JP4283056B2 - Electric motor control device - Google Patents

Description

  The present invention relates to a motor control device used in industrial machines such as machine tools and robots.

A conventional motor control device will be described with reference to Patent Document 1. In a speed control system such as speed PI (proportional integral) control, a low-pass filter is used to ensure stability against detection noise or mechanical resonance with poor attenuation in a high frequency region. Also, based on the input of response setting parameters for setting the response speed and the nominal value of the inertia of the mechanical system, speed gain and speed are adjusted so that the control error can be corrected as quickly as possible by simple adjustment. Calculate and set multiple control parameters such as integral gain, position gain, and low-pass filter cutoff frequency. Also, the decision method is based on the response setting parameter and the control system band, that is, the open-loop crossing frequency, so that the frequency PI control break frequency and the low-pass filter cutoff frequency are determined to have an appropriate ratio. Yes.
JP 2002-27784 A

  In the conventional motor control device, when the rigidity of the mechanical system is low, the control system tends to become unstable due to the phase delay caused by the set low-pass filter, and a sufficiently fast response control characteristic is obtained. There was a problem that was difficult.

The present invention has been made in order to solve the above-described problems, and even when the rigidity of the mechanical system is low, it is difficult to become unstable, and a plurality of controls are performed according to response setting parameters for setting an input response speed. An object of the present invention is to provide a control device that sets parameters and corrects control errors stably and quickly.

  An electric motor control device according to a first aspect of the present invention comprises a mechanical system comprising a load coupled to an electric motor having an electric motor inertia value Jm, and controls the electric motor that generates a driving force corresponding to a driving force command signal τr. In the apparatus, a speed proportionality is calculated so that a signal component obtained by multiplying the speed detection signal ωm of the motor by a speed gain Kv and a negative sign and applying a low-pass filter having a cutoff frequency ωf is added to the driving force command signal τr. A feedback unit, and a speed integration feedback for performing an operation so as to add a signal component obtained by integrating the speed detection signal ωm or a low frequency component thereof to the speed integration gain Kvi and a negative sign to the driving force command signal τr. The speed gay based on the response setting parameter ωs inputted from the outside, the motor inertia value Jm, and the total inertia value J0 of the entire mechanical system. A parameter setting unit for setting Kv, the speed integral gain Kvi, and the cutoff frequency ωf, and the parameter setting unit is a break point that is a value obtained by dividing the speed integral gain Kvi of the cutoff frequency ωf by the speed gain Kv. The speed gain Kv, the speed integral gain Kvi, and the cutoff frequency ωf are set so that the ratio to the frequency ωvi increases as the ratio of the total inertia value J0 to the motor inertia value Jm increases. It is.

  According to a second aspect of the present invention, there is provided a control device for an electric motor, wherein a signal component obtained by multiplying a speed detection signal ωm of the electric motor by a speed gain Kv and a negative sign and operating a low-pass filter having a cutoff frequency ωf is used as the driving force command signal τr. A speed proportional feedback unit that performs an operation so as to be added to the signal, and a signal component obtained by integrating the speed detection signal ωm or a low frequency component thereof multiplied by an integral gain Kvi and a negative sign is added to the driving force command signal τr. A speed integration feedback unit that performs an operation so that the speed gain Kv and the speed integral gain are based on a response setting parameter ωs input from the outside, an inertia value Jm of the motor, and a total inertia value J0 of the entire mechanical system. A parameter setting unit for setting Kvi and the cut-off frequency ωf, and the parameter setting unit sets the speed integral gain Kvi to the speed The ratio of the breakpoint frequency ωvi, which is a value divided by In Kv, to the cross frequency ωc, which is a value obtained by dividing the velocity gain Kv by the total inertia value J0, is a preset constant r2, and the cutoff frequency ωf The ratio of the speed gain Kv divided by the motor inertia value Jm to the cross frequency ωcm of the single motor is set to a preset constant r3.

  According to a third aspect of the present invention, there is provided a control device for an electric motor which performs an operation so as to add a signal component obtained by multiplying a speed detection signal ωm of the electric motor by a speed gain Kv and a negative sign to operate a low-pass filter to the driving force command signal. A speed proportional feedback unit for performing position proportional feedback for performing calculation so as to add a signal component obtained by multiplying the position detection signal xm of the motor or its low frequency component by a position gain Kx and a negative sign to the driving force command signal τr. The speed gain Kv, the position gain Kx, and the cutoff frequency ωf of the low-pass filter are set based on the response setting parameter ωs input from the outside, the motor inertia value Jm, and the total inertia value J0 of the entire mechanical system. A parameter setting unit configured to convert the position gain Kx of the cutoff frequency ωf to the speed gain K The speed gain Kv, the position gain Kx, and the cutoff frequency ωf are set so that the ratio of the total inertia value J0 to the motor inertia value Jm increases as the ratio to the breakpoint frequency ωx that is a value divided by It is characterized by this.

