JP2017192294A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device capable of suppressing pulsation of rotary speed immediately after start of operation even without using a large-scale detector.SOLUTION: A pulsation extraction unit 30 extracts speed of a pulsation component having a specific frequency, pulsation speed, from a speed detection value calculated by a speed calculator 80. A pulsation acceleration calculator 41 calculates acceleration of the pulsation component, pulsation acceleration, from the pulsation speed extracted by the pulsation extraction unit 30. A multiplier 42 multiplies the pulsation acceleration by a predetermined coefficient k and converts a multiplication result to a voltage to calculate a compensation voltage value. An adder 50 adds the compensation voltage value to a q-axis voltage command value calculated by a current controller 13 to correct the q-axis voltage command value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric motor control device that controls an electric motor.

  When driving the electric motor, pulsation occurs in the rotational speed due to disturbance torque due to periodic fluctuations in the load and disturbance torque such as magnet torque and cogging torque of the electric motor itself. This pulsation causes vibration and noise of the motor itself and a mechanical device using the motor as a drive source. Such pulsation is particularly noticeable during low-speed driving, and becomes a barrier when realizing smooth and highly accurate driving of the mechanical device.

  The following patent documents are known as conventional techniques for solving these problems. In Patent Document 1, a torque detector is provided between an electric motor and a load, a torque pulsation component is detected by Fourier transforming a torque detection value detected by the torque detector, and torque pulsation compensation is performed based on the detected torque pulsation component. A technique for suppressing pulsation by learning electric current is disclosed.

  In Patent Document 2, a torque detector is provided on the output shaft of an electric motor, an m-dimensional harmonic component is calculated from the torque detected by the torque detector, and the calculated m-dimensional harmonic component is time-integrated to obtain an m-dimensional harmonic. A correction value for correcting the wave component is learned. And the technique which outputs the electric current command to an electric motor based on the learned correction value, and suppresses a torque pulsation is disclosed.

  Patent Document 3 extracts a vibration component of a specific frequency from the vibration of a motor detected by an acceleration sensor, decomposes the vibration component into a main vibration component and a pulsation vibration component of the specific frequency, and obtains the obtained main vibration component. The technology which suppresses the pulsation of a motor by generating the compensation signal which suppresses all of the pulsation vibration component and the pulsation vibration component simultaneously is disclosed.

International Publication No. 2010/024194 JP 2013-198221 A JP 2012-80614 A

  In any of the above technologies, dedicated detectors such as a torque detector and an acceleration detector are added to suppress pulsation and vibration, but such a dedicated detector is large and expensive. However, there is a problem that the cost of the system is increased, and at the same time, the number of parts is increased and the reliability of the system is lowered.

  In particular, since the torque detector increases in cost and size as the torque to be detected increases, there is a problem in terms of mountability on a mechanical device.

  Furthermore, in Patent Documents 1 and 2, learning control is used, but learning requires a certain amount of time and learning must be performed every time the apparatus is operated. There is a problem that a time lag occurs every time until the pulsation is sufficiently suppressed. In particular, when the techniques of Patent Documents 1 and 2 are applied to a working machine operated by an operator, a pulsation is generated every time, which causes a problem of annoying the operator. Further, since the pulsation is suppressed after the time lag elapses, there arises a problem that the operator feels different operation feeling before and after the time lag elapses.

  The objective of this invention is providing the control apparatus of the electric motor which can suppress the pulsation of rotational speed immediately after an operation start, without using a large-scale detector.

A motor control device according to an aspect of the present invention includes a voltage command value calculation unit that calculates a voltage command value for setting the rotation speed of the motor to a target speed,
A drive unit that drives the electric motor based on the voltage command value calculated by the voltage command value calculation unit;
A speed detector for detecting the rotational speed of the electric motor;
A pulsation extraction unit that extracts a pulsation component of a specific frequency from the rotation speed detected by the speed detection unit;
A pulsation acceleration that is an acceleration of the pulsation component is calculated from the pulsation component extracted by the pulsation extraction unit, and the calculated pulsation acceleration is multiplied by a predetermined coefficient for applying a virtual inertial load to the pulsation component. A compensation voltage calculation unit that calculates a compensation voltage value by converting the multiplication result into a voltage;
An adder for adding the compensation voltage value calculated by the compensation voltage calculation unit to the voltage command value.

  According to this aspect, the pulsation component is extracted from the detected rotational speed, the pulsation acceleration is calculated from the extracted pulsation component, the calculated pulsation acceleration is multiplied by the predetermined coefficient, and the multiplication result is converted into a voltage. Thus, the compensation voltage value is calculated, and this compensation voltage value is added to the voltage command value. As a result, the voltage value of the pulsating component increases in the voltage command value, and a virtual inertia load can be applied only to the pulsating component. As a result, the electric motor can be controlled using a voltage command value that suppresses the pulsation component, and the rotation speed pulsation can be suppressed.

  Thus, in this aspect, since the pulsation component can be suppressed without learning, the pulsation component can be suppressed immediately after the start of operation of the electric motor.

  In this aspect, since a high-cost and large-scale torque detector and acceleration sensor are not used, the apparatus can be configured at a low cost and on a small scale.

In the above aspect, the pulsation component includes first and second pulsation components having different frequencies,
The pulsation extraction unit includes first and second pulsation extraction units corresponding to the first and second pulsation components,
The compensation voltage calculation unit includes first and second compensation voltage calculation units corresponding to the first and second pulsation components,
An integrator for adding the first and second compensation voltage values calculated by the first and second compensation voltage calculators;
The adder may add the added first and second compensation voltage values to the voltage command value.

