HK1089517B

HK1089517B - Motor control device

Info

Publication number: HK1089517B
Application number: HK06111362.1A
Authority: HK
Inventors: 勇治井出
Original assignee: 山洋电气株式会社
Priority date: 2003-03-17
Filing date: 2004-03-17
Publication date: 2009-05-29

Description

Motor control device

Technical Field

The present invention relates to a motor control device used in a machine tool or the like, and more particularly to a motor control technique suitable for a motor speed control device, a current control device for controlling a primary current of a motor, and a position control device for a high-speed positioning motor.

Background

A conventional motor speed control device includes a control device shown in fig. 23 (see fig. 1 of japanese unexamined patent publication No. h 10-254550). In this device, the deviation between the speed feedback obtained by converting the position feedback output from the encoder E and the speed command is calculated by a subtractor SB included in the speed control unit 3 and the speed calculating unit 2. This deviation is processed in the speed control unit 3, and the speed control unit 3 outputs a torque command to the torque control unit 4. The torque control unit 4 controls the current flowing through the motor so that a torque such as a torque command is output from the motor M.

In general, the speed control unit 3 in this device is constituted by a proportional-integral control (PI control) unit. The PI control unit calculates a deviation between the speed command and the speed feedback by the subtractor SB, and inputs the deviation to the adder AD by a proportional control system of gain 1. In the integral control system, the multiplier 31 multiplies the deviation by the integral gain, and the speed integrator 32 integrates the deviation and inputs the result to the adder AD. The adder AD adds the output of the proportional control system and the output of the integral control system, and outputs the result to the multiplier 33. The multiplier 33 multiplies the output of the adder AD by the proportional gain, and outputs the result as a torque command. Thus, by configuring the speed control unit 3 with the PI control unit, not only transient variation in speed but also steady-state variation can be suppressed. In addition, according to the integral term of the speed deviation, the anti-interference capability of the motor can be improved.

Generally, the response of the control system is limited, and even if a speed command is output, it takes time to respond to the speed feedback. Although the speed command is output and the motor starts rotating, the speed integrator 32 performs an integration operation during a period from when the speed command is output until the speed feedback is responded (a period until the speed feedback corresponding to the speed command appears). While the motor M is rotating at a constant speed, the integral value decreases. However, the motor M is still subjected to the integration operation during deceleration, and the motor M stops after all remaining integrated values disappear from the output. Therefore, in the conventional control device, even after the speed command is 0, the speed response is delayed by the time length of the accumulation amount of the speed integrator. As a result, overshoot occurs in the velocity feedback, and the velocity integral gain cannot be increased.

A conventional current control device for a motor includes a control device shown in fig. 24. In this apparatus, current deviations between respective current commands for the dq axes and current feedback detected by a current detector D are calculated by subtracting means SBa and SBb, and the respective current deviations are used by current controllers 4a and 4b to obtain a D-axis voltage command and a q-axis voltage command. Then, after dq conversion of each voltage command is performed by the coordinate converter 15a, two-phase and three-phase conversion is performed, and the motor M is driven by the PWM inverter 17 in accordance with the converted command. The current feedback is performed to dq-convert the 3-phase current detected by the current detector D in the coordinate converter 15 b. The coordinate converter 15b performs three-phase and two-phase conversion and dq conversion by a signal generation mechanism 18 that generates a signal corresponding to the rotational position of the encoder E.

Typically, the current controllers 4a, 4b in this device are constituted by PI controllers. For example, as shown in fig. 25, the current controller 4a is configured by an integral control system (I system) which calculates a current deviation between a current command and a current feedback by a subtraction means SBa, multiplies the current deviation by an integral gain by a multiplier 191, and integrates the multiplied value by a current integrator 193, and a proportional control system (P system) which multiplies the current deviation calculated by the subtraction means SBa by a constant factor. The current controller 4a also adds the outputs of the integral control system and the proportional control system by an adding mechanism ADa, multiplies the addition value by a proportional gain by a multiplying mechanism 195, and outputs a voltage command. Thus, by configuring the current controller by PI control, not only transient variation but also steady-state variation of the current can be suppressed.

Generally, the response of the control system is limited, and it takes time to respond to the motor current even if a current command is output. Although the current command is output and the current starts to flow to the motor, the current integrator 193 performs the integration operation during a period from when the current controller 4a outputs the voltage command to when the motor current is responded. Therefore, in the conventional control device, the response of the current is delayed by the time length of the accumulated amount of the current integrator 193, and overshoot occurs.

On the other hand, as shown in japanese unexamined patent publication No. 8-66075, the control device calculates a delay in current feedback from the amount of change in the current command, the motor inductance, and the motor resistance, and adds the delay to a current deviation portion to compensate for the delay. However, a differential component such as a change amount of the current command is not preferable for realizing smooth control because the command response tends to vibrate. Further, constants such as a motor inductance and a motor resistance are required, and the motor inductance changes an inductance value according to the magnitude of a current flowing through the motor, and the motor resistance changes a resistance value according to the temperature. Thus, compensation of the magnitude of the motor current and the motor temperature also needs to be considered.

A conventional motor position control device includes a control device shown in fig. 26 (see fig. 1 of japanese unexamined patent publication No. h 10-254550). In this device, a deviation between a position command and position feedback is calculated by a subtractor included in a position controller, and the deviation is processed by a position control unit and output as a speed command. Then, the deviation between the speed feedback obtained by converting the position feedback output from the encoder E and the speed command is calculated by the subtractor included in the speed control unit 3 by the speed calculation unit 2. This deviation is processed in the speed control unit 3, and the speed control unit 3 outputs a torque command to the torque control unit 4. The torque control unit 4 controls the current flowing through the motor M so that a torque such as a torque command is output from the motor M.

In general, the position control unit 1 in this apparatus is configured as a proportional control (P control), and the speed control unit 3 is configured as a proportional-integral control (PI control) unit. The PI control unit constituting the conventional speed control unit 3 has a configuration as shown in fig. 27. The PI control unit calculates a deviation between the speed command and the speed feedback by a subtractor SB, and inputs the deviation to an adder AD by a proportional control system of gain 1. In the integral control system, the integral gain is multiplied by the deviation by a multiplier 31, and the deviation is integrated by a velocity integrator 32 and input to an adder AD. The adder AD adds the output of the proportional control system and the output of the integral control system and outputs the result to the multiplier 33, and the multiplier 33 multiplies the output of the adder AD by a proportional gain and outputs the result as a torque command. Thus, by configuring the speed control unit 3 with the PI control unit, not only transient variation in speed but also steady-state variation can be suppressed.