  According to a fourth aspect of the present invention, there is provided a motor control apparatus, wherein a signal component obtained by multiplying the speed detection signal ωm of the motor by a speed gain Kv and a negative sign and applying a low-pass filter is added to the driving force command signal τr. A speed proportional feedback unit that performs calculation, and a position that performs calculation so that a signal component obtained by multiplying the position detection signal xm of the motor or a low frequency component thereof by a position gain Kx and a negative sign is added to the driving force command signal τr. The speed gain Kv, the position gain Kx, and the cutoff frequency ωf of the low-pass filter based on the proportional feedback unit, the response setting parameter ωs input from the outside, the motor inertia value Jm, and the total total inertia value J0 in the mechanical system. The parameter setting unit is a value obtained by dividing the position gain Kx by the speed gain Kv. The ratio of the speed gain Kv of a certain breakpoint frequency ωx to the crossing frequency ωc, which is a value obtained by dividing the speed gain Kv by the total inertia value J0, is a preset constant r2, and the speed gain Kv of the cutoff frequency ωf is set to the motor inertia. The ratio of the electric motor alone, which is a value divided by the value Jm, to the crossing frequency ωcm is set so as to be a preset constant r3.

  According to a fifth aspect of the present invention, there is provided a motor control apparatus, wherein a speed deviation signal, which is a difference between a motor speed command signal and the motor speed detection signal, is generated through a speed gain Kv to generate a first compensation signal. A speed integration control unit that integrates the speed deviation signal and generates a second compensation torque signal via a speed integration gain Kvi, and adds the first compensation signal and the second compensation signal. First adding means for generating the first total compensation signal, and filter means for inputting the first total compensation signal and generating the driving force command signal having a low-pass characteristic of the cutoff frequency ωf. The motor inertia value Jm and the total inertia value J0 are input, and the ratio ωf / ωvi between the cut-off frequency ωf and the break-point frequency ωvi of the proportional / integral control unit is set to the motor inertia value Jm and the total inertia. Large ratio with value J0 Comes to, and is characterized in that it comprises the speed gain Kv as to increase, the rate integral gain Kvi, and a parameter setting means for setting the cutoff frequency .omega.f.

  A motor control device according to a sixth aspect of the invention includes a first speed control unit that differentiates a position deviation signal and generates a third compensation signal via a differential gain Kv, a position command signal of the motor, and the A position deviation signal that is a difference from the position detection signal of the electric motor is added to a position control unit that generates a fourth compensation signal via a position gain Kx, and the third compensation signal and the fourth compensation signal are added. Second adding means for generating the second total compensation signal, and filter means for inputting the second total compensation signal and generating the driving force command signal having a low-pass characteristic of the cutoff frequency ωf. The motor inertia value Jm and the total inertia value J0 are input, and the ratio ωf / ωvi between the cut-off frequency ωf and the break-point frequency ωvi of the proportional / integral control unit is set to the motor inertia value Jm and the total inertia. When the ratio with the value J0 increases The speed gain Kv as to increase, the rate integral gain Kvi, is characterized in that and a parameter setting means for setting the cutoff frequency .omega.f.

  A motor control device according to a seventh aspect of the invention includes a second speed control unit that differentiates a position detection signal and generates a fifth compensation signal via a differential gain Kv, a position command signal of the motor, and the A position control unit that generates a fourth compensation signal via a position gain Kx, and a fifth compensation torque signal that is the fourth compensation signal; a position deviation signal that is a difference from the position detection signal of the electric motor; Calculating means for obtaining a third total compensation signal which is a difference between the first and second, a filter means for inputting the third total compensation signal and generating the driving force command signal having a cutoff frequency ωf and a low-pass characteristic; The motor inertia value Jm and the total inertia value J0 are input, and the ratio ωf / ωvi between the cut-off frequency ωf and the breakpoint frequency ωvi of the proportional / integral control unit is set to the motor inertia value Jm and the total inertia value J0. As the ratio increases, The velocity gain Kv to hear, the velocity integral gain Kvi, is characterized in that and a parameter setting means for setting the cutoff frequency .omega.f.

The motor control apparatus according to the eighth aspect of the invention satisfies the following equation, where k is a constant: ωf / ωvi = k · J0 / Jm
It is characterized by this.

According to a ninth aspect of the present invention, there is provided a control apparatus for an electric motor, wherein the speed gain Kv is set based on a product of the input first parameter r1 and second parameter ωs, and the cutoff frequency is ωc. ωf satisfies the following equation: ωf = r3 · r1 · ωs · (J0 / Jm) (where r3 is a constant)
It is characterized by this.

  As described above, according to the first invention, even when the rigidity of the controlled object is low and the total inertia ratio is large, the control system is less likely to become unstable, and a faster control system response can be easily obtained. There is an effect to become.

  According to the second invention, the parameter setting unit applies to the cross frequency ωc, which is a value obtained by dividing the speed gain Kv of the breakpoint frequency ωvi, which is a value obtained by dividing the speed integral gain Kvi by the speed gain Kv, by the total inertia value J0. The ratio is set to a preset constant r2, and the ratio of the speed gain Kv of the cut-off frequency ωf to the cross frequency ωcm of the single motor, which is a value obtained by dividing the speed gain Kv by the motor inertia value Jm, is set to a preset constant r3. Therefore, even if the rigidity of the controlled object is low, the open loop gain is unlikely to be greater than 0 dB, and the control system is unlikely to become unstable. Therefore, there is an effect that a faster control system response can be easily obtained.

