JP4312115B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor control device that controls a motor that generates torque by performing high rotation control.

  Conventionally, as a technique for driving a synchronous motor such as a brushless DC motor, techniques described in Patent Document 1 and Patent Document 2 below are known.

  In Patent Document 1, in order to expand the high-speed operation range of a brushless DC motor, the phase angle for switching the energization mode to the motor winding is higher than that at high load when the torque range is low or medium. A technique for improving the output torque and the rotational speed by advancing is disclosed.

  Patent Document 2 discloses a technique for reducing the induced voltage of a brushless DC motor by controlling the phase of the armature current to be more advanced than the induced voltage by inverter control in order to achieve high-speed rotation of the brushless DC motor. Is disclosed.

Japanese Patent Laid-Open No. 11-299278

JP-A-5-211796

  By the way, considering various applications, including the above-described conventional technology, performing variable speed driving with high efficiency without reducing the voltage drop rate, and expanding the high-speed operable range of the motor are many. Further improvements are desired for phase motors.

  Accordingly, the present invention has been proposed in view of the above-described circumstances, and provides a motor drive device that can perform high-speed rotation without lowering the voltage drop rate and realize a wide range of speed control. With the goal.

  The present invention provides a rotor in which a plurality of magnets divided into a plurality about a rotation shaft to be driven for rotation are arranged, and currents corresponding to each phase arranged around the rotation shaft around the rotor. A motor driving device for driving a three-phase brushless motor provided with an armature supplied to a coil, the rotational position detecting means for detecting the rotational position of the rotor, and each phase connected to a positive terminal of a power source An upper switching element group composed of a plurality of switching elements connected to an armature corresponding to the above and a lower switching composed of a plurality of switching elements connected to the armature corresponding to each phase connected to the negative terminal of the power source An inverter that drives an element group to supply current to the brushless motor, and the upper switching element based on the rotational position detected by the rotational position detecting means. And a pair of first and second switching elements that supply current to the two-phase armature windings to be energized from each of the lower switching element groups and the selected first and second switching elements And a control means for supplying current to the first and second two-phase armature windings to be energized.

  The motor driving device selects a third switching element that is controlled to be in an ON state following the selected first and second switching elements based on the rotational position detected by the rotational position detecting means. While the first and second switching elements are controlled to be in the on state, the third switching element is controlled to be turned on and off to supply current to the armature winding of the third phase. Solve the problem.

  According to the motor drive device of the present invention, when controlling the rotational speed of the three-phase brushless motor, the switching element that supplies current to the two-phase armature winding to be energized is selected based on the rotational position, The selected switching element is controlled to be in an on state or an off state. Then, the magnetic flux generated by the two-phase armature is applied from the armature to the rotor to control the rotation speed, and another one-phase armature is selected and connected to the other one-phase switching. By applying PWM control to the element and applying a magnetic flux generated by current generated according to the on / off timing of the PWM control from the armature to the rotor, and by PWM controlling the current flowing through the other one-phase armature The generated magnetomotive force acts to demagnetize the rotor magnet (permanent magnet). As a result, the induced voltage depending on the magnetic flux is reduced by the demagnetizing action, and thus the rotational speed of the rotor is increased. At this time, the phase of the armature current is advanced with respect to the induced voltage. Therefore, according to this motor drive device, it is possible to perform high-speed rotation without reducing the voltage drop rate and to realize wide-range speed control including a high-speed region.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The present invention is applied to, for example, a motor driving device configured as shown in FIG.

  This motor drive device controls and drives a brushless DC motor (BLDCM) 1 to be controlled according to the rotational speed of the brushless DC motor 1. The brushless DC motor 1 controls the current values supplied from the power source 2 to the U-phase, V-phase, and W-phase via the PWM inverter 3, thereby controlling the currents flowing in the internal coils and generating torque. Be controlled. In this example, the brushless DC motor 1 is a permanent magnet synchronous motor, and includes a rotor that is a rotor having an internal embedded magnet structure and a stator that is a stator having a concentrated winding structure. (Surface Permanent Magnet) motor.

  This motor drive device is supplied with a speed command value for controlling the rotation speed (speed) of the brushless DC motor 1 from the outside, and performs various calculations for generating torque of the speed command value, thereby performing brushless DC The current supplied to the motor 1 is controlled.

  When driving and controlling the brushless DC motor 1 according to the speed command value, the motor driving device detects the rotor position in each phase of the brushless DC motor 1 by the position detector 4. The position detector 4 is composed of a Hall element, and detects the magnetic flux that changes as the rotor rotates as a current value, thereby outputting the rotation angle of the brushless DC motor 1 to the position detection unit 5 and the speed detection unit 6.