Further, japanese patent application laid-open No. 3-15911 discloses a method of controlling a servo motor, in which a position command is differentiated to obtain a feedforward amount of a position, a control amount obtained by position loop control is added to the feedforward control amount to obtain a velocity command, and a feedforward control amount of a velocity obtained by differentiating the feedforward control amount of the position is added to a value obtained by velocity loop control to obtain a current command, thereby improving responsiveness and obtaining a stable servo system.

The conventional control device improves the tracking performance by increasing the feedforward gain, but if the feedforward gain is increased to 100%, the overshoot increases. Since the overshoot deteriorates the processing quality, it is necessary to suppress the overshoot as much as possible. Fig. 15 is a diagram for simulating a position control operation when the feedforward gain is 0% in a conventional control device. As shown in this figure, if the feedforward gain is small, the overshoot is small, but as shown in fig. 17, if the feedforward gain is 100%, the overshoot becomes large. Therefore, the conventional technique improves the tracking performance in a range where the feed forward gain is about 50% and the overshoot does not become large, as shown in fig. 16.

In the control theory, the feedforward control is a control that, when the characteristics of the controlled object are known, performs an inverse operation on the manipulated variable so that the controlled variable matches the target value. In a conventional control system, if a control target at the time of position control is found in a speed control system, an operation amount is a speed command and a control amount is a position. If the speed control system is approximated by the simplest model, it can be represented by a first order delay system, and if an inverse function of the controlled object is obtained, it becomes a first order lead system. In the prior art, since the operation is required to be performed with a certain guarantee, the high-order delay amount cannot be compensated, and overshoot occurs.

Further, the problem of the speed command output from the position controller is another main cause. Generally, the response of the control system is limited, and even if a speed feedforward command is output, it takes time to respond to speed feedback. The motor starts to be driven by outputting the speed feedforward command, but the speed command is output from the position controller based on the position deviation generated during the period from the time when the speed feedforward command is output to the time when the speed feedback is responded. While the motor is rotating at a constant speed, the positional deviation is reduced, but a speed command for generating the positional deviation is output even when the motor is decelerating.

As described above, since the speed command generated in accordance with the positional deviation is added to the speed feedforward command, the speed command equal to or higher than the speed command that is originally necessary is provided, and overshoot occurs.

There is also a problem with speed controllers as another important reason. The speed controller is generally constituted by PI control, and is constituted as shown in fig. 27. Fig. 15 to 17 are simulation results of the case where the conventional speed controller is used. Since the response of the control system is limited, even if a speed command is given, it takes time until the speed feedback responds, and the speed integrator performs the integration operation during this period. The time response of the speed controller is reduced by the charging and discharging of the integrator, and overshoot is also generated. As described above, in the conventional control device, the position control system is configured without considering the response delay of the velocity system and the velocity control system is configured without considering the response delay of the velocity system based on the coefficient configuring the feedforward system by the proportional system, and overshoot occurs, and the feedforward gain cannot be increased to 100%. Therefore, there is a limit to improving traceability.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object thereof is to provide a motor control device with a small overshoot.

Another object of the present invention is to provide a speed control device for a motor, which is small in overshoot, high in speed, and excellent in disturbance suppression capability.

The invention aims to provide a current control device which can speed up the current response of a current control system without adding motor parameters and has small overshoot.

The invention aims to provide a motor position control device which has small overshoot, can increase the feedforward gain to 100% and improves the tracking performance.

The motor control device of the present invention includes: a position detection unit that detects a position of a motor to be controlled; a speed calculation unit that calculates a speed of the motor based on the position of the motor detected by the position detection unit; a speed control unit that outputs a torque command to perform speed control so that the speed fed back from the speed calculation unit matches the speed command, based on proportional-integral control; and a torque control unit that performs torque control based on the torque command.

In the control device of the present invention, the speed control unit is constituted by: a velocity integral compensation low pass filter having a transfer function equivalent to the delay of the velocity control system; an integral control system including a speed integrator that integrates a speed deviation between a delay speed command obtained by inputting a speed command to a speed integral compensation low-pass filter and a speed; a proportional control system that outputs a command proportional to a difference between the speed command and the speed of the motor; an addition mechanism that adds an output of the integral control system and an output of the proportional control system; and a multiplying means for multiplying the speed proportional gain by the output of the adding means to obtain a torque command. In the proportional control system, the speed proportional gain may be multiplied by the speed deviation, and in the integral control system, the speed proportional gain may be multiplied by the calculated value in the control and output.

If a velocity integral compensation low pass filter is used as in the present invention, the deviation between the delayed velocity command having a delay equivalent to the velocity control system and the velocity of the actually delayed velocity feedback can be made close to 0. Therefore, the accumulation amount of the velocity integrator can be made substantially 0, and overshoot of the velocity feedback can be reduced.

When the accuracy of the position detection unit (e.g., encoder) is poor, the pulsation due to the quantization error or the position error is included in the velocity feedback. In order to cope with this, it is preferable to provide a velocity feedback/low-pass filter having a transfer function for preventing pulsation caused by a quantization error and/or a position error of the position detection unit from appearing in the torque command. In this case, the proportional control system is configured to include a subtracting means for obtaining a deviation between the filtered speed obtained by inputting the speed to the speed feedback/low-pass filter and the speed command. Further, if the position detecting unit employs a device having high accuracy and resolution, the position error is also small, and therefore, it is not necessary to employ such a configuration.

Further, the present invention is directed to a motor control device including: a current detection unit that detects a motor current of a motor to be controlled; a current controller that outputs a voltage command based on a current deviation between a current feedback according to the motor current detected by the current detection unit and the current command; and a drive mechanism that supplies a motor current to the motor based on the voltage command. In the present invention, the current controller is composed of: a current-control-side delay compensation low-pass filter having a transfer function equivalent to a delay of a current control system; an integration control system including a current integrator that integrates a current deviation between a delayed current command obtained by inputting a current command to a current control-side delay compensation low-pass filter and a current feedback; a proportional control system that outputs a command proportional to a current deviation between the current command and the current feedback; an addition mechanism that adds an output of the integral control system and an output of the proportional control system; and a multiplying means for multiplying the current proportional gain by the output of the adding means to obtain a voltage command.

In the proportional control system, the current proportional gain may be multiplied by the current deviation, and in the integral control system, the current proportional gain may be multiplied by the calculated value in the control.

If the current control side delay compensation low-pass filter is employed like the present invention, the current deviation between the speed command having a delay equivalent to the delay of the current control system and the actually delayed current feedback can be made close to 0. Therefore, the amount of accumulation of the current integrator can be made substantially 0. As a result, overshoot can be reduced.

