JP2018023208A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter device capable of recovering an original function by appropriately determining a step-out state for restart.SOLUTION: The inverter device includes: a motor 15 having a permanent magnet and a winding; an inverter circuit 16 for supplying an electric current to the winding; first control means 19 for outputting a driving signal to the inverter circuit 16 according to a phase of the permanent magnet of the motor 15; second control means 20 for outputting a predetermined signal different from that of the first control means 19; switching means 22 for switching output between the first control means 19 and the second control means 20; and restart means 23 for outputting a restart signal. The restart means 23, after switching the switching means 22 to the second control means 20 at least once, generates a restart signal and restarts the motor 15, thereby appropriately determining a step-out state for recovery of an original function.SELECTED DRAWING: Figure 1

Description

  The present invention relates to household appliances such as an electric washing machine, an air conditioner, and a refrigerator that are used as a general household, and an inverter device that is used as a power source for offices, business use, and transportation.

  Conventionally, this type of inverter device estimates the rotational speed of a rotor of an electric motor using a permanent magnet and outputs a first estimated rotational speed. The first estimated rotational speed is a speed command. Step-out is detected by providing second speed estimating means for controlling the electric motor so as to follow and outputting a second estimated rotational speed having an estimation method different from the first speed estimating means (for example, patents) Reference 1).

  In addition, when the motor is started, the input active power is calculated based on the correlation value of the current value input from the current detection means and the voltage command value applied to the motor, and the shaft locks when the input active power is smaller than a predetermined threshold value. Some detected (that is, step-out) (for example, see Patent Document 2).

  FIG. 11 shows a first conventional inverter device described in Patent Document 1. In FIG. As shown in FIG. 11, an electric motor 1 having a permanent magnet, a PWM inverter 2, coordinate converters 3 and 4, a current control unit 5, a speed control unit 6, a magnetic flux control unit 7, a first speed estimation unit 8, and an integrator 9 The second speed estimation unit 10 and the step-out determination unit 11 are provided, the first speed estimation unit 8 estimates the rotational speed of the rotor of the electric motor 1, and the obtained first estimated rotational speed ωe is used as the speed command ω *. The electric motor 1 is controlled to follow. The second speed estimator 10 estimates the rotational speed of the rotor using an estimation method different from that of the first speed estimator 8, and the step-out determination unit 11 is a second speed estimator. The step-out is detected based on a comparison between the second estimated rotational speed ω2e obtained by 10 and the first estimated rotational speed ωe or the speed command ω *.

  FIG. 12 shows a second conventional inverter device described in Patent Document 2. In FIG. As shown in FIG. 12, the shaft lock detection unit 14 includes an input active power calculation unit 12 and a shaft lock determination unit 13. The input active power calculation unit 12 inputs and calculates Idc and Iqc, which are correlation values of the motor current value, and voltage command values V * dc and V * qc corresponding to the voltage applied to the motor when the motor is started. The input active power value Pi is output. The shaft lock determination unit 13 inputs the input active power value Pi and the speed command value ω1 *, and determines that the shaft lock of the motor has occurred when the input active power Pi is smaller than the threshold value in the ω1 * condition. The drive of the electric motor is stopped.

JP 2007-282389 A JP 2013-146162 A

However, the conventional configuration is a specification in which the speed of the electric motor having a permanent magnet is considerably high, the induced electromotive force generated in the winding is sufficiently high, and the resistance and induction coefficient of the winding are small to some extent. This is a configuration aimed at detecting step-out in some cases. Therefore, under conditions that do not satisfy them, if a wrong judgment is made, i.e., it is judged that the operation is out of step despite the fact that the operation is not actually out of step, and conversely, the step out is actually performed. However, it was not configured to cope with the case where it is determined that the state is normal despite the state.

  That is, in the first conventional inverter device, for example, during operation (powering) where the resistance of the winding is large and torque is required at low speed, the induced electromotive force generated by the rotation of the motor is small, The voltage drop due to the winding resistance is large, and the variation due to the variation in the winding resistance and the change in the winding resistance due to the temperature is large, so the reliability of the second estimated rotational speed is low. . Therefore, for example, determination from the voltage of the δ-axis component becomes impossible. During operation that requires torque at low speed (powering), the induced electromotive force generated by the rotation of the motor is small, while the voltage drop due to the winding resistance is large, and also due to variations in winding resistance and temperature. Since the fluctuation due to the change in the winding resistance also becomes large, the reliability of the second estimated rotation speed is low. Therefore, for example, determination from the voltage of the δ-axis component becomes impossible.

  Further, in the second conventional inverter device, the reliability of the shaft lock detection is lowered when the resistance of the winding is large, and the required torque immediately after starting is large. Because the power consumed by the winding resistance (copper loss) becomes large regardless of whether or not the shaft is locked, it is difficult to determine whether or not the shaft is locked based on the output difference of the input active power calculation unit. On the contrary, even when the required torque is small, the input power to the motor in a state where the shaft is not locked is small, so the shaft locked state is determined with a smaller threshold. It becomes difficult.

