switch pattern. Changes in the magnetic flux flowing in the U-phase to W-phase iron cores when transient currents are passed through the U-phase or W-phase armature coils with the rotor in the respective positions P1 to P12 shown in FIG. It is the chart shown collectively. A graph showing changes in magnetic flux flowing through a U-phase or W-phase iron core due to a transient current, a graph showing peak values Δiu, Δiv and Δiw of the detected transient current, and controlling an inverter circuit by 180 ° switching FIG. 4 is a diagram in which a chart showing an initial switch pattern when the rotor is located at positions P1 to P13 in FIG. (A) to (C) are waveform diagrams showing the waveforms of transient currents flowing through the U-phase or W-phase armature coils in the process of energizing the transient current when the rotor is at the position P1 in FIG. (A) to (C) are waveform diagrams showing the waveforms of transient currents flowing through the U-phase or W-phase armature coils in the process of energizing the transient current when the rotor is at position P7 in FIG. (A) And (B) is a figure for demonstrating the method to discriminate | determine whether the waveform of a transient current is a convex waveform or a triangular waveform. 3 is a flowchart showing an example of an algorithm of a program executed by a microprocessor in order to constitute first switch pattern determination means of the control device shown in FIG. 6 is a flowchart showing another example of an algorithm of a program executed by a microprocessor to constitute the first switch pattern determining means of the control device shown in FIG. A graph showing changes in magnetic flux flowing through a U-phase or W-phase iron core due to a transient current, a graph showing peak values Δiu, Δiv and Δiw of the detected transient current, and controlling an inverter circuit by 120 ° switching FIG. 4 is a diagram in which a chart showing an initial switch pattern when the rotor is located at positions P1 to P13 in FIG. FIG. 6 is a circuit diagram illustrating a state in which an attenuation current flows in a driving stop process of current limit control in the embodiment of the present invention. (A) is explanatory drawing which showed the electric current which flows into the three-phase coil of an armature coil, when a rotor exists in three positions which differ by 30 degrees in embodiment of this invention. (B) is a chart showing the state of magnetization of the iron core when the rotor is at each position shown in (A). It is the graph which showed an example of the change of the electric current which flows into a three-phase coil, when current limiting control is performed in embodiment of this invention. It is the graph which showed the relationship between the attenuation | damping rate of the electric current which flows through the two phases of a determination object phase in the embodiment of this invention, the difference of an attenuation | damping rate, and a rotor position. It is the graph which showed the switch pattern of the switch element of the inverter circuit used by embodiment of this invention with respect to the position of a rotor. It is a graph for demonstrating the operation | movement which detects the electric current of the two phase of a determination object phase at the time of current limiting control in embodiment of this invention. FIG. 3 is a flowchart showing a main part of a task algorithm executed by a microprocessor in order to configure the control device shown in FIG. 2. FIG. FIG. 25 is a flowchart showing an algorithm of a program executed by a microprocessor when performing a part of the task shown in FIG. 24. FIG. FIG. 25 is a flowchart showing an algorithm of a program executed by the microprocessor when other processing of the task shown in FIG. 24 is performed. FIG. 3 is a flowchart showing a modified example of an algorithm of a task to be executed by a microprocessor in order to configure the control device shown in FIG. 2. FIG. 3 is a circuit diagram illustrating a configuration of a main part of a circuit used when switching between a drive stop process and a drive process in current limiting control using a hardware circuit in the embodiment of the present invention. FIG. 29 is a waveform diagram showing waveforms of signals applied to the latch circuit shown in FIG. 28.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor 2 DC power supply 3 Inverter circuit 4 Controller 5 Signal generator 20 Transient current energizing means 21 Starting rotor position judging means 22 Starting rotor position judging means 23 Starting energizing pattern determining means 24 Starting inverter control means 25 Inverter control unit at start 26 Constant rotor position determination means 27 Constant energization pattern determination means 28 Constant inverter control means 29 Constant inverter control section 30 Current limit signal generation means 31 Inverter control means at driving stop 32 Decay at current limit Ratio calculation means 33 Current limit rotor position determination means 34 Current limit energization pattern determination means 35 Current limit motor drive inverter control means 36 Current limit inverter control section

Claims (13)

In order to rotate the rotor of a brushless motor having a stator having an armature coil composed of a three-phase coil connected so as to have a neutral point and a rotor having a field in a predetermined direction A brushless motor control method for controlling an armature current flowing from a power source to the armature coil,