The motor control device of the present invention further includes: a position detection unit that detects a position of a motor to be controlled; a speed calculation unit that calculates a speed of the motor; a position control unit that outputs a speed command and performs position control so that the position of the motor fed back from the position detection unit matches the position command; a speed control unit that outputs a torque command and performs speed control so that the speed fed back from the speed calculation unit matches the speed command, based on proportional-integral control; and a torque control unit that performs torque control based on the torque command. The position control unit includes: a subtracting unit that obtains a positional deviation between the position command and the position detected by the position detecting unit; a position loop multiplying unit that multiplies the position proportional gain by the position deviation; a differentiator for differentiating the position command; a feedforward-gain multiplying unit that multiplies the feedforward-gain by the output of the differentiator; a proportional differential mechanism for performing proportional differential control on the output of the feedforward-gain multiplication mechanism and compensating for the delay of the speed control system; a feedforward/low-pass filter having a transfer function for removing a ripple caused by a quantization error of the position command, and filtering an addition value of an output of the proportional differentiating unit and an output of the feedforward/gain multiplying unit; and an addition means for adding the output of the feedforward/low-pass filter to the output of the position loop multiplication means to output a speed command.

As described in the present invention, if the position control unit performs proportional-differential control on the feedback multiplication output, it is possible to obtain the characteristic of the first-order lead, compensate for the delay of the speed control system, and improve the follow-up performance with respect to the position command. Further, if the speed control-side delay compensation low-pass filter is used, the deviation between the speed command having a delay corresponding to the delay of the speed control system and the speed of the speed feedback actually delayed can be made close to 0, and the amount of accumulation of the speed integrator can be made substantially zero. Further, even when the feedforward gain is increased to 100%, a control system with a small overshoot can be configured, and position control with higher tracking performance can be realized. Further, if the feedforward/low-pass filter is used, it is possible to prevent the pulsation based on the quantization error generated by the position command unit from being included in the speed command itself.

Further, a position control side delay compensation low-pass filter having a transfer function corresponding to the delay of the speed control system may be provided, and a position deviation between the position command and the position fed back by the position control side delay compensation low-pass filter may be input to the position loop multiplication means. Further, when the position deviation is obtained by integrating the deviation between the output of the differentiator for differentiating the position command and the differential value of the position by the integrator, a position-control-side delay compensation low-pass filter having a transfer function corresponding to the delay of the speed control system may be disposed between the differentiator and the integrator, or the deviation between the output of the differentiator and the differential value of the position by the position-control-side delay compensation low-pass filter may be input to the integrator.

By providing the delay compensation low-pass filter for position control, the position command input to the position control unit rises at substantially the same time as the position feedback during acceleration. As a result, the speed command from the position control unit becomes a considerably small value. With this configuration, the velocity feedforward gain can be set to a value of 1 or close to 1, and the tracking ability with respect to the position command can be improved.

Further, in the present invention, the speed control section is constituted by: a speed-control-side delay compensation low-pass filter having a transfer function equivalent to the delay of the speed control system; an integration control system including a speed integrator for integrating a speed deviation between a speed and a delayed speed command obtained by inputting the speed command to a speed control side delay compensation low-pass filter; a proportional control system that outputs a command proportional to a difference between the speed command and the speed; an addition mechanism that adds an output of the integral control system and an output of the proportional control system; and a multiplying means for multiplying the speed proportional gain by the output of the adding means and outputting the result as a torque command. In the proportional control system, the speed deviation may be multiplied by a speed proportional gain, and in the integral control system, the speed proportional gain may be multiplied by a calculated value in the control. If the speed control-side delay compensation low-pass filter is used as in the present invention, the deviation between the speed command having a delay corresponding to the delay of the speed control system and the speed of the speed feedback actually delayed can be made close to 0. The amount of the velocity integrator is made substantially zero, and the tracking of the position command is improved.

Preferably, the position control unit includes a subtracting means for determining a positional deviation between the position command and the position detected by the position detecting unit, and a position loop multiplying means for multiplying the positional proportional gain by the positional deviation. In this case, the position control unit preferably further includes: a differentiator for differentiating the position command; a multiplication means for multiplying the feedforward gain by the output of the differentiator; and a feedforward/low-pass filter having a transfer function for removing a ripple caused by a quantization error of the position command. The position control unit may be configured to perform filtering processing by a feedforward/low-pass filter on an output obtained by adding an output of a differentiator for differentiating the position command and an output of a differentiating means for performing proportional differentiation control on an output obtained by multiplying a feedforward/gain by the output of the differentiator to compensate for a delay in the speed control system, to an output obtained by adding the outputs of the feedforward/gain multiplying means.

Drawings

Fig. 1 is a block diagram showing an example of a specific configuration of a speed control device used in the present invention.

Fig. 2 is a block diagram showing an example of a specific configuration of another speed control device used in the present invention.

Fig. 3 is a diagram showing simulation results when a velocity integral compensation low-pass filter is inserted.

Fig. 4 is a diagram showing a simulation result when no velocity integral compensation low-pass filter is inserted.

Fig. 5 is a block diagram showing an example of a specific configuration of a current controller used in another embodiment of the present invention.

Fig. 6 is a block diagram showing an example of a specific configuration of another current controller used in the present invention.

Fig. 7(a) to (C) are simulation diagrams showing operation waveforms of the motor when the current control side delay compensation low-pass filter is inserted.

Fig. 8(a) to (C) are simulation diagrams showing operation waveforms of the motor when the current control side delay compensation low-pass filter is not inserted.

Fig. 9 is a block diagram showing a configuration of an embodiment of a motor position control device according to the present invention.

Fig. 10 is a block diagram showing an example of a specific configuration of a speed control unit employed in the present invention.

Fig. 11 is a block diagram showing an example of a specific configuration of another speed control unit employed in the present invention.

Fig. 12 is a block diagram showing the configuration of another embodiment of the motor position control device according to the present invention.

Fig. 13 is a block diagram showing a configuration of a motor position control device according to still another embodiment of the present invention.

Fig. 14 is a block diagram showing a configuration of a motor position control device according to still another embodiment of the present invention.

Fig. 15 is a diagram showing a result of simulation of a position control operation when a feedforward gain is 0% in a conventional position control device.

Fig. 16 is a diagram showing a result of simulation of a position control operation in a conventional position control device in which a feedforward gain is 50%.

Fig. 17 is a diagram showing a result of simulation of a position control operation when a feedforward gain in a conventional position control device is 100%.