  According to this aspect, a plurality of sets of pulsation extraction units and compensation voltage calculation units are provided in parallel corresponding to a plurality of pulsation components having different frequencies, so that a plurality of pulsation components can be suppressed simultaneously.

Further, in the above aspect, a third pulsation extraction unit that extracts a pulsation component of the specific frequency from the target speed;
A response compensation voltage is calculated by calculating a third pulsation acceleration from the pulsation component extracted by the third pulsation extraction unit, multiplying the calculated third pulsation acceleration by the predetermined coefficient, and converting the multiplication result into a voltage. A third compensation voltage calculation unit for calculating a value;
A first subtractor that subtracts the response compensation voltage value from the compensation voltage value calculated by the compensation voltage calculation unit;
The adder may add a compensation voltage value obtained by subtracting the response compensation voltage value to the voltage command value.

  If only a virtual inertia load is applied to a pulsation component of a specific frequency, an excessive inertia load is applied when the target speed changes, and the responsiveness of the rotational speed to the change in the target speed deteriorates. In this aspect, the response compensation voltage value is calculated based on the pulsation component extracted from the target speed, and this response compensation voltage value is subtracted from the compensation voltage value calculated by the compensation voltage calculation unit. For this reason, the compensation voltage value can be applied only to suppression of pulsation, and deterioration of responsiveness to speed control can be avoided.

In the above aspect, the voltage command value calculation unit calculates a target current value for setting a speed deviation between the rotation speed of the electric motor detected by the speed detection unit and the target speed to 0, and the target current value And a voltage command value for making a current deviation between the current value supplied to the electric motor 0 and zero,
A second subtracter for subtracting the pulsation component extracted by the third pulsation extraction unit from the pulsation component extracted by the pulsation extraction unit;
You may further provide the 3rd subtracter which subtracts the subtraction result by the said 2nd subtracter from the speed deviation of the said target speed and the rotational speed of the said motor detected by the said speed detection part.

  When the compensation voltage value obtained by reducing the response compensation voltage value is added to the voltage command value, the difference term between the pulsation component of the target speed and the pulsation component of the rotational speed included in the reduced compensation voltage value is current feedback control. There is a possibility that a large pulsation will occur at the start of the control due to interference with the voltage command value calculated by.

  According to this aspect, the pulsation component extracted by the third pulsation extraction unit is subtracted from the pulsation component extracted by the pulsation extraction unit, and the subtraction result is calculated between the target speed and the rotation speed detected by the speed detection unit. It is subtracted from the speed deviation.

  Therefore, the difference term between the pulsation component of the target speed and the pulsation component of the rotational speed included in the reduced compensation voltage value is weakened by the subtraction result, and the influence of the interference can be weakened. Large pulsations appearing can be suppressed.

  In the above aspect, the target speed may change periodically.

  According to this aspect, even when the target speed changes periodically, it is possible to avoid deterioration of responsiveness to speed control.

  In addition, the pulsation extraction unit may extract the pulsation component using a bandpass filter having the specific frequency as a pass frequency.

  According to this aspect, since the band pass filter having a specific frequency as the pass frequency is used, the pulsation component can be accurately extracted.

Further, in the above aspect, the voltage command value calculation unit calculates voltage command values for the d axis and the q axis,
The adder may add the compensation voltage value to the q-axis voltage command value.

  Since the compensation voltage value is calculated by multiplying the pulsation acceleration by a coefficient and converting it to a voltage, it indicates a voltage command value corresponding to the inertia torque of a virtual inertia load. In this aspect, since the compensation voltage value is added to the q-axis voltage command value, which is the torque component of the voltage command value, inertia torque can be accurately applied to the motor.

  According to the present invention, it is possible to suppress the pulsation of the rotational speed immediately after the start of operation without using a dedicated detector such as a torque detector or an acceleration detector.

It is a block diagram which shows the structure of the control apparatus of the motor which concerns on embodiment of this invention. It is a figure explaining the voltage compensation by the compensation voltage value shown in FIG. It is a block diagram which shows the detail of the pulsation extraction part shown in FIG. 1, and a compensation voltage calculation part. It is a Bode diagram of a band pass filter shown in Formula (1). 6 is a graph showing the results of a simulation performed to confirm the suppression effect of pulsation components in the first embodiment. It is a block diagram of the control apparatus which concerns on Embodiment 2 of this invention. It is a figure explaining the fall of the responsiveness by having provided the inertial load to the motor when the target speed changes. It is a block diagram which shows the structure of the control apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows the detail of the pulsation extraction part shown in FIG. 8, and a compensation voltage calculation part. 10 is a graph showing the results of a simulation performed to confirm the suppression effect of pulsation components in the third embodiment. It is a block diagram which shows the structure of the control apparatus of the motor which concerns on Embodiment 4 of this invention. 10 is a graph showing the results of a simulation performed to confirm the effect of suppressing a pulsating component in Embodiment 4. 10 is a graph showing the results of a simulation performed to confirm the effect of suppressing a pulsating component in Embodiment 4.

  Hereinafter, a control device for an electric motor (hereinafter referred to as “motor”) according to an embodiment of the present invention will be described with reference to the drawings. In recent years, vector control is generally used for speed control of a three-phase brushless motor such as a permanent magnet synchronous motor. Therefore, also in this embodiment, vector control is adopted as the motor speed control.

