Control device, motor, actuator, control method and program

Abstract

To suppress responsiveness reduction of an actual current value with respect to a current command value.SOLUTION: A control device comprises: a voltage control section which calculates a voltage command value on the basis of a differential value between a current command value and an actual current value; a counter electromotive force compensation section for imparting a compensation amount, which compensates influences of a counter electromotive force of a motor, to the voltage command value; and a filter section which causes a low-pass filter corresponding to acceleration of the motor to act upon the compensation amount.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device, a motor, an actuator, a control method, and a program. [Background technology]

[0002] When a motor rotates, a back electromotive force is generated, and this back electromotive force acts as a disturbance and enters the motor control feedback loop. The role of the control device that controls the motor is to pass an actual current to the motor according to a current command value, but the motor control is disrupted by the disturbance of the back electromotive force. For this reason, for example, Patent Document 1 proposes a control device having a function for suppressing the influence of disturbances caused by back electromotive voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-141691 Summary of the Invention [Problem to be solved by the invention]

[0004] In the back electromotive force compensation, a low-pass filter is sometimes used to suppress detection noise of the rotation angle. However, the phase delay of the low-pass filter reduces the responsiveness of the actual current value to the current command value. Therefore, an object of the present invention is to suppress the decrease in responsiveness caused by the low-pass filter. [Means for solving the problem]

[0005] In order to solve the above problem, one aspect of a control device according to the present invention includes a voltage control unit that calculates a voltage command value based on a difference value between a current command value and an actual current value, a back electromotive force compensation unit that imparts a compensation amount that compensates for the effect of the back electromotive force of the motor to the voltage command value, and a filter unit that applies a low-pass filter corresponding to the acceleration of the motor to the compensation amount.

[0006] According to such a control device, the effect of the phase delay caused by the low-pass filter is reduced by the low-pass filter according to the acceleration, so that a decrease in the responsiveness of the actual current value to the current command value is suppressed. In the above control device, it is preferable that the filter unit changes the cutoff frequency of the low-pass filter according to the acceleration of the motor, and at a second acceleration smaller than the first acceleration, uses a second cutoff frequency higher than the first cutoff frequency at the first acceleration.

[0007] According to such a control device, the low-pass filter operates in response to the pseudo high acceleration that accompanies the detection noise of the rotation angle, so that the noise can be suppressed. In order to solve the above problem, one aspect of a motor device according to the present invention includes the above control device, a voltage output device that outputs a voltage in accordance with the voltage command value, and the motor driven by the voltage of the voltage output device.

[0008] According to such a motor device, the decrease in the responsiveness of the actual current value to the current command value is suppressed, and therefore the responsiveness of the motor output to the command is improved. In order to solve the above problem, one aspect of the actuator of the present invention includes the above control device, a voltage output device that outputs a voltage according to the voltage command value, the motor driven by the voltage of the voltage output device, and a drive mechanism driven by the motor to output an external force.

[0009] According to such an actuator, a decrease in the responsiveness of the actual current value to the current command value is suppressed, and therefore the responsiveness of the actuator operation to a command is improved. In order to solve the above problem, one aspect of a control method according to the present invention includes a voltage control step of calculating a voltage command value based on a difference value between a current command value and an actual current value, a back electromotive force compensation step of applying a compensation amount for compensating for an effect of the back electromotive force of the motor to the voltage command value, and a filtering step of applying a low-pass filter corresponding to the acceleration of the motor to the compensation amount.

[0010] According to this control method, the effect of the phase delay caused by the low-pass filter is reduced by the low-pass filter according to the acceleration, so that a decrease in the responsiveness of the actual current value to the current command value is suppressed. In order to solve the above problems, one aspect of the program according to the present invention causes an information processing device to operate as each component of the control device. With such a program, the control device can be easily realized by the information processing device. Effect of the Invention

[0011] According to the present invention, it is possible to suppress the decrease in responsiveness caused by the low-pass filter. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram showing an embodiment of an actuator of the present invention. [Diagram 2] FIG. 2 is a functional block diagram showing an example of a functional configuration of a motor control unit. [Diagram 3] FIG. 1 is a diagram illustrating a configuration of a back electromotive force compensation unit. [Figure 4] FIG. 2 is a schematic diagram showing frequency characteristics of a low-pass filter. [Diagram 5] FIG. 2 is a schematic diagram showing a first example of a method for changing a cutoff frequency. [Figure 6] FIG. 11 is a schematic diagram showing a second example of a method for changing a cutoff frequency. [Figure 7] FIG. 11 is a schematic diagram showing a third example of a method for changing a cutoff frequency. [Figure 8] FIG. 11 is a schematic diagram showing a fourth example of a method for changing a cutoff frequency. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, in order to avoid the following description becoming unnecessarily redundant and to facilitate understanding by those skilled in the art, more detailed description than necessary may be omitted. For example, detailed description of already well-known matters and duplicated description of substantially the same configuration may be omitted. In addition, elements shown in the previously described figures may be appropriately referenced in the description of the later figures.

