JP2005304120A - Controller of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high speed response by suppressing vibration of a load machine in the controller for controlling the rotational speed or position of a motor. <P>SOLUTION: The controller for motor comprises a position controller receiving an external position command value and outputting an internal speed command value, a switching section for selecting and outputting an external speed command value or an internal speed command value as a speed command value, a feedforward controller receiving the speed command value and outputting a corrected speed command value and a feedforward torque command, a feedback controller receiving the corrected speed command value and the motor speed and outputting a feedback torque command value, and a torque control section receiving a feedforward torque command value and the feedback torque command value and outputting a torque command value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric motor control device that controls a state quantity of an electric motor or a load by suppressing mechanical resonance when a machine serving as a load is driven by the electric motor.

2. Description of the Related Art As a conventional motor control device, there is known a motor control device that controls the rotational speed or position of a motor by a torque command signal generated based on a position command signal input from the outside. (For example, see Patent Document 1)
This conventional apparatus includes a feedforward circuit that receives a position command signal as an input and calculates a feedforward torque signal by a transfer function calculation. By adjusting parameters in the feedforward circuit, the position command signal is adjusted by an electric motor. The rotational position of the driven load machine is made to respond in a good manner without overshoot, and the speed of the response is arbitrarily changed.

FIG. 3 shows a control block diagram of the motor control device as the above-mentioned conventional technique.
In FIG. 3, 101 is an electric motor that is rotated by an electric motor torque τ _M , 102 is a load machine that is driven by the electric motor, 103 is a torque transmission unit that connects the electric motor 101 and the load machine 102, and 104 is an electric motor rotational position x _M and the electric motor A rotation detector 105 that detects the rotation speed v _M is a mechanical system that combines the electric motor 101, the load machine 102, the torque transmission unit 103, and the rotation detector 104.
Reference numeral 106 denotes a torque control circuit that matches the motor torque τ _M with the torque command signal τr, and reference numeral 107 denotes a control object that combines the mechanical system 105 and the torque control circuit 106.

108 is a position command signal generation circuit for generating a position command signal xr for the electric motor 101 and the load machine 102, 109 is a speed compensation circuit composed of a proportional-integral (PI) controller, a 2-degree-of-freedom PI controller, and the like. A position compensation circuit including a proportional controller, 111 is a feedback compensation circuit including a speed compensation circuit 109 and a position compensation circuit 110, and 112 is a position command signal xr as an input, and a feedforward torque signal τf and a response target position signal xf. This is a feedforward circuit that outputs a response target speed signal vf.
Reference numeral 113 denotes an overall position control circuit including the feedback compensation circuit 111 and the feedforward circuit 112, and 114 denotes a load disturbance torque τd input to the load machine 102.

The mechanical system 105 has mechanical resonance characteristics, and the mechanical system 105 will be described as a two-inertia system having only one resonance characteristic. At this time, the transfer function from the motor torque τ _M of the mechanical system 105 to the motor rotation speed v _M is G _M (s), and the transfer function from the motor torque τ _M to the rotation speed of the load machine 102 is G _L (s). When expressed, G _M (s) and G _L (s) are expressed by the following equations (1) and (2), respectively.
G _M (s) = (ωz ⁻² s ² +1) / {J · s · (ωp ⁻² s ² +1)} (1)
G _L (s) = 1 / {J · s · (ωp ⁻² s ² +1)} (2)

Here, ωz is an anti-resonance frequency and ωp is a resonance frequency. J is the total inertia of the mechanical system. In this case, J is the sum of the inertia J _M of the motor 101 and the inertia J _L of the load machine 102.
FIG. 4 is a block diagram showing details of the feedforward circuit 112. In FIG. 4, 140 is a response target load position signal generation filter, 141 is a feedforward torque signal generation filter, 142 is a response target motor position signal generation filter, and 143 is a differentiation circuit.

Next, the operation of the control system and the adjustment method will be described. First, when the position of the electric motor 101 is controlled, the switch 126 is switched to a), and the control object 107 is controlled using the position command signal generation circuit 108 and the position control circuit 113.
In the position control circuit 113, a difference signal between the actual motor rotational position x _M and response target position signal xf as compensation position signal xc, also compensate for the difference signal between the target response speed signal vf and the actual motor rotation speed v _M Each is input to the feedback compensation circuit 111 as a speed signal vc.

