JP7032635B2 - Wasted time compensation device and resonance suppression control device equipped with it - Google Patents

Description

The present invention relates to a wasted time compensating device that compensates for the wasted time for a controlled object having wasted time.

It is known that when the control target is controlled, the command actually input to the control target is delayed with respect to the input command due to the sampling cycle, communication in the control device, and the like. Such delays are commonly referred to as wasted time. It is known that this wasted time affects the control of the controlled object.

For example, in the case of a multi-inertial resonance system in which the controlled object has a plurality of inertias and causes resonance, it is known that if the multi-inertial resonance system has wasted time, the vibration of the controlled object is affected. ..

In order to reduce the influence of vibration due to such wasted time, for example, the resonance suppression control device disclosed in Patent Document 1 is known. This resonance suppression control device suppresses the resonance frequency component by passing the shaft torsion torque detection value through a high-pass filter in consideration of the wasted time element due to the detection delay of the shaft torsion torque and the wasted time element of the torque transmission characteristic of the inverter. do.

Specifically, the resonance suppression control device subtracts the output of the high-pass filter from the torque command, passes the subtracted output through a phase compensator to obtain the torque command value after phase compensation, and obtains the torque command value after phase compensation. Is given to the inverter as a motor torque command. The transfer function _GPHC of the phase compensator is as follows.
G _PHC = (α ・ s + ω _phc ) / (s + ω _phc )

However, α is a phase compensation parameter, and ω _phc is a phase compensation filter cutoff frequency.

Japanese Unexamined Patent Publication No. 2017-99084

The resonance suppression control device disclosed in Patent Document 1 described above can suppress the resonance frequency component of the shaft torsional torque detection value without affecting the DC component by using the high-pass filter. However, in the resonance suppression control device of Patent Document 1, in order to reduce the influence of wasted time in the motor torque command, the phase compensation parameter α is appropriately adjusted in consideration of the wasted time in the transfer function _GPHC of the phase compensator. There is a need to.

An object of the present invention is to provide a wasted time compensating device capable of easily compensating for the wasted time for a controlled object having wasted time.

The wasted time compensating device according to the embodiment of the present invention is a wasted time compensating device that compensates for the wasted time for a controlled object having wasted time. The wasted time compensating device includes a wasted time compensating unit that considers the wasted time in an input command to the controlled object by modeling the wasted time, and the wasted time compensating unit is a padé approximation of the wasted time. It has a transfer function whose denominator is replaced by the transfer function of the low-pass filter in the reciprocal of (first configuration).

The present inventor has examined a wasted time compensating unit that compensates for wasted time. The present inventor noticed the following points in the process of examining compensation for wasted time.

By expressing the wasted time by the Padé approximation and finding the reciprocal of it, a transfer function that takes the wasted time into consideration can be obtained. However, for example, when the waste time is expressed by a first-order Padé approximation, the equation (4) is obtained, and the reciprocal thereof is the equation (4)'.

As described above, the reciprocal of the Padé approximation of the wasted time has a positive value when denominator = 0, so that the value diverges with the passage of time. That is, the denominator of the reciprocal is an unstable element in control.

On the other hand, as in the above configuration, by setting the reciprocal denominator as the transfer function of the low-pass filter (1 + Ts: T is a time constant), control is performed in consideration of wasted time in the frequency domain passing through the low-pass filter. And can prevent the control from diverging.

In the first configuration, the wasted time compensating device further includes a feedback loop for negatively feeding back the output value of the controlled object to the input command, and the wasted time compensating unit is provided in the feedback loop (the waste time compensating unit is provided in the feedback loop). Second configuration). As a result, in the feedback loop used for controlling the controlled object, the wasted time can be taken into consideration, so that the controlled object can be accurately controlled, for example, vibration can be quickly and effectively suppressed in the controlled object where resonance occurs. ..