[Embodiment 1]
FIG. 1 is a block diagram showing a configuration of a control device 1 for a motor M according to an embodiment of the present invention. The control device 1 includes a subtracter 5, a voltage command value calculation unit 10, a drive unit 20, a pulsation extraction unit 30, a compensation voltage calculation unit 40, an adder 50, an uvw / dq converter 60, an angle detector 70 (speed detection unit). ), A speed calculator 80 (corresponding to a speed detector), and current sensors 81, 82, 83.

  The angle detector 70 is composed of, for example, a resolver, an encoder, and the like, detects the rotation angle of the motor M, and outputs the detected rotation angle to the speed calculator 80 as an angle detection value. Here, as the angle detection value, for example, the rotation angle of the rotor with respect to the reference rotation position can be adopted. The speed detection value (an example of the rotation speed) has a positive value, for example, when the rotor is rotating in a predetermined first direction (for example, clockwise direction), and the rotor is in the first direction. When rotating in a second direction opposite to (for example, counterclockwise direction), the rotation direction may be distinguished by having a negative value.

  The speed calculator 80 differentiates the detected angle value detected by the angle detector 70, calculates the rotational speed of the motor M, and outputs it as a detected speed value.

  The subtracter 5 subtracts the speed detection value from the target speed to calculate a speed deviation. The target speed varies depending on the device to which the motor M is applied. For example, if the motor M is used to drive a winch drum, an upper swing body, or a lower traveling body of a construction machine, the target speed is set to a value corresponding to the operation amount of the operation lever. Further, if the motor M is applied to a travel motor of an electric vehicle or a hybrid vehicle, the target speed is set to a value corresponding to the accelerator operation amount.

  The voltage command value calculation unit 10 calculates a target current value for setting the speed deviation between the rotation speed of the motor M calculated by the speed calculator 80 and the target speed to 0, and is supplied to the target current value and the motor M. A voltage command value for making the current deviation from the current value to be zero is calculated. Specifically, the voltage command value calculation unit 10 includes a speed controller 11, a current command generator 12, a current controller 13, and subtracters 14 and 15.

  The speed controller 11 receives the speed deviation from the subtractor 5 and calculates a torque command value for setting the speed deviation to zero. Here, the speed controller 11 may calculate the torque command value using, for example, PI (proportional / integral) control. This is merely an example, and the speed controller 11 may calculate the torque command value using PID (proportional / integral / differential) control.

  The current command generator 12 calculates a d-axis target current value Id_ref and a q-axis target current value Iq_ref based on the torque command value. Here, the current command generator 12 may generate, for example, values predetermined for the torque command value as the target current values Id_ref and Iq_ref.

  The subtractor 14 subtracts the d-axis actual current value Id from the target current value Id_ref to calculate a d-axis current deviation. The subtracter 15 subtracts the q-axis actual current value Iq from the target current value Iq_ref to calculate a q-axis current deviation.

  The current controller 13 calculates a d-axis voltage command value for making the d-axis current deviation from the subtractor 14 zero, and q for making the q-axis current deviation from the subtractor 15 zero. Calculate the voltage command value of the shaft. The d-axis voltage command value is a command value for controlling the field component of the voltage output to the motor M, and the q-axis voltage command value is a command value for controlling the torque component of the voltage output to the motor M. . Here, the current controller 13 may calculate the voltage command values for the d and q axes using, for example, PI control. However, this is an example, and the current controller 13 may calculate the voltage command values for the d and q axes using PID control.

  The drive unit 20 includes a dq / uvw converter 21 and an inverter 22, and drives the motor M based on the d and q axis voltage command values generated by the current controller 13.

  The dq / uvw converter 21 performs coordinate conversion of the voltage command values for the d and q axes, generates a PWM signal composed of three phases of the uvw phase, and outputs the PWM signal to the inverter 22.

  The inverter 22 is configured by, for example, a three-phase inverter, generates UVW three-phase AC power from the three-phase PWM signal, and outputs the generated AC power to the motor M.

  The motor M is constituted by, for example, a three-phase brushless motor and is driven according to UVW three-phase AC power output from the inverter 22. For example, if the control device 1 is applied to a construction machine such as a crane or an excavator, the motor M rotates the upper swing body or rotates the winch drum. Moreover, if the control apparatus 1 is applied to an electric vehicle, the electric vehicle is caused to travel.

  The current sensors 81, 82, and 83 are each configured by, for example, a Hall type current sensor using a Hall element, and detect U, V, and W phase alternating currents.

  The uvw / dq converter 60 performs coordinate conversion of the U, V, and W phase AC currents detected by the current sensors 81, 82, and 83, calculates actual current values Id and Iq of the d and q axes, and a subtractor. 14 and 15 are output.

  The above is the basic configuration of the control device 1, and the motor M is feedback-controlled so that the detected speed value follows the target speed.

  The pulsation extraction unit 30 extracts a pulsation speed that is a speed of a pulsation component having a specific frequency from the speed detection value calculated by the speed calculator 80. Here, the pulsation extraction unit 30 may extract the pulsation speed using, for example, a second-order bandpass filter represented by the transfer function of Expression (1).

s: Laplace operator f0: Pass frequency ζ: Damping ratio The compensation voltage calculation unit 40 includes a pulsation acceleration calculator 41, a multiplier 42, and a converter 43. The pulsation acceleration calculator 41 calculates a pulsation acceleration that is an acceleration of a pulsation component from the pulsation speed extracted by the pulsation extraction unit 30. Here, the pulsation acceleration calculator 41 calculates pulsation acceleration by performing a differentiation process on the pulsation speed extracted by the pulsation extraction unit 30.