In the feedback compensation circuit 111, the position compensation circuit 110 receives the compensated position signal xc, and outputs the position compensation speed signal vcx by performing PI calculation using the position gain Kp and the position integral gain Kpi. The speed compensation circuit 109 receives a sum signal of the position compensation speed signal vcx and the compensation speed signal vc, multiplies the speed gain Kv, and outputs a compensation torque signal τc.
Then, the position control circuit 113 inputs the sum signal of the feedforward torque signal τf and the compensation torque signal τc as a torque command signal τr to the torque control circuit 106, and the torque control circuit 106 uses the motor torque τ _M as the torque command signal τr. The operation of the electric motor is controlled by controlling so as to match the above.

Next, the operation of the feedforward circuit 112 will be described. First, the position command signal xr is input to the feedforward circuit 112. When the transfer characteristic of the torque control circuit 106 is ideally 1 and the transfer characteristic of the mechanical system 105 is a two-inertia system in which attenuation is negligible as in the expressions (1) and (2), the feedforward circuit 112 is. position command signal ideally like to respond feedforward torque signal τf the rotational position of the load machine 102 with respect to xr, and their time expected motor rotation position x _M response target position signal xf responses of the expected This is a circuit for outputting the response of the motor rotation speed v _M to be output as the response target speed signal vf.

In the feedforward circuit 112, as shown in FIG. 4, the response target load position signal generation filter 140 inputs the position command signal xr, and as an ideal response of the rotational position of the load machine 102, a response to the position command signal xf is obtained. Using the target value response speed adjustment parameter ωr for adjusting the speed, a response target load position signal x _Lf is output by performing a low-pass filter calculation.

The feedforward torque signal generation filter 141 receives the response target load position signal x _Lf and uses the inertia estimated value Je that is the estimated value of the total inertia J and the estimated resonance frequency ωpe that is the estimated value of the resonance frequency ωp. In the transfer function calculation of the following equation (3) corresponding to the inverse function of the equation (2), the feed forward torque signal τf is output.
τf = Je · s ² (ωpe ⁻² · s ² +1) · x _Lf (3)

Next, the response target motor position signal generation filter 142 receives the response target load position signal x _Lf , and uses the estimated value ωze of the anti-resonance frequency ωz of the mechanical system 105, the expressions (1) and (2) of the arithmetic ratios below that corresponding to (4) of the right side, and outputs the response target position signal xf is a response target signal of the motor rotation position x _M. The differentiating circuit 143 receives the response target position signal xf and performs a differentiation operation to output a response target speed signal vf.
xf = (ωze ⁻² · s ² +1) · x _Lf (4)

As described above, the feedforward circuit 112 receives the position command signal xr and outputs the feedforward torque signal τf, the response target position signal xf, and the response target speed signal vf, so that the transfer characteristic of the torque control circuit 106 is obtained. Is ideally 1 and the characteristics of the mechanical system 105 coincide with the equations (1) and (2), and the mechanical parameters Je, ωze, and ωpe are accurately estimated, the feedforward torque signal τf is By driving the control object 107 as the torque command signal τr, the motor rotation position x _M is the response target position signal xf, the motor rotation speed v _M is the response target speed signal vf, and the load machine rotation position x _L is the response target load. It coincides with the position signal x _Lf .
Therefore, the load machine rotational position x _L with respect to the position command signal xf responds with overshoot without good form and speed of the response can be arbitrarily varied by adjusting the target value response speed adjustment parameter .omega.r.

Next, a method for adjusting the feedforward circuit 112 will be described.
Estimated inertia Je, estimated antiresonance frequency ωze, and estimated resonance frequency ωpe, which are adjustment parameters of the feedforward torque signal generation filter 141, are estimated values of the total inertia J, antiresonance frequency ωz, and resonance frequency ωp of the mechanical system 105, respectively. Use.
If the mechanical system 105 is a two-inertia system and the above estimated value is accurate, the target value response speed adjustment parameter ωr, which is an adjustment parameter of the response target load position signal generation filter 140, is adjusted, so that the load machine The rotational position response can theoretically be adjusted to an arbitrary speed.
By adjusting the speed adjustment parameter ωr to a preset constant multiple, it is possible to obtain an effect of obtaining a quick response within a range in which the mechanical system 105 is not burdened.

Next, the operation of the automatic adjustment circuit 128 will be described.
First, when performing automatic adjustment, the switch 126 is switched to b), and a torque command signal τr such as a pseudo-random signal is output to the controlled object 107 to perform a drive test. The torque command signal τr and the motor rotational speed v at that time are tested. _M is input to the automatic adjustment circuit 128.
Next, the automatic adjustment circuit 128 calculates the parameters of the built-in higher-order transfer function model by using, for example, the least square method, so that the torque command signal τr of the controlled object 107 to the motor rotation speed v _M is calculated. Detailed identification of the transfer function G (s) is performed, and the absolute value of the smallest complex zero is selected as the estimated anti-resonance frequency ωze, and the total inertia is estimated from the gain characteristics in the low-frequency region of the high-order model to obtain the estimated inertia Je. The estimated antiresonance frequency ωze and the estimated inertia Je are output.

