Motor drive device, precharge method and program

Abstract

A motor drive device and the like that can reduce the number of precharge circuits is provided. [Solution] The motor includes a first drive circuit and a second drive circuit connected to the first winding and the second winding, respectively, which are made redundant with each other; a ripple absorption capacitor corresponding to the second drive circuit; and a control unit that applies high-frequency current to the first winding via the first drive circuit. The induced electromotive force generated in the second winding by applying high-frequency current to the first winding is rectified by a parasitic diode provided in the switching element of the second drive circuit, and pre-charges the ripple absorption capacitor.

Description

[Technical Field]

[0001] The present invention relates to a motor drive device, a precharge method, and a program. [Background technology]

[0002] Patent Document 1 discloses a motor drive device that includes multiple inverter circuits that drive a motor having multiple winding sets, each of which is provided with a power supply stabilization capacitor and a precharge circuit that charges it. By providing a precharge circuit, it is possible to suppress inrush current to the power supply stabilization capacitor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6529459 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a precharge circuit for charging a power supply stabilization capacitor is provided for each inverter circuit, the circuit size will increase.

[0005] The present invention has been made to solve the above problems, and has an object to provide a motor drive device or the like that can reduce the number of precharge circuits. [Means for solving the problem]

[0006] In order to solve the above problem, one aspect of the present invention is to a first drive circuit and a second drive circuit connected to a first winding and a second winding of the motor, respectively, which are made redundant with each other; a ripple absorbing capacitor corresponding to the second drive circuit; a control unit that applies high frequency current to the first winding by the first drive circuit; Equipped with The motor drive device provides a motor in which an induced electromotive force generated in the second winding by passing high frequency current through the first winding is rectified by a parasitic diode provided in a switching element of the second drive circuit, thereby precharging the ripple absorption capacitor. [Effects of the Invention]

[0007] According to this invention, the number of precharge circuits can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a motor drive device according to an embodiment of the present invention. [Figure 1A] FIG. 2 is a diagram illustrating the configuration of a control system of the motor drive device of the present embodiment. [Figure 2] FIG. 10 is a diagram showing the configuration of a second driving circuit. [Figure 3] 10 is a flowchart showing a process related to precharge performed by a control unit when starting up the motor drive device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] FIG. 1 is a diagram showing the configuration of a motor drive device of this embodiment, FIG. 1A is a diagram showing the configuration of a control system of the motor drive device of this embodiment, and FIG. 2 is a diagram showing the configuration of a second drive circuit.

[0011] The motor drive device of this embodiment can be used for any purpose, but for example, it can be applied to driving a motor for power steering operation of a vehicle.

[0012] As shown in Figures 1 and 2, the motor drive device of this embodiment includes a first drive circuit 20A and a second drive circuit 20B as mutually redundant inverter circuits, a ripple absorption capacitor 30A corresponding to the first drive circuit 20A, a ripple absorption capacitor 30B corresponding to the second drive circuit 20B, and a control unit 50 (Figure 1A).

[0013] As shown in Fig. 1, the first drive circuit 20A and the second drive circuit 20B are connected to the first winding 10A and the second winding 10B of the motor, respectively, which are made redundant to each other. That is, the same motor is provided with the first winding 10A and the second winding 10B having the same function. In this way, by making both the first drive circuit 20A and the second drive circuit 20B and the first winding 10A and the second winding 10B redundant, a fail-safe function can be provided to the operation of the motor.

[0014] In addition, a switch 60A serving as a power relay is provided between the first drive circuit 20A and the power supply line L, and a switch 60B serving as a power relay is provided between the second drive circuit 20B and the power supply line L.

[0015] Furthermore, a precharge circuit consisting of a resistor 41 and a switch 42 is provided between the ripple absorbing capacitor 30A and the power supply line L.