[0014] FIG. 1 is a schematic diagram showing an embodiment of an actuator of the present invention. The electric actuator 100 corresponds to one embodiment of the actuator of the present invention, and is incorporated in a vibration control device or the like to generate thrust. The electric actuator 100 includes a drive unit 110 and a control unit 120 .

[0015] The drive unit 110 outputs a thrust force based on the control of the control unit 120 . The control unit 120 performs control based on commands received from a host device 200, such as a computer, connected to the electric actuator 100. The host device 200 may give commands to multiple electric actuators 100.

[0016] The drive unit 110 includes a motor 111, a rotational position sensor 112, a reducer 113, a linear motion mechanism 114, a connecting mechanism 115, and an output shaft . The motor 111 is, for example, a three-phase motor, and is driven to rotate by a current supplied from the control unit 120 .

[0017] The rotational position sensor 112 is, for example, an encoder or a resolver, which detects the rotational position associated with the rotation of the motor 111 and transmits a detection signal to the control unit 120 . The reducer 113 transmits the torque of the motor 111 to the linear motion mechanism 114 while reducing the number of rotations using a plurality of gears.

[0018] The linear motion mechanism 114 rotates by receiving the rotational force transmitted by the reducer 113, and the connecting mechanism 115 moves linearly in the axial direction (the direction indicated by the arrow A in FIG. 1) of the linear motion mechanism 114 in accordance with the rotation of the linear motion mechanism 114. The linear motion mechanism 114 and the connecting mechanism 115 are formed by, for example, a ball screw.

[0019] The output shaft 116 is coupled to the linear motion mechanism 114 by being coupled with the connecting mechanism 115. The output shaft 116 also moves linearly in accordance with the linear movement of the connecting mechanism 115 to output thrust. The linear motion mechanism 114, the connecting mechanism 115, and the output shaft 116 together correspond to an example of the drive mechanism according to the present invention. The control unit 120 includes a motor control unit 121, a power supply 122, an inverter 124, and a current sensor 125. The motor control unit 121 corresponds to one embodiment of the control device of the present invention. The inverter 124 and the power supply 122 together correspond to one example of the voltage output device of the present invention. The control unit 120 and the motor 111 are realized, for example, in a mechanically and electrically integrated structure, and constitute one embodiment of the motor device of the present invention.

[0020] The motor control unit 121 receives a thrust command from the higher-level device 200 and operates the inverter 124 so that a current equal to a target current corresponding to the thrust command is supplied to the motor 111. Hereinafter, the current supplied to the motor 111 is referred to as an "actual current" to distinguish it from the target current.

[0021] The inverter 124 has a PWM (Pulse Width Modulation) control function, converts the power supplied from the power supply 122 into an actual current for operating the motor 111, and supplies the actual current to the motor 111. The current sensor 125 detects the actual current supplied from the inverter 124 to the motor 111 and inputs the detected value to the motor control unit 121 .

[0022] FIG. 2 is a functional block diagram showing an example of the functional configuration of the motor control unit 121. As an example, the motor control unit 121 performs vector control of the motor 111. The functions of the motor control unit 121 are realized, for example, by an information processing device such as an embedded computer executing an embodiment of the program of the present invention. The functional block diagram of Fig. 2 shows an example of the functional configuration of the motor control unit 121, and also shows an example of the program configuration in an embodiment of the program of the present invention.

[0023] The motor control unit 121 includes a unit conversion unit 41, a dead zone processing unit 42, PI (Proportional Integral) control units 43, 44, a two-phase / three-phase conversion unit 45, a duty conversion unit 46, an angle derivation unit 47, a three-phase / two-phase conversion unit 48, a dead time compensation unit 49, a rotation speed calculation unit 51, and a back electromotive force compensation unit 52.

[0024] The unit conversion unit 41 receives a thrust command input from the higher-level device 200 and converts the thrust command from units of thrust to units of current. The thrust command is a command that indicates the thrust of the electric actuator 100, and essentially indicates a target current for the motor 111. The unit conversion unit 41 converts the thrust command into a q-axis current command value iq * For the d-axis, the current command value id * For example, "0" is set as the value.

[0025] The dead zone processing unit 42 detects a current command value iq that is smaller than a threshold value. * By forming a dead zone of output "0" against the input, the operation of the motor 111 at the time of small thrust is stabilized. On the other hand, the actual currents iu, iv, and iw flowing through each phase of the motor 111 are detected by the current sensors 125 provided for each phase, and the detected values ​​of the actual currents iu, iv, and iw are converted into actual current values ​​iq and id of the dq2 axes by the 3-phase / 2-phase conversion unit 48. The converted actual current values ​​iq and id are fed back to obtain the current command value iq of the dq2 axes. * , id * The difference value between them is calculated.

