JP2016163370A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device capable of reducing a speed ripple and a torque ripple of a motor .SOLUTION: The motor control device 1 includes: a compensation data storage unit 11, storing cogging torque data according to a position of a motor 2 as data corresponding to a torque variation by the cogging torque of the motor 2; and a disturbance observer 10, for calculating a cogging torque estimation value from a position of the motor 2 input on the basis of the compensation data storage unit 11 and performing disturbance suppression compensation on the basis of the calculated cogging torque estimation value.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a motor control device that estimates and suppresses disturbance of a motor.

  In machine tools, due to demands for micromachining and the like, it is necessary to further improve the processing quality, and high precision motor drive is required. Further, in order to shorten the cycle time, it is required to shorten the positioning time.

  On the other hand, miniaturization of the motor is also demanded, and when the motor is miniaturized, the cogging torque may increase due to restrictions on the structure of the motor. Such torque ripple due to cogging torque acts as a disturbance during machining, thereby reducing the surface accuracy of the workpiece, and acts as a disturbance during positioning to cause a variation in position deviation. This variation in position deviation delays the positioning time and lengthens the cycle time of the machine. In addition, there is friction in the mechanical system, and such friction causes a decrease in machining accuracy and a delay in positioning.

  FIG. 5 is a configuration diagram of a conventional disturbance observer for suppressing such disturbance. In the conventional disturbance observer, the load torque is estimated through a low-pass filter based on the torque command and the motor speed. However, there is a problem that the estimated value is attenuated and phase-shifted by the low-pass filter inserted for noise removal by the differential operation, and appropriate compensation for torque ripple cannot be performed.

  As an example of increasing the response of such a disturbance observer, there is Patent Document 1. Patent Document 1 discloses a servo motor control device that includes an observer that estimates disturbance torque and a correction unit that corrects the torque command using the estimated disturbance torque. The observer has a disturbance torque that is constant over time. A servo motor control apparatus using an observer is described, which is configured to be supplied to a servo motor through a low-pass filter, and the correction means corrects a torque command with an estimated disturbance torque obtained by the observer.

JP-A-4-69082

  Here, there is a resolution limitation in an actual encoder, and a quantization error exists. For this reason, in the method of Patent Document 1, since the high-frequency gain of the disturbance torque estimated by the observer is increased, a ripple due to the quantization error of the encoder appears in the estimated disturbance torque, especially when the resolution of the encoder is low. There was a problem that the torque noise increased.

  The object of the present invention was invented in view of the above circumstances, by estimating the disturbance torque including the cogging torque of the motor without being affected by the quantization error of the encoder, and performing disturbance suppression compensation, An object of the present invention is to provide a motor control device that can suppress the influence of friction and reduce the speed ripple and torque ripple of the motor.

  In order to achieve the above object, a motor control device according to the present invention calculates a cogging torque estimated value from a compensation data storage unit that stores data corresponding to torque fluctuations due to cogging torque of the motor, and a compensation data storage unit, A disturbance observer that performs disturbance suppression compensation based on the calculated cogging torque estimated value is provided.

  According to the present invention, it is possible to estimate disturbance torque including the cogging torque and torque ripple of the motor without being influenced by the quantization error of the encoder, and by performing disturbance suppression compensation using this disturbance observer, It is possible to provide a motor control device that can suppress the influence of friction or the like and reduce the speed ripple and torque ripple of the motor.

It is a figure which shows an example of the block diagram of the motor control apparatus of this invention. It is a figure which shows an example of the block diagram of the disturbance observer with which the motor control apparatus of this invention is provided. It is a figure which shows an example of the block diagram of the speed control system to which the disturbance observer with which the motor control apparatus of this invention is provided is applied. It is a figure which shows the simulation result at the time of performing disturbance suppression compensation. It is a block diagram of the conventional disturbance observer.