[0016] 1A, the first drive circuit 20A, the second drive circuit 20B, the switch 42, the switch 60A, and the switch 60B are connected to the control unit 50. The control unit 50 controls the states of the first drive circuit 20A, the second drive circuit 20B, the switch 42, and the switches 60A and 60B. The control unit 50 also receives input of the values ​​of the voltages (pre-charge voltage values) applied to the ripple absorption capacitors 30A and 30B.

[0017] 2, second drive circuit 20B includes a pair of switching elements 21U and 22U corresponding to the U phase, a pair of switching elements 21V and 22V corresponding to the V phase, and a pair of switching elements 21W and 22W corresponding to the W phase. Switching element 21U is connected between a U-phase terminal of second winding 10B and power supply line L, and switching element 22U is connected between a U-phase terminal of second winding 10B and ground. Switching element 21V is connected between a V-phase terminal of second winding 10B and power supply line L, and switching element 22V is connected between a V-phase terminal of second winding 10B and ground. Switching element 21W is connected between a V-phase terminal of second winding 10B and power supply line L, and switching element 22W is connected between a W-phase terminal of second winding 10B and ground.

[0018] The first drive circuit 20A can be configured similarly to the second drive circuit 20B.

[0019] Although FIG. 2 illustrates a MOSFET as an example of a switching element, any type of switching element may be used.

[0020] Next, the operation of the motor drive device of this embodiment will be described.

[0021] Fig. 3 is a flowchart showing a process related to precharging performed by the control unit 50 when the motor drive device is started up. The process shown in Fig. 3 precharges the ripple absorption capacitor 30A and the ripple absorption capacitor 30B. Precharging can suppress inrush currents to the ripple absorption capacitor 30A and the ripple absorption capacitor 30B.

[0022] In step S102 of FIG. 3, the control unit 50 performs initialization. Here, the control unit 50 turns off the switches 60A and 60B. The control unit 50 also turns off the switching elements of the first drive circuit 20A (switching elements corresponding to the switching elements 21U, 21V, and 21W and the switching elements 22U, 22V, and 22W of the second drive circuit 20B). The control unit 50 also turns off the switching elements 21U, 21V, and 21W and the switching elements 22U, 22V, and 22W of the second drive circuit 20B. The control unit 50 also turns off the switch 42.

[0023] In step S104, the control unit 50 turns on the switch 42.

[0024] In step S106, the control unit 50 determines whether the ripple absorption capacitor 30A has been precharged to a predetermined precharge voltage (target voltage), and proceeds to step S108 after waiting for a positive determination. Note that the precharging of the ripple absorption capacitor 30A may be completed by turning on the switch 42 for a predetermined time without making such a determination.

[0025] In step S108, the control unit 50 turns off the switch 42.

[0026] In step S110, control unit 50 turns on switch 60A, causing first drive circuit 20A to apply high-frequency current to first winding 10A. Here, control unit 50 controls the on / off of the switching elements of first drive circuit 20A (switching elements corresponding to switching elements 21U, 21V, and 21W and switching elements 22U, 22V, and 22W of second drive circuit 20B) at predetermined timings to perform high-frequency current application. At this time, the high-frequency current applied to first winding 10A generates an induced electromotive force in second winding 10B. For example, if first winding 10A and second winding 10B have the same turns ratio, a voltage substantially equal to the voltage applied to first winding 10A will be generated in second winding 10B.

[0027] 2 shows the current due to the voltage generated between the U-phase terminal and the V-phase terminal of the second winding 10B. In the example shown in FIG. 2, a circuit passing through parasitic diode 21D of switching element 21U and parasitic diode 22D of switching element 22V functions as a rectifier circuit for the AC voltage generated between the U-phase terminal and the V-phase terminal of the second winding 10B, and charges ripple absorption capacitor 30B. That is, the induced electromotive force is rectified by parasitic diode 21D and parasitic diode 22D, and ripple absorption capacitor 30B is precharged. The same applies to the voltage generated between the V-phase terminal and the W-phase terminal of the second winding 10B and the voltage generated between the W-phase terminal and the U-phase terminal of the second winding 10B, and the ripple absorption capacitor 30B is charged by a current obtained by combining these currents.

