阅读说明：本技术 电动机的控制装置 (Control device for motor ) 是由 藤原弘 田泽徹 于 2018-12-20 设计创作，主要内容包括：一种用于驱动作为被控制对象的负载(机械负载)的电动机的控制装置,具备前馈控制部、反馈控制部以及加减法运算器。前馈控制部被输入用于指定被控制对象的负载目标位置的位置指令信号,输出表示电动机的目标位置的前馈位置指令信号、表示电动机的目标速度的前馈速度指令信号以及表示在电动机中为了进行目标位置或目标速度所表示的动作而需要的转矩的前馈转矩指令信号。反馈控制部被输入前馈位置指令信号、前馈速度指令信号、表示电动机的位置的电动机位置信号以及表示电动机的速度的电动机速度信号,输出反馈转矩指令信号,该反馈转矩指令信号表示用于进行反馈控制使得电动机位置信号与前馈位置指令信号一致的转矩指令。加减法运算器从将前馈转矩指令信号与反馈转矩指令信号相加所得到的转矩指令信号减去负载加速度反馈转矩信号,将其结果作为转矩指令校正信号输出,该负载加速度反馈转矩信号是对表示作为被控制对象的负载的加速度的负载加速度信号乘以负载加速度反馈增益所得到的。前馈控制部生成前馈转矩指令信号,使得预先补偿在加减速动作时从转矩指令信号减去的负载加速度反馈转矩信号的影响。(A control device for a motor for driving a load (mechanical load) to be controlled includes a feedforward control unit, a feedback control unit, and an addition/subtraction arithmetic unit. The feedforward control unit receives a position command signal for specifying a target load position of a controlled object, and outputs a feedforward position command signal indicating a target position of the motor, a feedforward speed command signal indicating a target speed of the motor, and a feedforward torque command signal indicating a torque required for the motor to perform an operation indicated by the target position or the target speed. The feedback control unit receives a feedforward position command signal, a feedforward speed command signal, a motor position signal indicating the position of the motor, and a motor speed signal indicating the speed of the motor, and outputs a feedback torque command signal indicating a torque command for performing feedback control so that the motor position signal matches the feedforward position command signal. The addition/subtraction arithmetic unit subtracts a load acceleration feedback torque signal, which is obtained by multiplying a load acceleration signal indicating the acceleration of the load as the controlled object by a load acceleration feedback gain, from a torque command signal obtained by adding a feedforward torque command signal and a feedback torque command signal, and outputs the result as a torque command correction signal. The feedforward control unit generates a feedforward torque command signal so that the influence of a load acceleration feedback torque signal subtracted from the torque command signal at the time of acceleration/deceleration is compensated in advance.)

1. A control device for an electric motor for driving a load to be controlled, the control device comprising:

a feedforward control unit that receives a position command signal for specifying a target load position of the controlled object, and outputs a feedforward position command signal indicating a target position of the motor, a feedforward speed command signal indicating a target speed of the motor, and a feedforward torque command signal indicating a torque required by the motor to perform an operation indicated by the target position or the target speed;

a feedback control unit that receives the feedforward position command signal, the feedforward speed command signal, a motor position signal indicating a position of the motor, and a motor speed signal indicating a speed of the motor, and outputs a feedback torque command signal indicating a torque command for performing feedback control so that the motor position signal matches the feedforward position command signal; and

an addition/subtraction arithmetic unit that subtracts a load acceleration feedback torque signal, which is obtained by multiplying a load acceleration signal indicating an acceleration of the load to be controlled by a load acceleration feedback gain, from a torque command signal obtained by adding the feedforward torque command signal and the feedback torque command signal, and outputs the result as a torque command correction signal,

wherein the feedforward control unit generates the feedforward torque command signal so that an influence of the load acceleration feedback torque signal subtracted from the torque command signal at the time of acceleration and deceleration is compensated in advance.

2. The control device of an electric motor according to claim 1,

the feedforward control unit generates the feedforward torque command signal by multiplying a feedforward acceleration command signal calculated by a second order differential of the feedforward position command signal by a sum of the inertia of the electric motor and the inertia of the load to be controlled and the load acceleration feedback gain.