In the second configuration, the wasted time compensator considers the wasted time in the input value to the differentiator in the feedback loop (third configuration). This makes it possible to consider wasted time in the feedback loop that performs differential feedback control. That is, when differential feedback control is performed on the controlled object, resonance may occur, but by using the reciprocal of the Padé approximation of the wasted time as in the first configuration described above, resonance can be performed quickly and effectively. Can be suppressed.

The resonance suppression control device according to an embodiment of the present invention is a resonance suppression control device that suppresses resonance of a multi-inertial resonance system including a feedback loop that negatively feeds back an output value of a controlled object having wasted time to an input command. Is. This resonance suppression control device is provided in the feedback loop, has a wasted time compensating device having any one of the first to third configurations described above, and is provided in the feedback loop to control the vibration damping ratio. A damping ratio adjusting unit for adjusting is provided (fourth configuration).

As a result, the resonance of the multi-inertia resonance system provided with the feedback loop for the controlled object in which the resonance occurs can be effectively suppressed in consideration of the wasted time.

According to the wasted time compensating device according to the embodiment of the present invention, the wasted time compensating unit that considers the wasted time for the input command to be controlled has the denominator of the low-pass filter in the reciprocal of the Padé approximation of the wasted time. It has a transfer function that has been replaced by a transfer function. Thereby, the control target can be controlled in consideration of the wasted time while preventing the control from diverging. Therefore, it is possible to obtain a wasted time compensating device that can easily compensate for the wasted time in the control of the controlled object.

FIG. 1 is a functional block diagram showing a schematic configuration of a test device provided with a waste time compensation device according to an embodiment. FIG. 2 is a block diagram showing a feedback loop that performs differential feedback control with respect to a controlled object. FIG. 3 is a Bode diagram to be controlled. FIG. 4 is a diagram showing a step response to be controlled.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the figure are designated by the same reference numerals and the description thereof will not be repeated.

(overall structure)
FIG. 1 is a diagram showing a schematic configuration of a test device 1 provided with a waste time compensating device according to an embodiment of the present invention in functional blocks. This test device 1 is a test device for testing the characteristics of a specimen M such as an automobile motor. The specimen M to be tested by the test apparatus 1 may be a rotating body other than the motor.

Specifically, the test device 1 includes a control device 2, a motor drive circuit 3, an electric motor 4, and a torque detector 5.

The control device 2 generates a drive command for the motor drive circuit 3 by using the motor torque command r which is an input command and the feedback value described later. The control device 2 has a feedback loop 10 (resonance suppression control device) that negatively feeds back to the motor torque command r using the output value of the torque detector 5 (see FIG. 2). Since the configuration in which the control device 2 generates the drive command is the same as in the conventional case, detailed description of the control device 2 will be omitted. The configuration of the feedback loop 10 will be described later.

Although not particularly shown, the motor drive circuit 3 has a plurality of switching elements. The motor drive circuit 3 supplies electric power to a coil (not shown) of the electric motor 4 by driving the plurality of switching elements based on the drive command.

The electric motor 4 has a rotor and a stator (not shown). By supplying electric power from the motor drive circuit 3 to the coil of the stator, the rotor rotates with respect to the stator. The rotor is rotatably connected to the specimen M with respect to the specimen M via an intermediate shaft (not shown). As a result, torque can be output from the electric motor 4 to the specimen M by the rotation of the rotor. Since the configuration of the electric motor 4 is the same as the configuration of a general motor, detailed description of the electric motor 4 will be omitted.

The torque detector 5 is provided on an intermediate shaft connecting the electric motor 4 and the specimen M. The torque detector 5 detects the torque output from the electric motor 4. The output value of the torque detected by the torque detector 5 is input to the control device 2 as an input value of the feedback loop 10. That is, the output value of the torque detector 5 is used for feedback control. Since the configuration of the torque detector 5 is the same as the conventional configuration, detailed description of the torque detector 5 will be omitted.