[0028] In step S112, it is determined whether the ripple absorbing capacitor 30B has been precharged to a predetermined precharge voltage, and if the determination is affirmative, the process proceeds to step S114, and if the determination is negative, the process proceeds to step S110.

[0029] In step S114, the control unit 50 stops the supply of high-frequency current to the first winding 10A by the first drive circuit 20A.

[0030] In step S116, the control unit 50 turns on the switch 60B, and ends the process.

[0031] The above process allows the system to transition to normal operation, such as normal power steering operation, using the first drive circuit 20A and the second drive circuit 20B. In normal power steering operation, the first drive circuit 20A and the second drive circuit 20B may simultaneously supply current to the first winding 10A and the second winding 10B. Alternatively, either the first drive circuit 20A or the second drive circuit 20B may selectively supply current to either the first winding 10A or the second winding 10B.

[0032] In step S110, the waveform of the voltage generated by high-frequency current application may be any waveform, but high-frequency current application may be performed using a waveform that does not generate motor torque or noise. For example, a sine wave may be used as the waveform. High-frequency current application may also be performed on three phases, or on any two of the U, V, and W phases.

[0033] Furthermore, by adjusting the amplitude or frequency of the high-frequency current, the charging rate of the ripple absorption capacitor 30B can be optimized. For example, if the resistance values ​​of the first winding 10A and the second winding 10B are low, the charging current value may be too large. However, even in such a case, an appropriate charging current value can be ensured. The amplitude or frequency of the high-frequency current may be adjusted by the control unit 50 in accordance with changes in the precharge voltage of the ripple absorption capacitor 30B. In this case, the charging current value can be appropriately controlled in accordance with changes in the charge state (precharge voltage) of the ripple absorption capacitor 30B.

[0034] As described above, in this embodiment, the ripple absorption capacitor 30B corresponding to the second drive circuit 20B can be precharged without using a circuit equivalent to the precharge circuit consisting of the resistor 41 and the switch 42. This allows the circuit equivalent to the precharge circuit to be omitted, thereby reducing the circuit size. For example, the board mounting area corresponding to the second drive circuit 20B can be reduced, allowing for a more compact device. Furthermore, the reduced circuit size reduces costs, and the reduced number of components reduces the failure rate and improves the reliability of the device.

[0035] Although this embodiment shows an example in which two drive circuits are provided, the present invention can also be applied to cases in which three or more drive circuits are provided. Even when three or more drive circuits are provided, a precharge circuit only needs to be provided for one of the systems that performs high-frequency current application.

[0036] The following additional notes are provided regarding the above-described embodiments of the present invention.

[0037] [Appendix 1] a first drive circuit (20A) and a second drive circuit (20B) respectively connected to a first winding (10A) and a second winding (10B) of a motor which are made redundant with each other; a ripple absorbing capacitor (30B) corresponding to the second drive circuit; a control unit (50) that applies high-frequency current to the first winding by means of the first drive circuit; Equipped with A motor drive device in which an induced electromotive force generated in the second winding by passing high-frequency current through the first winding is rectified by parasitic diodes (21D, 22D) provided in switching elements (21U, 21V, 21W, 22U, 22V, 22W) of the second drive circuit, and pre-charges the ripple absorption capacitor.

[0038] According to the configuration described in Supplementary Note 1, an induced electromotive force generated in the second winding by passing high-frequency current through the first winding is rectified by a parasitic diode provided in the switching element of the second drive circuit and precharges the ripple absorption capacitor, so that a precharge circuit corresponding to the second drive circuit can be omitted.

[0039] [Appendix 2] 2. The motor drive device according to claim 1, wherein the control unit performs high-frequency energization by the first drive circuit while keeping a switching element of the second drive circuit off.