  In addition, about the winding resistance of the motor, since the copper wire that has been used for a long time has been replaced with aluminum wire in recent years, the tendency to increase the resistance value is often seen, There was also a tendency for the degree of the above problems to increase.

  Furthermore, although there are inverter devices that use a signal related to the speed and position of a permanent magnet by providing a light emitting element, a light receiving element, a hall element, etc. in an electric motor, estimation that interpolates discrete speed and position information is performed. As for the thing, since it is sometimes difficult or difficult to detect that the step-out has occurred, a similar problem exists for such an inverter device.

  The present invention solves the above-mentioned conventional problems, and even when the winding resistance is large and the speed is low, the step-out state is properly judged, and when it is detected as the step-out state, it is restarted early. An object of the present invention is to provide an inverter device in which the original function of the inverter device is restored to reduce electric energy and time loss.

  In order to solve the conventional problem, an inverter device of the present invention includes a motor having a permanent magnet and a winding, an inverter circuit that supplies a current to the winding, and a phase of the permanent magnet of the motor. First control means for outputting a drive signal to an inverter circuit, second control means for outputting a predetermined signal different from the first control means, the first control means, and the second control means Switching means for switching the output and restarting means for outputting a restart signal, the restarting means switching the switching means to the second control means at least once, and then issuing a restart signal, The electric motor is restarted.

  As a result, even in the specification where the resistance value of the winding of the motor is large, the condition where the induced electromotive force is low at low speed, etc., there are few misjudgments of detection, and in the step-out state, appropriate restart is performed by the restarting means, Electric energy and waste of time can be reduced.

  The inverter device of the present invention can improve performance in terms of suppressing electric energy and waste of time by detecting an appropriate step-out state.

Block diagram of the inverter device in the first embodiment of the present invention The circuit diagram of the inverter circuit of the inverter apparatus in the 1st Embodiment of this invention, and an electric current detection means Configuration diagram of electric motor and load in the first embodiment of the present invention Operation waveform diagram of inverter device in first embodiment of present invention The block diagram of the inverter apparatus in the 2nd Embodiment of this invention Operation waveform diagram of inverter device in second embodiment of the present invention. The block diagram of the inverter apparatus in the 3rd Embodiment of this invention Operation waveform diagram of inverter apparatus in third embodiment of the present invention. The block diagram of the inverter apparatus in the 4th Embodiment of this invention Operation waveform diagram of inverter apparatus in fourth embodiment of the present invention. Block diagram of first conventional inverter device Block diagram of second conventional inverter device

  1st invention outputs the drive signal to the said inverter circuit according to the phase of the permanent magnet of the said motor, the inverter circuit which supplies an electric current to the said winding, and the permanent magnet of the said motor A control means, a second control means for outputting a predetermined signal different from the first control means, a switching means for switching the outputs of the first control means and the second control means, and a restart signal The restarting means outputs the restart signal after switching the switching means to the second control means at least once, and restarts the motor, thereby restarting the motor. Even in specifications with large winding resistance, low speed and low induced electromotive force, there are few detection errors, and in the out-of-step condition, restarting is performed properly by restarting means, wasting time and energy. To suppress It can be.

  The second invention outputs the drive signal to the inverter circuit so that the voltage supplied to the winding is substantially zero, particularly the second control means having the configuration of the first invention, and the restarting means When the current of the winding is smaller than the threshold value, the restarting signal is issued, so that the restarting means appropriately restarts in the step-out state.

  According to a third aspect of the present invention, the second control means of the first aspect of the invention outputs a drive signal to the inverter circuit so that the current supplied to the winding is substantially zero, and the restarting means When the voltage generated in the winding is smaller than the threshold value, it is possible to determine whether or not the step-out is not affected by the value of the winding resistance by issuing a restart signal. In the state, an appropriate restart is performed by the restarting means.

  According to a fourth aspect of the invention, the first control means of the configuration of the first aspect of the invention is characterized in that the speed detection means for detecting the speed of the electric motor, the speed command means for outputting a command speed, the command speed and the speed A speed error amplifier is provided that outputs a current command value in response to a difference in output of the detection means, and the second control means is a current having a response to the output of the speed detection means different from that of the first control means. The inverter circuit outputs a command value, and the inverter circuit is configured to supply a current to the electric motor so that a torque substantially proportional to the current command value of the switching means is generated from the electric motor. Even when the operation by the control means is such that the difference between the output of the speed detection means and the command speed is kept small, the output of the speed detection means in the state where the switching means selects the second control means is out of step. Not doing It enables determination since it differs from the value of a state.

  According to a fifth aspect of the invention, the first control means having the configuration of the first or fourth aspect of the invention has speed command means for outputting a command speed, and the speed command means receives a restart signal from the restart means. Therefore, the electric motor can be restarted in a state where the possibility of another step-out is low by adopting a configuration in which the command speed is reduced to substantially zero.