  In this embodiment, the pulsation acceleration calculator 41 performs an approximate differentiation process represented by the transfer function of Expression (2) in order to numerically perform this differentiation process.

s: Laplace operator T: Time constant It is assumed that the time constant T is a sufficiently small value that satisfies T << 1, for example.

  The multiplier 42 calculates the inertia torque by multiplying the pulsation acceleration by a predetermined coefficient k. Here, the coefficient k is a coefficient for giving a virtual inertial load to a specific pulsation component.

  The converter 43 calculates a compensation voltage value by performing a predetermined calculation for converting the inertia torque calculated by the multiplier 42 into a voltage. The predetermined calculation will be described later.

  The adder 50 corrects the q-axis voltage command value by adding the compensation voltage value to the q-axis voltage command value calculated by the current controller 13, and converts the corrected q-axis voltage command value to dq. / Uvw converter 21 for output. Thereby, the pulsation component contained in the rotational speed of the motor M is suppressed, and smooth driving of the motor M is realized.

  FIG. 2 is a diagram for explaining voltage compensation by the compensation voltage value shown in FIG. As the inertia load of the object to be driven increases, the motor M needs to apply a large torque (inertia torque) during acceleration / deceleration of the object. The magnitude of this inertia torque has a value obtained by multiplying the moment of inertia indicating the magnitude of the inertia load by the angular acceleration.

  Therefore, the multiplication result obtained by multiplying the pulsation acceleration by the coefficient k represents the inertia torque when the inertia load 200 having the inertia moment of the coefficient k is connected to the motor M. Therefore, in this embodiment, the inertial torque is converted into a voltage to calculate a compensation voltage value, and the calculated compensation voltage value is added to the q-axis voltage command value.

  Thereby, torque control as if the inertial load 200 effective only at the frequency of the pulsating component is connected to the motor M can be performed on the motor M. As a result, the responsiveness of the rotational speed of the motor M to the pulsation component is reduced, the pulsation component is suppressed, and smooth driving of the motor M can be realized. Here, the disturbance torque corresponds to a torque applied to the motor M due to a periodic variation of a load connected to the motor M or a cogging torque. Moreover, as a load which brings about disturbance torque, a speed reducer corresponds, for example.

  Next, a predetermined calculation by the converter 43 will be described. Since the multiplier 42 calculates the inertia torque and does not have a voltage dimension, it cannot be directly added to the q-axis voltage command value. Therefore, in the present embodiment, a converter 43 is provided to calculate a compensation voltage value that is a voltage value corresponding to the inertia torque.

  Specifically, the converter 43 calculates the compensation voltage value using the formula (3) or the formula (4).

Δvq: q axis voltage command value change amount Ra: winding resistance ΔTq: inertia torque change amount Pn: number of pole pairs Ψa: interlinkage magnetic flux of permanent magnet Lq: q axis inductance Ld: d axis inductance iq: q axis Actual current value of id: Actual current value of d-axis ΔT: Calculation cycle In equations (3) and (4), Ra, Pn, Ψa, Lq, Ld, ΔT are known, and id, iq are uvw The actual current values Id and Iq calculated by the / dq converter 60.

  The relationship between the torque and the current command value is expressed by the following equation (5). When only the winding resistance Ra is considered, the voltage command value required when adding the current command value by Δiq is expressed by the following equation (6).

  Furthermore, when considering the q-axis inductance Lq in addition to the winding resistance Ra, the voltage command value required when adding the current command value by Δiq is expressed by the above equation (7).

  Solving equation (5) for iq and substituting into equation (6) yields equation (3). Further, when equation (5) is solved for iq and substituted into equation (7), equation (3) is obtained. Therefore, when the multiplier 42 outputs the change amount (ΔTq) of the inertia torque, the converter 43 obtains the change amount (Δvq) of the voltage command value using the equation (3) or the equation (4), and calculates the calculated voltage. The change amount (Δvq) of the command value may be output as the change amount of the compensation voltage value.

  FIG. 3 is a block diagram showing details of the pulsation extraction unit 30 and the compensation voltage calculation unit 40 shown in FIG. Hereinafter, a case where cogging torque is employed as the disturbance torque and the cogging torque is targeted for suppression will be described as an example. As described above, the pulsation extraction unit 30 uses the bandpass filter of Expression (1). Here, the frequency of the cogging torque can be obtained in advance from the number of poles and the number of slots of the motor M. The pulsation acceleration calculator 41 uses the transfer function of Expression (2).

  FIG. 4 is a Bode diagram of the bandpass filter G401 shown in Equation (1), where the vertical axis indicates gain and the horizontal axis indicates frequency. As shown in FIG. 4, the band-pass filter G401 has a symmetrical shape in which the gain decreases with a constant slope around the pass frequency f0 corresponding to the peak. In the band-pass filter G401, the pass frequency f0 matches the frequency of the cogging torque. The pass band B centered on the pass frequency f0 is a band where the gain is equal to or higher than a certain ratio with respect to the peak. For example, a value such as 80% or 90% can be adopted as the fixed ratio. Here, the attenuation ratio ζ is set so that the width of the passband B can be secured.

  By setting the passband B in this way, even if the actual cogging torque frequency is slightly deviated from the cogging torque frequency obtained from the number of poles and the number of slots of the motor M, the bandpass filter G401 is used. Can extract the pulsation component.