When the armature current reaches a set upper limit value, the supply of current from the DC power source to the armature coil is stopped, and the two-phase coils of the three-phase coils are neutralized. Stop driving the circulating current through the armature coil by flowing the current in the same direction with respect to the point and flowing the current of the sum of the currents flowing through the two-phase coils to the other one-phase coil. Current limiting control is performed to alternately perform a process and a driving process of supplying current from the DC power source to the armature coil,
Attenuation of the current flowing through the coil of the determination target phase with the two phases of the armature coil in which current flows in the same direction with respect to the neutral point in the drive stop process of the current limit control as the determination target phase The current limit rotor position determination process for determining the position of the rotor from the state, and the current limit control driving process based on the rotor position determined in the current limit rotor position determination process Performing a current-limiting energization pattern determining process for determining an energization pattern when a current is passed from the DC power source to the three-phase coil and a position at which energization is started in the energization pattern;
In the driving process of the current limiting control, a brushless motor control method for controlling the inverter circuit so that a current flows from the DC power source to the three-phase coil in accordance with the energization pattern determined in the current limiting energization pattern determination process. . In order to rotate the rotor of a brushless motor having a stator having an armature coil composed of a three-phase coil connected so as to have a neutral point and a rotor having a field in a predetermined direction A brushless motor control method for controlling an armature current flowing from a power source to the armature coil,
When the armature current reaches a set upper limit value, the supply of current from the DC power source to the armature coil is stopped, and the two-phase coils of the three-phase coils are neutralized. Stop driving the circulating current through the armature coil by flowing the current in the same direction with respect to the point and flowing the current of the sum of the currents flowing through the two-phase coils to the other one-phase coil. Current limiting control is performed to alternately perform a process and a driving process of supplying current from the DC power source to the armature coil,
In the drive stop process of the current limit control, the two phases of the armature coil in which current flows in the same direction with respect to the neutral point is set as the determination target phase, and one and the other of the two phases of the determination target phase are set as the determination target phase. The current-limit-time rotor position determination process for determining the position of the rotor from the difference between the first and second attenuation ratios, where the current attenuation ratio is a first attenuation ratio and a second attenuation ratio, respectively. Based on the rotor position determined in the current limit rotor position determination process, an energization pattern for flowing current from the DC power source to the three-phase coil in the driving process of the current limit control and the energization pattern Conduct the current limit energization pattern determination process to determine the position to start energization,
In the driving process of the current limiting control, a brushless motor control method for controlling the inverter circuit so that a current flows from the DC power source to the three-phase coil in accordance with the energization pattern determined in the current limiting energization pattern determination process. .   3. The method of controlling a brushless motor according to claim 1, wherein, in the current limit control, the driving process is started after a predetermined time has elapsed after the supply of current from the DC power supply to the armature coil is stopped.   In the current limit control, after the supply of current from the DC power source to the armature coil is stopped, it is detected that the armature current has decreased to a limit release value set lower than the upper limit value. The method for controlling a brushless motor according to claim 1, wherein the driving process is started.   The energization pattern when the current flows from the DC power source to the three-phase coil in the driving process of the current limit control is a current in the same direction with respect to the neutral point in the two-phase coil of the three-phase coils. The brushless motor control method according to any one of claims 1 to 4, wherein a current pattern of a sum of currents flowing through the two-phase coils is applied to the other one-phase coil. Provided between the armature coil of a brushless motor and a DC power source having a stator having an armature coil composed of a three-phase coil connected to have a neutral point and a rotor having a field. A brushless motor control device comprising: a bridge-type inverter circuit; and a controller for controlling the inverter circuit to rotate the rotor in a predetermined direction.