3. The control device of an electric motor according to claim 1,

the addition/subtraction calculator generates a torque command correction signal by subtracting a load acceleration feedback torque signal, which is obtained by multiplying a signal obtained by applying filtering processing to a load acceleration signal representing an acceleration of the load to be controlled by the load acceleration feedback gain, from the torque command signal,

the feedforward control unit generates the feedforward torque command signal by adding one of a feedforward acceleration command signal calculated by a second order differential of the feedforward position command signal and a sum of the inertia of the motor and the inertia of the load to be controlled, and the other of the feedforward torque command signal and the feedforward position command signal is obtained by multiplying a signal obtained by applying a filtering process equivalent to the filtering process to the feedforward acceleration command signal and the load acceleration feedback gain.

Technical Field

The present invention relates to a motor control device that controls a driving operation such as a speed or a position of a motor with respect to the motor and a mechanical load driven by the motor. In particular, the present invention relates to a motor control device having a control structure for suppressing vibration due to antiresonance of a mechanical load generated during driving or the like.

Background

Such a motor control device includes at least one of a feedforward control system and a feedback control system inside so that a position command input from a host controller matches the positions of the motor and a load (mechanical load) to be controlled. Such a motor control device calculates a torque command value for matching a position command with a motor position based on the position command and a position detection value of the motor, and controls a current to be supplied to a stator winding of the motor so that the same torque as the torque command value is generated in the motor, thereby controlling the positions of the motor and a load (mechanical load) to be controlled. However, when the mechanical rigidity of the joint between the motor and the load (mechanical load) to be controlled is low, vibration due to antiresonance is likely to occur in the load (mechanical load) to be controlled at the time of acceleration/deceleration or at the time of disturbance application, and it is recognized that the stability and disturbance suppression performance are further improved as compared with the conventional one.

To solve the problem, a conventional feed control device is configured to: an acceleration sensor is provided on a slider, which is a load (mechanical load) to be controlled, and an acceleration feedback loop for subtracting a value obtained by multiplying an acceleration detection value of the load (mechanical load) to be controlled by an acceleration feedback gain, which is a weighting coefficient, from a torque command value is provided to suppress vibration generated in the load (mechanical load) to be controlled at the time of acceleration and deceleration or at the time of disturbance application (for example, see patent document 1).

In the configuration represented by patent document 1 and the like, the vibration caused by the mechanical rigidity is reduced as the acceleration feedback gain is increased. On the other hand, when the present configuration is applied to a motor control device having a feedforward control system, the torque required for the acceleration/deceleration operation of the load is subtracted from the torque command value. Therefore, there are the following problems: the command follow-up performance is deteriorated, and operation delay, overshoot, undershoot, or the like occurs during the stop, and stability and vibration suppression cannot be achieved at the same time. In other words, there is a trade-off relationship between the acceleration feedback gain (acceleration feedback amount) and the command tracking performance, and further improvement is desired in order to achieve both stability and vibration suppression.

Disclosure of Invention

The present invention is intended to solve the conventional problems. The present invention provides a control device for a motor, which has a feedforward control system and a load acceleration feedback system, and which can achieve both stability and vibration suppression by obtaining a vibration suppression effect by load acceleration feedback while maintaining a command follow-up performance. That is, the present invention provides a control device for an electric motor, which can reduce or avoid a trade-off relationship between a load acceleration feedback gain (acceleration feedback amount) and a command follow-up performance, and improve a vibration suppression effect by acceleration feedback from a load side while maintaining the command follow-up performance.

In order to solve the above problems, the inventors of the present application have repeatedly conducted experiments and have intensively studied. Then, a new control device for an electric motor has been found which improves the vibration suppression effect by the acceleration feedback from the load side while maintaining the command follow-up performance. The details thereof are as follows.

A first aspect of the present invention is a control device for a motor that drives a load (mechanical load) to be controlled, the control device including a feedforward control unit, a feedback control unit, and an addition/subtraction arithmetic unit.

The feedforward control unit receives a position command signal for specifying a target load position of a controlled object, and outputs a feedforward position command signal indicating a target position of the motor, a feedforward speed command signal indicating a target speed of the motor, and a feedforward torque command signal indicating a torque required for the motor to perform an operation indicated by the target position or the target speed.