  FIG. 5 is a graph showing the results of a simulation performed to confirm the effect of suppressing the pulsating component in the first embodiment, where the vertical axis shows the rotation speed of the motor M and the horizontal axis shows time. In the graph of FIG. 5, the pulsation suppression control by the pulsation extraction unit 30 and the compensation voltage calculation unit 40 is not operated until time T1, and the pulsation suppression control is operated after time T1. In this simulation, the motor M is controlled to have a constant target speed V0.

  Until the pulsation suppression control is activated, the rotational speed V largely fluctuates up and down around the target speed V0, and it can be seen that pulsation caused by cogging torque occurs. On the other hand, when the pulsation suppression control is activated, the amplitude of the pulsation component is reduced to about 10% or less compared to the amplitude of the pulsation component before time T1, and it can be seen that the pulsation is sufficiently suppressed.

  If the coefficient k is excessive, the inertia torque due to the inertia load 200 is excessive, and the response is deteriorated. On the other hand, if the coefficient k is too small, the inertia torque due to the inertial load 200 becomes too small to suppress the pulsation component sufficiently.

  Therefore, as the coefficient k, for example, a value that can sufficiently suppress the pulsating component and maintain a certain level of responsiveness is employed. Specifically, the coefficient k is a value on the order of twice or three times the moment of inertia of the motor M, but this is an example.

  As described above, since the control device 1 adds the compensation voltage value to the q-axis voltage command value, the virtual inertia torque can be applied only to the pulsation component, and the pulsation component can be suppressed. Further, since the control device 1 calculates the compensation voltage value corresponding to the torque based on the angle detection value detected by the small angle detector 70 such as a rotary encoder, it is like a torque detector or an acceleration detector. In addition, the compensation voltage value can be calculated without using a large-scale and expensive sensor. Furthermore, since the control device 1 calculates the compensation voltage value without adopting the learning control, the pulsation can be quickly suppressed from the start of operation.

  Note that a periodic disturbance torque such as a cogging torque is likely to occur when the motor M is driven at a speed slower than the rated speed. For example, in a scene where a delicate positioning operation is performed such as lifting and lowering a suspended load in a crane, when positioning control is performed using the motor M, the motor M is frequently driven at a speed lower than the rated speed. To do. Therefore, the control device 1 is effective in such a scene. That is, when the target speed is set to a speed range lower than the rated speed range of the motor M, the control method by the control device 1 is effective.

[Embodiment 2]
In the first embodiment, one type of disturbance torque is to be suppressed, but in the second embodiment, a plurality of types of disturbance torque is to be suppressed. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The same applies to the third embodiment.

  As described above, the rotational speed of the motor M is pulsated by applying a cogging torque or a periodic pulsation of a load connected to the motor M to the motor M as a disturbance torque. As described above, there are a plurality of periodic disturbance torques, and there is a case where it is desired to simultaneously suppress pulsation due to the plurality of disturbance torques. The second embodiment solves this problem.

  FIG. 6 is a block diagram of the control device 1 according to Embodiment 2 of the present invention. The difference from FIG. 1 is that a pulsation extraction unit 30 and a compensation voltage calculation unit 40 are provided for each frequency of the pulsation component to be suppressed, and an integrator 51 is provided. In the example of FIG. 6, n types of pulsation extraction units 30_1 (30),..., 30_n (30) and compensation voltage calculation units corresponding to n (n is an integer of 2 or more) types of pulsation components having different frequencies. 40_1 (40),..., 40_n (40) are provided. The pulsation extraction unit 30_1 corresponds to the first pulsation extraction unit, and the pulsation extraction units 30_2, ..., 30_n correspond to the second pulsation extraction unit. Further, the compensation voltage calculation unit 40_1 corresponds to a first compensation voltage calculation unit, and the compensation voltage calculation units 40_2, ..., 40_n correspond to a second compensation voltage calculation unit.

  Specifically, in each of the pulsation extraction units 30_1,..., 30_n, the pass frequency f0 of the bandpass filter G401 is set according to the frequency of the corresponding pulsation component. Thereby, each of the pulsation extraction units 30 </ b> _ <b> 1,..., 30 </ b> _n extracts a corresponding pulsation component from the detected speed value detected by the speed calculator 80.

  The compensation voltage calculation units 40_1,..., 40_n include a pulsation acceleration calculator 41, a multiplier 42, and a converter 43, respectively. In the present embodiment, the same value may be adopted as the coefficient k of the multiplier 42 regardless of the corresponding pulsation component, or a different value may be adopted for each corresponding pulsation component.

  The integrator 51 adds n compensation voltage values calculated by the compensation voltage calculators 40 </ b> _ <b> 1,..., 40 </ b> _n, calculates an added compensation voltage value, and outputs it to the adder 50.

  The adder 50 adds the addition compensation voltage value output from the integrator 51 to the q-axis voltage command value output from the current controller 13 and outputs the result to the dq / uvw converter 21.

  As described above, the compensation voltage value corresponding to the n types of pulsation components to be suppressed is added to the q-axis voltage command value output from the current controller 13. As a result, torque control as if a virtual n-type inertia load 200 having an inertia moment of coefficient k and effective only at the frequency of n types of pulsating components is connected to the motor M is performed. This can be done for M. Thereby, a plurality of types of pulsating components can be suppressed simultaneously.

[Embodiment 3]
FIG. 7 is a diagram for explaining a decrease in responsiveness due to the application of the inertial load 200 to the motor M when the target speed changes.