A steady-state inverter control unit for controlling the inverter circuit during steady-state operation of the brushless motor;
When the armature current reaches a set upper limit value, a drive stop process for stopping the supply of current from the DC power source to the armature coil and supplying current from the DC power source to the armature coil A current limiting inverter control unit that controls the inverter circuit so as to alternately perform a driving process to perform current limiting control for limiting the armature current to the upper limit value or less;
Comprising
The current control inverter control unit is
When the armature current reaches a set upper limit value, the supply of current from the DC power source to the armature coil is stopped, and a neutral point is added to the two-phase coil of the three-phase coils. The inverter is configured such that a current flows in the same direction with respect to the other one-phase coil and a circulating current flows through the armature coil in a manner of flowing a current that is the sum of the currents flowing through the two-phase coils in the other one-phase coil. A drive stop time inverter control means for controlling the circuit to perform the drive stop process of the current limiting control;
While the supply of current from the DC power supply to the armature coil is stopped, two phases of the armature coil in which current flows in the same direction with respect to the neutral point are set as the determination target phase, and the determination target phase Current limiting rotor position determination means for determining the position of the rotor from the state of attenuation of the current flowing through
An energization pattern for flowing current from the DC power source to the three-phase coil in the driving process of the current limit control with respect to the rotor position determined by the rotor position determination means at the time of current limit, Current limit energization pattern determination means for determining a position to start energization;
Current limiting time for controlling the inverter circuit so that the current limiting control is driven by causing current to flow from the direct current power source to the three-phase coil with the energization pattern determined by the current limiting time energization pattern determining means. An inverter control means for driving the motor;
A control device for a brushless motor. Provided between the armature coil of a brushless motor and a DC power source having a stator having an armature coil composed of a three-phase coil connected to have a neutral point and a rotor having a field. A brushless motor control device comprising: a bridge-type inverter circuit; and a controller for controlling the inverter circuit to rotate the rotor in a predetermined direction.
A steady-state inverter control unit for controlling the inverter circuit during steady-state operation of the brushless motor;
When the armature current reaches a set upper limit value, a drive stop process for stopping the supply of current from the DC power source to the armature coil and supplying current from the DC power source to the armature coil A current limiting inverter control unit that controls the inverter circuit so as to alternately perform a driving process to perform current limiting control for limiting the armature current to the upper limit value or less;
Comprising
The current control inverter control unit is
When the armature current reaches a set upper limit value, the supply of current from the DC power source to the armature coil is stopped, and a neutral point is added to the two-phase coil of the three-phase coils. The inverter is configured such that a current flows in the same direction with respect to the other one-phase coil and a circulating current flows through the armature coil in a manner of flowing a current that is the sum of the currents flowing through the two-phase coils in the other one-phase coil. A drive stop time inverter control means for controlling the circuit to perform the drive stop process of the current limiting control;
While the supply of current from the DC power supply to the armature coil is stopped, two phases of the armature coil in which current flows in the same direction with respect to the neutral point are set as the determination target phase, and the determination target phase Current limiting attenuation rate calculating means for calculating the attenuation rate of the current flowing in one and the other of the two phases as the first and second attenuation rates, respectively;
Current limiting rotor position determination means for determining the position of the rotor from the difference between the first and second attenuation ratios;
An energization pattern for flowing current from the DC power source to the three-phase coil in the driving process of the current limit control with respect to the rotor position determined by the rotor position determination means at the time of current limit, Current limit energization pattern determination means for determining a position to start energization;
Current limiting time for controlling the inverter circuit so that the current limiting control is driven by causing current to flow from the direct current power source to the three-phase coil with the energization pattern determined by the current limiting time energization pattern determining means. An inverter control means for driving the motor;
A control device for a brushless motor. Provided between the armature coil of a brushless motor and a DC power source having a stator having an armature coil composed of a three-phase coil connected to have a neutral point and a rotor having a field. A brushless motor control device comprising: a bridge-type inverter circuit; and a controller for controlling the inverter circuit to rotate the rotor in a predetermined direction.