Also, the two-inertia system optimum gain Kopt is calculated and output using the estimated anti-resonance frequency ωze and the estimated inertia Je. Further, from the frequency response obtained from the higher order model, the maximum gain Gmax is obtained using a preset set phase margin θm of 0 or more and a set gain margin Gm of 1 or more, and the limit gain Kmax is calculated.
Then, the smaller one of the two-inertia system optimum gain Kopt and the limit gain Kmax is determined as the speed gain Kv of the speed compensation circuit 109, the crossover frequency ωc of the feedback loop is obtained using the estimated inertia Je, and the position compensation circuit 110 A position gain Kp and a position integral gain Kpi are determined.
Japanese Patent No. 3404388 (page 5, FIG. 11)

However, in the above conventional motor control device, the position command is input to control the position of the motor, or the speed command is input to control the motor speed. It does not operate unless the control system is fixed by position control or speed control, such as by adjusting parameters while fixing to the speed command.
For this reason, there is an unsolved problem that the responsiveness may be impaired when the control system is switched and operated in accordance with the input external command (position command or speed command).
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and even when switching between speed control and position control, an electric motor capable of following an external command signal at high speed It aims to provide a control device.

  In order to achieve the above object, an electric motor control device according to claim 1 outputs a state speed detection means for detecting an actual speed and an actual position of the motor, and an internal speed command value with the external position command value as an input. A position control means, a switching means for selecting any one of the external speed command value and the internal speed command value output from the position control means, and outputting it as a speed command value, and a speed command value output from the switching means The feedforward control means for outputting the corrected speed command value and the feedforward torque command value, the corrected speed command value output from the feedforward control means and the actual speed detected by the state quantity detecting means Feedback control means for outputting a feedback torque command value with the difference as an input, and output from the feedforward control means Torque command value output means for outputting the sum of the feedforward torque command value and the feedback torque command value output from the feedback control means as the torque command value, and the feedforward control means includes the speed command value The speed response characteristic of the load machine driven by the electric motor is configured to be changeable.

  In the invention according to claim 1, since the control system can be switched according to the situation by the switching means, the speed control is performed when the external speed command is input, and the speed control is performed when the external position command is input. The position control of the minor loop can be performed. In addition, by configuring a feedforward unit that takes into account the characteristics of the load machine, a corrected speed command value is output as a response target signal for the operation of the motor with respect to the speed command value so as not to vibrate the load machine. A torque signal that is calculated in a feed-forward manner so as to match the response target signal can be output as a feed-forward torque command value, and a feedback unit that receives the difference between the corrected speed command value and the actual motor speed as an input Since the feedback torque command value in which the disturbance component is compensated can be output, the response with the mechanical resonance suppressed by the feedforward unit and the feedback unit can be realized.

According to a second aspect of the present invention, there is provided the motor control device according to the first aspect, wherein the position control means includes a position command compensation means for receiving the external position command value and outputting an internal position command value; An internal speed command value output means for outputting an internal speed command value with the difference between the internal position command value output from the command compensation means and the actual position detected by the state quantity detection means as an input, and the position The command compensation means outputs an internal position command value in consideration of a characteristic of a target value response that is a response of the speed of the motor to the speed command value.
According to the second aspect of the present invention, the external position command value can be input and an internal position command value can be output in consideration of the speed control characteristics. A response with suppressed vibration can be realized.

According to the first aspect of the present invention, the speed control and the position control having the speed control in the minor loop can be switched in accordance with a command input from the outside, and the motor is driven in any case. The effect that the external command signal can be followed at high speed without exciting the vibration of the mechanical system is obtained.
According to the second aspect of the present invention, the external position command value can be input and the internal position command value can be output in consideration of the speed control characteristics. Therefore, the position control using the speed control as a minor loop is performed. In this case, it is possible to obtain an effect that a high-speed response can be realized by suppressing vibration of the load machine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a first embodiment of the present invention, in which 1 is a rotary electric motor, 2 is a detector as state quantity detection means for detecting the speed ωm and position θm of the electric motor 1, 3 is a connecting body, and 4 is a load machine driven by the electric motor 1 through the connecting body 3.
The control block corrects the external position command value θr so as not to excite the vibration of the machine while taking into account the target value response characteristic of the speed control system with the external position command value θr input from the outside as an input, the difference between the pre-compensator 5, output from the predistorter 5 the internal position command value [theta] r ^* and the detected position θm at detector 2 as the position command compensating means for outputting the internal position command value [theta] r ^* As an input, a position controller 6 as an internal speed command value output means for outputting an internal speed command value ωir, an internal speed command value ωir output from the position controller 6 and an external speed command value ωer input from the outside. And a switching unit 7 serving as a switching unit that selects and outputs a speed command value ωr.