  According to a sixth aspect of the invention, in addition to the configuration of the first aspect of the invention, the first control means includes first speed command means for outputting a first speed command value, and the second control means is the first control means. A second speed command means for outputting a speed command value of 2, wherein the restarting means is configured to generate a restart signal in response to the output of the speed detecting means after switching by the switching means. From the difference in response of various physical quantities after the switching operation by the switching means is performed from the first speed command value to the second speed command value, it is possible to determine whether or not there is an appropriate step-out state. In the step-out state, the motor can be restarted by generating a restart signal from the restarting means.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram of an inverter device according to the first embodiment of the present invention. In FIG. 1, an electric motor 15, an inverter circuit 16, coordinate converters 17 and 18, first control means 19, second control means 20, speed / position detection means 21, switching means 22, restart means 23, current detection Means 24 are provided. The first control means 19 includes speed command means 25, subtractors 26, 27, 28, speed error amplifier 29, direct axis current command means 30, and current error amplifier 31. The second control means 20 has zero output devices 33 and 34.

  FIG. 2 shows a circuit diagram of the inverter circuit 16 and the current detection means 24 of the inverter device according to the first embodiment of the present invention. In FIG. 2, the inverter circuit 16 includes a DC power supply 36, an on / off circuit 37, IGBTs 38, 39, 40, 41, 42, 43, and diodes 45, 46, 47, 48, 49, 50. The current detection unit 24 includes shunt resistors 51, 52, and 53 and an amplifier 54. The amplifier 54 generates a voltage generated in the shunt resistors 51, 52, and 53 during the ON period of the low-potential-side IGBTs 41, 42, and 43. Is amplified and converted into a range of 0 to 5 V in the current (positive / negative) range to be used, and an analog voltage signal corresponding to the values of the three-phase currents Iu, Iv, and Iw is obtained. It has become a thing.

  In addition to such a configuration, the current detection means can be separated into three phases by sampling considering the timing with only one shunt resistor, and can detect current detection from a direct current component called DCCT. It is also possible to use only one or two-phase currents directly without using all three phases, and use Kirchhoff's law or the like.

  FIG. 3 shows a configuration diagram of the electric motor 15 and a portion connected thereto in the first embodiment of the present invention. In FIG. 3, the electric motor 15 has a stator 57 and a rotor 58, and the stator 57 is provided with three-phase windings 60, 61, and 62 that are concentratedly wound. Magnets 63, 64, 65, and 66 are provided on the surface of the iron core 67. However, the windings 60, 61, 62 may be distributed windings, and the permanent magnets 63, 64, 65, 66 may also be configured as an embedded magnet type provided embedded in the iron core 67. The number and the number of slots are not limited.

A coupling 71 is connected to the center of the rotor 58 by a shaft 70, and a load 73 having an inertia moment is rotatably provided through the shaft 72. The coupling 71 is in a state where the primary member 75 and the secondary member 76 are engaged with each other, and is coupled with a slight backlash, that is, play (backlash) in the rotation direction.

  In the above configuration, in the inverter device according to the first embodiment, current is supplied from the inverter circuit 16 to the windings 60, 61, 62, and the current detection unit 24 detects the currents Iu, Iv, Iw of each phase. . The drive signal from the first control means 19 reaches the inverter circuit 16 via the switching means 22 and the coordinate converter 17 and is separated into the straight axis component Iγ and the horizontal axis component Iδ by the coordinate converter 18. The speed / position detecting means 21 detects the instantaneous value of the electrical angle of the rotor 58 relative to the stator 57 from Iγ, Iδ, Vγ, Vδ. The γ-axis and the δ-axis are coordinate axes obtained by estimating the actual d-axis (straight axis) and q-axis (horizontal axis) of the electric motor 15 on the control side, respectively.

  In the present embodiment, the coordinate converter 17 converts Vγ, Vδ and the estimated phase θ into Vu, Vv, and Vw using Expression 1, and the coordinate converter 18 uses Expression 2 to convert Iu, Iv , Iw and the estimated phase θ are converted into Iγ and Iδ.

  As described above, the control for converting the voltage and current into the orthogonal coordinates that rotate in synchronization with the rotor 58 is generally called vector control, and various expressions other than cos can be used for the trigonometric function. What is necessary is just to select suitably by the convenience of the program of the microcomputer used for control, etc., and it does not stick to Formula 1 and Formula 2.

  The speed / position detection means 21 calculates the estimated position (estimated phase) θ by time integration of the estimated speed ω and always uses the equation 3 to keep the estimated coordinate γδ equal to the dq coordinate of the motor 15. The estimated speed ω is increased or decreased in such a direction that the phase error Δθ becomes zero. Here, Ra represents winding resistance, L represents an induction coefficient, and p represents time differentiation.