  In the first embodiment, as shown in the section (a) of FIG. 7, the compensation voltage value is added to the q-axis voltage command value, and the inertial load 200 effective only at the frequency of the disturbance torque is applied to the motor M. Thus, the pulsation of the rotational speed was suppressed. However, if the target speed changes, the response of the motor M deteriorates as much as the inertia load 200 is applied to the motor M. Therefore, as shown in the section (b) of FIG. 7, the actual rotational speed follows the target speed. May be reduced.

  Therefore, in the third embodiment, the configuration shown in FIG. 8 is adopted. FIG. 8 is a block diagram showing the configuration of the control device 1 according to Embodiment 3 of the present invention. 8 differs from FIG. 1 in that a pulsation extraction unit 300 (corresponding to the third pulsation extraction unit) and a compensation voltage calculation unit 400 (corresponding to the third compensation voltage calculation unit) are further provided. .

  The pulsation extraction unit 300 extracts a pulsation component having a specific frequency from the target speed. Here, the pulsation extraction unit 300 extracts the pulsation component using the same bandpass filter as the bandpass filter used by the pulsation extraction unit 30 to extract the pulsation component. However, the pulsation extraction unit 300 is different from the pulsation extraction unit 30 in that the pulsation component is extracted from the target speed instead of the speed detection value.

  The compensation voltage calculation unit 400 includes a pulsation acceleration calculator 401, a multiplier 402, and a converter 403. The pulsation acceleration calculator 401 calculates pulsation acceleration from the pulsation component extracted by the pulsation extraction unit 300. The multiplier 402 multiplies the pulsation component extracted by the pulsation acceleration calculator 401 by a coefficient k to calculate an inertia torque. The converter 403 converts the inertia torque calculated by the multiplier 402 using the above formula (3) or formula (4), and calculates a response compensation voltage value. Here, the configurations of the pulsation acceleration calculator 401, the multiplier 402, and the converter 403 are the same as those of the pulsation acceleration calculator 41, the multiplier 42, and the converter 43.

  The subtractor 52 (an example of a first subtractor) corrects the compensation voltage value by subtracting the response compensation voltage value output from the converter 403 from the compensation voltage value output from the converter 43, and the corrected compensation. The voltage value is output to the adder 50.

  As a result, the compensation voltage value obtained by subtracting the response compensation voltage value is added to the q-axis voltage command value. Since the compensation voltage value output from the converter 43 is a voltage value calculated by extracting the pulsation component from the speed detection value, the influence of the pulsation component of the target speed and the influence of the pulsation component of the speed detection value are included. .

  On the other hand, since the response compensation voltage value output from the converter 403 is a voltage value calculated by extracting the pulsation component of the target speed, only the influence of the pulsation component of the target speed is included. Therefore, by subtracting the response compensation voltage value from the compensation voltage value output by the converter 43, it is possible to remove the influence of the pulsation of the target speed included in the compensation voltage value. As a result, it is possible to suppress deterioration in the responsiveness of the rotational speed of the motor M when the target speed fluctuates periodically.

  FIG. 9 is a block diagram showing details of the pulsation extraction units 30 and 300 and the compensation voltage calculation units 40 and 400 shown in FIG. As shown in FIG. 9, the pulsation extraction unit 300 employs a band-pass filter represented by Expression (1), similarly to the pulsation extraction unit 30. Here, various parameters (f0: pass frequency ζ: damping ratio) of the bandpass filter employed by the pulsation extraction unit 300 are the same as those of the pulsation extraction unit 30.

  Also, the pulsation acceleration calculator 401 adopts the transfer function represented by the equation (2), similarly to the pulsation acceleration calculator 41. Here, various parameters (T: time constant) adopted by the transfer function of the pulsation acceleration calculator 401 are the same as those of the pulsation acceleration calculator 41. Further, the coefficient k employed by the multiplier 402 is the same as that of the multiplier 42.

  FIG. 10 is a graph showing the results of a simulation performed to confirm the effect of suppressing the pulsating component in the third embodiment, where the vertical axis shows the rotation speed of the motor M and the horizontal axis shows time.

  In FIG. 10, section (a) shows the result of simulation when pulsation suppression control by pulsation extraction unit 30 and compensation voltage calculation unit 40 is not operated, and section (b) operates only pulsation suppression control. Section (c) shows the simulation result when the response improvement control by the pulsation extraction unit 300 and the compensation voltage calculation unit 400 is operated in addition to the pulsation suppression control.

  In this simulation, the target speed is changed with a sine wave having a constant frequency, and the motor M is controlled by the control device 1 so as to follow the target speed. However, this is only an example, and the target speed may be changed by a periodic waveform other than a sine wave, such as a pulse wave having a constant period. In this simulation, cogging torque is used as disturbance torque.

  As shown in the section (a) of FIG. 10, in the normal vector control in which pulsation suppression control and response improvement control are not performed, the rotational speed V follows the target speed V0, but greatly increases around the target speed V0. It can be seen that pulsation occurs. This is the influence of the cogging torque of the motor M as in the simulation of FIG. 5, and pulsation occurs at a frequency corresponding to the number of poles and the number of slots.

  On the other hand, when only the pulsation suppression control is operated, as shown in the section (b) of FIG. 10, it can be seen that the pulsation due to the cogging torque observed in the section (a) is sufficiently suppressed.