In the test device 1 having the above-described configuration, mechanical resonance (simply referred to as resonance) occurs when the electric motor 4 rotates due to the rigidity of the shaft system including the electric motor 4, the torque detector 5, and the specimen M. In the test of the test piece M, when the resonance occurs within the frequency measurement range, the torque detector 5 detects the torque (for example, shaft torque) obtained by adding the vibration component of the resonance to the output torque of the electric motor 4. To torque. Therefore, it is desired to remove the vibration component of the resonance. Further, when a disturbance is applied to the shaft system, the value of the shaft torque detected by the torque detector 5 tends to fluctuate greatly.

On the other hand, in the present embodiment, as shown in FIG. 2, the control device 2 has a feedback loop 10 that feeds back the output value of the torque detector 5 to the motor torque command r which is an input command. That is, the test device 1 of the present embodiment controls the drive of the electric motor 4 by a control system including the control device 2, the motor drive circuit 3, the electric motor 4, and the torque detector 5 and not including the specimen M.

In FIG. 2, r is a target value as a motor torque command, y is an output value of the torque detector 5, d is a disturbance, K _D is a differential coefficient, and s is a differential element. , Fd1 and Fd2 are transfer functions of the filter 52.

Further, the reference numeral P in FIG. 2 is a control target, and in the present embodiment, the control target P includes a motor drive circuit 3, an electric motor 4, and a torque detector 5. The controlled object P also includes a range from the electric motor 4 to the torque detector 5 in the intermediate shaft connecting the electric motor 4 and the specimen M.

The feedback loop 10 is a differential feedback system including the differential element s. The output value of the torque detector 5 is input to the feedback loop 10. The feedback loop 10 has an attenuation ratio adjusting unit 51 (differentiator) and a filter 52 (wasted time compensating device). The damping ratio adjusting unit 51 adjusts the damping ratio with respect to the controlled object by the differential element s and the differential coefficient _KD . The filter 52 has a vibration mode extraction unit 52a that extracts a part of each vibration mode of resonance of the controlled object P, and a waste time compensation unit 52b that eliminates the influence of wasted time. In the feedback loop 10, the output value of the torque detector 5 is processed by the filter 52 and the damping ratio adjusting unit 51, and then negatively fed back to the motor torque command r as a feedback value.

In this embodiment, a case where the controlled object P has a secondary vibration mode will be described. That is, in the following description, the controlled object P is represented by P = P1 and P2 using the controlled object P1 involved in the primary vibration mode and the controlled object P2 involved in the secondary vibration mode. The vibration mode of the controlled object P may be third or higher.

The transfer function of the controlled object P that causes resonance can be approximated by a second-order lag standard type transfer function as in Eq. (1) using the natural frequency ω _n and the damping ratio ζ.

Here, K is the gain of the vibration mode. Further, in each symbol, when the subscript is "1", it means a value related to the primary vibration mode, and when the subscript is "2", it means a value related to the secondary vibration mode. do.

In the feedback loop 10, a predetermined vibration mode for which resonance is desired to be suppressed is extracted by the filter 52, and then a signal subjected to differential processing and coefficient calculation ( _KD · s) is negatively fed back to the motor torque command r. It is possible to suppress vibration only in the predetermined vibration mode.

Specifically, when it is desired to suppress the vibration of the primary vibration mode generated in the controlled object P1, P · F _d1 = P1 is substituted into the equation (1), and the filter 52 is as shown in the equation (2). The transfer function F _d1 in the vibration mode extraction unit 52a of the above is represented by an inverse function of the quadratic vibration mode generated in the controlled object P2.

By using the transfer function F _d1 in the vibration mode extraction unit 52a of the filter 52 obtained from the above equation (2), only the primary vibration mode generated in the controlled object P1 is extracted by the filter 52. As a result, the frequency characteristic between the input side and the output side in the feedback loop 10 is expressed by the equation (3).

As shown in the above equation (3), the frequency characteristic is expressed in the form of a product of a rational function representing the frequency characteristic of the first-order vibration mode and a rational function representing the frequency characteristic of the second-order vibration mode. .. Therefore, the adjustment term of the damping ratio ζ ₁ is included only in the primary vibration mode.

