JP2004201383A - Control method and device for motor speed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method and a device for motor speed which realizes easy adjustment because of few parameters and little vibration at a stopping position. <P>SOLUTION: In this motor speed control method, a torque command is generated through a speed control means which includes an integral element 9 and a proportional element 10 from a speed command 8, the rotational position of a motor 14 driven based on the torque command is detected by an encoder 16, and an actual speed of the motor 14 is operated and fed back to the torque command 8 based on an output of the encoder 16. The difference between an actual speed signal of the motor 16, and an estimated speed signal of the motor in which the torque signal is converted into an encoder pulse and inputted in a motor model 2, is taken as a estimated disturbance speed signal, and an output signal which multiplies the estimated disturbance speed signal by a gain 5 is inputted between the integral element 9 and the proportional element 10 of the speed control means. In the speed control method, the parameter is only an adjustable gain, therefore only by adjusting it, the optimum motor speed control is conducted. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor speed control method and apparatus having a mechanical system in which there is mechanical vibration, rotation ripple generated by a motor and a gear, or rotation speed ripple generated by a motor itself.
[0002]
[Prior art]
Conventionally, in a motor speed control device in which such mechanical vibration occurs, a disturbance observer (load torque estimator) is provided as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-341852 (Patent Document 1). In most cases, the load disturbance torque is fed back to the torque command. In this case, it is possible to estimate the load disturbance torque added to the motor torque by the disturbance observer, and it is possible to suppress mechanical vibration such as shaft torsional vibration generated in the conventional speed control device.
[0003]
However, the prior art disclosed in the above-mentioned Patent Document 1 has a problem that ripples which are periodic disturbances as described below cannot be dealt with by a disturbance observer or the like.
1. 1. Rotary ripple generated by motor and gear 2. Rotational ripple due to eccentricity due to misalignment of the motor and coupling. Rotational speed ripple due to torque ripple components such as motor cogging
In addition, when a disturbance observer is configured, disturbance estimation is inadequate, so that disturbance suppression is insufficient.
Furthermore, since the disturbance observer requires a differentiator, it has the adverse effect of feeding back the noise component to the torque, and as a countermeasure this can be dealt with by using a filter or the like, but multiple parameter adjustments are required. However, there is a problem that adjustment cannot be easily performed.
[0005]
On the other hand, Japanese Patent Laying-Open No. 9-56183 (Patent Document 2) discloses a vibration damping control device that detects mechanical vibration of a motor and feeds it back to a torque command to suppress the mechanical vibration. FIG. 9 shows an arrangement of the configuration.
In FIG. 9, a speed control device includes a proportional device 10 that multiplies a speed command 8 by a speed gain Kv to obtain a torque command, a torque filter 11 that removes high-frequency components from the torque command, and a D that converts a digital signal into an analog signal. / A converter 12, a motor 14 having a moment of inertia Jm, a load device 13 driven by the motor 14, an integrator 15 for integrating the rotational speed of the motor 14, and detecting the integrated rotational position of the motor 14. And a difference calculator 17 that calculates the difference between the motor rotation position feedback signal 4 detected by the encoder 16 and outputs the difference to the subtractor 37 as the motor speed feedback signal 7 for the speed command 8. Further, a vibration damping control device 24 is added to the above configuration.
[0006]
In the vibration suppression control device 24, an adder 35 adds a value obtained by multiplying the torque command by the vibration suppression control inertia 18 and a value obtained by multiplying the motor speed feedback signal calculated by the difference calculator 17 by the vibration suppression control frequency 20. Then, the signal is integrated by the integrator 19 and subtracted from the motor speed feedback signal by the subtractor 36. The output of the subtractor 36 passes through the high-pass filter 21 and the low-pass filter 22, is multiplied by the damping gain 23, is subtracted from the motor speed feedback signal by the subtractor 37, and the value is subtracted from the speed command 8 by the subtractor 31.
By providing such a vibration suppression control device 24, mechanical vibration can be suppressed.