  However, with regard to the followability with respect to the target speed V0, a virtual inertia load that impedes the change in the rotational speed V of the motor M that attempts to follow the target speed V0 is applied to the motor M, and the target speed is reached. It can be seen that there is a region that cannot follow V0. Specifically, the rotational speed V greatly exceeds the target speed V0 at the peak point (mountain and valley) of the sine wave at which the target speed V0 switches greatly, and the rotational speed V becomes the target speed V0 at this point. You can see that they are not following.

  On the other hand, when the response improvement control is activated in addition to the pulsation suppression control, it is avoided that the inertial load 200 acts excessively on the change in the rotational speed V for following the target speed V0. Therefore, as shown in the section (c) of FIG. 10, it is possible to suppress the occurrence of the pulsation seen in the section (a) and the location where the followability is deteriorated as seen in the section (b). As a result, the pulsation due to the cogging torque can be suppressed, and at the same time, the decrease in the followability of the rotational speed V with respect to the target speed V0 can be suppressed.

[Embodiment 4]
The control device 1 according to the third embodiment improves the responsiveness as described above, but a large pulsation may occur at the start of the pulsation suppression control and the response improvement control. Hereinafter, a description will be given with reference to FIG. In FIG. 8, the pulsation extraction unit 30 and the compensation voltage calculation unit 40 are blocks related to pulsation suppression control, and the pulsation extraction unit 300 and the compensation voltage calculation unit 400 are blocks related to response improvement control. Blocks other than these are blocks related to normal current feedback control for the motor M.

  The current controller 13 is assumed to be a controller that executes PI control. In this case, the current controller 13 is an equation that combines the proportional term and the integral term with respect to the current deviation between the target current value Iq_ref (hereinafter, denoted by the sign of iq *) and the actual current value iq ( The q-axis voltage command value (vq *) is calculated by the calculation of 8). Note that description of the d-axis is omitted.

K_cq: current feedback control proportional gain T_cq: current feedback control integration time vq *: q-axis voltage command value determined by the current controller 13 iq *: q-axis target current value Id_ref iq: q-axis actual Current Value Further, it is assumed that the current command generator 12 is also a controller that performs PI control in the same manner. In this case, the current command generator 12 calculates the target current value (iq *) of the q axis by performing the calculation of Expression (9).

Ksp: proportional gain of speed control Ksi: integral gain of speed control V0: target speed V: rotational speed of motor M With respect to the speed deviation between the target speed V0 and the rotational speed V of the motor from equations (8) and (9), The voltage command value (vq *) is determined by the following equation (10). The voltage command value (vq *) shown in Equation (10) is a voltage command value (vq *) obtained by normal current feedback control.

  On the other hand, assuming that the pulsation component of the rotational speed V extracted by the pulsation extraction unit 30 is V ′ and the pulsation component of the target speed V0 extracted by the pulsation extraction unit 300 is V0 ′, the compensation voltage calculation units 40 and 400 and the subtractor 52 Thus, the compensation voltage value (Δvq) is determined by the equation (11).

  When there is a controller for pulsation suppression control and response improvement control, the compensation voltage value (Δvq) of equation (11) is added to the voltage command value (vq *) of equation (10) as a result. The term (V′−V0 ′) interferes with the term (V−V0) shown in equation (10). As a result, the compensation voltage value (Δvq) shown in the equation (11) interferes with the voltage command value (vq *) calculated by the normal current feedback control shown in the equation (10), and a large pulsation occurs at the start of the control. It can happen. In particular, when integral control (I operation) is performed, overshoot and hunting are likely to occur at the start of control, and this pulsation increases.

  Therefore, in the fourth embodiment, the zero influence of the term of the difference (V′−V0 ′) between the pulsating component (V ′) and the pulsating component (V0 ′), which is an interference term, expressed by the equation (11). In order to weaken the above, the configuration shown in FIG. 11 is adopted.

  FIG. 11 is a block diagram showing a configuration of the control device 1 according to Embodiment 4 of the present invention. The control device 1 in FIG. 11 further includes a subtractor 111 (an example of a second subtractor) and a subtractor 112 (an example of a third subtractor), compared to the control device 1 in FIG.

  The subtractor 111 subtracts the pulsation component (V 0 ′) extracted by the pulsation extraction unit 300 from the pulsation component (V ′) extracted by the pulsation extraction unit 30. The subtractor 112 subtracts the subtraction result (V′−V0 ′) from the subtractor 111 from the speed deviation (V−V0) between the target speed V0 and the rotation speed V.

  In this way, the difference (V′−V0) term between the pulsation component (V ′) and the pulsation component (V0 ′), which is an interference term in the compensation voltage value (Δvq), is subtracted (V′−V0 ′). And the influence of the compensation voltage value (Δvq) on the normal current feedback control can be weakened.

  12 and 13 are graphs showing the results of a simulation performed to confirm the effect of suppressing the pulsating component in the fourth embodiment, where the vertical axis indicates the rotational speed of the motor M and the horizontal axis indicates time. ing.

  FIG. 12 shows a simulation result when the interference suppression control and response improvement control shown in the fourth embodiment are not applied, and FIG. 13 shows a simulation result when the interference suppression control and response improvement control are applied. . In the graphs of FIGS. 12 and 13, the pulsation suppression control and the response improvement control are not operated until time T1, and only the normal current feedback control is operated, and after time T1, the pulsation suppression control and Response improvement control is activated. In this simulation, the motor M is controlled to have a constant target speed V0. In this simulation, disturbance torque is given by a sine wave having a constant frequency. Note that the target speed V0 is not a constant speed, and a waveform that varies periodically may be employed, and the disturbance torque may be a periodic waveform other than a sine wave.