  According to the third aspect of the invention, the motor position xm, which is a position signal of the motor, or a position where calculation is performed such that a signal component obtained by multiplying the low frequency component by the position gain Kx and a negative sign is added to the driving force command τr. A proportional feedback unit is provided, and the parameter setting unit is configured such that the ratio of the position gain Kx of the cutoff frequency ωf to the breakpoint frequency ωx, which is a value obtained by dividing the position gain Kx by the speed gain Kv, is large when the ratio of the total inertia value J0 to the motor inertia value Jm is large. Since the speed gain Kv, the position gain Kx, and the cutoff frequency ωf are set so as to increase, the control system is unstable even when position control is performed, even when the rigidity of the controlled object is low and the total inertia ratio is large. There is an effect that a faster control system response can be easily obtained.

  According to the fourth aspect of the invention, the parameter setting unit compares the ratio of the position gain Kx to the crossover frequency ωc, which is a value obtained by dividing the velocity gain Kv of the breakpoint frequency ωx, which is a value obtained by dividing the position gain Kx by the velocity gain Kv, by the total inertia value J0. Is set to a preset constant r2, and a ratio of the speed gain Kv of the cut-off frequency ωf divided by the motor inertia value Jm to the cross frequency ωcm of the single motor is set to a preset constant r3. For this reason, even in the case of position control, even if the rigidity of the controlled object is low, the open loop gain is less likely to be greater than 0 dB, and the control system is unlikely to become unstable. Therefore, there is an effect that the response of the faster control system can be simplified.

  According to the fifth invention, the control system is less likely to become unstable even when the rigidity of the controlled object is low and the total inertia ratio is large, and it is possible to easily obtain a faster speed control system response. is there.

  According to the sixth or seventh invention, even when the rigidity of the controlled object is low and the total inertia ratio is large, the control system is less likely to become unstable, and a quick position control system response can be easily obtained. effective.

  According to the eighth or ninth invention, even when the rigidity of the controlled object is lower and the total inertia ratio is large, the control system is less likely to become unstable, and the response of the faster position control system or speed control system can be simplified. There is an effect that can be obtained.

Embodiment 1
An embodiment of the present invention will be described with reference to a block diagram of a motor control device shown in FIG.
The motor control apparatus includes a control target 101 including an electric motor 21, a mechanical load 23 coupled to the electric motor 21, and a detector (not shown) that detects and outputs the speed of the electric motor 21, and the electric motor 21 receives a driving force command signal τr. To generate a driving force (torque in the case of a rotating system, propulsive force in the case of a direct acting system) to drive a mechanical system composed of an electric motor 21 and a mechanical load 23, and a speed detection signal vm of the electric motor 21 is obtained. Output. Next, the PI (proportional integral) controller 12 obtains a speed deviation signal ve which is a difference between the speed command signal vr and the speed detection signal vm inputted from the outside by the subtractor 3 and inputs the speed deviation signal ve to the PI controller 12. Then, PI calculation is performed and a PI compensation signal τc is output.

The PI controller 12 multiplies the speed deviation signal ve by the speed gain Kv to generate a first compensation signal, and integrates the speed deviation ve by multiplying the speed deviation ve by the speed integral gain Kvi. A speed integration amplifier 9 as a speed integration control unit for generating a compensation signal of 2, and the sum of the output of the speed amplifier 7 and the output of the speed integration amplifier 9 to obtain a PI compensation signal τc as a first total compensation signal And an adder 10 as the first adding means.
The low-pass filter 15 serving as a filter means performs an operation of a low-pass filter having a cutoff frequency ωf that represents the input PI compensation signal τc as a transfer function F (s). The PI controller 12 outputs a torque command signal τr as a driving force command signal as shown in the following equation.
τr = F (s) · (Kv + Kvi / s) · (vr−vm) (1)
Here, s: Laplace operator When the above equation (1) is expanded, the following equation is obtained.
τr = F (s) .A.vr-F (s) .Kv.vm-F (s). (Kvi / s) .vm .. (2)
Where A: Kv + Kvi / s
Therefore, a signal component obtained by multiplying the speed detection signal vm by −Kv and causing the low-pass filter 15 to act is added to the torque command signal τr of the above equation (2), and the speed detection signal vm is integrated and multiplied by −Kvi. Are calculated so as to add the low frequency components. That is, a speed proportional feedback unit represented by the second term on the right side of the equation (2) and a speed integral feedback unit represented by the third term are provided.

  Next, the parameter setting unit 13 inputs preset constants r1, r2, and r3 and a response setting parameter ωs (rad / sec) that is a parameter for setting a response speed from the outside, and the inertia value Jm of the electric motor 21. Then, the total inertia value J0 of the entire mechanical system in the controlled object 101 is input from the outside (a method such as automatic estimation).