Fig. 18 is a diagram showing a result of simulation of a position control operation when the velocity control-side delay compensation low-pass filter is inserted and the feedforward gain is set to 0 in the embodiment of fig. 9 and 10.

Fig. 19 is a diagram showing a result of simulation of the position control operation when the differential gain is set to 0 and the feedforward gain is set to 100% based on the condition of fig. 18.

Fig. 20 is a diagram showing a simulation result of the position control operation when the differential gain is inserted based on the condition of fig. 19.

Fig. 21 is a diagram showing a result of simulation of a position control operation when the position-control-side delay compensation low-pass filter is inserted as shown in the configuration of fig. 13 based on the condition of fig. 19.

Fig. 22 is a diagram showing a result of simulation of a position control operation when a differential gain is inserted based on the condition of fig. 21.

Fig. 23 is a block diagram showing a configuration of a conventional speed control device.

Fig. 24 is a diagram showing a configuration of a current control device of a conventional motor.

Fig. 25 is a diagram showing a configuration of a conventional current controller.

Fig. 26 is a diagram showing a configuration of a conventional motor position control device.

Fig. 27 is a block diagram showing a configuration of a conventional speed control unit.

Detailed Description

Fig. 1 is a block diagram showing an example of a specific configuration of a speed control device used in the present invention. The system configuration of fig. 1 is not substantially changed from the conventional configuration of fig. 23 except for the configuration of the speed control unit 13 and the provision of the speed feedback low-pass filter 135.

This system includes an encoder E as a position detection unit for detecting the position of the motor M to be controlled. The output of the encoder E is position feedback indicating the position of the output shaft of the motor. The speed calculation unit 2 is configured to calculate the speed of the motor based on the output of the encoder E, and the output of the speed calculation unit 2 is speed feedback. The speed feedback represents the speed of the output shaft of the motor M.

The speed control unit 13 outputs a torque command and performs speed control so that the speed fed back from the speed calculation unit 2 matches the speed command, based on proportional-integral control. As shown in fig. 1, the speed control unit 13 of the present embodiment includes a speed integral compensation low-pass filter 133 having a transfer function (1/(1+ STc)) corresponding to the delay of the speed control system. Further, the speed control unit 13 includes: an integral control system 136 and a proportional control system 137, wherein the integral control system 136 has: a multiplying means 131 for determining a speed deviation between the speed and the delay speed command obtained by inputting the speed command to the speed integral compensation low-pass filter 133 by a subtracting means SB2 and multiplying the speed deviation by an integral gain (1/Tvi); and a velocity integrator 132 that integrates the output of the multiplication mechanism 131. The proportional control system 137 obtains a deviation between the speed command and the speed feedback by the subtracting means SB1, and outputs a command proportional to the deviation. The speed control unit 13 further includes a multiplying means 134 for multiplying the speed proportional gain KVP and the output of the integral control system 136 by the adding means AD1 with the proportional control system 137The result of the addition of the outputs of (a) is multiplied and output as a torque command. Although the above configuration has the basic configuration, in the present example, the speed feedback/low pass filter 135 having the transfer function (1/(1+ ST) for preventing the pulsation generated by the quantization error and/or the position error of the encoder (position detecting unit) from appearing in the torque command is further provided_FB)). In this case, the proportional control system 137 includes a subtracting means SB1 for determining a deviation between the speed command and the speed after the filtering process in which the speed is input to the speed feedback/low pass filter 135.

In this example, the subtraction means SB2 calculates the difference between the value obtained by passing the velocity command through the velocity integral compensation low-pass filter 133 and the velocity feedback, multiplies the difference by the velocity gain (1/Tvi), and passes through the velocity integrator 132. The difference between the velocity command and the value obtained by passing the velocity feedback through the velocity feedback low-pass filter 135 is obtained by the subtracting means SB1, and added to the output of the velocity integrator 132 by the adding means AD 1. Finally, the torque command is multiplied by the speed proportional gain (KVP) and output to the torque control unit 4. The torque control unit 4 controls the current so as to output a torque as a torque command.

The velocity feedback/low pass filter 135 described above is a filter for suppressing a ripple caused by a quantization error and a position error of the encoder E. This filter plays a role of inserting only feedback of the proportional control system 137 and not causing a pulsation amount to appear in the torque command. The integral control system 136, since the velocity integrator 132 performs smoothing, does not require such a filter.

The speed integral compensation low-pass filter 133 sets a time corresponding to the delay of the speed control system so that the delay compensation output and the speed feedback have substantially the same rising tendency, and reduces the amount of integration of the speed integrator 132 when the speed command changes. By configuring the speed control unit 13, it is possible to simultaneously realize the control of the pulsation included in the speed feedback and the reduction of the amount of accumulation of the speed integrator 132 at the time of the change of the speed command.

When the quantization error of the encoder E is small, the velocity feedback/low pass filter 135 is not necessary. Note that, if the velocity integral compensation low-pass filter 133 is a transfer function simulating the delay of the velocity control system, any transfer function may be used, and is not limited to the transfer function of the present embodiment.

Fig. 2 is a block diagram when the speed control device of fig. 1 includes a speed control unit 13' that modifies the speed control unit 13. If the speed control unit 13 and the speed control unit 13 ' in fig. 1 are compared, the speed control unit 13 ' in fig. 2 differs from the speed control unit 13 ' in the former configuration in that the multiplication means 134 ' for the speed proportional gain KVP is located inside the proportional control system (at the point of insertion before the addition means AD 1), and in that the transfer function of the multiplication means 131 ' is changed so that the multiplication means 131 ' multiplies KVP/Tvi so as to multiply the speed proportional gain KVP by the calculated value in the integral control system 136 '. Even in this case, the same operational effects as those of the speed control unit 13 in fig. 1 can be obtained.

Fig. 3 and 4 show an example of a result of simulation of the response of the speed command step in the control system shown in fig. 1. In each figure, the vertical axis represents the velocity command and velocity feedback in the upper graph (a), and the velocity integrator output in the lower graph (B). All are ratios of the same speed, and represent values normalized to 10 with the same speed value as a reference. The horizontal axis is the unit of 0.01 second for total time. Fig. 3 is a simulation result when the velocity integral compensation low pass filter 133 is not inserted. Fig. 4 is a simulation result when the velocity integral compensation low-pass filter 133 is inserted. In either of fig. 3(a) and 4(a), the velocity command is shown in a stepwise waveform, and a rising waveform delayed from the command shows velocity feedback. In any of the figures, the rising of the velocity feedback is delayed by about 1/3 to 1/2 of 0.01 seconds with respect to the stepwise rising of the velocity command. The delay time represents a delay in the time response of the speed control system. When the velocity integration compensating low-pass filter 133 is not inserted, the output of the velocity integrator 132 shows a small peak in the region of the rise of velocity feedback as shown in fig. 3 (B). In this region, there is a deviation between the speed command and the speed feedback, and this indicates a state in which an integral of the speed deviation is accumulated. That is, a small peak of the output of the velocity integrator at the rise time of the velocity feedback indicates the state of the accumulated amount of the velocity deviation accumulated during the time. As shown in fig. 3(a), the accumulation amount speed feedback is overshot to about 12. The output of the velocity integrator converges to the time region of 0, and as shown in fig. 3(a), the overshoot of the velocity feedback also converges to the velocity command value 10. As is clear from the increase in the amount of the accumulated material of the speed integrator 132 at the rising point of the speed feedback, the amount of the accumulated material of the speed integrator 132 changes with the acceleration and deceleration of the motor.