Further, the speed command value ωr output from the switching unit 7 is input, and the corrected speed command value ωf and the feedforward torque command τrf that do not excite the vibration of the machine are output in consideration of the characteristics of the electric motor 1 and the load 4. Feedforward controller 8 as feedforward control means, and input of deviation between corrected speed command value ωf output from feedforward controller 8 and motor speed ωm detected by detector 2, and outputs feedback command τrb The sum of the feedback controller 9 as the feedback control means, the feedforward torque command τrf output from the feedforward controller 8 and the feedback command τrb output from the feedback controller 9 is set as the torque command τr, and this is input. Torque for controlling the torque of the electric motor 1 as And a control unit 10.
FIG. 2 is a block diagram showing details of the feedforward controller 8. The feedforward controller 8 includes a pole canceling unit 21 and a zero canceling unit 22 that receive a speed command value ωr.

Next, the operation of this embodiment will be described. First, the case where the speed of the electric motor 1 is controlled will be described.
When the speed of the electric motor 1 is controlled, the switching unit 7 is switched to the switch a, and the electric motor 1 is controlled using the external speed command value ωer. By switching the switching unit 7 to the switch a, the external speed command value ωer is input to the feedforward controller 8 as the speed command value ωr. The feedforward controller 8 feedforwards the corrected speed command value ωf as the response target signal of the operation of the motor 1 with respect to the speed command value ωr so that the load 4 does not vibrate, and the operation of the motor 1 matches the response target signal. A feedforward torque command τrf is output as a torque signal that is calculated automatically.

More specifically, in the feedforward controller 8, the moment of inertia J _M of the electric motor side, the load side inertia J _L, motor - spring coefficient between the load K _R, based on the damping D _R of the spring, the motor 1 The characteristic from the torque τm generated by the speed ωm to the speed ωm of the electric motor 1 is expressed by the following equation (5).

At this time, the pole canceling unit 21 and the zero point canceling unit 22 are configured so that the characteristic from the speed command value ωr to the speed ω _{L of the} load 4 is a filter that determines the response of the following equation (6). .
ω _L (s) / ωr (s) = n _D0 / (s ³ + n _D2 s ² + n _D1 s + n _D0 ) (6)
That is, the pole canceling unit 21 and the zero point canceling unit 22 perform calculations represented by the following equations (7) and (8), and output the feedforward torque command τrf and the corrected speed command value ωf.

Here, if n _D0 , n _D1 , and n _D2 are determined to be a standard form such as a Butterworth filter, the coefficients can be uniquely determined from the cutoff frequency.
Thus, since the feedforward controller 8 receives the speed command value ωr and outputs the feedforward torque command τrf and the corrected speed command value ωf, the characteristic of the torque control unit 10 is close to 1 in the band of the filter, When the parameters J _M , J _L , K _R , and D _R are accurate, the electric motor 1 responds promptly, and the speed ω _{L of the} load 4 can respond in a good manner without overshooting. Moreover, the speed of the response can be arbitrarily determined by the filter of the equation (6).

Then, the feedback controller 9 receives the deviation ωe between the corrected speed command value ωf for compensating for the disturbance component output from the feedforward controller 8 and the speed ωm of the electric motor 1, and receives the gain Kv and the integration time. The feedback torque command τrb is output by performing PI control represented by the following equation (9) using the constant Tv.
τrb (s) = Kv (1 + 1 / Tvs) ωe (9)
Here, s is a Laplace operator.

Next, the torque control unit 10 determines that the torque τm generated by the electric motor 1 is the sum of the feedforward torque command τrf output from the feedforward controller 8 and the feedback torque command τrb output from the feedback controller 9. The operation of the electric motor 1 is controlled by performing control so as to match the torque command τr.
On the other hand, when controlling the position of the electric motor 1, the switching part 7 is switched to the switch b, and the electric motor 1 is controlled using the external position command value θr. First, the precompensator 5 outputs the internal position command value θr ^* in consideration of the target value response from the speed command value ωr in the speed control to the speed ωm of the electric motor 1.
The target value response from the speed command value ωr to the speed ωm of the electric motor 1 in the speed control is expressed by the following equation (10).