The parameter setting unit 13 sets the speed gain Kv of the speed amplifier 7 and the speed integration gain Kvi of the speed integration amplifier 9 based on the input r1, r2, r3, the response setting parameter ωs, the motor inertia value Jm, and the total inertia value J0. The cutoff frequency ωf of the low-pass filter 15 is calculated and set.
Kv = ωc, J0 = r1, ωs, J0 (3)
Kvi = r 2 · ωc · Kv = r 2 · (r 1 · ωs) ² · J 0 (4)

  Next, in setting the cutoff frequency ωf of the low-pass filter 15, the characteristics of the controlled object 101 are considered. The controlled object 101 is configured to drive the mechanical load 23 via a shaft of the electric motor 21 and a driving force transmission mechanism such as a coupling, a ball screw, and a belt. In FIG. 2, an example of the frequency response gain from the driving force command τr to the speed detection signal vm in the controlled object 101 when the electric motor 21 and the rigid mechanical load 23 are coupled by an elastic body such as a spring is shown by a polygonal line approximation. Show. Here, it is assumed that the control of the driving force of the electric motor 21 with respect to the driving force command τr in the control target 101 has a sufficiently fast response. 2A shows a case where the rigidity is low, and FIG. 2B shows a case where the rigidity is relatively high.

  The characteristic of the controlled object 101 may be a plurality of resonance peaks, and is approximated to a characteristic in which a plurality of inertias are coupled by a plurality of springs. FIG. 2C shows the frequency response when there are two resonance peaks.

As described above, the characteristic of the controlled object 101 when the rigidity is low is that when the driving force command τr changes at a low frequency, the motor 21 and the mechanical load 23 operate integrally, so that the inertia is the total inertia. This is similar to the characteristic of the rigid body having the value J0, and can be approximated to the characteristic of the following expression.
P (s) = 1 / (J0 · S) (5)
On the other hand, when the driving force command τr changes at a high frequency, due to the elasticity of the motor shaft and the driving force transmission mechanism, the mechanical load does not operate and only the motor operates at a high frequency. Therefore, the frequency response of the controlled object 101 approaches the characteristics of the motor 21 alone, whose inertia is the motor inertia Jm at a high frequency, and the frequency response gain becomes high, and can be approximated by the following expression.
P (s) = 1 / (Jm · s) (6)

Further, in the middle of the low frequency range and high frequency range, the resonance characteristics indicated by the upward peak line in FIG. 2, the anti-resonance characteristic indicated by a downward notch (downward cut) in FIG appears.
The characteristic of the controlled object 101 is such that the gain increases at a high frequency, and the gain in the high frequency region approximates the characteristic of the motor inertia value Jm if the peak characteristic of resonance is ignored. As a result, as the ratio of the total inertia J0 to the motor inertia Jm (hereinafter referred to as the total inertia ratio J0 / Jm) is larger, the gain of the controlled object 101 in the higher frequency region is relatively higher.

Next, the operation of the parameter setting unit 13 in the present embodiment will be described with reference to FIG. FIG. 3 shows an example of an open loop frequency response gain (hereinafter simply referred to as an open loop gain) of the control system when the parameter setting unit 13 according to the present embodiment is used, and FIG. , (B) shows a case where the rigidity is relatively high. In the present embodiment, in the low frequency region, the control parameter is set on the assumption that the transfer function P (s) of the controlled object 101 is approximated by the above equation (5). Accordingly, the overall frequency of the open loop gain is adjusted according to the response setting parameter ωs input from the outside, and the break frequency ωvi of the PI controller 12 is set to the following crossing frequency ωc so as to converge the control error as quickly as possible. It is set to be about a fraction of the.
ωc = Kv / J0 (7)

On the other hand, as described above, if the resonance peak is ignored in the high frequency region, the frequency response gain of the controlled object 101 approaches the characteristics of the single motor whose inertia shown in the above equation (6) is the motor inertia value Jm. Further, the crossing frequency ωcm of the electric motor 21 alone in the open loop gain is expressed by the following equation.
ωcm = Kv / Jm = ωc · J0 / Jm (8)
Therefore, in order to maintain stability, in order to reduce the influence of model errors and observation noise in the high frequency region so as not to delay the phase in the frequency region where the open loop gain is greater than 0 dB even when the rigidity is low. The low-pass filter 15 is set so that frequency components higher than the crossover frequency ωcm of the motor 21 alone are removed from the feedback loop.
That is, the cutoff frequency ωf of the low-pass filter 15 is set from several times to about 10 times based on the crossing frequency ωcm of the electric motor 21 alone. Specifically, for example, the cutoff frequency ωf of the low-pass filter 15 is set as shown in the following equation using the input constants r1 and r3, the total inertia value J0, the motor inertia value Jm, and the response setting parameter ωs.
ωf = r3 ・ ωcm = r3 ・ r1 ・ (J0 / Jm) ・ ωs (9)
Further, the relationship between ωf / ωvi and the total inertia ratio J0 / Jm is obtained as follows.
ωf / ωvi = r3 / r2 / (J0 / Jm) = k. (J0 / Jm) (10)
By setting as described above, the ratio of the cut-off frequency ωf of the low-pass filter 105 to the breakpoint frequency ωvi may be set to increase as the total inertia ratio J0 / Jm increases.
In the present embodiment, when the parameter setting unit 13 operates as described above, as shown in FIG. 3, in a frequency region higher than ωf where the phase is delayed, the attenuation is very small, and thus there is a high resonance peak. Other than the above, even if the rigidity of the control object 101 is low, the open loop gain does not become larger than 0 dB, and as a result, the control system is less likely to become unstable compared to the conventional case. Therefore, it is possible to increase the crossover frequency ωc and the breakpoint frequency ωvi while maintaining the stability of the control system as compared with the prior art, and it is possible to easily obtain a faster response of the control system.