Next, fig. 4 shows the result when the velocity integral compensation low-pass filter 133 is inserted. In this case, the step-like speed command shown in fig. 4(a) is output as a delay speed command through the speed integrating low-pass filter 133, and the rising edge of the delay speed command is adjusted to have the same delay as the rising edge of the speed feedback shown in fig. 4 (a). Thus, the deviation between the delay speed command and the speed feedback is obtained by the subtracting means SB2, multiplied by 1/Tvi times by the multiplying means 131, and integrated by the speed integrator 132. In this case, the deviations obtained by the subtracting means SB2 are very small in the rising edge region of the delay speed command and the speed feedback, and as shown in fig. 4(B), the accumulated amount of the speed deviations in the speed integrator 132 represents a small peak, and thereafter, a constant value substantially approximating 0 is maintained. In this case, the height of the small peak of the accumulated amount of the velocity integrator 132 is reduced from a large value to a negligible value as compared with the case of fig. 3 (B). As shown in fig. 4(a), the velocity feedback quickly converges to the same value 10 as the velocity command without overshoot of the velocity command value 10 or more.

As described above, in the present control apparatus, by inserting the speed integral compensation low pass filter 133, since the amount of integration of the speed integrator 132 during the rotation of the motor can be made small to a value of approximately 0, the integral gain of the value can be increased, and the disturbance suppression capability can be improved. The velocity feedback low-pass filter 135 may be configured by a transfer function in a general functional form such as an actual measured value or a theoretical value of the response characteristic of the simulated velocity, in addition to the low-pass filter configured to attenuate exponentially with time as described in the embodiment of the present invention.

Fig. 5 is a block diagram showing an example of a specific configuration of the current controllers 4a and 4b using the current controller 213 instead of the conventional device shown in fig. 24.

As shown in fig. 5, the current controller 213 of the present embodiment includes a current control-side delay compensation low-pass filter 233 having a transfer function (1/(1+ STc)) corresponding to the delay of the current control system. Further, the current controller 213 includes: an integral control system and a proportional control system that outputs a command proportional to a current deviation between the current command and the current feedback. Wherein, the integral control system includes: a multiplying means 231 for obtaining a current deviation between a delay current command obtained by inputting the current command to the current control side delay compensation low-pass filter 233 and the motor current (current feedback) by a subtracting means SB2, and multiplying the current deviation by an integral gain (1/Tvi); and a current integrator 232 that integrates the output of the multiplication mechanism 231. The current controller 213 further includes a multiplying unit 234 that multiplies the current proportional gain KIP by the result of adding the output of the integral control system and the output of the proportional control system by the adding unit AD1, and outputs the result as a voltage command. The current controller 213 includes an integral control system including a delay current command obtained by inputting the current command to the current control-side delay compensation low-pass filter 233, and a multiplying mechanism 231 for multiplying the current deviation by a current integral gain (1/Tvi); the output of the multiplying mechanism 231 is integrated by a current integrator 232. The current controller 213 further includes a multiplying means 234 for adding the output of the integral control system and the output of the proportional control system by an adding means AD1 and multiplying the result by a current proportional gain KIP to output as a voltage command. In this example, the current deviation between the delay current command and the current feedback is obtained by the subtraction means SB2, and the output of the current integrator 232 is added to the output of the proportional control system by the addition means AD 1. The voltage command is obtained by multiplying the current proportional gain KIP by the output of the adding means AD1 by the multiplying means 234.

The current control side delay compensation low-pass filter 233 sets a transfer function corresponding to the delay of the current control system so that the delayed current command and the current feedback have substantially the same rising tendency, and reduces the amount of accumulation of the current integrator 232 when the current command changes. Thus, by configuring the current controller 213, it is possible to simultaneously realize control of the ripple included in the speed feedback and reduction of the amount of accumulation of the speed integrator 232 at the time of change of the current command.

Note that, if the velocity integral compensation low-pass filter 233 is a transfer function that simulates the delay of the current control system, any transfer function may be used, and is not limited to the transfer function of the present embodiment. Furthermore, when the delay of the control system is large, 1 sample or several sample delays may be combined with the low-pass filter.

Fig. 6 is a block diagram showing a modification of the current controller. When the current controller 213 'is compared with the current controller 213 of fig. 5, the current controller 213' of fig. 6 differs from the current controller 213 of the former in that the multiplication means 234 'of the current proportional gain KIP is located inside the proportional control system (at the point of insertion before the addition means ADI), and the transfer function of the multiplication means 231' is changed so as to multiply the current proportional gain KIP by the calculated value in the integral control system. Even in this case, the same operational effects as those of the current control unit 213 in fig. 2 can be obtained.

Fig. 7(a) to (C) and fig. 8(a) to (C) are results of simulations of current responses in the control system, which are respective current commands, current feedback, and integrator outputs. All are ratios of the same current, and represent values normalized to 1 with the same current value as a reference. The horizontal axis of each graph represents the total time in units of 0.001 msec. Fig. 7 shows simulation results of the case where the current-control-side delay compensation low-pass filter 233 is inserted, and fig. 8 shows simulation results of the case where the current-control-side delay compensation low-pass filter 233 is not inserted. In either of fig. 7 and 8, the rise of the current feedback is delayed by about 1/5 of 0.001 msec from the rise of the current command. As shown in fig. 7, when the delay compensating low-pass filter 233 on the current control side is inserted, the rising edge of the output current from the current integrator 233 is delayed by the same degree as the rising edge of the current feedback, and the difference is canceled by the addition means AD1, so that the integrator output maintains a constant value substantially equal to 0 except that the integrator output shows a small peak at the rising time of the current feedback. In this case, the height of the small peak of the integrator output is reduced from large to almost negligible. However, in the case where the current-control-side delay compensating low-pass filter 233 is not inserted, as shown in fig. 8, the current feedback in the adding mechanism AD1 in the time of the rise of the current feedback and the output of the current integrator 232 cannot be completely cancelled, and the peak value shown by the current integrator output in the rise of the current feedback becomes larger than in the case where the current-control-side delay compensating low-pass filter 233 is inserted.