  As shown in FIG. 1, the motor control device 1 of the present invention includes a compensation data storage unit 11 that stores cogging torque data corresponding to the position of the motor 2 as data for suppressing torque fluctuation due to the cogging torque of the motor. A disturbance observer 10 that inputs the position of the motor 2, calculates a cogging torque estimated value from the input motor position based on the compensation data storage unit 11, and performs disturbance suppression compensation based on the calculated cogging torque estimated value; It has. The motor control device 1 includes a speed controller 4, a torque controller 5, and a speed calculator 13. This configuration will be described later with reference to FIG.

  The disturbance observer 10 calculates a cogging torque estimated value calculation unit 100 that calculates a cogging torque estimated value, a first speed calculation unit 200 that calculates a first speed using a nominal inertia, and a second speed excluding the cogging torque estimated value. A second speed calculating unit 300, a disturbance torque estimated value calculating unit 400 for calculating a disturbance torque estimated value excluding the cogging torque estimated value, and a total disturbance torque calculating unit 500 for calculating the total disturbance torque.

  The cogging torque estimated value calculation unit 100 has a compensation data storage unit 11, inputs the motor position detected by the encoder 3, and calculates the cogging torque estimated value from the input motor position based on the compensation data storage unit 11. Then, the calculated cogging torque estimated value is output to the first speed calculation unit 200 and the total disturbance torque calculation unit 500.

  The first speed calculation unit 200 receives the cogging torque estimated value calculated by the cogging torque estimated value calculation unit 100, calculates the first speed by using the input cogging torque estimated value by the nominal inertia, and calculates the calculated first speed. Is output to the second speed calculation unit 300.

  The second speed calculation unit 300 receives the motor speed calculated by the speed calculator 13 and the first speed calculated by the first speed calculation unit 200, subtracts the first speed from the motor speed, and performs cogging torque. The second speed excluding the estimated value is calculated, and the calculated second speed is output to the disturbance torque estimated value calculation unit 400.

  The disturbance torque estimation value calculation unit 400 receives the torque command and the second speed calculated by the second speed calculation unit 300, and based on the torque command and the second speed, the disturbance torque estimation excluding the cogging torque estimation value. The value is calculated, and the calculated disturbance torque estimated value is output to the total disturbance torque calculation unit 500.

  Total disturbance torque calculation section 500 receives the disturbance torque estimated value calculated by disturbance torque estimated value calculation section 400 and the cogging torque estimated value calculated by cogging torque estimated value calculation section 100, and inputs the disturbance torque estimated value and cogging. The total disturbance torque is calculated by adding the estimated torque value, and the calculated total disturbance torque is fed back.

  In the present embodiment, the compensation data storage unit 11 is disposed on the disturbance observer 10 side. However, the disturbance observer 10 may be configured to include the cogging torque estimated value calculation unit 100, and the compensation data storage unit 11 may be configured as the encoder 3. It may be arranged on the side.

  Next, an example of a specific configuration of the compensation data storage unit 11 and the disturbance observer 10 will be described.

First, in the motor control device 1, from the equation of motion of the motor,
Jnωm · s = Tcmd−TD = Tcmd−TL−TR (1)
TL = Tcmd−Jn {ωm + TR / (Jn · s)} · s (2)
It is. Therefore, in equation (2), if the estimated cogging torque component value is TR ^ and the other component estimated value is TL ^, the total disturbance torque estimated value TD ^ can be estimated by the following equation.
TD ^ = TL ^ + TR ^
= Gd / (s + gd) {Tcmd-Jn (ωm + TR ^ / (Jn.s) .s} + TR ^ (3)
Where, Jn: inertia nominal value, ωm: motor speed, Tcmd: torque command, gd: cut-off frequency of low-pass filter

  By using the above equation (3), it is possible to configure the disturbance observer 10 that compensates for both the compensation data storage unit 11 and the instantaneous disturbance estimation.