In the above description, the ratio between the cut-off frequency ωf and the crossover frequency ωcm of the electric motor 21 is described as a fixed value r3. However, the ratio may not be a completely fixed value, and the larger the total inertia ratio J0 / Jm is, the greater the ratio is. If the ratio of the cut-off frequency ωf to the crossing frequency ωc is increased, the same effect can be obtained that is less likely to be unstable.
At the same time, in order to converge the control error at a low frequency as quickly as possible, the ratio between the breakpoint frequency ωvi and the crossover frequency ωc is close to a constant value, so that the response is as fast as possible while maintaining stability. In order to obtain fast convergence characteristics, the ratio is set such that the ratio of the cutoff frequency ωf to the breakpoint frequency ωvi increases as the total inertia ratio J0 / Jm increases.
Thereby, even when the rigidity of the controlled object 101 is low and the total inertia ratio is large, it is difficult to become unstable, and as a result, it is possible to easily obtain a faster control system response.

Further, even when there is a backlash at the coupling portion between the electric motor 21 and the mechanical load 23, the mechanical load does not operate in the small amplitude operation, and only the electric motor operates. (6) above. In general, the small-amplitude operation of the control system in which backlash becomes a problem occurs in a high frequency region, and is therefore considered to have the same characteristics as when the rigidity is low. Therefore, even when backlash exists, the above setting makes it difficult to become unstable, and it is possible to easily obtain a faster control system response.

In the above description, the output of the low-pass filter 15 is directly used as the driving force command τr. However, the driving force command τr includes, for example, a feedforward signal obtained by performing an appropriate transfer function calculation from the speed command vr. Needless to say, further additions may be made.
In the above description, the ratio between the response setting parameter ωs and the crossing frequency ωc is described as fixed at r1, but may be changed according to the total inertia ratio J0 / Jm.
In the above description, the low-pass filter 15 is inserted so as to act on the output of the PI controller 12, but the part where the low-pass filter 15 is inserted may be another part in the control loop, for example, the input of the PI controller 12. Needless to say, a low-pass filter may be directly applied to the speed detection signal vm detected from the motor 21 or the motor 21.

<Comparative example>
The operation of the parameter setting unit 13 will be described with reference to FIG. FIG. 4 shows the open loop gain of the control system in a polygonal line approximation when set using the parameter setting unit 13 according to the comparative example. In the comparative example, control parameters are set on the assumption that the transfer function P (s) of the controlled object 101 is basically a rigid mechanical system model represented by the following equation.
P (s) = 1 / (J0 · s) (11)

In addition, by adjusting the response setting parameter ωs input from the outside, the control system is adjusted so as to obtain a response as fast as possible within a stable range, that is, the open loop gain is adjusted to be large as a whole, and low frequency control is performed. In order to converge the error as quickly as possible, the break frequency ωvi of the PI controller 12 expressed by the following equation (12) is about a fraction of the crossing frequency ωc expressed by the equation (7). Set to.
ωvi = Kvi / Kv (12)
Here, the cross frequency ωc is substantially the same as an index called a control band, and the control system operates so as to reduce the control error in a frequency region lower than the cross frequency ωc.
Further, for the purpose of reducing the influence of the model error and the detection noise in the high frequency region such as mechanical resonance with poor attenuation in the controlled object 101, the low-pass filter 15 so as to remove the frequency component higher than the cross frequency ωc from the feedback loop. Set. That is, the cutoff frequency ωf of the low-pass filter 105 is set from several times to about 10 times with respect to the crossing frequency ωc. Specifically, the cutoff frequency ωf is set as in the following equation.
ωf = r3 · ωc = r3 · r1 · ωs (13)
By setting as described above, in the comparative example, the ratio of the cutoff frequency ωf to the breakpoint frequency ωvi is always equal to r3 / r regardless of the ratio of the total inertia J0 to the motor inertia Jm (hereinafter referred to as the total inertia ratio). It becomes a constant value of r2.
The solid line in FIG. 4 shows the open loop gain when the controlled object 101 is expressed by the equation (5) , that is, when the rigidity is sufficiently high. Also shown in the figure is the relationship between the crossover frequency ωc, the breakpoint frequency ωvi, the cutoff frequency ωf, and the open loop gain.

Next, the point that the comparative example is inferior to the first embodiment in performance will be described. An example of the open loop gain of the control system when the rigidity of the control object 101 is low is shown by a broken line in FIG . As shown in the figure, when the rigidity of the control object 101 is low, the open loop gain is higher in a higher frequency region than in the case of the rigid body.
Further, when the mechanical resonance attenuation due to the low rigidity is small, a resonance peak (upward gain peak line) appears. Here, in the frequency region higher than the cutoff frequency ωf, the phase is delayed by the action of the low-pass filter 15. As a result, as shown in FIG. 4, when the open loop gain becomes higher than 0 dB in a frequency region higher than the cutoff frequency ωf where the phase is delayed, the control system becomes unstable. Therefore, in such a case, there is a problem that the response setting parameter ωs must be reduced so that the entire open loop gain is reduced, and as a result, the response of the control system is delayed. As described above, the larger the total inertia ratio, the larger the effect of increasing the open loop gain in the high frequency region. As a result, the control system is likely to become unstable, and the response of the control system becomes slower.