That is, after removing the vibration mode other than the primary vibration mode (secondary vibration mode in this embodiment) by the vibration mode extraction unit 52a of the filter 52, the differential processing and the coefficient calculation can be performed. As a result, even for the controlled object P (= P1 and P2) having a plurality of vibration modes, only the predetermined resonance mode (primary vibration mode) is extracted by the vibration mode extraction unit 52a of the filter 52, and the vibration mode is extracted. The damping ratio related to the primary vibration mode can be adjusted. Therefore, the effect of suppressing resonance can be obtained with respect to the primary vibration mode.

Even when the effect of resonance suppression is obtained for the secondary vibration mode of the controlled object P, the vibration mode extraction unit 52a of the filter 52 is obtained by substituting P · Fd ₂ = P2 into the above equation (1). It suffices to obtain the transfer function F _d2 in. Further, when implementing the above-mentioned control in a control device or the like, a low-pass filter that does not affect the control band is added to the denominator so that F _d1 and F _d2 become proper functions.

By the way, when the control target P is controlled by the test device 1, the torque input to the test piece M is delayed with respect to the motor torque command r due to the sampling cycle and communication of the control device 2. Such a delay is so-called wasted time and affects the control of the controlled target P.

In particular, in the case of the controlled object P that causes resonance as in the present embodiment, if the above-mentioned wasted time exists when the controlled object P is controlled, the resonance generated in the controlled object P may not be sufficiently suppressed.

FIG. 3 shows a Bode diagram when the differential feedback control is not performed and when the above-mentioned resonance suppression control is performed. In FIG. 3, the upper figure is a Bode diagram showing the gain characteristics, and the lower figure is a Bode diagram showing the phase characteristics. In the Bode diagram of FIG. 3, the waveform when the differential feedback control is not performed (“without differential FB” in FIG. 3) is shown by a alternate long and short dash line, and when the above-mentioned resonance suppression control is performed (“with differential FB” in FIG. 3). The waveform of ") is shown by a broken line.

As shown in FIG. 3, when the differential feedback control is not performed, the vibration becomes large due to resonance at a predetermined frequency. Further, even when the resonance suppression control described above is performed, the peak is smaller than that when the differential feedback control is not performed, but the vibration becomes large due to the resonance.

On the other hand, in the present embodiment, the wasted time is taken into consideration in the transfer function F _d2 of the wasted time compensating unit 52b of the filter 52. In general, the Padé approximation is widely known as a method for approximating the wasted time to a rational function. The equation expressing the wasted time by the Padé approximation is shown in equation (4). By using this Padé approximation, the wasted time can be considered by the transfer function F _d2 of the wasted time compensating unit 52b of the filter 52.

Here, L is wasted time.

The present inventor has come up with the idea of using the reciprocal of the Padé approximation of the wasted time expressed by the above equation (4) in order to consider the wasted time in the transfer function F _d2 of the wasted time compensating unit 52b of the filter 52. .. However, if the above equation (4) is simply reciprocal, s becomes positive when the denominator = 0, as in the equation (4)', so that the value diverges with the passage of time. That is, the denominator of the reciprocal is an unstable element in control, and the control target P cannot be controlled using the feedback loop.

On the other hand, as a result of diligent studies, the present inventor replaced the denominator with the transfer function of the low-pass filter (1 + Ts: T is a time constant) in the above equation (4)'as in equation (5). I came up with the idea that differential feedback control that takes into account wasted time is possible without diverging the values.

That is, by using the reciprocal of the Padé approximation of the wasted time, it is possible to prevent the control from diverging by replacing the denominator of the reciprocal with the transfer function of the low-pass filter while considering the wasted time in the differential feedback control. As a result, in the differential feedback control, it is possible to achieve both control in consideration of wasted time and control that does not diverge even if the padé approximation of wasted time is used.