The feedback control unit receives a feedforward position command signal, a feedforward speed command signal, a motor position signal indicating the position of the motor, and a motor speed signal indicating the speed of the motor, and outputs a feedback torque command signal indicating a torque command for performing feedback control so that the motor position signal matches the feedforward position command signal.

The addition/subtraction arithmetic unit subtracts a load acceleration feedback torque signal, which is obtained by multiplying a load acceleration signal representing the acceleration of a load to be controlled by a load acceleration feedback gain, from a torque command signal obtained by adding a feedforward torque command signal and a feedback torque command signal, and outputs the result as a torque command correction signal.

The feedforward control unit generates a feedforward torque command signal so that the influence of a load acceleration feedback torque signal subtracted from the torque command signal at the time of acceleration/deceleration is compensated in advance.

In a second aspect, in the control device of an electric motor according to the first aspect, the feedforward control unit generates the feedforward torque command signal by multiplying the feedforward acceleration command signal calculated by the second order differential of the feedforward position command signal by an addition value of the inertia of the electric motor and the inertia of the load to be controlled and the load acceleration feedback gain.

In the motor control device according to the first aspect, the addition/subtraction unit generates the torque command correction signal by subtracting a load acceleration feedback torque signal, which is obtained by multiplying a signal obtained by performing a filtering process on a load acceleration signal representing an acceleration of a load to be controlled, by the load acceleration feedback gain, from the torque command signal.

The feedforward control unit generates a feedforward torque command signal by adding one of a feedforward acceleration command signal calculated by second-order differentiation of a feedforward position command signal and a sum of inertia of the motor and inertia of a load to be controlled, and the other of the feedforward acceleration command signal and the sum of a signal obtained by applying filtering equivalent to filtering to the feedforward acceleration command signal and a load acceleration feedback gain.

By solving the above-described problems, a control device for an electric motor having a feedforward control system and a load acceleration feedback system can improve the vibration suppression effect by the load acceleration feedback while maintaining the command tracking performance without causing the command tracking performance to be degraded by the load acceleration feedback. Therefore, stability and vibration suppression can be achieved at the same time.

A control device for an electric motor according to the present invention compensates in advance a subtracted portion of an acceleration/deceleration torque generated by load acceleration feedback in a feedforward torque calculation by a feedforward control system. The motor control device of the present invention can improve the vibration suppression effect by the load acceleration feedback while maintaining the command tracking performance, and is industrially valuable.

Drawings

Fig. 1 is a diagram showing an example of a configuration of a motor control device according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing an example of the configuration of the load acceleration correction unit according to embodiment 1 of the present invention.

Fig. 3 is a diagram showing an example of the configuration of the feedforward torque command generating unit in embodiment 1 of the present invention.

Fig. 4 is a diagram showing an example of the configuration of a motor control device according to embodiment 2 of the present invention.

Fig. 5 is a diagram showing an example of the configuration of the feedforward torque command generating unit according to embodiment 2 of the present invention.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiment.

(embodiment mode 1)

Fig. 1 is a diagram showing an example of a configuration of a motor control device according to embodiment 1 of the present invention. The motor control device 100 shown in fig. 1 is connected to a motor 201, a position detector 202 for detecting the position of the motor 201, and an acceleration detector 205 for detecting the acceleration of a load 204 to be driven, which is connected to the motor 201 via a joint 203. The motor control device 100 receives a position command signal from a host controller (not shown) and controls a current flowing through a stator winding of the motor so that the position command signal matches the positions of the motor and a load (mechanical load) to be controlled. The position detector 202 detects the position of the motor, and outputs the detected position of the motor as a motor position signal θ m to the motor control device 100. The acceleration detector 205 detects the acceleration of the load, and outputs the detected acceleration of the load to the motor control device 100 as a load acceleration signal AL.