FIG. 2 is a diagram illustrating an example of a configuration diagram of the disturbance observer 10 included in the motor control device 1 of the present invention based on the above equation (3).

  Here, the cogging torque data stored in the compensation data storage unit 11 is obtained by measuring and storing the cogging torque data corresponding to the motor position in advance.

  As shown in FIG. 2, the disturbance observer 10 obtains a cogging torque estimated value a <b> 1 using the compensation data storage unit 11 based on the motor position detected by the encoder 3, and the first speed calculator 12 uses the nominal inertia. The first speed a2 based on the estimated cogging torque is calculated.

  Next, the disturbance observer 10 obtains the motor speed a3 from the motor position using the speed calculator 13, subtracts the speed a2 based on the estimated cogging torque value from the motor speed a3, and removes the estimated cogging torque value. The speed a4 is calculated.

  Then, the disturbance observer 10 adds the torque command Tcmd and the value a5 multiplied by gd · Jn using the first multiplier 14 to the second speed a4 excluding the estimated cogging torque, and gd / (s + gd) A value a6 that has passed through the low-pass filter 15 is calculated. The disturbance observer 10 subtracts the value a7 obtained by multiplying gd · Jn by using the second multiplier 16 from the value a6 passed through the low-pass filter 15 to the second speed a4 obtained by removing the estimated cogging torque value. A disturbance torque estimated value a8 excluding the torque estimated value is calculated.

  Finally, the disturbance observer 10 adds the disturbance torque estimated value a8 excluding the cogging torque estimated value and the cogging torque estimated value a1 to estimate the total disturbance torque TD ^.

  The configuration of the disturbance observer 10 only needs to be configured by an equivalent circuit based on the above equation (3), and the low-pass filter may be configured as a filter other than the first order such as a second order.

  FIG. 3 is a diagram illustrating an example of a configuration diagram of a speed control system to which a disturbance observer included in the motor control device 1 of the present invention is applied.

  The motor control device 1 detects the motor position by the encoder 3 and calculates the motor speed by differentiating the motor position by the speed calculator 13.

  Next, the motor control device 1 compares the speed command with the motor speed (subtracts the motor speed from the speed command), and the speed controller 4 calculates a torque command based on the speed control.

  Then, the motor control device 1 calculates the torque command Tcmd after disturbance suppression compensation by adding the total disturbance torque TD ^ estimated by the disturbance observer 10 to the torque command based on the calculated speed control. 5 drives the motor 2.

  Thereby, based on the motor speed of the motor 2, the total disturbance torque TD ^ can be estimated by the disturbance observer 10 shown in FIG. 2, and disturbance suppression compensation can be performed using the output.

  In the case of position control, if the position command is compared with the position command based on the position detected by the encoder 3, the speed command is calculated by the position controller, and given as the speed command in FIG. Good.

  FIG. 4 is a diagram illustrating a simulation result when disturbance suppression compensation is performed.

  The upper part of FIG. 4 shows the response at the motor speed, and the lower part of FIG. 4 shows the response at the motor torque. In addition, 0 to 0.5 sec indicates a response when no disturbance observer is applied and no compensation is performed, and 0.5 to 1.0 sec indicates a response when the conventional disturbance observer shown in FIG. 5 is applied. The response, 1.0 to 1.5 sec, is a response when the disturbance observer 10 of the present invention is applied.

  As shown in FIG. 4, it can be seen that by applying the disturbance observer 10 of the present invention, the speed ripple and torque ripple can be significantly reduced.

  As described above, the motor control device 1 according to the present invention combines the compensation data storage unit 11 for compensating for the torque ripple and the disturbance observer 10 for performing the instantaneous disturbance estimation, so that an appropriate instantaneous disturbance estimation is performed. Thus, disturbance suppression compensation using the estimated value can be appropriately performed.