A start-up inverter control unit for controlling the inverter circuit at the start of the brushless motor;
A steady-state inverter control unit for controlling the inverter circuit during steady-state operation of the brushless motor;
When the armature current reaches a set upper limit value, a drive stop process in which supply of current from the DC power supply to the armature coil is stopped, and current is supplied from the DC power supply to the armature coil. A current limiting inverter control unit for controlling the inverter circuit to alternately perform a driving process and performing current limiting control for limiting the armature current to the upper limit value or less;
Comprising
The starting inverter control unit is:
Transient current energizing means for applying a transient current energizing process to each of the three-phase coils to apply a transient current to the coils of each phase by temporarily applying a DC voltage to the coils of each phase of the stator; A starting rotor position determining means for detecting a transient current flowing through each of the three-phase coils in a transient current application process and determining the position of the rotor from the detected transient current;
A starting energization pattern determining means for determining the energization pattern necessary for rotating the rotor in a predetermined direction with respect to the position of the rotor determined by the starting rotor position determining means;
Starting inverter control means for controlling the inverter circuit so as to energize the armature coil with the energization pattern determined by the starting energization pattern determining means;
With
The current control inverter control unit is
When the armature current reaches a set upper limit value, the supply of current from the DC power source to the armature coil is stopped, and a neutral point is added to the two-phase coil of the three-phase coils. The inverter is configured such that a current flows in the same direction with respect to the other one-phase coil and a circulating current flows through the armature coil in a manner of flowing a current that is the sum of the currents flowing through the two-phase coils in the other one-phase coil. A drive stop time inverter control means for controlling the circuit to perform the drive stop process of the current limiting control;
While the supply of current from the DC power supply to the armature coil is stopped, two phases of the armature coil in which current flows in the same direction with respect to the neutral point are set as the determination target phase, and the determination target phase Current limiting attenuation rate calculating means for calculating the attenuation rate of the current flowing in one and the other of the two phases as the first and second attenuation rates, respectively;
Current limiting rotor position determination means for determining the position of the rotor from the difference between the first and second attenuation ratios;
An energization pattern for flowing current from the DC power source to the three-phase coil in the driving process of the current limit control with respect to the rotor position determined by the rotor position determination means at the time of current limit, Current limit energization pattern determination means for determining a position to start energization;
Current limiting time for controlling the inverter circuit so that the current limiting control is driven by causing current to flow from the direct current power source to the three-phase coil with the energization pattern determined by the current limiting time energization pattern determining means. An inverter control means for driving the motor;
A control device for a brushless motor.   The energization pattern when the current flows from the DC power source to the three-phase coil in the driving process of the current limit control is a current in the same direction with respect to the neutral point in the two-phase coil of the three-phase coils. The brushless motor control device according to any one of claims 6 to 8, wherein a current of a sum of currents flowing through the two-phase coils is supplied to the other one-phase coil.   9. The brushless according to claim 8, wherein the starting rotor position determining means is configured to determine a position of the rotor relative to the three-phase coil from a peak value of the transient current. Motor control device.   9. The starting rotor position determination means is configured to determine a position of the rotor relative to the three-phase coil from a peak value and a waveform of the transient current. The brushless motor control device described.   The current limiting inverter control unit restarts the supply of current from the DC power supply to the three-phase coil after a certain time has elapsed after stopping the supply of current from the DC power supply to the armature coil. The brushless motor control device according to any one of claims 6 to 11, wherein the controller is configured to perform the driving process. The current limit inverter control unit detects that the armature current has decreased to a limit release value set lower than the upper limit value after stopping the supply of current from the DC power source to the armature coil. 12. The brushless motor control device according to claim 6, wherein the driving process is performed by restarting the supply of current from the DC power source to the three-phase coil.

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