The structure of the motor control device 100 will be described. The motor control device 100 includes therein a feedforward control unit 1001, a feedback control unit 1002, a torque control unit 103, a speed conversion unit 104, a load acceleration correction unit 105, and an addition/subtraction calculator 108. The feedforward control unit 1001 receives the position command signal θ s and outputs a feedforward position command signal θ ff indicating a target operation of the motor, a feedforward speed command signal ω ff, and a feedforward torque command signal τ ff that is a torque required for the motor to perform the target operation.

The feedback control unit 1002 receives the feedforward position command signal θ ff, the feedforward speed command signal ω ff, the motor position signal θ m, and the motor speed signal ω m calculated by the speed conversion unit 104 from the motor position signal θ m, and outputs a feedback torque command signal τ fb indicating a torque for reducing a position deviation between the feedforward position command signal θ ff and the motor position signal θ m and a speed deviation between the feedforward speed command signal ω ff and the motor speed signal ω m.

The addition/subtraction arithmetic unit 108 outputs a torque command correction signal τ in obtained by subtracting a load acceleration feedback torque signal τ acc, which will be described later, from a torque command signal τ s, which is the sum of the feedforward torque command signal τ ff and the feedback torque command signal τ fb. The torque control unit 103 receives the torque command correction signal τ in as input, and controls the current flowing through the stator winding of the motor so that the same torque as the torque command correction signal τ in is generated in the motor.

The load acceleration correction signal a' L obtained by subtracting the command acceleration signal As from the load acceleration signal AL is input to the load acceleration correction unit 105, and the load acceleration correction unit 105 outputs the load acceleration feedback torque signal τ acc.

In this way, the motor control device 100 includes a feedforward control system and a cascade-type feedback control system that feeds back the motor position, the motor speed, and the load speed so that the position command matches the positions of the motor and the load.

Next, the configuration of the motor control device will be described in detail.

The feedforward control unit 1001 internally includes a feedforward operation command generation unit 106 and a feedforward torque command generation unit 107.

The feedforward operation command generation unit 106 receives the position command signal θ s and outputs a feedforward position command signal θ ff, a feedforward speed command signal ω ff, and a feedforward acceleration command signal Aff. For example, the position command signal θ s is directly output as a feedforward position command signal θ ff, the feedforward position command signal θ ff is subjected to first-order differential operation to calculate a feedforward speed command signal ω ff, and the feedforward position command signal θ ff is subjected to second-order differential operation to calculate a feedforward acceleration command signal Aff.

The feedforward torque command generating unit 107 receives the feedforward acceleration command signal Aff as input, and outputs a feedforward torque command signal τ ff that is a torque required to match the acceleration of the motor 201 or the load 204 with the feedforward acceleration command signal Aff.

For example, the feedforward torque command τ ff is calculated by multiplying the feedforward acceleration command Aff by a weighting coefficient indicating the total inertia of the motor, the load, or the like. The configuration of calculating the feedforward torque command signal τ ff in the feedforward torque command generating unit 107 will be described in detail later.

In this way, the feedforward control unit 1001 outputs the feedforward position command signal θ ff, the feedforward speed command signal ω ff, and the feedforward torque command signal τ ff based on the input position command signal θ s by the actions of the feedforward operation command generation unit 106 and the feedforward torque command generation unit 107. The feedback control unit 1002 includes therein a position control unit 101 and a speed control unit 102. The position control unit 101 receives the feedforward position command signal θ ff and the motor position signal θ m, and outputs a speed command signal ω s for reducing the difference between the two signals. The position control unit 101 performs, for example, a proportional control calculation in which a signal obtained by multiplying the feedforward position command signal θ ff and the motor position signal θ m by a weighting coefficient is output as the speed command signal ω s.

The speed control unit 102 receives the feedforward speed command signal ω ff, the speed command signal ω s, and the motor speed signal ω m. The speed control unit 102 outputs a feedback torque command signal τ fb for reducing a difference between the motor speed signal ω m and an addition value of the feedforward speed command signal ω ff and the speed command signal ω s. The speed control unit 102 performs, for example, a proportional-integral operation in which an added value of a value obtained by subtracting the motor speed signal ω m from the added value of the feedforward speed command signal ω ff and the speed command signal ω s and a value obtained by multiplying an integral value of the value obtained by subtracting the motor speed signal ω m from the added value of the feedforward speed command signal ω ff and the speed command signal ω s and a weighting coefficient is output as the feedback torque command signal τ fb.