  The speed detector 6 calculates the rotation speed of the brushless DC motor 1 based on the rotation angle, generates a speed calculation value, and supplies it to the adder 7. The adder 7 is supplied with the speed calculation value from the speed detection unit 6 and the speed command value from the microcomputer, and supplies a deviation obtained by subtracting the speed calculation value from the speed command value to the speed control unit 8. When the deviation between the speed command value and the speed calculation value is supplied, the speed control unit 8 is configured to reduce the deviation, that is, the duty ratio of the PWM inverter 3, that is, the pulse given from the PWM inverter 3 to the brushless DC motor 1. Obtain the modulation rate. The position detection unit 5 generates a position signal indicating the current positional relationship between the current rotor and the stator of the brushless DC motor 1 based on the rotation angle.

  Based on the modulation factor from the speed control unit 8 and the position signal from the position detection unit 5, the output control unit 9 performs on / off control or PWM control of a switching element (FET (Field Effect Transistor)) constituting the PWM inverter 3. The control signal to be sent is sent to the PWM inverter 3. In FIG. 1, the position detector 5, speed detector 6, adder 7, speed controller 8 and output controller 9 may be included in the microcomputer (not shown).

  As shown in FIG. 2, the PWM inverter 3 is connected to the positive terminal of the power source 2 and is connected to the upper switching element groups UP, VP, WP corresponding to the U-phase, V-phase, and W-phase of the brushless DC motor 1. A lower switching element group UB, VB, WB corresponding to the U phase, V phase, and W phase of the brushless DC motor 1 connected to the negative terminal is provided. The PWM inverter 3 is connected to the control circuit 11 and the drive circuit 12 configured by the above-described units 5 to 9.

  The drive circuit 12 is connected to the switching elements UP, VP, WP and UB, VB, WB of the PWM inverter 3. Then, the drive circuit 12 turns on and off the switching elements UP, VP, WP and UB, VB, WB according to a control signal from the output control unit 9 of the control circuit 11, and the coils 21U, 21V, 21W of the brushless DC motor 1. To control the current supplied to the.

  As shown in FIG. 3, the brushless DC motor 1 driven by such a configuration is a rotor that is a rotor in which a plurality of magnets divided into a plurality about a rotating shaft that is rotationally driven are arranged. 31, and a stator 32 that is an armature and a stator that are arranged around the rotor 31 around the rotation axis and that supply current corresponding to each phase to the coil. This brushless DC motor 1 is provided with a coil of a stator 32 connected to UP, VP and WP and a coil of a stator 32 connected to UB, VB and WB, and current from the PWM inverter 3 is supplied to each coil. As a result, the magnetic flux generated in the stator 32 is supplied to the rotor 31 and gives a rotational force to the rotor 31.

  Further, in such a brushless DC motor 1, the Hall ICs constituting the position detector 4 may be provided at an angle of 60 ° as shown in FIG. 4A, as shown in FIG. 4B. May be provided at intervals of 120 °. Further, in the brushless DC motor 1, the rotor 31 may be configured by a 4-pole permanent magnet (IPM) as shown in FIG. 5 (a), and as shown in FIG. An 8-pole type (SPM) in which a plurality of permanent magnets are continuously provided may be used. Furthermore, as shown in FIG. 6, when the brushless DC motor 1 is composed of three phases, the number of stators 32 (the number of slots) is an integer multiple of the number of phases of 6, 9, and 12, and the rotor The number of 31 may be an even number corresponding to the number of slots. That is, any of the brushless DC motors 1 shown in FIGS. 4 to 6 can exhibit the effects described later by performing the driving operation of the brushless DC motor 1 described later.

  The driving operation of the motor driving apparatus for the brushless DC motor 1 is performed by supplying two of the three phases of the PWM inverter 3 to the brushless DC motor as shown in FIG. 7 when power is supplied from the power source 2 to the brushless DC motor 1. There are known two-phase energization connected to 1 and three-phase energization in which the three phases of the PWM inverter 3 are connected to the brushless DC motor 1 as shown in FIG.

  That is, when performing three-phase energization, this motor drive device performs on / off control for all three phases in accordance with the detection signal of the position detector 4 as disclosed in FIG. On the other hand, in the motor drive device to which the present invention is applied, in the brushless DC motor 1 energized with 120 °, as shown in FIG. 9, when the electrical angle is 60 ° to 120 °, the switching element WP and When the switching element VB is energized from the W phase to the U phase by turning on the switching element UB, the switching element VB is PWM-controlled, and the switching is performed when the next electrical angle is 120 ° to 180 °. When the element WP and the switching element VB are turned on to energize the W phase to the V phase and perform PWM control of the switching element UP. When the next electrical angle is 180 ° to 240 °, the switching element UP In addition, the switching element VB is turned on to energize the U-phase to the V-phase, and the switching element WB is PWM-controlled.

  Thus, the PWM inverter 3 is driven and the current is supplied to the brushless DC motor 1 when the next two-phase energization is switched, the switching element of the phase is turned 60 ° before the phase from the off state to the on state. Drive by PWM control. As a result, for example, when current flows from the W phase to the U phase in the range of electrical angles of 60 ° to 120 °, the electromotive force generated in the W-phase and U-phase armatures decreases, and the W-phase electric machine The current flowing from the child to the U-phase armature increases, the torque generated by the current flowing from the W-phase to the U-phase increases, and the rotational speed of the rotor 31 can be improved. Also, at other electrical angles, as shown in FIG. 9, by starting PWM control 60 degrees before the transition from the off state to the on state, the number of revolutions in the period can be increased.