As a result, although the current overshoot is large when the current control-side delay compensating low-pass filter 233 is not inserted, the overshoot can be reduced by setting the amount of accumulation of the current integrator 232 during the motor rotation to a value close to 0 when the current control-side delay compensating low-pass filter 233 is inserted.

The present invention is also applicable to control of a dc motor. In this case, the dq-axis current control system and the coordinate converter shown in the conventional example of fig. 24 are not required.

Fig. 9 is a block diagram showing a configuration of an embodiment in which the present invention is applied to a position control device for a motor. The system includes an encoder E as a position detection unit that detects a position of the motor M to be controlled. The output of the encoder E is position feedback indicating the position of the output shaft of the motor. The speed calculation unit 302 is configured to calculate the speed of the motor based on the output of the encoder E, and the output of the speed calculation unit 302 is speed feedback. Speed feedback representation motor M output shaftThe rotational speed of (2). The position control unit 311A is configured to output a speed command and perform position control so that the position of the motor M fed back from the encoder E as a position detection unit coincides with the position command. In the present embodiment, the position control unit 311A includes: a differentiator 412 for differentiating the position command; a feedforward-gain multiplying means 413 for multiplying the feedforward-gain VFF by the output of the differentiator 412; a differentiator 417 for differentiating the output from the multiplying means 413; a multiplier 418 that multiplies the differential gain (Ks) by the output from the differentiator 417; an adding means AD3 for adding the output of the multiplier 418 to the output of the feedforward/gain multiplying means 413; and a transfer function (1+ (1+ ST) with the ripple caused by the quantization error of the position instruction removed_FF) ) a feedforward-low-pass filter 414. In this example, a proportional differential mechanism for compensating for the delay of the speed control system is configured by a differentiator 417 and a multiplier 418. In general, the feedforward gain VFF is set to about 40 to 60% (0.4 to 0.6). The deviation between the position command and the position feedback is obtained by the subtracting means SB3, and the deviation is multiplied by the position proportional gain KP by the position loop multiplying means 411.

The position control unit 311A outputs, as a speed command, a command obtained by adding the command output from the position loop multiplication means 411 and the speed feedforward command (speed FF command) output from the feedforward/low-pass filter 414 by the addition means AD 2. By performing proportional differential control on the feedforward multiplication output, the delay of the speed control system in which the primary advance characteristic is obtained is compensated, and the follow-up performance for the position command can be improved. Further, the feedforward/low-pass filter 414 can prevent pulsation caused by a quantization error included in the position command, which is included in the speed command itself.

The speed command is a torque command by the speed control unit 313. The torque control unit 304 controls the current so that a torque like a torque command is output. In the present embodiment, the positioning setting time can be shortened compared to the conventional art by adding feedforward.

FIG. 10 shows a method of producing a steel sheet according to the present inventionFig. 9 is a block diagram showing an example of a specific configuration of the speed control unit 313. The speed control unit 313 outputs a torque command and performs speed control so that the speed fed back from the speed calculation unit 302 in fig. 9 matches the speed command, according to proportional-integral control. As shown in fig. 10, the speed control unit 313 according to the present embodiment includes a speed-control-side delay compensation low-pass filter 433 having a transfer function (1/(1+ STc)) corresponding to the delay of the speed control system. Further, the speed control unit 313 includes: an integral control system; and a proportional control system that outputs a command proportional to the speed command. Wherein, the integral control system includes: a multiplying means 431 for obtaining a speed deviation between the speed and the delay speed command obtained by inputting the speed command to the speed control side delay compensation low-pass filter 433 and multiplying the speed deviation by an integral gain (1/Tvi) by a subtracting means SB 2; and a velocity integrator 432 that integrates the output of the multiplication mechanism 431. The speed control unit 313 further includes a multiplying unit 434 that multiplies the speed proportional gain KVP by the result of adding the output of the integral control system and the output of the proportional control system by the adding unit AD1, and outputs the result as a torque command. Although the above configuration has the basic configuration, in this example, the speed feedback/low pass filter 435 is further provided, which has a transfer function (1/(1+ ST) to prevent pulsation caused by a quantization error and/or a position error of an encoder (position detection unit) from appearing in the torque command_FB)). In this case, the proportional control system includes a subtracting means SB1 that determines the deviation between the filtered speed obtained by inputting the speed to the speed feedback/low pass filter 435 and the speed command.

In this example, the subtraction means SB2 obtains the difference between the result of passing the velocity command through the velocity control-side delay compensation filter 433 and the velocity feedback, and passes the difference and the velocity integration gain (1/Tvi) through the velocity integrator 432. The difference between the velocity command and the result of the velocity feedback through the velocity feedback low-pass filter 435 is obtained by the subtracting means SB1, and is added to the output of the velocity integrator 432 by the adding means AD 1. And finally, multiplies by a speed proportional gain (KVP) and outputs a torque command.

The velocity feedback/low pass filter 435 is a filter for suppressing a ripple caused by a quantization error and a position error of the encoder E. This filter plays a role of inserting only feedback of the proportional control system and not causing a pulsation amount to appear in the torque command. The integral control system does not need such a filter because the velocity integrator 432 performs smoothing.

The speed control side delay low-pass filter 433 sets a time corresponding to the delay of the speed control system so that the delay compensation output and the speed feedback have substantially the same rising tendency, and reduces the amount of accumulation of the speed integrator 432 at the time of the change of the speed command. Thus, the speed control unit 313 can simultaneously control the pulsation included in the speed feedback and reduce the amount of accumulation of the speed integrator 432 at the time of the change of the speed command.

When the quantization error of the encoder E is small, the velocity feedback/low pass filter 435 is not necessary. Note that, if the speed control side delay compensation low-pass filter 433 is a transfer function simulating the delay of the speed control system, any transfer function may be used, and is not limited to the transfer function of the present embodiment.

Fig. 11 is a block diagram showing a modification of speed control unit 313'. If the speed control unit 313 and the speed control unit 313 'in fig. 10 are compared, the speed control unit 313' in fig. 11 differs from the speed control unit 313 in the former in that the multiplication means 434 'of the speed proportional gain KVP is located inside the proportional control system (inserted before the addition means AD 1), and the transfer function of the multiplication means 431' is changed so as to multiply the calculated value by the speed proportional gain KVP in the integral control system. Even in this case, the same operational effects as those of the speed control unit 313 of fig. 10 can be obtained.