Thus, the feedback control unit 1002 outputs the feedback torque command signal τ fb based on the feedforward position command signal θ ff, the feedforward speed command signal ω ff, the motor position signal θ m, and the motor speed signal ω m that are input thereto.

The speed conversion unit 104 receives the motor position signal θ m and outputs a motor speed signal ω m indicating the motor speed. The speed conversion unit 104 performs, for example, a differential operation on the motor position signal θ m, and outputs the calculation result as a motor speed signal ω m.

The load acceleration correction unit 105 receives the load acceleration signal AL, and outputs a value obtained by multiplying the load acceleration signal AL by a weighting coefficient as the load acceleration feedback torque signal τ acc. Then, a value obtained by subtracting the load acceleration feedback torque signal τ acc, which is the sum of the feedforward torque command signal τ ff and the feedback torque command signal τ fb, from the torque command signal τ s is input to the torque control unit 103 as a torque command correction signal τ in.

However, when the motor or the load is subjected to acceleration/deceleration operation so that the motor position signal θ m or the load position θ L follows the position command signal θ s, the load acceleration feedback torque signal τ acc is subtracted from the feedforward torque command signal τ ff calculated as the torque required for the acceleration/deceleration operation when the load acceleration feedback torque signal τ acc is subtracted from the torque command signal τ s. The operation when the load acceleration feedback torque signal τ acc is subtracted from the feed-forward torque command signal τ ff will be described in conjunction with the operation principle of the load acceleration correction unit 105.

Fig. 2 is a diagram showing an example of the configuration of the load acceleration correction unit 105 according to embodiment 1 of the present invention. The load acceleration correction unit 105 receives the load acceleration signal AL, and outputs a value obtained by multiplying the load acceleration signal AL by a load acceleration feedback gain Kacc, which is a weighting coefficient, as the load acceleration feedback torque signal τ acc. In this case, if the command acceleration signal As is 0, the transfer function G τ s → θ m(s) of the motor position signal θ m for the torque command signal τ s and the transfer function G τ s → θ L(s) of the load position θ L for the torque command signal are expressed by the following equations (1) and (2).

[ numerical formula 1]

[ numerical formula 2]

[ numerical formula 3]

[ numerical formula 4]

In equations (1) and (2), s is the laplacian, Jm is the inertia of the motor 201, JL is the inertia of the load 204, ω' p is the resonance frequency in the transmission characteristic from the torque command signal τ s to the motor position signal θ m, and ω z is the anti-resonance frequency in the transmission characteristic from the torque command signal τ s to the motor position signal θ m. The relationship between motor inertia Jm, load inertia JL, and load acceleration feedback gain Kacc and resonance frequency ω' p is expressed by equation (3), and the relationship between the motor inertia Jm, load inertia JL, and load acceleration feedback gain Kacc and anti-resonance frequency ω z is expressed by equation (4). In expressions (3) and (4), Ks represents the elastic coefficient of the joint portion 203. When the load 204 is driven by the motor 201 in the motor control device 100, vibration of the anti-resonance frequency ω z is excited in the load 204 by the acceleration and deceleration operation, and this causes deterioration of stability at the time of stop.

When equation (1) is concerned, it is found that when the load acceleration feedback gain Kacc is increased, the resonance frequency ω' p increases and the anti-resonance frequency ω z does not change. The larger the difference between the resonance frequency and the antiresonance frequency, the smaller the gain at the antiresonance frequency, and therefore the less the antiresonance effect. On the other hand, as can be seen from equations (1) and (2), the relationship between the motor position signal θ m and the load position θ L with respect to the torque command signal τ s is expressed by equation (5) below.

[ numerical formula 5]

According to equation (5), the relationship between the motor position signal θ m and the load position θ L is always constant regardless of the load acceleration feedback gain Kacc. Therefore, in equation (1), when the gain at the antiresonant frequency ω z of the transmission characteristic of the motor position signal θ m with respect to the torque command signal τ s is small by increasing the load acceleration feedback gain Kacc, the gain at the antiresonant frequency ω z of the transmission characteristic of the load position θ L with respect to the torque command signal τ s is also small. Therefore, the vibration of the anti-resonance frequency ω z of the load 204 caused by the acceleration/deceleration operation also becomes small.