In the Bode diagram of FIG. 3, a case where waste time is taken into consideration (“this embodiment” in FIG. 3) is shown by a solid line. As shown in FIG. 3, when the wasted time is taken into consideration, it is compared with the case where the differential feedback control is not performed (the alternate long and short dash line in FIG. 3) and the case where only the resonance suppression control described above is performed (the broken line in FIG. 3). Therefore, vibration due to resonance can be suppressed.

FIG. 4 shows the step response. In FIG. 4, the case where the waste time is taken into consideration (“the present embodiment” in FIG. 4) is shown by a solid line, and the case where only the resonance suppression control described above is performed without considering the waste time (“differential FB” in FIG. 4). Yes ") is indicated by a broken line. As shown in FIG. 4, when the wasted time is taken into consideration, the vibration converges faster than when the wasted time is not taken into consideration.

Therefore, by considering the wasted time in the differential feedback control as described above, the resonance can be suppressed quickly and easily.

(Other embodiments)
Although the embodiment of the present invention has been described above, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the embodiment is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented within a range that does not deviate from the gist thereof.

In the embodiment, the filter 52 has a vibration mode extraction unit 52a that extracts a part of the vibration modes of each vibration mode of the controlled object P, and a waste time compensation unit 52b that eliminates the influence of wasted time. However, the filter may have only the wasted time compensating section 52b. Further, the vibration mode extraction unit 52a and the waste time compensation unit 52b may be configured by different filters.

In the above embodiment, the wasted time is considered by the transfer function F _d2 of the wasted time compensating unit 52b of the filter 52 in the differential feedback control. However, the waste time may be considered by the transfer function of the filter as in the above-described embodiment for the control other than the differential feedback control and in which the waste time affects the control. Further, the configuration of the embodiment can be applied to other than the case of suppressing the resonance of the controlled object.

For example, control in consideration of wasted time as in the above embodiment may be applied to feedforward control. That is, even if the transfer function in which the denominator is replaced with the transfer function of the low-pass filter in the reciprocal of the Padé approximation of the wasted time is used when the command to the controlled object is generated by the feed forward, the instruction considering the wasted time is generated. good.

In the embodiment, the controlled object P includes a motor drive circuit 3, an electric motor 4, and a torque detector 5. However, the controlled object may include other configurations or may include an axis system having other configurations.

In the above embodiment, the first-order Padé approximation of the wasted time has been described, but depending on the wasted time (phase shift), the second-order or higher Padé approximation may be used. Further, for a plurality of vibration modes, the waste time may be considered by using the Padé approximation.

INDUSTRIAL APPLICABILITY The present invention can be used as a wasted time compensating device that compensates for the wasted time for a controlled object having wasted time.

1 Test device 2 Control device 3 Motor drive circuit 4 Electric motor 5 Torque detector 10 Feedback loop (resonance suppression device)
51 Attenuation ratio adjustment unit (differentiator)
52 filter (waste time compensation device)
52a Vibration mode extraction unit 52b Wasted time compensation unit P, P1, P2 Control target

Claims (4)

A wasted time compensating device that compensates for the wasted time for a controlled object having wasted time.
By modeling the waste time, an input command for the control target is provided with a waste time compensation unit that considers the waste time.
The wasted time compensating unit is a wasted time compensating device having a transfer function whose denominator is replaced with a transfer function of a low-pass filter in the reciprocal of the Padé approximation of the wasted time. In the wasted time compensating device according to claim 1,
Further provided with a feedback loop for negatively feeding back the output value of the controlled object to the input command is provided.
The wasted time compensating unit is a wasted time compensating device provided in the feedback loop. In the wasted time compensating device according to claim 2,
The wasted time compensating unit is a wasted time compensating device that considers the wasted time in the input value to the differentiator in the feedback loop. It is a resonance suppression control device that suppresses the resonance of a multi-inertial resonance system equipped with a feedback loop that negatively feeds back the output value of the controlled object with wasted time to the input command.
The wasted time compensating device according to any one of claims 1 to 3, which is provided in the feedback loop.
A damping ratio adjusting unit provided in the feedback loop to adjust the damping ratio of vibration,
A resonance suppression control device.

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