Fig. 12 is a block diagram showing a modification of the embodiment of fig. 9. In the embodiment of fig. 12, the configuration of the position control unit 311B is different from that of the embodiment of fig. 9, and in fig. 12, the same components as those of the embodiment of fig. 9 are given the same reference numerals as those of fig. 9, and the description thereof is omitted. If the embodiment of fig. 9 is compared with the embodiment of fig. 12, the position of the differentiator 412 is different from the point that the integrator 416 and the differentiator 305 are newly added. That is, the position controller 311B inserts the differentiator 412 for differentiating the position command before the subtracting means SB3, inserts the differentiator 305 for differentiating the position detected by the position detector before the subtracting means SB3, and inserts the integrator 416 for integrating the difference (position differential difference) between the output of the differentiator 412 (the result of differentiating the position command) and the output of the differentiator 305 (the result of differentiating the position) before the position loop multiplying means 411 for multiplying the position proportional gain. The same effect as that of the embodiment of fig. 9 can be obtained according to this embodiment.

Fig. 13 is a block diagram showing the configuration of another embodiment of the motor position control device according to the present invention. The same components as those of the embodiment shown in fig. 9 are denoted by the same reference numerals as those of fig. 9, and description thereof is omitted. In the present embodiment, in addition to the constituent elements of the embodiment of fig. 9, the position control unit 311C further includes a position-control-side delay compensation low-pass filter 415 having a transfer function (1/(1+ STd)) corresponding to the delay of the speed control system. In the present embodiment, the position deviation between the position command and the position feedback by the position control side delay compensation low-pass filter 415 is obtained by the subtracting means SB3, and the position deviation is input to the position loop multiplying means 411. In this example, the feedforward gain VFF is set to a value of 1 or a value close to 1.

The position control side delay compensation low pass filter 415 sets the delay of the speed control system to a transfer function. The transfer function of the position-control-side delay compensation low-pass filter 415 is defined so that the output of the position-control-side delay compensation low-pass filter 415 rises to the same extent as the position feedback. If the position-control-side delay compensation low-pass filter 415 is added, the output of the position loop multiplication means 411 of the position control unit 311C becomes a considerably small value. In this apparatus, by adding the position control side delay compensation low-pass filter 415, the feedforward gain VFF can be increased to a value of 100% or close to 100% (a value of 1 or close to 1), and the positioning setting time can be shortened slightly as in the case of the embodiment of fig. 9.

Fig. 14 shows a configuration in which the position control side delay compensation low-pass filter 415 is added to the embodiment of fig. 12. The other points are the same as those in the embodiment of fig. 12, and therefore, the description thereof is omitted.

Fig. 18 shows the result of simulation of the position control operation when the velocity control-side delay compensation low-pass filter 433 is inserted and the feedforward gain is set to 0 in the embodiment of fig. 9 and 10. When compared with the conventional example of fig. 15, it is found that the amount of the rate integrator is close to 0. Fig. 19 shows the result of simulation of the position control operation when the differential gain is set to 0 and the feedforward gain is set to 100% based on the conditions in fig. 18. Thus, it is understood that the position overshoot is increased. Fig. 20 shows the result of simulation of the position control operation when the differential gain is inserted based on the condition of fig. 19. As compared with fig. 19, it is understood from fig. 20 that the overshoot amount can be reduced even when the feedforward gain is set to 100%. Fig. 21 shows the result of simulation of the position control operation when the low-pass filter 415 is inserted into the position control side delay compensation in the configuration shown in fig. 13 based on the conditions shown in fig. 19. It is also understood that the overshoot amount can be reduced by comparing the case of fig. 21 with that of fig. 19. Fig. 22 shows a simulation result of the position control operation when the differential gain is inserted based on the condition of fig. 21. As is clear from fig. 22, the velocity command from the position controller at the time of acceleration/deceleration is substantially 0, and overshoot can be reduced and tracking performance can be greatly improved even if the feed forward gain is set to 100%. Finally, it is found that the positional deviation at the constant speed can be reduced to about 1/2 when the feedforward gain of the conventional example shown in fig. 16 is 50%, and the tracking performance can be improved by about two times as compared with the conventional one.

Industrial applicability of the invention

According to the present invention, since the velocity integral compensation low-pass filter is used, the deviation between the velocity command having a delay corresponding to the delay of the velocity control system and the velocity of the velocity feedback actually delayed can be made close to 0, and the amount of accumulation of the velocity integrator can be made substantially 0. Thus, by applying this control device, the amount of accumulation of the speed integrator can be reduced, and therefore, a speed control device which has a simple configuration, reduces overshoot, increases the integral gain of the amount, and has excellent high-speed disturbance suppression capability can be realized

According to the present invention, since the current control-side delay compensation low-pass filter is used, the current deviation between the delayed current command having the delay corresponding to the delay of the current control system and the actually delayed current feedback can be made close to 0, the amount of accumulation of the current integrator can be made substantially 0, and the current response can be speeded up. Therefore, by applying the current control device of the present invention, the current response can be speeded up with a simple configuration, and overshoot can be reduced.

According to the present invention, the position control unit performs proportional-differential control on the feedforward multiplication output, thereby obtaining a characteristic of a first-order lead, compensating for a delay in the speed control system, and improving the follow-up performance with respect to the position command. Further, if the speed control-side delay compensation low-pass filter is used, the deviation between the speed command having a delay corresponding to the delay of the speed control system and the speed of the speed feedback actually delayed can be made close to 0, and the amount of accumulation of the speed integrator can be made substantially zero. Further, even when the feedforward gain is increased to 100%, there are advantages in that a control system with a small overshoot can be configured, position control with higher tracking performance can be realized, and higher-speed tracking performance can be realized.

Claims

1. A motor control device is provided with: a position detection unit that detects a position of a motor to be controlled; a speed calculation unit that calculates a speed of the motor based on the position of the motor detected by the position detection unit; a speed control unit that outputs a torque command to perform speed control so that the speed fed back from the speed calculation unit matches a speed command, based on proportional-integral control; and a torque control unit for performing torque control based on the torque command,

the speed control unit is composed of:

a velocity integral compensation low pass filter having a transfer function equivalent to the delay of the velocity control system;

an integral control system including a speed integrator that integrates a speed deviation between a delay speed command obtained by inputting the speed command to the speed integral compensation low-pass filter and the speed;

a proportional control system that outputs a command proportional to a difference between the speed command and a speed of the motor;

an addition mechanism that adds an output of the integral control system and an output of the proportional control system; and

and a multiplying means for multiplying the output of the adding means by a speed proportional gain to obtain the torque command.