[0007]
[Patent Document 1]
JP-A-11-341852 (paragraphs 0026 to 0029, FIGS. 1 and 2)
[Patent Document 2]
JP-A-9-56183 (paragraphs 0017 to 0018, FIG. 2)
[0008]
[Problems to be solved by the invention]
However, in the vibration suppression control device described in Patent Document 2 described above, there are five parameter settings: a high-pass filter 21, a low-pass filter 22, a vibration suppression gain 23, a vibration suppression control frequency 20, and a vibration suppression control inertia 18. In addition, it is not easy to adjust, and after driving the motor from a certain position to a target position, if the motor is stopped at the target position, one bit of vibration at the stop position remains and the vibration cannot be suppressed. was there.
Therefore, an object of the present invention is to provide a motor speed control method and apparatus which have a small number of parameters, are easy to adjust, and have no vibration at a stop position.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 generates a torque command from a speed command through speed control means having an integral element and a proportional element, and determines a rotational position of a motor driven based on the torque command. In a motor speed control method of detecting by an encoder, calculating the actual speed of the motor based on the output of the encoder, and feeding back the torque to the torque command, the motor model is obtained by converting the actual speed signal and the torque command of the motor into encoder pulses. A difference between the estimated speed signal of the motor and the estimated speed signal of the motor is used as a disturbance estimated speed signal, and an output signal obtained by multiplying the gain of the estimated disturbance speed signal is input between an integral element and a proportional element of the speed control means. I do.
[0010]
Further, the invention according to claim 2 is a speed control means having an integral element and a proportional element for generating a torque command from a speed command, an encoder for detecting a rotational position of a motor driven based on the torque command, A motor speed control device including a speed calculation unit that calculates an actual speed of the motor based on an output of an encoder and feeds back the torque command to the torque command; an encoder pulse conversion unit that converts the torque command into a pulse of the encoder; A motor model for estimating the motor speed from the output of the encoder pulse conversion means, and a disturbance estimated speed signal which is a difference between the actual motor speed calculated by the speed calculation means and the estimated motor speed estimated by the motor model. A gain adjuster for multiplying the gain by an adjustment gain. Preparative, characterized in that a speed disturbance estimating means for feedback during the integration element and the proportional element of said speed control means.
[0011]
In the motor speed control method and apparatus according to the present invention, the estimated speed of the motor is calculated from the torque command of the motor and the motor model, and the difference between the estimated speed and the actual speed of the motor is calculated as the estimated disturbance speed. The motor control is performed by multiplying the adjustment gain as a signal and feeding it back between the integral element and the proportional element of the speed control means. Therefore, the parameter is only the adjustment gain, and the optimum motor speed control can be performed only by adjusting the adjustment gain. Also, unlike the conventional vibration suppression control that removes only the vibration component, vibration and disturbance that appear as a difference between the actual motor and the motor model can be estimated, so that when the operation state is stopped from the operation state, the final Vibration of the motor with one pulse can be suppressed.
According to a third aspect of the present invention, the gain adjusted by the gain adjuster can be adjusted from 0 to 100% of the difference between the motor model and the actual speed. Accordingly, the adjustment gain may be set to a value within the range, and the range of adjustment can be limited.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a motor speed control device according to an embodiment of the present invention. In the figure, an IP (integral proportional) speed control device includes an integrator 9 for integrating a speed command 8, a proportional device 10 for multiplying the integrated value by a speed gain Kv to obtain a torque command, and a high frequency component from the torque command. A torque filter 11 to be removed, a D / A converter 12 for converting a digital signal to an analog signal, a motor 14 having a moment of inertia Jm, a load device 13 driven by the motor 14, and a rotation speed of the motor 14 are integrated. , An encoder 16 for detecting the integrated rotational position of the motor 14, and a difference between the motor rotational position feedback signal 4 detected by the encoder 16 and subtracting the difference as the motor speed feedback signal 7 to the speed command 8. And a difference calculator 17 for outputting to the calculators 31 and 32. Further, a speed disturbance estimating device 1 which is a feature of the present invention is added to the above configuration.
[0013]
The speed disturbance estimating device 1 subtracts the output of the motor model 2 from the output of the motor model 2 and the output of the difference calculator 17 to convert the torque command into the number of pulses of the encoder. It comprises a gain adjuster 5 that feeds back to the input side.