  In FIG. 12 and FIG. 13, disturbance torque having the same amplitude and frequency is applied. When FIG. 12 is compared with FIG. 13, the amplitude of the waveform in FIG. 13 is smaller than that in FIG. 12 before the pulsation suppression control and response improvement control are activated, and the pulsation is suppressed. Therefore, it can be seen that the amplitude of the waveform in FIG. 13 is smaller and the pulsation is suppressed even after the pulsation suppression control and response improvement control are activated compared to FIG. In particular, the hunting that appeared in FIG. 12 immediately after starting the pulsation suppression control and response improvement control is greatly improved in FIG.

  Thus, in Embodiment 4, since interference suppression control is performed, the pulsation at the time of the start of operation | movement of pulsation suppression control and response improvement control can be suppressed.

[Modification]
(1) In FIG. 8, one pulsation extraction unit 30 and one compensation voltage calculation unit 40 are provided, but this is an example, and according to a plurality of pulsation components to be suppressed as in the second embodiment. A plurality of them may be provided. In this case, a plurality of pulsation extraction units 300 and compensation voltage calculation units 400 may be provided for each of the plurality of pulsation extraction units 30 and compensation voltage calculation units 40. Further, in this case, the pulsation extraction unit 300 may adopt a bandpass filter having the same pass frequency f0 with respect to the corresponding pulsation extraction unit 30.

  (2) In the above description, the disturbance torque has been described as having periodicity, but may not have periodicity. For example, when the disturbance torque is an aperiodic impulse wave or pulse wave, these waveforms have a steep rise and fall, and therefore include a plurality of frequency components. Therefore, even if a bandpass filter having a pass frequency f0 is used, this bandpass filter can extract any frequency component included in these waveforms as a pulsation component. Therefore, the inertial load 200 can be applied to the pulsating component to suppress the pulsation.

Id, Iq Actual current value Id_ref, Iq_ref Target current value M Motor V0 Target speed 1 Controller 5, 52, 111, 112 Subtractor 10 Voltage command value calculator 11 Speed controller 12 Current command generator 13 Current controller 14, DESCRIPTION OF SYMBOLS 15 Subtractor 20 Drive part 21 dq / uvw converter 22 Inverter 30,30_1, ..., 30_n, 300 Pulsation extraction part 40,40_1, ..., 40_n, 400 Compensation voltage calculation part 41,401 Pulsation acceleration calculator 42, 402 Multiplier 50 Adder 51 Integrator 60 uvw / dq converter 70 Angle detector 80 Speed calculator 200 Inertial load

Claims (7)

A voltage command value calculation unit for calculating a voltage command value for setting the rotation speed of the electric motor to a target speed;
A drive unit that drives the electric motor based on the voltage command value calculated by the voltage command value calculation unit;
A speed detector for detecting the rotational speed of the electric motor;
A pulsation extraction unit that extracts a pulsation component of a specific frequency from the rotation speed detected by the speed detection unit;
A pulsation acceleration that is an acceleration of the pulsation component is calculated from the pulsation component extracted by the pulsation extraction unit, and the calculated pulsation acceleration is multiplied by a predetermined coefficient for applying a virtual inertial load to the pulsation component. A compensation voltage calculation unit that calculates a compensation voltage value by converting the multiplication result into a voltage;
An electric motor control device comprising: an adder that adds a compensation voltage value calculated by the compensation voltage calculation unit to the voltage command value. The pulsating component includes first and second pulsating components having different frequencies,
The pulsation extraction unit includes first and second pulsation extraction units corresponding to the first and second pulsation components,
The compensation voltage calculation unit includes first and second compensation voltage calculation units corresponding to the first and second pulsation components,
An integrator for adding the first and second compensation voltage values calculated by the first and second compensation voltage calculators;
The motor control device according to claim 1, wherein the adder adds the added first and second compensation voltage values to the voltage command value. A third pulsation extraction unit that extracts a pulsation component of the specific frequency from the target speed;
A response compensation voltage is calculated by calculating a third pulsation acceleration from the pulsation component extracted by the third pulsation extraction unit, multiplying the calculated third pulsation acceleration by the predetermined coefficient, and converting the multiplication result into a voltage. A third compensation voltage calculation unit for calculating a value;
A first subtractor that subtracts the response compensation voltage value from the compensation voltage value calculated by the compensation voltage calculation unit;
The motor control device according to claim 1, wherein the adder adds a compensation voltage value obtained by subtracting the response compensation voltage value to the voltage command value. The voltage command value calculation unit calculates a target current value for setting a speed deviation between the rotation speed of the motor detected by the speed detection unit and the target speed to 0, and applies the target current value and the motor to the target current value. Calculate the voltage command value to make the current deviation from the supplied current value 0,
A second subtracter for subtracting the pulsation component extracted by the third pulsation extraction unit from the pulsation component extracted by the pulsation extraction unit;
4. The motor control according to claim 3, further comprising a third subtracter that subtracts a subtraction result obtained by the second subtracter from a speed deviation between the target speed and the rotation speed of the motor detected by the speed detection unit. apparatus.   The motor control device according to claim 3 or 4, wherein the target speed changes periodically.   The motor control device according to claim 1, wherein the pulsation extraction unit extracts the pulsation component using a band-pass filter having the specific frequency as a pass frequency. The voltage command value calculation unit calculates voltage command values for the d-axis and the q-axis,
The motor control device according to claim 1, wherein the adder adds the compensation voltage value to the q-axis voltage command value.

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