2. A motor control device is provided with: a position detection unit that detects a position of a motor to be controlled; a speed calculation unit that calculates a speed of the motor based on the position of the motor detected by the position detection unit; a speed control unit that outputs a torque command to perform speed control so that the speed fed back from the speed calculation unit matches a speed command, based on proportional-integral control; and a torque control unit for performing torque control based on the torque command,

the speed control unit is composed of:

an integral control system for multiplying a speed proportional gain by an operation value in a control system including a speed integrator for integrating a speed deviation between a delayed speed command obtained by inputting the speed command to the speed integral compensation low-pass filter and the speed and outputting the result;

a proportional control system that outputs a command obtained by multiplying a difference between the speed command and the speed by a speed proportional gain; and

and an addition mechanism that adds an output of the integral control system and an output of the proportional control system.

3. The motor control device according to claim 1 or 2,

further comprising a velocity feedback/low-pass filter having a transfer function for preventing pulsation generated due to a quantization error and/or a position error of the position detection unit from occurring in the torque command,

the proportional control system includes a subtracting unit that obtains a deviation between the filtered speed obtained by inputting the speed to the speed feedback/low-pass filter and the speed command.

4. A motor control device is provided with: a current detection unit that detects a motor current of a motor to be controlled; a current controller that outputs a voltage command based on a current deviation between a current feedback according to the motor current detected by the current detection unit and a current command; and a drive mechanism for supplying the motor current to the motor based on the voltage command,

the current controller is composed of the following parts:

a current-control-side delay compensation low-pass filter having a transfer function equivalent to a delay of a current control system;

an integration control system including a current integrator that integrates a current deviation between a delayed current command obtained by inputting the current command to the current control-side delayed compensation low-pass filter and the current feedback;

a proportional control system that outputs a command proportional to a current deviation between the current command and the current feedback;

and a multiplying unit that multiplies the output of the adding unit by a current proportional gain to obtain the voltage command.

5. A motor control device is provided with: a current detection unit that detects a motor current of a motor to be controlled; a current controller that outputs a voltage command based on a current deviation between a current feedback according to the motor current detected by the current detection unit and a current command; and a drive mechanism for supplying the motor current to the motor based on the voltage command,

the current controller is composed of the following parts:

an integral control system that multiplies a current proportional gain by an operation value in a control system including a current integrator that integrates a current deviation between a delayed current command obtained by inputting the current command to the current control-side delay compensation low-pass filter and the current feedback;

a proportional control system that outputs a command obtained by multiplying a current deviation between the current command and the current feedback by a current proportional gain; and

6. A motor control device is provided with: a position detection unit that detects a position of a motor to be controlled; a speed calculation unit that calculates a speed of the motor; a position control unit that outputs a speed command and performs position control so that the position of the motor fed back from the position detection unit matches a position command; a speed control unit that outputs a torque command and performs speed control so that the speed fed back from the speed calculation unit matches the speed command, based on proportional-integral control; and a torque control unit for performing torque control based on the torque command,

the position control unit includes:

a subtracting unit that obtains a positional deviation between the position command and the position detected by the position detecting unit;

a position loop multiplying unit that multiplies the position deviation by a position proportional gain;

a differentiator that differentiates the position command;

a feedforward-gain multiplying unit that multiplies the feedforward-gain by the output of the differentiator;

a proportional differential unit for performing proportional differential control on the output of the feedforward/gain multiplication unit and compensating for a delay in a speed control system;

a feedforward/low-pass filter having a transfer function for removing a ripple caused by a quantization error of the position command, the feedforward/low-pass filter performing filter processing on an added value of an output of the proportional differentiating unit and an output of the feedforward/gain multiplying unit; and

and an adding unit that adds an output of the feedforward/low-pass filter to an output of the position loop multiplying unit and outputs the speed command.

7. The motor control apparatus according to claim 6,

and a position-control-side delay compensation low-pass filter having a transfer function equivalent to the delay of the speed control system,

the position command is input to the subtracting means through the position-control-side retardation compensation low-pass filter.

8. The motor control device according to claim 6 or 7,

the speed control unit includes: a speed-control-side delay compensation low-pass filter having a transfer function equivalent to the delay of the speed control system;

an integration control system including a velocity integrator that integrates a velocity deviation between a delayed velocity command obtained by inputting the velocity command to the velocity control-side delayed compensation low-pass filter and the velocity;

a proportional control system that outputs a command proportional to a difference between the speed command and the speed;

9. The motor control device according to claim 6 or 7,

the speed control unit is composed of:

a speed-control-side delay compensation low-pass filter having a transfer function equivalent to the delay of the speed control system;

an integral control system that multiplies and outputs a velocity proportional gain by an operation value in a control system including a velocity integrator that integrates a velocity deviation between a delayed velocity command obtained by inputting the velocity command to the velocity control-side delay compensation low-pass filter and the velocity;

a proportional control system that outputs a command obtained by multiplying a difference between the speed command and the speed by a speed proportional gain;

10. A motor control device is provided with: a position detection unit that detects a position of a motor to be controlled; a speed calculation unit that calculates a speed of the motor; a position control unit that outputs a speed command and performs position control so that the position of the motor fed back from the position detection unit matches a position command; a speed control unit that outputs a torque command and performs speed control so that the speed fed back from the speed calculation unit matches the speed command, based on proportional-integral control; and a torque control unit for performing torque control based on the torque command,

the position control unit includes:

a differentiator that differentiates the position command;

a proportional differential unit for performing proportional differential control on the output of the feedforward/gain multiplication unit to compensate for a delay in a speed control system;

a feedforward/low-pass filter having a transfer function for removing a ripple caused by a quantization error of the position command, the feedforward/low-pass filter performing filter processing on an added value of an output of the proportional differentiating unit and an output of the feedforward/gain multiplying unit;

an integrator that integrates a deviation between an output of the differentiator and a differential value of the position detected by the position detecting unit, and outputs a position deviation;

a position loop multiplying mechanism that multiplies a position proportional gain by an output of the integrator; and

and an adding unit that adds the command output from the position loop multiplying unit and the speed feedforward command output from the feedforward/low-pass filter to output the resultant as the speed command.

11. The motor control apparatus of claim 10,

a position-control-side delay compensation low-pass filter having a transfer function equivalent to the delay of a speed control system is arranged between the differentiator and the integrator,

a deviation between an output of the differentiator through the position control side delay compensation low pass filter and a differentiation value of the position is input to the integrator.