Therefore, the load acceleration correction unit 105 feeds back the load acceleration, thereby having an effect of reducing the gain at the antiresonant frequency, that is, the sensitivity, according to the above principle. As a result, when the motor 201 or the load 204 is driven by the motor control device 100, the anti-resonance vibration generated in the load 204 during acceleration/deceleration operation or during disturbance can be reduced.

As described above, by feeding back the load acceleration signal AL by the load acceleration correction unit 105, an effect of suppressing the vibration caused by the antiresonance can be obtained.

On the other hand, as can be seen from equations (1) and (2), the total inertia is the sum of motor inertia Jm, load inertia JL, and load acceleration feedback gain Kacc, based on the transfer functions of motor position signal θ m and load position θ L for torque command signal τ s. That is, the following is shown: by performing load acceleration feedback by the load acceleration correction unit 105, the total inertia of the controlled object including the motor 201 and the load 204 is increased by the load acceleration feedback gain Kacc with respect to the torque command signal τ s.

This shows that subtracting the load acceleration feedback torque command τ acc from the torque command signal τ s is equivalent to increasing the load acceleration feedback gain Kacc relative to the torque command signal τ s for the total inertia of the controlled object.

When the feedforward torque command generating unit 107 does not take into account the change in the total inertia of the controlled object with respect to the torque command signal τ s due to the load acceleration feedback, the operation command output from the feedforward operation command generating unit does not match the motor operation even if only the feedforward torque command signal τ ff is applied to the motor during the acceleration/deceleration operation. That is, the instruction tracking performance based on the feedforward control becomes poor.

The difference between the operation command and the motor operation is compensated for by the position control unit 101 and the speed control unit 102, and the position control unit 101 and the speed control unit 102 perform control so that the operation command matches the motor operation, but the position control unit 101 and the speed control unit 102 perform control based on the difference between the operation command and the motor operation due to the disparity. Therefore, the control is delayed, and an operation delay, an overshoot, an undershoot, or the like occurs during the stop period due to the control delay.

That is, in the motor control device having the feedforward control system and the load acceleration feedback system, as the load acceleration feedback gain is increased, the command follow-up performance is deteriorated, and the operation delay, the overshoot, the undershoot, or the like occurs during the stop. In other words, there is a trade-off relationship between the acceleration feedback gain (acceleration feedback amount) and the command tracking performance, and there is a problem that stability and vibration suppression cannot be achieved at the same time.

In order to prevent operation delay, overshoot, or undershoot during the stop period and achieve both stability and vibration suppression, it is necessary to consider a load acceleration feedback torque signal τ acc, which is a subtraction amount from a torque command signal τ s generated by load acceleration feedback, in the calculation of the feedforward torque command signal τ ff by the feedforward torque command generating unit 107. That is, it is necessary to consider a change in the total inertia of the controlled object with respect to the torque command signal τ s, which is caused by the load acceleration feedback.

Fig. 3 is a diagram showing an example of the configuration of the feedforward torque command generating unit 107 according to embodiment 1 of the present invention. The feedforward torque command generating unit 107 multiplies the input feedforward acceleration command Aff by the sum of the motor inertia Jm, the load inertia JL, and the load acceleration feedback gain Kacc to calculate a feedforward torque command signal.

In this way, in the motor control device 100, the feedforward torque command generating unit 107 calculates the feedforward torque command τ ff in consideration of the influence of the change in the total inertia of the controlled object due to the load acceleration feedback with respect to the torque command τ s, by considering the load acceleration feedback gain Kacc in addition to the inertia of the motor and the load when calculating the feedforward torque command τ ff from the feedforward acceleration command signal Aff. This reduces the difference between the operation command and the motor operation during the acceleration/deceleration operation, thereby improving the command follow-up performance and improving the operation delay, overshoot, undershoot, and the like during the stop.

