Motor controller and electric actuator

Abstract

To realize means for dealing with a reverse electromotive voltage with a simple configuration.SOLUTION: A motor controller according to an embodiment includes: a supply unit for supplying an actual current to a motor on the basis of a differential value between a current target value and a detected value of the actual current; and an interruption part which interrupts the actual current between the supply unit and the motor in a case where the current target value is closer to zero as predetermined.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, there is known a motor control device that performs feedback control of the current supplied to a motor. When the motor to be controlled is a motor that drives an electric actuator such as a vibration damper or an electric power steering, the motor is rotated by an external force applied to the electric actuator from the outside, generating a back electromotive force, and the current associated with the back electromotive force affects the feedback control.

[0003] In particular, when the target value of the supply current is close to zero, a control loop occurs in which the motor control device passes current to the motor, even though the target value does not generate thrust in the electric actuator. For this reason, electric actuators have been proposed that incorporate back electromotive force compensation (EMF compensation) into their control.

[0004] For example, Patent Document 1 proposes a technique for dealing with the generation of unintended current due to reverse operation in electric power steering by using back electromotive force compensation (EMF compensation). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5012258 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology of Patent Document 1 is a software-based solution, which requires tuning for back electromotive force compensation and complicates the control logic, increasing the processing load on the motor control device. Therefore, a solution to the back electromotive force with a simpler configuration is desired. Therefore, an object of the present invention is to realize a countermeasure against the back electromotive force with a simple configuration. [Means for solving the problem]

[0007] In order to solve the above problem, one aspect of a motor control device according to the present invention includes a supply unit that supplies an actual current to a motor based on a difference value between a current target value and a detected value of the actual current, and a cut-off unit that cuts off the actual current between the supply unit and the motor when the current target value is close to zero to a predetermined extent.

[0008] According to such a motor control device, the influence of the back electromotive force on the feedback control can be prevented by a simple configuration provided with a cutoff section. In the motor control device, it is preferable that the cutoff unit switches the actual current on and off. Since the on-off switching is a simple operation, the control and configuration of the cutoff unit are simpler.

[0009] In the motor control device, it is preferable that the cutoff unit cuts off the actual current by a relay switch or a MOSFET. A relay switch and a MOSFET are themselves simple elements, and are highly reliable and durable. It is also preferable that the motor control device further comprises an input unit that receives an input of the current target value. By providing the input unit, the motor control device can be applied to various applications requiring control of motor output.

[0010] In order to solve the above problems, an electric actuator according to the present invention includes the motor control device, the motor, and a drive mechanism driven by the motor to output an external force. With such an electric actuator, a countermeasure against the back electromotive force is realized by the motor control device having a simple configuration, so that the electric actuator can operate with high precision without being affected by the external force. Effect of the Invention

[0011] According to the present invention, a countermeasure against the back electromotive force can be realized with a simple configuration. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram showing one embodiment of an electric 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 an example of an interrupter circuit. [Figure 4] FIG. 13 is a diagram illustrating another example of an interrupter circuit. [Diagram 5] 4A and 4B are diagrams illustrating the operation of an interrupter circuit. 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 the configuration of an electric actuator according to one embodiment of the present invention. The electric actuator 100 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 device 120. The control device 120 corresponds to one embodiment of the motor control device of the present invention, and the drive unit 110 corresponds to one example of the drive mechanism referred to in the present invention.

[0015] The drive unit 110 outputs thrust under the control of the control device 120 . The control device 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 device 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 device 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 joined with the connecting mechanism 115. As the connecting mechanism 115 moves linearly, the output shaft 116 also moves linearly to output thrust. The control device 120 includes a motor control unit 121, an inverter 122, a power supply 123, an interruption circuit 124, a current sensor 125, and an angle derivation unit 126. The combination of the motor control unit 121, the inverter 122, and the power supply 123 corresponds to an example of the supply unit referred to in the present invention, and the interruption circuit 124 corresponds to an example of the interrupter referred to in the present invention.

[0020] The motor control unit 121 receives a thrust command from the higher-level device 200 and operates the inverter 122 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 122 converts the power supplied from the power source 123 into an actual current for operating the motor 111 and supplies the actual current to the motor 111 . When the target current is close to zero, the cutoff circuit 124 cuts off the actual current supplied from the inverter 122 to the motor 111 .

[0022] The current sensor 125 detects the actual current supplied from the inverter 122 to the motor 111 and inputs the detected value to the motor control unit 121 . The angle derivation unit 126 derives the rotation angle of the motor 111 based on the detection signal input from the rotation position sensor 112 , and inputs it to the motor control unit 121 .

[0023] FIG. 2 is a functional block diagram showing an example of the functional configuration of the motor control unit 121. The motor control unit 121 includes a low pass filter (LPF) 41, a limiter / unit conversion unit 42, a q-axis PI (Proportional Integral) control unit 43, a d-axis PI control unit 44, a two-phase / three-phase conversion unit 45, a PWM (Pulse Width Modulation) control unit 46, and a three-phase / two-phase conversion unit 47. 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 a processor of an embedded computer executing a computer program stored in a storage device.

[0024] The low-pass filter 41 is an example of an input unit that receives a thrust command input from the higher-level device 200, and removes noise from the thrust command. 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 limiter / unit converter 42 limits the upper limit of the thrust for the thrust command and converts the thrust unit into the current unit. The limiter / unit converter 42 outputs a q-axis current command value iq * is output. Current command value iq *indicates the target current. Furthermore, when the thrust command falls below the lower limit of the thrust, the limiter / unit conversion unit 42 outputs an instruction signal to the interrupter circuit 124 to interrupt the actual current.