[0040] According to the configuration described in Appendix 2, the control unit applies high-frequency current through the first drive circuit while keeping the switching element of the second drive circuit off, so that the switching element of the second drive circuit can be effectively used for rectification.

[0041] [Appendix 3] A precharging method for precharging a ripple absorption capacitor of a motor drive device including a first drive circuit and a second drive circuit connected to a first winding and a second winding, respectively, which are made redundant with each other, and a ripple absorption capacitor corresponding to the second drive circuit, the method comprising: a precharging method comprising a step of rectifying an induced electromotive force generated in the second winding by applying high frequency current to the first winding by the first drive circuit, by a parasitic diode provided in a switching element of the second drive circuit, and precharging the ripple absorption capacitor.

[0042] According to the configuration described in Supplementary Note 3, an induced electromotive force generated in the second winding by passing a high frequency current through the first winding is rectified by a parasitic diode provided in the switching element of the second drive circuit and precharges the ripple absorption capacitor, so that a precharge circuit corresponding to the second drive circuit can be omitted.

[0043] [Appendix 4] A program for causing a computer to execute a method for precharging a ripple absorption capacitor in a motor drive device including a first drive circuit and a second drive circuit connected to a first winding and a second winding, respectively, which are made redundant with respect to each other, and a ripple absorption capacitor corresponding to the second drive circuit, the program comprising: The precharge method includes: a program comprising a step of rectifying an induced electromotive force generated in the second winding by applying high frequency current to the first winding by the first drive circuit, by a parasitic diode provided in a switching element of the second drive circuit, and precharging the ripple absorption capacitor.

[0044] According to the configuration described in Supplementary Note 4, an induced electromotive force generated in the second winding by passing a high frequency current through the first winding is rectified by a parasitic diode provided in the switching element of the second drive circuit and precharges the ripple absorption capacitor, so that a precharge circuit corresponding to the second drive circuit can be omitted. [Explanation of symbols]

[0045] 10A First Winding 10B Second winding 20A First Drive Circuit 20B Second driving circuit 21U, 21V, 21W, 22U, 22V, 22W Switching elements 21D, 22D Parasitic diodes 30A ripple absorption capacitor 30B Ripple absorption capacitor 50 control section

Claims

1. a first drive circuit and a second drive circuit connected to a first winding and a second winding of the motor, respectively, which are made redundant with each other; a ripple absorbing capacitor corresponding to the second drive circuit; a control unit that applies high frequency current to the first winding by the first drive circuit; Equipped with a motor drive device in which an induced electromotive force generated in the second winding by passing high-frequency current through the first winding is rectified by a parasitic diode provided in a switching element of the second drive circuit, and pre-charges the ripple absorption capacitor.

2. 2. The motor drive device according to claim 1, wherein the control unit causes the first drive circuit to apply high-frequency current while keeping a switching element of the second drive circuit off.

3. A precharging method for precharging a ripple absorption capacitor of a motor drive device including a first drive circuit and a second drive circuit connected to a first winding and a second winding, respectively, which are made redundant with respect to each other, and a ripple absorption capacitor corresponding to the second drive circuit, the method comprising: a precharging method comprising a step of rectifying an induced electromotive force generated in the second winding by applying high frequency current to the first winding by the first drive circuit, by a parasitic diode provided in a switching element of the second drive circuit, and precharging the ripple absorption capacitor.

4. A program for causing a computer to execute a precharging method for precharging a ripple absorption capacitor of a motor drive device including a first drive circuit and a second drive circuit connected to a first winding and a second winding, respectively, which are made redundant with respect to each other, and a ripple absorption capacitor corresponding to the second drive circuit, the program comprising: The precharge method includes: a program comprising a step of rectifying an induced electromotive force generated in the second winding by applying high frequency current to the first winding by the first drive circuit, by a parasitic diode provided in a switching element of the second drive circuit, and precharging the ripple absorption capacitor.

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