Regarding the induction coefficient, in the present embodiment, since the motor 15 is configured to have the permanent magnets 63, 64, 65, 66 on the surface of the rotor 58, the induction coefficient is almost a single value. When is a permanent magnet type, it is effective to use a q-axis inductance Lq.

  In addition, about the direct-axis current command means 30, when it is set as the structure which provided the permanent magnets 63, 64, 65, 66 on the surface of the rotor 58, it is good also as what outputs only zero, and the actual Iγ value is If the value is sufficiently close to zero, it is possible to omit the term multiplied by Iγ as appropriate. In that case, the microcomputer used for the control may have a low capacity and a low price. It becomes possible.

  Although Equation 3 is described using an arctangent function, 0 to 2π or −π to + π, which is an angle corresponding to four quadrants with the denominator as the X axis and the numerator as the Y axis, is output. The function may be used, and even when there is a large angle deviation, the control is performed as intended, and Δθ can be converged to zero at an early stage.

  As a result of the operation of the speed / position detection means 21, a current corresponding to the phase (position) of the permanent magnets 63, 64, 65, 66 of the electric motor 15 is supplied from the inverter circuit 16 to the windings 60, 61, 62. The horizontal axis current command value Iδr, which is a command value that is substantially proportional to the torque, is output from the speed error amplifier 29. As a result, the speed signal ωs output from the speed / position detection means 21 is in a state in which the speed control is performed so as to be substantially equal to the output ωr of the speed command means 25, and a highly efficient operation is performed.

  On the other hand, since the second control means 20 outputs a value different from the first control means 19 and becomes zero, the switching means 22 switches from the first control means 19 to the second control means 20. At this stage, the inputs Vγ and Vδ of the coordinate converter 17 are both zero, and Uc, Vc and Wc are all zero in the inverter circuit 16. Accordingly, the second control means 20 outputs a drive signal (Vγ = 0, Vδ = 0) to the inverter circuit 16 so that the voltage supplied to the windings 60, 61, 62 is substantially zero.

  Here, as a result of the IGBTs 41, 42 and 43 being continuously turned on, the input voltage of the motor 15 is zero V, that is, a state equivalent to a short-circuit state, and the motor 15 is in a state where a short-circuit brake is applied.

  Even when the IGBT circuit 38, 39, 40, 41, 42, 43 is turned on / off with PWM having a predetermined triangular wave carrier frequency (for example, 15.625 kHz) while the inverter circuit 16 is three-phase modulated, the input of the motor 15 is zero. Thus, if it is configured so that the compensation for the dead time is properly performed in the on / off circuit 37, a completely equivalent short-circuit state is obtained.

  FIG. 4 shows an operation waveform diagram of the inverter device according to the first embodiment of the present invention. In FIG. 4, (a) is the state in which the first control means 19 is selected in the waveform of the switching signal S of the switching means 22, and the state in which the second control means 20 is selected is S2. (A) shows the voltage Vuv between UVs among the input voltages between the lines of the electric motor 15, and other line voltages are omitted because they become complicated. (C) shows the U-phase line current Iu in the input current of the motor, and other line currents are omitted because they become complicated.

  The period immediately before t1 is the state in which the switching signal S is S1, and the power control operation is performed by the first control means 19, and both the line voltage Vuv and the line current Iu are substantially sinusoidal. The value is almost constant.

During the period from t1 to t2, the switching signal S is in the state of S2, and the second control means 20 is in a short-circuit braking state, so the line voltage Vuv becomes substantially zero. t1 to t2
The line current Iu during this period is greatly different between when the motor 15 is in a step-out state and when it is operating normally. In step (c), the step-out state is almost zero as shown by the solid line. When normal, the waveform is close to a sine wave having an amplitude as indicated by a broken line.

  This is because the motor 15 is actually rotating at the normal time, and the moment of inertia of the load 73 also has motion energy. Therefore, during the period from t1 to t2, the motor 15 is rotated by the motion energy and is caused by the induced electromotive force. This is because current flows. On the other hand, since the rotation of the load 73 is almost zero at the time of step-out and the movement energy is also almost zero, the current value during the period from t1 to t2 is almost zero.

  Therefore, the line current (winding current) Iu in the period from t1 to t2 is compared with a predetermined threshold in the restarting means 23, and when the winding current is smaller than the threshold, the step-out is performed. A restart signal F is issued when the state is determined.

  In this embodiment, in addition to the switching means 22, the restarting means 23 inputs signals to the speed error amplifier 29 and the current error amplifier 31. For the period of S 2, the subtractors 26, 27, and 28 Regardless of the output value, the speed error in the speed error amplifier 29 and the current error in the current error amplifier 31 are all forcibly fixed to zero. As a result, the value of the integrator built in the speed error amplifier 29 and the current error amplifier 31 to realize PI control (feetback control using a proportional component and an integrator component) is S2 during the period. It is assumed to be fixed, and unnecessary values are prevented from being accumulated in these integrators.