In the speed disturbance estimating apparatus 1 having this configuration, the torque command output from the torque filter 11 is converted into an encoder pulse number by the encoder pulse converter 3, and the output is converted into a speed conversion value by the motor model 2. The difference between this speed conversion value and the motor rotation speed feedback signal 7 calculated by the difference calculator 17 is calculated by the subtractor 34 and input to the gain adjuster 5, and the obtained estimated speed disturbance value 6 is subtracted by the subtractor 32. As a result, the difference between the motor rotation speed feedback signal 7 and the speed command 8 is calculated by the subtracter 31, and the difference is input to the integrator 9. The estimated speed disturbance 6 and the motor speed feedback signal 7 are obtained from the output of the integrator 9. Is subtracted by the subtractor 32, the output of which is input to the proportional unit 10, passes through the torque filter 11, and generates a torque command.
[0014]
Since the torque command is a digital signal, it is converted into an analog current value by the D / A converter 12 and supplied to the motor 14. A load device 13 is coupled to a shaft end of the motor 14 by a coupling or the like and driven.
In FIG. 1, Ti is the integration time constant, Ts is the sampling time, z ^{-1 is the} dead time model, Jm is the moment of inertia of the motor 14, Jm 'is the moment of inertia of the motor model 2, and α is the moment of inertia of the gain adjuster 5. Adjustment gain.
[0015]
Next, simulation results of the prior art and the embodiment of the present invention are shown in FIGS. In this simulation, the resonance frequency was set to 200 Hz using a two-inertia model using the motor 14 and the load device 13. The reason why the resonance frequency is set to 200 Hz is that the region in which the torque filter 11 composed of the notch filter can be set is a frequency higher than 200 Hz, and there is a problem that oscillation occurs when the frequency is set to 200 Hz or less. In the related art, vibration cannot be suppressed for vibration of 200 Hz or less unless vibration suppression control or the like is used.
[0016]
FIG. 2 shows a simulation result in the conventional speed IP (integral proportional) position P (proportional) control. FIG. 3 is a simulation result when the vibration suppression control shown in Reference 2 is applied. FIG. 4 is a simulation result when the present invention is applied. 2 to 4, (a) shows a time chart of a motor position, (b) shows a time chart of a motor torque, (c) shows a time chart of a rotational speed deviation, and (d) shows a time chart of a load position. ing. As can be seen from (a) and (d) of these figures, the motor position and the load position reach the target position in approximately the same time of about 0.5 sec, respectively. , (C), the torque fluctuation is large, and the rotational speed deviation at the stop position vibrates greatly. In the vibration suppression control, the vibration of the motor torque is suppressed as shown in FIG. 3B, but the vibration of 1 rpm at the stop position remains as shown in FIG. 3C. On the other hand, in the apparatus provided with the speed disturbance estimating apparatus of the present invention, as shown in FIG. 4C, the vibration of the pulse in the stopped state is reduced.
[0017]
FIG. 5 is a simulation result including the case where the inertia set in the present invention is only the motor inertia. Normally, oscillation occurs when the gain is increased by the speed IP position P control. However, in the vibration suppression control of FIG. 9 and the simulation of the apparatus of the present invention, no vibration is applied to the torque waveform of (b), and the deviation of (c) There is an advantage that no vibration is applied to the signal. The reason for such a simulation result will be described using frequency characteristics.
[0018]
FIG. 6 shows the frequency characteristics ((a) is a gain and (b) is a phase) of the speed control system of the speed IP control, and the phase delay is 180 degrees near the anti-resonance frequency. In contrast, when the vibration suppression control of FIG. 7 is used, the phase delay does not reach 180 degrees near 1 kHz. Also, in FIG. 8 showing the frequency response of the present invention, similarly, the phase delay does not reach 180 degrees up to around 1 kHz.
That is, it can be said that the vibration suppression control shown in FIG. 9 and the speed control device of the present invention shown in FIG. 1 have characteristics in phase characteristics. In particular, the present invention is characterized in that it is designed to perform phase compensation even though it does not have a special means for performing phase compensation.
[0019]
In the frequency characteristic according to the embodiment of the present invention, a filter or the like is not provided other than the IP control. However, in an actual machine, a motor or the like may be smoothed by inserting a filter or the like, which causes a phase delay. The present invention works advantageously because of the above-mentioned phase compensation function.