Therefore, the precompensator 5 outputs the internal position command value θr ^* by inputting the external position command value θr and performing the calculation represented by the following equation (11) in order to cancel the zero point of the characteristic.
θr ^* / θr = {(J _L s ² + D _R s + K _R ) / (D _R s + K _R )} · {1 / (τ _p s + 1)} (11)
Here, τ _p is a time constant for determining responsiveness, and can be arbitrarily set.

Next, the position controller 6 receives the deviation θe between the internal position command value θr ^* output from the pre-compensator 5 and the position θm of the electric motor 1 and uses the gain Kp as the following equation (12). By performing the proportional control represented, the internal speed command value ωir is output.
ωir (s) = Kp · θe (12)
Since the switching unit 7 is switched to the switch b, the internal speed command value ωir output from the position controller 6 is input to the feedforward controller 8 as the speed command value ωr. The operations of the feedforward controller 8 and the feedback controller 9 are the same as in the case of controlling the speed of the electric motor 1 described above.

As described above, in the above embodiment, since the switching unit can switch between speed control and position control having the speed control in the minor loop, the control system can be switched according to a command situation input from the outside.
In addition, when performing speed control, the mechanical resonance can be suppressed by the feedforward controller and the feedback controller, and also when performing the position control, the characteristics of the speed control are considered by the position command compensation means. By outputting the internal position command value, mechanical resonance can be suppressed by the feedforward controller and the feedback controller, so even when switching between speed control and position control with speed control in a minor loop. The command signal can be followed at high speed without exciting the vibration of the mechanical system driven by the electric motor.

  Furthermore, by configuring a feedforward controller capable of changing the characteristics of the load machine, a corrected speed command value is output as a response target signal for the operation of the motor with respect to the speed command value so as not to vibrate the load machine. A torque signal that is calculated in a feed-forward manner so that the operation matches the response target signal can be output as a feed-forward torque command value, so that vibration of the load machine is suppressed in speed control and a high-speed response is realized. Can do.

Also, by providing a pre-compensator that takes the external position command value as input and outputs the internal position command value considering the speed control characteristics, it is possible to achieve a response that suppresses vibration of the load machine even in position control. Even when the position control is performed with the speed control as a minor loop, it is possible to suppress the vibration of the load machine and realize a high-speed response.
In the above embodiment, in representing the characteristics of the load machine 4 and the electric motor 1 may be calculated as zero damping D _R of the spring.

In the above embodiment, the motor side inertia moment J _M , the load side inertia moment J _L , the motor-load spring coefficient K _R , the spring damping D _R, etc. are input to the torque control unit 10. Alternatively, a random signal or the like may be input, and the motor speed or the motor position may be measured to perform system identification.
Further, in the above embodiment, the position controller 6 and the feedback controller 9 may be a controller including a notch filter or the like.

It is a block diagram which shows embodiment of this invention. It is a block diagram which shows the 2nd Embodiment of this invention. It is a block diagram which shows a conventional apparatus. FIG. 4 is a block diagram of the feedforward circuit of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Detector 4 Load machine 5 Precompensator 6 Position controller 7 Switching part 8 Feedforward controller 9 Feedback controller 10 Torque control part

Claims (2)

When the load machine is driven by the electric motor, the electric motor is driven by a torque command value for causing either the rotational speed or the rotational position of the motor to follow either the external speed command value or the external position command value input from the outside. In the motor control device that controls the torque of
State quantity detection means for detecting the actual speed and actual position of the motor, position control means for outputting the internal speed command value with the external position command value as an input, and output from the external speed command value and the position control means A switching means for selecting and outputting any of the internal speed command values as a speed command value, and a speed command value output from the switching means as an input, and a corrected speed command value and a feed corresponding to the response characteristic of the load machine A feedforward control means for outputting a forward torque command value, a difference between the corrected speed command value output from the feedforward control means and the actual speed detected by the state quantity detection means as inputs, and a feedback torque command value is obtained. Feedback control means for outputting, and feedforward torque command outputted from the feedforward control means And torque command value output means for outputting the sum of the feedback torque command value output from the feedback control means as the torque command value, and the feedforward control means is configured to output the load machine to the speed command value. An electric motor control device configured to be capable of changing a speed response characteristic.   The position control means is detected by a position command compensation means for outputting an internal position command value with the external position command value as an input, and an internal position command value output from the position command compensation means and the state quantity detection means. An internal speed command value output means for outputting an internal speed command value with the difference from the actual position as an input, the position command compensation means taking into account the response characteristics of the motor speed to the speed command value 2. The motor control device according to claim 1, wherein an internal position command value is output.

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