Another embodiment of the present invention will be described with reference to the block diagram of FIG. 5 showing a control device for an electric motor. Although the speed control has been described in the first embodiment, the position control will be described in the second embodiment. In FIG. 5, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.
In the second embodiment, instead of the speed detection signal vm, a motor position detection signal (motor position) xm in which the movement position is detected by a detector is output. A position deviation signal xe, which is the difference between the position command signal xr inputted from the outside and the position detection signal xm, is obtained by the subtractor 103, and the position deviation signal xe is inputted to the PID controller 112 to perform PID (proportional integral differentiation). The PID compensation signal τc as the second total compensation signal is output.

The PID controller 112 includes a speed amplifier (first speed control unit) 105 that generates a third compensation signal by multiplying a signal obtained by differentiating the position deviation signal xe by a speed gain Kv, and a position gain Kx to the position deviation signal xe. Is multiplied by a position amplifier (position control unit) 107 that generates a fourth compensation signal, and a position integration amplifier (position integration control unit) 109 that multiplies a signal obtained by integrating the position deviation signal xe with a position integration gain Kxi. An adder 110 is provided as second adding means for outputting the sum of the output of the amplifier 105, the output of the position amplifier 107, and the output of the position integrating amplifier 109 as a PID compensation signal τc.
The low-pass filter 15 receives a PID compensation signal τc and has a low-pass filter having a cutoff frequency ωf represented by a transfer function F (s).
The PID controller 112 calculates and outputs a torque command signal τr as a driving force command signal by the following equation.
τr = F (s) · (Kv · s + Kx + Kxi / s) · (xr−xm) (14)
When the above expression (14) is expanded, the following expression (15) is obtained.
τr = F (s) · B · xr−F (s) · Kv · s · xm−F (s) · Kxi · xm
-F (s) (Kxi / s) · xm (15)
Where B = Kv · s + Kx + Kxi / s
Therefore, with the configuration of FIG. 5, a signal obtained by multiplying the torque command signal τr by the differential signal of the position detection signal xm by −Kv and applying a low-pass filter of the cutoff frequency ωf is added, and the position detection signal xm of the electric motor 21 is added. The calculation is performed so as to add the low frequency components of the signal multiplied by -Kx. That is, a speed proportional feedback unit represented by the second term on the right side of the equation (15) and a position proportional feedback unit represented by the third term on the right side are provided.

The parameter setting unit 13 inputs a response setting parameter ωs, which is a parameter for setting the response speed from the outside, and inputs the motor inertia value Jm and the total inertia value J0 from the outside. The parameter setting unit 13 also determines the speed gain Kv of the speed amplifier 105, the position gain Kx of the position amplifier 107, and the position integration gain of the position integration amplifier 109 based on the response setting parameter ωs, the motor inertia value Jm, and the total inertia value J0. The crossover frequency ωc is set to r1 times the response setting parameter ωs using the preset constants r1, r2, r3, r4 as the cutoff frequency ωf of Kxi and the low-pass filter 15, and each control parameter is expressed by the following (16). Calculated and set by Equation (19).
Kv = ωc, J0 = r1, ωs, J0 (16)
Kx = r2, ωc, Kv = r2, (r1, ωs) ² , J0 (17)
Kxi = r4 · ωc · Kx = r4 · r2 · (r1 · ωs) ³ · J0 (18)
ωf = r3 · ωcm = r3 · r1 · (J0 / Jm) · ωs (19)
When the relationship between ωf / ωvi and the total inertia ratio J0 / Jm is obtained, the above equation (9) is obtained. By setting as described above, ωx and ωxi in the following equations (20) and (21) corresponding to the breakpoints of the PID controller 112 are set to r2 times and r4 times the crossing frequency, respectively, and r2 and If r4 is set appropriately in advance, a low frequency control error can be quickly converged.
ωx = Kx / Kv (20)
ωxi = Kxi / Kx (21)
The above will be described with reference to FIG. 6. FIG. 6 shows an example of the open loop gain of the control system when the parameter setting unit 13 is used. (A) is low in rigidity, (b) is relatively high in rigidity. Shows the case.

Further, if the cutoff frequency ωf of the low-pass filter 15 is set to r3 times the crossing frequency ωcm of the electric motor 21 alone and r3 is set to several times to about 10 times, as described in the first embodiment, the control is performed. Even if the rigidity of the object 101 is low, the open loop gain is less likely to be greater than 0 dB, and as a result, it is difficult to make the control system unstable compared to the conventional example. Therefore, the crossover frequency ωc and the breakpoint frequencies ωx and ωxi can be stably increased as compared with the conventional example, and a faster control system response can be easily obtained.

  As a result, if the total inertia ratio J0 / Jm increases, the ratio of the cutoff frequency ωf in the low-pass filter 15 to the breakpoint frequencies ωx and ωxi in the PID controller 112 inevitably increases. Even when the total inertia ratio is low, it is difficult to become unstable, and a faster control system response can be easily obtained.