As described above, in the present embodiment, by compensating in advance the subtraction amount of the acceleration/deceleration torque generated by the load acceleration feedback in the feedforward torque calculation by the feedforward control system, the vibration suppression effect by the load acceleration feedback can be improved while maintaining the command follow-up performance. Therefore, the vibration suppression effect by the load acceleration feedback can be obtained while maintaining the command tracking performance, and therefore, the stability and the vibration suppression can be simultaneously achieved.

As described above, the motor control device 100 according to the present embodiment is a control device for driving a motor that is a load to be controlled, and includes the feedforward control unit 1001, the feedback control unit 1002, and the addition/subtraction calculator 108. The feedforward control unit 1001 receives a position command signal θ s for specifying a target load position of a controlled object, and outputs a feedforward position command signal θ ff indicating a target position of the motor, a feedforward speed command signal ω ff indicating a target speed of the motor, and a feedforward torque command signal τ ff indicating a torque required by the motor to perform an operation indicated by the target position or the target speed. The feedback control unit 1002 receives a feedforward position command signal θ ff, a feedforward speed command signal ω ff, a motor position signal θ m indicating the motor position, and a motor speed signal ω m indicating the motor speed, and outputs a feedback torque command signal τ fb indicating a torque command for performing feedback control so that the motor position signal θ m matches the feedforward position command signal θ ff. The addition/subtraction arithmetic unit 108 subtracts a load acceleration feedback torque signal τ acc obtained by multiplying a load acceleration signal AL indicating the acceleration of the load as the controlled object by a load acceleration feedback gain Kacc from a torque command signal τ s obtained by adding the feedforward torque command signal τ ff and the feedback torque command signal τ fb, and outputs the result as a torque command correction signal τ in. The feedforward control unit 1001 generates the feedforward torque command signal τ ff so that the influence of the load acceleration feedback torque subtracted from the torque command signal τ s at the time of the acceleration/deceleration operation is compensated in advance.

Thus, by compensating in advance the subtraction amount of the acceleration/deceleration torque generated by the load acceleration feedback in the feedforward torque calculation by the feedforward control system, the vibration suppression effect by the load acceleration feedback can be improved while maintaining the command follow-up performance. Thereby, the vibration suppression effect by the load acceleration feedback can be obtained while maintaining the command tracking performance, and therefore, the stability and the vibration suppression can be simultaneously realized.

The feedforward control unit 1001 may also multiply the feedforward acceleration command signal Aff calculated by the second order differential of the feedforward position command signal θ ff by the sum of the inertia of the motor and the inertia of the load to be controlled and the load acceleration feedback gain Kacc to generate the feedforward torque command signal τ ff.

(embodiment mode 2)

Fig. 4 is a diagram showing an example of the configuration of a motor control device according to embodiment 2 of the present invention. Fig. 4 differs from fig. 1 in the acceleration detector 206 and the feedforward torque command generating unit 307. The operation of the other components is the same as that of the motor control device according to embodiment 1 of the present invention shown in fig. 1, and therefore, the description thereof is omitted.

The acceleration detector 206 outputs a signal obtained by performing low-pass filtering or high-pass filtering on the acceleration of the load 204 to remove a detection noise component or the like, as a load acceleration signal AL. When the filter process is performed in the acceleration detector 206, an apparent inertia change due to the load acceleration feedback is affected by the filter process. Therefore, the filter process in the acceleration detector 206 needs to be considered for the calculation process of the feedforward torque command signal τ ff in the feedforward torque command generating unit 307.

Next, the configuration of the feedforward torque command generating unit 307 will be described. Fig. 5 is a diagram showing an example of the configuration of the feedforward torque command generating unit 307 according to embodiment 2 of the present invention.

The feedforward torque command generating unit 307 includes therein an inertia multiplying unit 3071, a filter unit 3072, and a load acceleration feedback gain multiplying unit 3073.

The inertia multiplication unit 3071 receives the feedforward acceleration signal Aff. The inertia multiplication unit 3071 uses the sum of the motor inertia Jm and the load inertia JL as a weighting coefficient, and outputs the result of multiplying the feedforward acceleration signal Aff by the weighting coefficient as the first feedforward torque command signal τ ff 1.