[0026] The angle derivation unit 47 derives the rotation angle θ of the motor 111 based on the detection signal input from the rotation position sensor 112. The three-phase / two-phase conversion unit 48 receives the rotation angle θ from the angle derivation unit 47 and uses it for advance angle control. The q-axis PI control unit 43 and the d-axis PI control unit 44 respectively receive actual current values ​​iq, id and current command values ​​iq * , id * The difference between the current command value iq and the voltage command value Vq, Vd is calculated so that the difference between the current command value iq and the voltage command value Vd is 0. * , id * 4 indicates a voltage for causing an actual current equal to the target current indicated by the reference symbol to flow through the motor 111. The PI control units 43 and 44 correspond to an example of the voltage control unit referred to in the present invention.

[0027] A two-phase / three-phase converter 45 converts the voltage command values ​​Vq, Vd of the dq two axes into three-phase voltage command values ​​Vu, Vv, Vw. The duty conversion unit 46 converts the voltage command values ​​Vu, Vv, Vw of each phase into duties for PWM control, based on the voltage value V0 of the power source 122 of the inverter 124, and inputs them to the inverter 124. As a result, the inverter 124 outputs voltages according to the voltage command values ​​Vu, Vv, Vw, and the motor 111 is driven by the voltage output from the inverter 124. The motor 111 is driven by a current command value iq * , id * The actual currents iu, iv, and iw corresponding to the target currents indicated by are supplied from the inverter 124. The inverter 124 corresponds to an example of the voltage output device referred to in the present invention.

[0028] The dead time compensating unit 49 calculates a dead time compensation value for each of the three phases that compensates for the dead time of the inverter 124, and assigns the dead time compensation value to the duty of the three phases. In addition, the dead time compensating unit 49 receives the motor angle θ from the angle derivation unit 47 via a path not shown in the figure, and uses it to calculate the advance angle amount.

[0029] The rotation speed calculation unit 51 differentiates the motor angle θ obtained by the angle derivation unit 47 to calculate the rotation speed of the motor 111 . The back electromotive force compensation unit 52 calculates a compensation amount for compensating for the effect of the back electromotive force generated in the motor 111, and applies (adds) it to the voltage command value Vq. The back electromotive force compensation unit 52 corresponds to an example of the back electromotive force compensation unit referred to in the present invention. In the motor 111, a back electromotive force is generated by rotation, and the back electromotive force affects motor control via feedback to the motor control unit 121 and reverse power flow to the inverter 124. For this reason, the back electromotive force compensation unit 52 calculates a compensation amount for compensating for the estimated effect.

[0030] FIG. 3 is a diagram showing the configuration of the back electromotive force compensation unit 52. As shown in FIG. The back electromotive force compensation section 52 includes a back electromotive force coefficient calculation section 61 , a low pass filter 62 , and a differential calculation section 63 . The counter electromotive force coefficient calculation unit 61 calculates the amount of compensation for compensating for the influence of the counter electromotive force by multiplying the rotation speed of the motor 111 input from the rotation speed calculation unit 51 by a predetermined counter electromotive force coefficient.

[0031] The low-pass filter 62 corresponds to an example of the filter unit referred to in the present invention, and acts on the compensation amount output from the back electromotive force coefficient calculation unit 61 to suppress the influence of noise. The cut-off frequency of the low-pass filter 62 is variable, and the cut-off frequency is changed according to the acceleration of the motor 111 calculated by the differentiation of the rotation speed by the differentiation calculation unit 63. That is, when the acceleration is small, the cut-off frequency is changed to a higher frequency than when the acceleration is large. The motor control unit 121 shown in Fig. 2 and the back electromotive force compensation unit 52 shown in Fig. 3 may be configured by dedicated hardware, but in this embodiment, they are realized by executing a program on an information processing device such as a board computer. The functional blocks shown in Fig. 3 show a program configuration in one embodiment of the program of the present invention, and also show a control procedure in one embodiment of the control method of the present invention.

[0032] FIG. 4 is a schematic diagram showing frequency characteristics of an actual current value with respect to a command current value. FIG. 4 shows a schematic diagram of a frequency characteristic simulated for an actual current value when the cutoff frequency of the low-pass filter 62 is changed. The horizontal axis of FIG. 4 indicates frequency, and the vertical axis indicates amplitude. The frequency characteristics when the cutoff frequency of the low-pass filter 62 is 200 Hz are shown by a solid line, the frequency characteristics at 150 Hz are shown by a dashed line, and the frequency characteristics at 100 Hz are shown by a dashed line. The characteristics in the band from 3 Hz to 100 Hz approach an amplitude of 0 dB as the cutoff frequency of the low-pass filter 62 increases. An amplitude of 0 dB is an ideal characteristic in which the actual current value matches the command current value, and the higher the cutoff frequency of the low-pass filter 62, the closer the frequency characteristics approach the ideal characteristic. On the other hand, if the cutoff frequency of the low-pass filter 62 is low, the characteristics in the band from 3 Hz to 100 Hz deviate from the ideal characteristics, and the actual current value relative to the command current value is suppressed.