A block diagram of the motor control device shown in FIG. 7 will be described as a modification of the second embodiment. In FIG. 7, the same reference numerals as those in FIG.
In FIG. 7, the motor control device differentiates the position detection signal xm instead of the speed control unit 105 of FIG. 5 and generates a fifth compensation signal via the differential gain Kv. 5 instead of the adder 110 in FIG. 5, an arithmetic means for obtaining a third total compensation signal that is the difference between the fourth compensation signal and the fifth compensation signal that are output from the position amplifier (position control unit) 107. Even if the arithmetic unit 210 is provided, the same operation and effect as the motor control device shown in FIG. 5 can be obtained.
In the above description, the configuration including the position integrating amplifier 109 is described. However, the position integrating amplifier 109 is not necessarily required depending on the control target 101.

  As described above, the present invention can be applied to the use of speed control and position control of a motor in which the motor and the mechanical load are combined.

FIG. 2 is a block diagram showing a motor control device according to Embodiment 1; It is a gain vs. frequency characteristic diagram for explaining a characteristic of a controlled object. FIG. 3 is a characteristic diagram of gain versus frequency of the control device according to the first embodiment. It is a gain vs. frequency characteristic diagram for explaining the characteristic of a comparative example. FIG. 5 is a block diagram showing a motor control device according to a second embodiment. FIG. 10 is a gain vs. frequency characteristic diagram for explaining the characteristics of the second embodiment. FIG. 10 is a block diagram showing a motor control device according to a modification of the second embodiment.

Explanation of symbols

  12 PI controller, 7 speed amplifier, 9 speed integrating amplifier, 15 low-pass filter, 13 parameter setting unit, 101 controlled object, 112 PID controller, 105 speed amplifier, 107 position amplifier, 109 position integrating amplifier.

Claims (9)