The filter 3072 receives the feedforward acceleration signal Aff as well. The filter 3072 applies filter processing equivalent to the filter processing performed on the acceleration of the load by the acceleration detector 206 to the input feedforward acceleration signal Aff, and outputs a feedforward acceleration command correction signal Affc.

The load acceleration feedback gain multiplication unit 3073 receives the feedforward acceleration command correction signal Affc as input, and outputs the result of multiplying the feedforward acceleration command correction signal Affc by the load acceleration feedback gain Kacc as the second feedforward torque command signal τ ff 2.

The sum of the first feedforward torque command signal τ ff1 and the second feedforward torque command signal τ ff2 is output from the feedforward torque command generating unit 307 as the feedforward torque command signal τ ff.

In this way, when calculating the feedforward torque command τ ff from the feedforward acceleration command signal Aff, the feedforward torque command generating unit 307 performs filtering processing on the load acceleration in consideration of the load acceleration feedback gain in addition to the inertia of the motor and the load. Thus, a feedforward torque command is calculated in consideration of the total inertia change of the controlled object due to the load acceleration feedback with respect to the torque command signal τ s. Therefore, the difference between the operation command and the motor operation during the acceleration/deceleration operation is reduced, and the operation delay, overshoot, undershoot, and the like during the stop period can be improved.

As described above, in the present embodiment, in the feedforward torque calculation by the feedforward control system, the subtraction amount of the acceleration/deceleration torque by the load acceleration feedback is compensated in advance by the filter processing for the load acceleration in the acceleration detector, whereby the vibration suppression effect by the load acceleration feedback can be improved while the command follow-up performance is maintained. Thereby, the vibration suppression effect by the load acceleration feedback can be obtained while maintaining the command tracking performance, and therefore, the stability and the vibration suppression can be simultaneously realized.

As described above, in the control device 100 for an electric motor according to the present embodiment, the addition/subtraction unit 108 generates the torque command correction signal τ in by subtracting the load acceleration feedback torque, which is obtained by multiplying the load acceleration feedback gain Kacc by the signal obtained by performing the filtering process on the load acceleration signal AL representing the acceleration of the load as the controlled object, from the torque command signal τ s. The feedforward control unit 1001 generates the feedforward torque command signal τ ff by adding one of a signal obtained by multiplying the feedforward acceleration command signal Aff calculated by the second order differential of the feedforward position command signal θ ff by the sum of the inertia of the motor and the inertia of the load to be controlled and a signal obtained by multiplying the feedforward acceleration command signal Aff subjected to the filtering equivalent to the filtering by the load acceleration feedback gain Kacc.

This reduces the difference between the operation command and the motor operation during the acceleration/deceleration operation, and can improve the operation delay, overshoot, undershoot, and the like during the stop.

In the present embodiment, the load acceleration is filtered by the acceleration detector, but the load acceleration may be filtered by the motor control device.

Industrial applicability

As described above, the control device for an electric motor according to the present invention obtains the vibration suppression effect by the load acceleration feedback while maintaining the command follow-up performance. Therefore, stability and vibration suppression can be achieved at the same time. The following control device for an electric motor can be provided: by alleviating or avoiding the trade-off relationship between the load acceleration feedback gain (acceleration feedback amount) and the command tracking performance, it is possible to improve the vibration suppression effect by the acceleration feedback from the load side while maintaining the command tracking performance. Therefore, the present invention is suitable for use in a control device for a motor used in a semiconductor manufacturing apparatus, an electronic component mounting apparatus, or the like.

Description of the reference numerals

100: a control device for the motor; 1001: a feedforward control unit; 1002: a feedback control unit; 101: a position control unit; 102: a speed control unit; 103: a torque control unit; 104: a speed conversion unit; 105: a load acceleration correction unit; 106: a feedforward operation command generation unit; 107: a feedforward torque command generation unit; 108: an addition and subtraction operator; 201: an electric motor; 202: a position detector; 203: a joint portion; 204: a load; 205: an acceleration detector; 206: an acceleration detector; 307: a feedforward torque command generation unit; 3071: an inertia multiplication unit; 3072: a filtering section; 3073: a load acceleration feedback gain multiplication unit.