  In the present embodiment, detection is performed using the line currents Iu, Iv, and Iw. For example, the current is obtained by calculating the sum of squares from the outputs Iγ and Iδ converted to γδ coordinates by the coordinate converter 18. It may be possible to detect that the current of the winding is smaller than the threshold value by obtaining the magnitude of the vector and comparing the value with a threshold value.

  In FIG. 4, after t2, the switching signal S of the switching means 22 becomes S1 again, and the first control means 19 returns to the selected state. Under normal conditions, such an operation is thereafter t3, t4. , ... and will be repeated periodically.

  However, in the step-out state, it can be determined that the step-out state has occurred during the period (t1-t2, t3-t4) in which the switching unit 22 has switched to the second control unit 20 at least once. After the time point, the restart is performed by the restart signal F from the restarting means 23. At this time, in this embodiment, the speed command means 25 is assumed to reduce the command speed ωr to almost zero. Yes.

  When the motor 15 is started by the restarting means 23, the actual speed of the motor 15 is substantially zero at the initial stage, so that the speed ω and the position θ cannot be estimated by the speed / position detecting means 21. There is a period. Therefore, it is effective to accelerate the magnitude of the induced electromotive force to a speed at which the speed and position (phase) can be estimated by providing a period called forced synchronization. For this, those described in Japanese Patent Application Laid-Open No. 2014-113293 filed by the inventors can be used.

  By the operation described above, restart is performed from a state that is out of step and matches the state where the actual speed of the electric motor 15 is almost zero, and it is possible to recover a favorable operation.

(Embodiment 2)
FIG. 5 shows a block diagram of an inverter device according to the second embodiment of the present invention. Also in FIG. 5, the same reference numerals are given to the same components as those in the first embodiment. Components different from the first embodiment include a first control unit 78, a second control unit 79, a switching unit 80, and a restart unit 83. In the present embodiment, the second control unit 79 is provided. The inverter circuit via the switching means 80, the subtractors 27 and 28, the current error amplifier 31 and the coordinate converter 17 so that the currents Iu, Iv and Iw supplied to the windings 60, 61 and 62 are substantially zero. The drive signal is output to 16.

  The first control means 78 also outputs a drive signal to the inverter circuit 16 via the switching means 80, the subtractors 27 and 28, the current error amplifier 31, and the coordinate converter 17, and operates the motor 15. It has become.

  The restarting unit 83 generates a restart signal F when the voltage generated in the windings 60, 61, 62 is smaller than the threshold value.

  FIG. 6 is an operation waveform diagram of the inverter device according to the second embodiment of the present invention. In FIG. 6, (a) shows the state of selecting the first control means 78 in the waveform of the switching signal S of the switching means 80, and the state of selecting the second control means 79 is S2. (A) shows the voltage Vuv between UVs among the input voltages between the lines of the electric motor 15, and other line voltages are omitted because they become complicated. (C) shows the U-phase line current Iu in the input current of the motor, and other line currents are omitted because they become complicated.

  The period immediately before t1 is the state in which the switching signal S is S1, and the power control operation is performed by the first control means 78, and both the line voltage Vuv and the line current Iu are substantially sinusoidal. The value is almost constant.

  During the period from t1 to t2, the switching signal S is in the state S2, and as shown in (c) by the second control means 79, Iu, Iv and Iw are all zero, that is, open. On the other hand, for the line voltage Vuv shown in (a), an induced electromotive force having an amplitude proportional to the actual speed of the electric motor 15 is generated. The line voltage Vuv during the period from t1 to t2 is greatly different between when the motor 15 is in a step-out state and when it is operating normally, and the step-out state is indicated by a solid line in (a). It becomes almost zero at normal time, and becomes a waveform close to a sine wave having an amplitude as shown by a broken line in normal operation.

  This is because, as in the first embodiment, the motor 15 is actually rotating during normal operation, and the moment of inertia of the load 73 also has motion energy. Therefore, during the period from t1 to t2, the motion energy This is because the electric motor 15 is rotated and an induced electromotive force is generated. On the other hand, at the time of step-out, the rotation of the load 73 is almost zero and the movement energy is also almost zero, so that the voltage value during the period from t1 to t2 is almost zero.

  Therefore, the restart means 83 compares the voltage Vuv in the period from t1 to t2 with a predetermined threshold value. An activation signal F is issued.

  In the present embodiment, since the operation by the second control means 79 is performed so that the current value flowing through the windings 60, 61, 62 becomes zero, the resistance of the windings 60, 61, 62 is increased. Specifications, for example, a configuration in which a large number of thin aluminum wires are wound, can be made unaffected because the current value is zero, even if there are variations in winding resistance or changes due to temperature rise, etc. There is an advantage that reliable step-out detection becomes possible.