  In the present embodiment, the compensation data storage unit 11 preliminarily measures and stores cogging torque data corresponding to the motor position as data corresponding to torque fluctuation due to the cogging torque of the motor. As data corresponding to torque fluctuation due to torque, m pieces (m is a natural number of 2 or more) of sinusoidal frequency, amplitude, and phase data may be stored. When such a configuration is adopted, the disturbance observer 10 creates m sine waves based on the m frequencies, amplitudes, and phases stored in the compensation data storage unit 11, and adds them to generate a combined sine wave signal. To generate an estimated cogging torque value corresponding to the motor position.

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 2 Motor 3 Encoder 4 Speed controller 5 Torque controller 10 Disturbance observer 11 Compensation data storage part 12 1st speed calculator 13 Speed calculator 14 1st multiplier 15 Low pass filter 16 2nd multiplier 100 Cogging torque Estimated value calculating unit 200 First speed calculating unit 300 Second speed calculating unit 400 Disturbance torque estimated value calculating unit 500 Total disturbance torque calculating unit

First, in the motor control device 1, from the equation of motion of the motor,
Jnωm · s = Tcmd−TD = Tcmd−TL−TR (1)
TL = Tcmd−Jn {ωm + TR / (Jn · s)} · s (2)
It is. Therefore, in equation (2), if the estimated cogging torque component value is TR ^ and the other component estimated value is TL ^, the total disturbance torque estimated value TD ^ can be estimated by the following equation.
TD ^ = TL ^ + TR ^
= Gd / (s + gd) [ Tcmd−Jn { ωm + TR ^ / (Jn · s) · s} ] + TR ^ (3)
Where, Jn: inertia nominal value, ωm: motor speed, Tcmd: torque command, gd: cut-off frequency of low-pass filter

Finally, the disturbance observer 10 will estimate the total disturbance torque TD by adding the disturbance torque estimated value a8 cogging torque estimated value a1 except for this cogging torque estimated value.

Then, the motor control device 1 calculates the torque command Tcmd after disturbance suppression compensation by adding the total disturbance torque estimated value TD ^ estimated by the disturbance observer 10 to the torque command based on the calculated speed control. The motor 5 is driven by the controller 5.

Thereby, based on the motor speed of the motor 2, the total disturbance torque TD can be estimated by the disturbance observer 10 shown in FIG. 2, and disturbance suppression compensation can be performed using the output.

Claims (3)

  A disturbance observer that calculates a cogging torque estimated value corresponding to the position of the motor from a compensation data storage unit that stores data corresponding to torque fluctuation due to the cogging torque of the motor, and performs disturbance suppression compensation based on the calculated cogging torque estimated value A motor control device comprising: The disturbance observer is
A cogging torque estimated value calculation unit for calculating a cogging torque estimated value from the compensation data storage unit;
A first speed calculation unit that calculates a first speed by the nominal inertia, the cogging torque estimated value calculated by the cogging torque estimated value calculation unit;
A second speed calculator for subtracting the first speed calculated by the first speed calculator from a motor speed to calculate a second speed excluding the estimated cogging torque;
A disturbance torque estimated value calculating unit that calculates a disturbance torque estimated value excluding the cogging torque estimated value based on the second speed calculated by the second speed calculating unit;
A total disturbance torque calculating unit that calculates a total disturbance torque by adding the disturbance torque estimated value calculated by the disturbance torque estimated value calculating unit and the cogging torque estimated value calculated by the cogging torque estimated value calculating unit; ,
The motor control device according to claim 1, further comprising: The motor controller according to claim 1, wherein the disturbance observer is configured by an equivalent circuit based on the following equation.
TD ^ = gd / (s + gd) {Tcmd−Jn (ωm + TR / (Jn · s) · s} + TR
However, TD ^: Total disturbance torque estimated value, TR: Cogging torque estimated value, Jn: Inertial nominal value, ωm: Motor speed, Tcmd: Torque command, gd: Cut-off frequency of low-pass filter