In the present embodiment, the parameters to be adjusted are only the adjustment gain α of the gain adjuster 5 and Jm ′ of the motor model 2, but Jm ′ is basically a motor inertia value, which is originally known. Therefore, the adjustment is only one adjustment gain α. The adjustment gain α is adjusted so that the positional deviation at the time of stopping is 0 within a range of 0 to 100% of the difference between the motor model and the actual speed. When the adjustment gain is 0, the actual speed is used, and when the adjustment gain is 100%, the model speed is used. Therefore, an arbitrary value between them is set.
[0020]
【The invention's effect】
As described above, according to the present invention, the estimated speed of the motor is calculated from the torque command of the motor and the motor model, and the difference between the estimated speed and the actual speed of the motor is multiplied by an adjustment gain as a disturbance estimated speed signal to obtain a speed. Motor control is performed by feeding back between the integral element and the proportional element of the control means. Therefore, the parameter is only the adjustment gain, and the optimum motor speed control can be performed only by adjusting the adjustment gain. Also, unlike the conventional vibration suppression control that removes only the vibration component, vibration and disturbance that appear as a difference between the actual motor and the motor model can be estimated, so that when the operation state is stopped from the operation state, the final Vibration of the motor with one pulse can be suppressed. Thus, the number of parameters is smaller than in vibration suppression control, and there is no need to check and adjust the vibration frequency, so that adjustment is easy.
Further, the adjustment gain may be set to a value from 0% to 100% of the difference between the motor model and the actual speed, so that the adjustment range can be limited.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a motor speed control device according to an embodiment of the present invention.
FIG. 2 is a time chart showing a simulation result by a conventional speed IP position P control.
FIG. 3 is a time chart showing a simulation result when using a conventional vibration suppression control.
FIG. 4 is a time chart showing a simulation result when the motor speed control device of the present invention is used.
FIG. 5 is a time chart showing a simulation result when the inertia of the motor model is only the motor inertia in the motor speed control device of the present invention.
FIG. 6 is a graph showing frequency characteristics of conventional speed IP control.
FIG. 7 is a graph showing frequency characteristics when a conventional vibration suppression control is added.
FIG. 8 is a graph showing frequency characteristics in the motor speed control system of the present invention.
FIG. 9 is a block diagram showing a configuration of a conventional vibration suppression control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Speed disturbance estimation apparatus 2 ... Motor model 3 ... Encoder pulse converter 4 ... Motor rotation position feedback signal 5 ... Gain adjuster 6 ... Speed disturbance estimation value 7 ... Motor speed feedback signal 8 ... Speed command 9 ... Speed controller Integrator 10 ... Proportional unit 11 of speed controller 11 ... Torque filter 12 ... D / A converter 13 ... Load device 14 ... Motor 15 ... Integrator 16 ... Encoder 17 ... Difference calculators 31, 32, 33, 34 Subtractors

Claims (3)

A torque command is generated from the speed command through speed control means having an integral element and a proportional element, the rotational position of a motor driven based on the torque command is detected by an encoder, and the actual position of the motor is determined based on the output of the encoder. In a motor speed control method of calculating a speed and feeding back to the torque command,
The difference between the actual speed signal of the motor and the estimated speed signal of the motor input to the motor model by converting the torque command into an encoder pulse is defined as a disturbance estimated speed signal, and an output signal obtained by multiplying the disturbance estimated speed signal by a gain is defined as the speed. A motor speed control method characterized by inputting between an integral element and a proportional element of a control means. Speed control means having an integral element and a proportional element for generating a torque command from a speed command, an encoder for detecting a rotational position of a motor driven based on the torque command, and an actual motor of the motor based on an output of the encoder. A motor speed control device comprising a speed calculation means for calculating a speed and feeding back the torque command,
Encoder pulse conversion means for converting the torque command into pulses of the encoder, a motor model for estimating a motor speed from an output of the encoder pulse conversion means, an actual motor speed calculated by the speed calculation means, and the motor model A gain adjuster that multiplies a disturbance estimation speed signal that is a difference between the estimated motor speeds by an adjustment gain, and an output of the gain adjuster and an actual speed of the motor, and an integral element of the speed control unit. A motor speed control device comprising speed disturbance estimating means for feeding back between proportional elements. The motor speed control device according to claim 2, wherein a gain adjusted by the gain adjuster is adjustable from 0 to 100% of a difference between the motor model and an actual speed.

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