Therefore, it is effective when the speed / position detecting means 21 called sensorless is configured without using a rotation sensor such as a Hall element, a light emitting element, and a light receiving element, but is not limited thereto. In the present embodiment, as in the first embodiment, during the period when the second control means 79 is selected by the switching means 80, the operation is independent of the speed / position detection means 21. For example, even when the position and position of the rotor 58 is directly detected by using a Hall IC, a magnetic pickup, a light emitting element, a light receiving element or the like as a speed / position detection means, This effectively functions as step-out detection (abnormality detection) in the event of failure.

(Embodiment 3)
FIG. 7 is a block diagram of an inverter device according to the third embodiment of the present invention. Also in FIG. 7, the same reference numerals are given to the same components as those in the first embodiment.

  In the present embodiment, components different from the first embodiment include a first control means 85 and a second control means 86. The first control unit 85 includes a speed detection unit 87 that detects the speed of the electric motor 15, and a speed command unit 88 that outputs a command speed ωr, and the second control unit 86 outputs the output of the speed detection unit 87. The horizontal axis current setting means 93 outputs a current command value different from that of the first control means 85, and the inverter circuit 16 generates a torque from the motor 15 that is substantially proportional to the current command value Iδr of the switching means 91. The electric current is supplied to the electric motor 15 so that the electric current is generated.

  In the present embodiment, Vγ, Iγ, and Iδ are input to the speed detection means 87, and using Equation 4, an error between the estimated coordinate γδ and the actual dq coordinate of the motor 15 is detected as εγ, and this is zero. This is realized by performing feedback control to increase or decrease the estimated speed ω in the direction of

  In addition, when Iγ is set to zero and the control is performed to a value close to the command value, there are cases where it can be omitted, and the time derivative (d / dt) is indicated. p can be omitted if not necessary.

  The speed detecting means 87 constitutes a speed / position detecting means 95 that outputs the estimated speed to the integrator 94 and time-integrates the estimated speed to output the position estimation signal θ to the coordinate converter 18. As in the first embodiment, an operation for outputting the estimated phase θ is performed.

  Similar to the first embodiment, the speed error amplifier 29 receives the difference between the command speed ωr that is the output of the subtractor 26 and the output of the speed detector 87 and outputs a current command value Iδr.

  In addition to switching the switching means 91 between S1 and S2, the restarting means 90 outputs a signal to the speed error amplifier 29 as in the first embodiment. During the period of S2, the restarting means 90 By forcibly fixing the error to zero, the internal integrator is prevented from being piled up.

  In the present embodiment, the direct-axis current command means 30 always commands zero and outputs it to the subtractor 27 regardless of the switching means 91.

  The horizontal axis current setting means 93 receives the output signal of the speed error amplifier 29 and outputs a current command value obtained by adding 0.5 A to the value. In the S2 period, the current command value immediately before switching to S2 A fixed value obtained by adding 0.5 A to the current command value Iδr is output.

  When the restart signal F from the restarting means 90 enters the speed command means 88, the command speed ωr is reduced to almost zero.

  The operation of the above configuration will be described. FIG. 8 is an operation waveform diagram of the inverter device according to the third embodiment of the present invention. In FIG. 8, (a) shows the state of selecting the first control means 85 in the waveform of the switching signal S of the switching means 91, and the state of selecting the second control means 86 is S2. (B) indicates the current command value Iδr on the horizontal axis output from the switching means 91 to the subtractor 28, (c) indicates the speed command value ωr output from the speed command means 88 by a one-dot chain line, and the speed detection means 87 Shows the waveform of the output ωs. Furthermore, regarding ωs, the solid line indicates the step-out state, and the broken line indicates the normal state.

  During the period until just before t1, the switching signal S is in the state S1, and the normal operation in which the speed control is valid is performed by the first control means 85, and the output of the speed detection means 87 ωs is in a state where it is controlled to a value that is substantially equal to the speed command value ωr, that is, the speed error is close to zero.

  The period from t1 to t2 is a state in which the switching signal S is S2, and as shown in (b) by the second control means 86, 0.5 A with respect to the Iδr value at the time point t1. It is fixed to the value obtained by adding. However, the value added in this way does not necessarily have to be Iδr, and conversely, a value obtained by subtracting a predetermined value from the Iδr value at time t1 may also be used, and a fixed value unrelated to Iδr at time t1. And so on.

  When adding or subtracting from the Iδr value at the time t1, the necessary torque fluctuates when there is a large fluctuation in the load 73, and the Iδr value may be accompanied by vibration of a high frequency component. In many cases, it effectively functions if the value obtained by removing unnecessary high-frequency components through an LPF (low-pass filter) having an appropriate frequency characteristic is the Iδr value at the time t1.

  In any case, since the speed control loop including the speed error amplifier 29 does not function during the period in which the second control means 86 is selected, ωs has no element that follows the speed command value ωr, It becomes a divergence.

  FIG. 8 shows an example in which the high speed side, that is, the state where ωs exceeds ωr and further increases, there may be a case where the light diverges to the low speed side. In the case of divergence toward the high speed side, it is possible to provide an element for detecting step-out separately in the restarting means 90 when the step-out detection according to Formula 5 becomes possible. If the rotation is 100 revolutions per minute, it is possible to detect a step-out state where the actual speed of the electric motor 15 is almost zero and output the restart signal F because εδ according to Equation 5 is lower than a predetermined value. .