[0033] That is, in the back electromotive force compensator 52, when the acceleration is small, the cutoff frequency of the low-pass filter 62 is set high, thereby suppressing the effect of the low-pass filter 62 on the compensation amount. As a result, the phase delay caused by the effect of the low-pass filter 62 is also suppressed, improving the current responsiveness in motor control.

[0034] On the other hand, in the back electromotive force compensation section 52, when the acceleration is large, the cutoff frequency decreases in response to an increase in pseudo acceleration caused by detection noise of the rotation angle, and the low-pass filter 62 effectively acts on the compensation amount to suppress the noise. There are various possible methods for changing the cutoff frequency of the low-pass filter 62 in the back electromotive force compensation unit 52.

[0035] 5 to 8 are schematic diagrams showing specific examples of methods for changing the cutoff frequency. 5 to 8, the horizontal axis represents acceleration, and the vertical axis represents cutoff frequency. As a method for changing the cutoff frequency, for example, as shown in FIG. 5, a method for discretely switching the cutoff frequency according to an acceleration threshold TH can be considered.

[0036] As a method for changing the cutoff frequency, for example, as shown in FIG. 6, a method for switching the cutoff frequency stepwise using a plurality of threshold values ​​TH1 and TH2 may be considered. As a method for changing the cutoff frequency, for example, as shown in FIG. 7, a method for changing the cutoff frequency linearly in response to acceleration can be considered.

[0037] Furthermore, as a method for changing the cutoff frequency, for example, as shown in FIG. 8, a method for changing the cutoff frequency nonlinearly depending on the acceleration can be considered. Regardless of which of the change methods shown in Figs. 5 to 8 is used, the back electromotive force compensator 52 suppresses a decrease in the responsiveness of the actual current value relative to the current command value, and also suppresses noise.

[0038] Although the above description shows an example of application to an electric actuator, the motor device, control device, and control method of the present invention may also be applied to electric power steering, etc. Furthermore, in the above description, a linear actuator is shown as an example of an actuator, but the actuator of the present invention may be a rotary actuator or a curvilinear actuator. [Explanation of symbols]

[0039] 100...electric actuator, 110...drive unit, 111...motor, 112...rotational position sensor, 113...reduction gear, 114...linear motion mechanism, 115...coupling mechanism, 116...output shaft, 120...control unit, 121...motor control unit, 122...power supply, 124...inverter, 125...current sensor, 41...unit conversion unit, 42...dead band processing unit, 43, 44...PI control unit, 45...2-phase / 3-phase conversion unit, 46...Duty conversion unit, 47...angle derivation unit, 48...3-phase / 2-phase conversion unit, 49...dead time compensation unit, 51...rotation speed calculation unit, 52...back electromotive force compensation unit, 61...back electromotive force coefficient calculation unit, 62...low-pass filter, 63...differential calculation unit

Claims

1. a voltage control unit that calculates a voltage command value based on a difference value between a current command value and an actual current value; a back electromotive force compensator that imparts a compensation amount for compensating for an effect of a back electromotive force of a motor to the voltage command value; a filter unit that applies a low-pass filter corresponding to the acceleration of the motor to the compensation amount; A control device comprising:

2. 2. The control device according to claim 1, wherein the filter unit changes a cutoff frequency of the low-pass filter in accordance with an acceleration of the motor, and at a second acceleration smaller than a first acceleration, a second cutoff frequency higher than the first cutoff frequency at the first acceleration is used.

3. A control device according to claim 1 or 2; a voltage output device that outputs a voltage according to the voltage command value; the motor driven by the voltage of the voltage output device; A motor device comprising:

4. A control device according to claim 1 or 2; a voltage output device that outputs a voltage according to the voltage command value; the motor driven by the voltage of the voltage output device; a drive mechanism driven by the motor to output an external force; An actuator comprising:

5. a voltage control step of calculating a voltage command value based on a difference value between a current command value and an actual current value; a back electromotive force compensation step of adding a compensation amount for compensating for an effect of a back electromotive force of a motor to the voltage command value; a filtering step of applying a low-pass filter corresponding to the acceleration of the motor to the compensation amount; The control method includes:

6. A program for causing an information processing device to operate as each component of the control device according to claim 1 or 2.

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