[0025] d-axis current command value id * For the q-axis current command value iq * and the rotation angle θ of the motor 111 by a calculation unit (not shown). 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 47. 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 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 * 1 indicates a voltage for causing the motor 111 to flow with an actual current equal to the target current indicated by .

[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 PWM control unit 46 generates PWM-controlled gate signals based on the three-phase voltage command values ​​Vu, Vv, and Vw, and inputs the gate signals to the inverter 122. The inverter 122 is driven by the gate signals generated by the PWM control unit 46, and applies voltages indicated by the three-phase voltage command values ​​Vu, Vv, and Vw to each phase of the motor 111. As a result, the motor 111 is supplied with a current command value iq * , id * The actual currents iu, iv, and iw corresponding to the target currents indicated by are supplied.

[0028] The rotation angle θ of the motor 111 derived by the angle derivation unit 126 based on the detection signal of the rotational position sensor 112 is input to, for example, the two-phase / three-phase conversion unit 45 and the three-phase / two-phase conversion unit 47, and used for, for example, advance angle control. Note that, in the control device 120, the rotation angular velocity ω is calculated based on a change in the motor angle θ, and may be used for controlling the motor 111 together with the rotation angle θ or instead of the rotation angle θ.

[0029] 1, when an external force is applied to the output shaft 116, the external force is transmitted to the motor 111. The external force causes the motor 111 to rotate, generating a back electromotive force. Detection values ​​of actual currents iu, iv, and iw generated by the back electromotive force of the motor 111 are fed back to the motor control unit 121.

[0030] In particular, when the thrust command is close to zero, the feedback of the actual currents iu, iv, iw associated with the back electromotive force generates voltage command values ​​Vu, Vv, Vw for driving the motor 111, and even though the thrust command is close to zero, the inverter 122 generates a voltage for driving the motor 111. For this reason, the control device 120 of this embodiment is provided with a cutoff circuit 124, and when the thrust command is close to zero, the cutoff circuit 124 cuts off the actual currents iu, iv, iw.

[0031] As a result, the actual currents iu, iv, iw between the inverter 122 and the motor 111, including those associated with the back electromotive force, become zero, so that the output of the motor 111 becomes zero and unnecessary feedback of the current detection value also stops. Note that the blocking of the actual currents iu, iv, iw is not limited to the case where the actual currents iu, iv, iw are made completely zero, but also includes the case where the actual currents iu, iv, iw cannot be detected by the current sensor 125 or the actual currents iu, iv, iw are suppressed to such an extent that the feedback of the detection value becomes substantially zero.

[0032] FIG. 3 is a diagram illustrating an example of interrupter circuit 124. As shown in FIG. 3 includes a MOSFET 51 for each phase of the motor 111, and cuts off the actual current by the MOSFET 51. The cutoff circuit 124 using the MOSFET 51 has a simple configuration and can quickly cut off the actual current with a small electric signal.

[0033] FIG. 4 is a diagram showing another example of interrupter circuit 124. In FIG. 4 includes a relay switch 52 for each phase of the motor 111, and cuts off the actual current by the relay switch 52. The cutoff circuit 124 using the relay switch 52 has a simple configuration and can reliably cut off the actual current.

[0034] FIG. 5 is a diagram illustrating the operation of interrupter circuit 124. As shown in FIG. The horizontal axis of Fig. 5 is the current command value iq * 5 shows the on / off state of the interrupter circuit 124 and the current command value iq * The corresponding relationship is shown. The interrupter circuit 124 is normally in an ON state in which an actual current flows. * is near zero (i.e., within a range of −Δi or more and +Δi or less), the interrupter circuit 124 is in an OFF state to interrupt the real current. By the interrupter circuit 124 switching the real current on and off, the control is simplified and the calculation load on the control device 120 is reduced.

[0035] Although the above description shows an example of application of an electric actuator to a vibration damping device, the motor control device and electric actuator of the present invention may also be applied to electric power steering and the like. In addition, in the above description, a linear actuator is shown as an example of the electric actuator, but the electric actuator of the present invention may be a rotary actuator or a curvilinear drive actuator. [Explanation of symbols]

[0036] 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 device, 121...motor control unit, 41...low-pass filter, 42...limiter / unit conversion unit, 43, 44...PI control unit, 45...2-phase / 3-phase conversion unit, 46...PWM control unit, 47...3-phase / 2-phase conversion unit, 122...inverter, 123...power supply, 124...interrupter circuit, 125...current sensor, 126...angle derivation unit, 200...host device

Claims

1. a supply unit that supplies an actual current to the motor based on a difference between a current target value and a detected value of the actual current; a cutoff unit that cuts off the actual current between the supply unit and the motor when the current target value is close to zero to a predetermined extent; A motor control device comprising:

2. The motor control device according to claim 1 , wherein the cutoff unit switches the actual current on and off.

3. 2. The motor control device according to claim 1, wherein the cutoff unit cuts off the actual current with a relay switch or a MOSFET.

4. The motor control device according to claim 1 , further comprising an input unit for receiving an input of the current target value.

5. A motor control device according to any one of claims 1 to 4, The motor; a drive mechanism driven by the motor to output an external force; An electric actuator comprising:

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