Equation 5 is a value substantially equivalent to the induced electromotive force (ω · Ke) of the electric motor 15 under normal conditions. However, Equation 5 is also used by performing processing such as omitting a term having no problem even if it is absent. It doesn't matter.

  The normal state is the same in that the speed control diverges, but the speed of the speed increase that occurs because Iδr increases by 0.5 A in the period from t1 to t2, that is, the acceleration increases the torque. When the load 73 is a large moment of inertia such as a drum of a washing machine or a dewatering tub, the value is suppressed to a small value, and the speed increase in a period of 250 ms is several rotations per minute. Therefore, it is possible to make a design that does not hinder normal operation. Therefore, by comparing with the threshold value of ωth shown in (c), it is possible to distinguish between a step-out time and a normal time. The restart at the time of step-out by the restarting means 90 is the same as in the first embodiment.

(Embodiment 4)
FIG. 9 is a block diagram of an inverter device according to the fourth embodiment of the present invention. In FIG. 9, the same components as those in the third embodiment are denoted by the same reference numerals. In the present embodiment, the first control means is different from the third embodiment. 98, the second control means 99, and the switching means 100. The first control means 98 has the first speed command means 102 for outputting the first speed command value ωr1, and the second control. The means 99 has second speed command means 103 for outputting a second speed command value ωr2. The restarting unit 104 generates a restarting signal F in response to the output of the speed detecting unit 87 that detects the speed of the electric motor 15 after switching by the switching unit 100.

  The operation of the above configuration will be described. FIG. 10 is an operation waveform diagram of the inverter device according to the fourth embodiment of the present invention. In FIG. 10, (a) shows the state of selecting the first control means 98 in the waveform of the switching signal S of the switching means 100, and the state of selecting the second control means 99 is S2. (A) is the speed command value ωr output from the switching means 100 to the subtractor 26, and (c) is the output ωr1 of the first speed command means 102 and the output ωr2 of the second speed command means 103 to the thin broken line. In addition, the speed command value ωr serving as the output of the switching means 100 is indicated by a solid line (when out of step) and a broken line (when normal). In addition, the thick dashed-dotted line has shown the threshold value.

  The period until immediately before t1 is a state in which the switching signal S is S1, and the speed control of the normal operation is performed by the first control means 98, and the output ωs of the speed detection means 87 is almost equal. In this state, the speed command value ωr1 is almost equal to the value, that is, the speed error is controlled to a value close to zero.

  During the period from t1 to t2, the switching signal S is in the state S2, and as shown in (a), the second control means 99 increases ωr2 by 100 revolutions per minute through the switching means 100. The speed control command value ωr is switched to ωr2 by being input to the subtractor 26.

  In the present embodiment, since speed control is effective even during the period of S2, it does not shift to divergence, but since ωr2> ωr1, it is a command to accelerate.

  At the time of step-out, the actual motor 15 is in a state where the speed is substantially zero, and ωs is a value close to ωr regardless of the actual speed. Therefore, when the speed command value increases, It moves regardless of the moment of inertia, and when it follows ωr, it follows in a short time even if the application has a large moment of inertia. On the other hand, in the normal state, as in the third embodiment, since the motor 15 and the load 73 are actually rotating, the response of ωs affected by the moment of inertia is obtained.

  Therefore, in an application to which a load 73 having a large moment of inertia is connected, the speed increase is small at 200 ms as shown by the thick broken line in (c), and the design can be made without any trouble in normal operation. Therefore, by comparing the threshold value ωth for ωs between ωr1 and ωr2 shown in (c), it is possible to distinguish between step-out and normal time.

  At this time, if the Iδ value or its command value Iδr instead of ωs can be distinguished from the step-out time and the normal time by comparing with the threshold value based on the difference between the step-out time and the normal time, Such a configuration is also possible. The restarting means 104 is similar to the third embodiment in that it gives a signal to the speed command means 102 so as to reduce the speed command value ωr1 to zero in the case of step-out.

  As described above, the inverter device of each embodiment can appropriately detect the step-out state.

  In the step-out state in the inverter device, when the actual rotation of the electric motor continues to be almost zero (stopped), the inverter device is in a state where it cannot do the work that should be done, so time, electric energy is wasted, etc. Various problems occur, and in some cases, vibration and noise are scattered. Furthermore, there is a type of step-out state in which the estimated speed follows the command speed and the speed error approaches zero.

  First, regarding the induction coefficient value that is a parameter of the motor, if the value set in the speed / position estimation means is smaller than the actual value of the motor, the estimated speed tends to follow the command speed. There is an element in which the same speed control as in normal operation is established.