  At this time, the motor drive device selects a two-phase stator 32 for switching and controlling the on / off state of the switching element of the PWM inverter 3 based on the rotational position detected by the position detector 4. The generated magnetic flux is applied from the stator 32 to the rotor 31 to control the rotation speed, and another one-phase stator 32 is selected, and the switching element connected to the other one phase is PWM controlled, and the PWM The output control unit 9 controls the switching element so that a magnetic flux corresponding to the control on / off timing is applied from the stator 32 to the rotor 31.

  In this way, when conducting power in two phases, the line voltage and line current as shown in FIG. 10 can be realized by PWM control of the other one phase. In the motor drive device to which the invention is not applied, the line voltage and line current are as shown in FIG. Therefore, according to this motor drive device, as shown in FIG. 12, the rotational speed can be increased as compared with the 120 ° energized brushless DC motor having the line voltage and line current shown in FIG. In particular, the rotational speed can be increased in the low torque region and the high torque region.

  Further, in this motor drive device, it is possible to change the duty ratio of the switching element that performs the PWM control, thereby changing the degree of cancellation of the electromotive force and increasing the rotation speed of the brushless DC motor 1.

  Furthermore, according to this motor drive device, it is not necessary to perform switching control of the switching element in accordance with a timer that has been conventionally required. Cost reduction can be realized without the need for a timer.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

It is a block diagram which shows the functional structure of the motor drive device to which this invention is applied. It is a circuit diagram explaining the connection relation of the PWM inverter of the motor drive device to which this invention is applied, and a brushless DC motor. It is a figure which shows the structural example of a brushless DC motor. It is a figure which shows the example of installation of Hall IC provided in a brushless DC motor, Comprising: (a) is a 60 degree space | interval, (b) is a 120 degree space | interval. It is a structural example of the rotor of a brushless DC motor, Comprising: (a) is an IPM motor and (b) is a SPM motor. It is a figure for demonstrating the combination of the number of slots and the number of poles of a brushless DC motor. It is a circuit diagram for demonstrating two-phase electricity supply by the motor drive device to which this invention is applied. It is a circuit diagram for demonstrating three-phase electricity supply by the motor drive device to which this invention is applied. It is a figure which shows the switching sequence of the switching element by the motor drive device to which this invention is applied. It is a figure which shows the change of the line voltage and line current by the motor drive device to which this invention is applied. It is a figure which shows the change of the line voltage and line current of the comparative example with respect to the motor drive device to which this invention is applied. It is a figure which shows the system efficiency with respect to the torque of a motor drive device and the comparative example to which this invention is applied, rotation speed, and current consumption.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless DC motor 2 Power supply 3 PWM inverter 4 Position detector 5 Position detection part 6 Speed detection part 7 Adder 8 Speed control part 9 Output control part 11 Control circuit 12 Drive circuit 21 Coil 31 Rotor 32 Stator

Claims (3)

A rotor in which a plurality of magnets divided into a plurality of parts are arranged around a rotating shaft to be rotated, and a current corresponding to each phase arranged around the rotor axis around the rotor is supplied to the coil. A motor driving device for driving a three-phase brushless motor provided with an armature,
Rotational position detecting means for detecting the rotational position of the rotor;
An upper switching element group consisting of a plurality of switching elements connected to the positive terminal of the power supply and connected to the armature corresponding to each phase, and connected to the armature corresponding to the respective phase connected to the negative terminal of the power supply. An inverter that drives a lower switching element group composed of a plurality of switching elements and supplies current to the brushless motor;
Based on the rotational position detected by the rotational position detecting means, a pair of first and second currents for supplying current to the two-phase armature windings to be energized from each of the upper switching element group and the lower switching element group, Control for selecting a second switching element, controlling the selected first and second switching elements to be in an ON state, and supplying current to the first and second two-phase armature windings to be energized A motor drive device comprising:
Based on the rotational position detected by the rotational position detecting means, a third switching element that is controlled to be in an ON state is selected following the selected first and second switching elements, and the first and second switching elements are selected. A motor driving device that supplies current to the armature winding of the third phase by controlling on / off of the third switching element while the two switching elements are controlled to be on.   2. The motor driving apparatus according to claim 1, wherein the control unit performs PWM control by changing a duty ratio of a third switching element that supplies current to the armature winding of the third phase.   The plurality of switching elements of the upper switching element group of the inverter are controlled to be turned on by the control means, differing from each other by an electrical angle of 120 degrees, and the switching elements of the lower switching element group of the inverter are controlled by the control means Are controlled to be turned on by different electrical angles of 120 degrees from each other, and the switching elements of the upper switching element group and the switching elements of the lower switching element group are different from each other by an electrical angle of 60 degrees. 3. The motor driving device according to claim 1, wherein the motor driving device is controlled to be in an on state, and the third switching element is on / off controlled by an electrical angle of 60 degrees.

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