In a motor control device that forms a mechanical system composed of a load coupled to an electric motor having an electric motor inertia value Jm, and that generates a driving force corresponding to the driving force command signal τr to the electric motor,
A speed proportional feedback unit that performs a calculation so as to add a signal component obtained by multiplying the speed detection signal ωm of the motor by a speed gain Kv and a negative sign to apply a low-pass filter having a cutoff frequency ωf to the driving force command signal τr. When,
A speed integration feedback unit that performs an operation so as to add a signal component obtained by integrating the speed detection signal ωm or a signal component obtained by multiplying the low frequency component thereof by a speed integration gain Kvi and a negative sign to the driving force command signal τr;
A parameter setting unit for setting the speed gain Kv, the speed integral gain Kvi, and the cut-off frequency ωf based on a response setting parameter ωs input from the outside, the motor inertia value Jm, and the total total inertia value J0 in the mechanical system; Prepared,
If the ratio of the cutoff frequency ωf to the breakpoint frequency ωvi, which is a value obtained by dividing the speed integral gain Kvi by the speed gain Kv, is large, the ratio of the total inertia value J0 to the motor inertia value Jm is large. The speed gain Kv, the speed integral gain Kvi, and the cutoff frequency ωf are set so as to increase.
An electric motor control device. In a motor control device that forms a mechanical system composed of a load coupled to an electric motor having an electric motor inertia value Jm, and that generates a driving force corresponding to the driving force command signal τr to the electric motor,
A speed proportional feedback unit that performs a calculation so as to add a signal component obtained by multiplying the speed detection signal ωm of the motor by a speed gain Kv and a negative sign to apply a low-pass filter having a cutoff frequency ωf to the driving force command signal τr. When,
A speed integration feedback unit that performs an operation so as to add a signal component obtained by integrating the speed detection signal ωm or a signal component obtained by multiplying the low frequency component thereof by an integral gain Kvi and a negative sign to the driving force command signal τr;
A parameter setting unit for setting the speed gain Kv, the speed integral gain Kvi, and the cutoff frequency ωf based on the response setting parameter ωs input from the outside, the inertia value Jm of the motor, and the total inertia value J0 of the entire mechanical system. With
The parameter setting unit has a ratio of a break frequency ωvi that is a value obtained by dividing the speed integral gain Kvi by the speed gain Kv to a cross frequency ωc that is a value obtained by dividing the speed gain Kv by the total inertia value J0 in advance. In addition to the set constant r2, the ratio of the speed gain Kv of the cut-off frequency ωf divided by the motor inertia value Jm to the cross frequency ωcm of the single motor is set to a preset constant r3. ,
An electric motor control device. In a motor control device that forms a mechanical system composed of a load coupled to an electric motor having an electric motor inertia value Jm, and that generates a driving force corresponding to the driving force command signal τr to the electric motor,
A speed proportional feedback unit that performs an operation so as to add a signal component obtained by multiplying the speed detection signal ωm of the electric motor by a speed gain Kv and a negative sign to apply a low-pass filter to the driving force command signal;
A position proportional feedback unit that performs an operation so as to add a signal component obtained by multiplying the position detection signal xm of the electric motor or a low frequency component thereof by a position gain Kx and a negative sign to the driving force command signal τr;
Parameter setting for setting the speed gain Kv, the position gain Kx, and the cutoff frequency ωf of the low-pass filter based on the response setting parameter ωs input from the outside, the motor inertia value Jm, and the total inertia value J0 of the entire mechanical system. Part
The parameter setting unit increases the ratio of the cutoff frequency ωf to the breakpoint frequency ωx, which is a value obtained by dividing the position gain Kx by the speed gain Kv, if the ratio of the total inertia value J0 to the motor inertia value Jm is large. The speed gain Kv, the position gain Kx, and the cutoff frequency ωf are set so that
An electric motor control device. In a motor control device that forms a mechanical system composed of a load coupled to an electric motor having an electric motor inertia value Jm, and that generates a driving force corresponding to the driving force command signal τr to the electric motor,
A speed proportional feedback unit that performs a calculation so as to add a signal component obtained by multiplying the speed detection signal ωm of the electric motor by a speed gain Kv and a negative sign to apply a low-pass filter to the driving force command signal τr;
A position proportional feedback unit that performs an operation so as to add a signal component obtained by multiplying the position detection signal xm of the electric motor or a low frequency component thereof by a position gain Kx and a negative sign to the driving force command signal τr;
Parameter setting for setting the speed gain Kv, the position gain Kx, and the cutoff frequency ωf of the low-pass filter based on the response setting parameter ωs input from the outside, the motor inertia value Jm, and the total inertia value J0 of the entire mechanical system. Part
The parameter setting unit presets a ratio of a breakpoint frequency ωx, which is a value obtained by dividing the position gain Kx by the velocity gain Kv, to a cross frequency ωc, which is a value obtained by dividing the velocity gain Kv by the total inertia value J0. And the ratio of the speed gain Kv of the cutoff frequency ωf divided by the motor inertia value Jm to the crossover frequency ωcm of the single motor is set to a preset constant r3. An electric motor control device. A motor control device that forms a mechanical system by a load coupled to an electric motor having an electric motor inertia value Jm, the mechanical system having a total inertia value J0, and generating a driving force corresponding to the driving force command signal τr to the electric motor. In
A speed controller that generates a first compensation signal via a speed gain Kv, a speed deviation signal that is a difference between the speed command signal of the motor and a speed detection signal of the motor;
A speed integration controller that integrates the speed deviation signal and generates a second compensation torque signal via a speed integration gain Kvi;
First addition means for adding the first compensation signal and the second compensation signal to generate a first total compensation signal;
Filter means for receiving the first total compensation signal and generating the driving force command signal having a low-pass characteristic with a cutoff frequency ωf;
The motor inertia value Jm and the total inertia value J0 are input, and the ratio between the cutoff frequency ωf and the break-point frequency ωvi of the proportional / integral control unit, which is a value obtained by dividing the speed integral gain Kvi by the speed gain Kv. parameter setting means for setting the speed gain Kv, the speed integral gain Kvi, and the cutoff frequency ωf so as to increase ωf / ωvi as the ratio of the motor inertia value Jm to the total inertia value J0 increases;
An electric motor control device comprising: A motor control device that forms a mechanical system by a load coupled to an electric motor having an electric motor inertia value Jm, the mechanical system having a total inertia value J0, and generating a driving force corresponding to the driving force command signal τr to the electric motor. In
A first speed control unit that differentiates a position deviation signal that is a difference between a position command signal of the motor and a position detection signal of the motor, and generates a third compensation signal via a differential gain Kv;
A position control unit that generates a fourth compensation signal via the position gain Kx, the position deviation signal;
Second addition means for adding the third compensation signal and the fourth compensation signal to generate a second total compensation signal;
Filter means for inputting the second total compensation signal and having the low-pass characteristic of the cutoff frequency ωf to generate the driving force command signal;
The motor inertia value Jm and the total inertia value J0 are input, and the ratio ωf / ωvi between the cut-off frequency ωf and the breakpoint frequency ωvi of the proportional / integral control unit is set to the motor inertia value Jm and the total inertia value J0. Parameter setting means for setting the speed gain Kv, the speed integral gain Kvi, and the cut-off frequency ωf so as to increase as the ratio increases.
An electric motor control device comprising: A motor control device that forms a mechanical system by a load coupled to an electric motor having an electric motor inertia value Jm, the mechanical system having a total inertia value J0, and generating a driving force corresponding to the driving force command signal τr to the electric motor. In
A second speed controller for differentiating the position detection signal of the motor and generating a fifth compensation signal via a differential gain Kv;
A position control unit that generates a fourth compensation signal via a position gain Kx , a position deviation signal that is a difference between a position command signal of the motor and a position detection signal of the motor ;
Computing means for obtaining a third total compensation signal which is a difference between the fourth compensation signal and the fifth compensation torque signal;
Filter means for receiving the third total compensation signal and generating the driving force command signal having a low-pass characteristic with a cutoff frequency ωf;
The motor inertia value Jm and the total inertia value J0 are input, and the ratio ωf / ωvi between the cut-off frequency ωf and the breakpoint frequency ωvi of the proportional / integral control unit is set to the motor inertia value Jm and the total inertia value J0. And a parameter setting means for setting the speed gain Kv, the speed integral gain Kvi, and the cutoff frequency ωf so as to increase as the ratio increases. When the constant is k, the following equation is satisfied. Ωf / ωvi = k · J0 / Jm
The motor control device according to claim 5, wherein the motor control device is a motor control device. Based on the product of the input first parameter r1 and second parameter ωs, the speed gain Kv is set and the crossing frequency is ωc.
The cut-off frequency ωf is ωf = r3 · r1 · ωs · (J0 / Jm) (where r3 is a constant)
The motor control device according to claim 5, wherein the motor control device is a motor control device.

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