  If there is backlash, the estimated speed tends to follow the command speed. The backlash may be intentionally provided, but may occur unintentionally in a configuration in which the motor 15 and the load 73 are not directly connected by a single shaft.

  In any case, when the backlash moves, the reciprocating motion (alternating) is minute, and the direction of the reciprocation is small in phase with the current supplied to the winding, and the interlinkage flux of the winding However, the induced electromotive force generated in the winding at this time has a polarity that cancels the increase in the linkage flux of the winding, and the torque required to move the backlash is very small. The phase is approximately 90 degrees ahead of the current vector of the winding.

  The response of the speed / position estimation means when receiving such an induced electromotive force is as follows: the estimated speed <the command speed Iδ> 0 in the direction of increasing the estimated speed, and the estimated speed> the command speed Iδ < At 0, the estimated speed is reduced. Therefore, in any case, the absolute value of the speed error is reduced, that is, the estimated speed is brought closer to the command speed, and the estimated speed follows the command speed as if the speed control is established. It may occur.

  In a configuration where backlash exists, there is a tendency for noise and vibration due to movement of the backlash part to occur when the step-out state occurs, and the step-out state should be detected in the shortest possible time. Is also effective in terms of reducing noise and vibration.

Also, when there is an elastic element in the power transmission path from the motor to the load and a mechanical resonance frequency (also known as an anti-resonance frequency) due to the inertia element of the load, the estimated speed converges at or near that frequency. The phenomenon will also occur. As an elastic element, for example, in the case where a pulley is provided for both the electric motor and the load and a belt is stretched between them to transmit power, the elasticity of the belt corresponds to that, and the inertia moment on the electric motor side If there is a mechanical resonance, the above resonance frequency (anti-resonance frequency) is obtained.

  In the present invention, such a step-out state is accurately detected, a restart signal is output from the restart means, and the electric motor is restarted to return to a normal operating state in which work as an inverter device can be performed. Thus, the normal operation as the inverter device can be recovered early.

  Accordingly, it is possible to suppress waste of electric energy, time, etc. that occur when the step-out state continues, to realize energy saving and time reduction, and to minimize generation of noise and vibration.

  In addition, the sensorless operation at normal time (when not out of step) is good, but it is difficult to detect when it is out of step, so a position sensor and speed sensor can be provided. In this case, the improvement of the performance of step-out detection according to the present invention makes it possible to eliminate or reduce the number of sensors, thereby reducing costs, saving resources, reducing weight, and failure of sensor components. Effects such as a reduction in probability can be obtained.

  As described above, the inverter device according to the present invention is applied to various types of inverter devices used as a power source that improves the performance in terms of suppressing electric energy and waste of time by detecting an appropriate step-out state. it can.

DESCRIPTION OF SYMBOLS 15 Electric motor 16 Inverter circuit 19, 78, 85, 98 1st control means 20, 79, 86, 99 2nd control means 22, 80, 91, 100 Switching means 23, 83, 90, 104 Restart means 87 Speed Detection means 25, 88 Speed command means 29 Speed error amplifier 63, 64, 65, 66 Permanent magnet 60, 61, 62 Winding 102 First speed command means 103 Second speed control means

Claims (6)

A motor having a permanent magnet and a winding; an inverter circuit for supplying a current to the winding; a first control means for outputting a drive signal to the inverter circuit in accordance with a phase of the permanent magnet of the motor; Second control means for outputting a predetermined signal different from that of the first control means, switching means for switching the outputs of the first control means and the second control means, and restart means for outputting a restart signal And the restarting means generates an restart signal and restarts the electric motor after switching the switching means to the second control means at least once. The second control means outputs a drive signal to the inverter circuit so that the voltage supplied to the winding is substantially zero, and the restarting means has a case where the current of the winding is smaller than a threshold value. The inverter device according to claim 1, wherein a restart signal is issued. The second control means outputs a drive signal to the inverter circuit so that the current supplied to the winding is substantially zero, and the restarting means has a voltage generated in the winding smaller than a threshold value. The inverter device according to claim 1, wherein in some cases, a restart signal is issued. The first control means outputs a current command value in response to a difference between a speed detection means for detecting the speed of the electric motor, a speed command means for outputting a command speed, and a difference between the command speed and the output of the speed detection means. The second control means outputs a current command value that is different from the first control means in response to the output of the speed detection means, and the inverter circuit outputs a current command value of the switching means. The inverter device according to claim 1, wherein a current is supplied to the electric motor so that a torque substantially proportional to the value is generated from the electric motor. The first control means includes speed command means for outputting a command speed, and the speed command means receives a restart signal from the restart means and reduces the command speed to substantially zero. The inverter device described in 1. The first control means has first speed command means for outputting a first speed command value, and the second control means has second speed detection means for detecting the speed of the electric motor. 2. The inverter according to claim 1, further comprising a second speed command unit that outputs a speed command value, wherein the restart unit generates a restart signal in response to an output of the speed detection unit after switching by the switching unit. apparatus.

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