WO2019049449A1

WO2019049449A1 - Electric power converting device, motor module, and electric power steering device

Info

Publication number: WO2019049449A1
Application number: PCT/JP2018/022031
Authority: WO
Inventors: アハマッドガデリー
Original assignee: 日本電産株式会社
Priority date: 2017-09-08
Filing date: 2018-06-08
Publication date: 2019-03-14
Also published as: JPWO2019049449A1

Abstract

This electric power converting device is provided with: an inverter connected to other ends of windings of an n-phase (where n is an integer at least equal to 3) motor of which one end of each winding is connected in a Y shape, the inverter having n legs each of which includes a low side switch element and a high side switch element; a first phase splitting relay circuit which, for each phase, switches between connection and non-connection, by way of the inverter, of a power supply and the n-phase windings; a sub-inverter having at least one leg connected in parallel with the n legs of the inverter, and connected to said other ends of the n-phase windings; and a second phase splitting relay circuit which switches between connection and non-connection, by way of the sub-inverter, of the power supply and the n-phase windings.

Description

Power converter, motor module and electric power steering apparatus

The present disclosure relates to a power conversion device, a motor module, and an electric power steering device.

2. Description of the Related Art In recent years, an electromechanical integrated motor has been developed in which an electric motor (hereinafter simply referred to as a "motor"), a power conversion device, and an ECU are integrated. Particularly in the automotive field, high quality assurance is required from the viewpoint of safety. Therefore, a redundant design is adopted that can continue safe operation even if part of the part fails. As an example of redundant design, it is considered to provide two power converters for one motor. As another example, it is considered to provide a backup microcontroller on the main microcontroller.

Patent Document 1 discloses a motor drive device having a first system and a second system. The first system is connected to a first winding set of the motor, and includes a first inverter unit, a power supply relay, a reverse connection protection relay, and the like. The second system is connected to a second winding set of the motor, and includes a second inverter unit, a power supply relay, a reverse connection protection relay, and the like. When no failure occurs in the motor drive device, it is possible to drive the motor using both the first system and the second system. On the other hand, when a failure occurs in one of the first system and the second system, or one of the first winding set and the second winding set, the power supply relay receives from the power supply the failed system or the failed winding. Shut off the power supply to the grid connected to the wire set. It is possible to continue motor drive using the other system which has not failed.

Patent documents 2 and 3 also disclose a motor drive device having a first system and a second system. Even if one system or one winding set fails, the motor drive can be continued by the system which has not failed.

Patent Document 4 discloses a motor drive device having four electrical separation means and two inverters and converting power supplied to a three-phase motor. For one inverter, one electrical separation means is provided between the power supply and the inverter, and one electrical separation means is provided between the inverter and GND. It is possible to drive the motor with a non-faulty inverter using the neutral point of the winding in the faulted inverter. At that time, the failed inverter is separated from the power supply and GND by putting the two electrical separation means connected to the failed inverter into the cut off state.

JP, 2016-34204, A JP, 2016-32977, A JP 2008-132919 A Patent No. 5779751

In the above-mentioned prior art, further improvement of the motor output in control at the time of abnormality was called for.

An embodiment of the present disclosure provides a power converter that can improve motor output in control at the time of abnormality.

An exemplary power converter of the present disclosure converts power from a power source into power supplied to a motor having n-phase (n is an integer of 3 or more) windings Y-connected at one end. An inverter having n legs connected to the other end of the n-phase winding, each including a low-side switch element and a high-side switch element, the power supply, and the n-phase winding A sub-inverter having a first phase separation relay circuit that switches connection / non-connection via an inverter for each phase, and at least one leg connected in parallel with the n legs of the inverter, the n-phase And a second phase separation relay circuit for switching connection / disconnection between the power supply and the n-phase winding via the sub-inverter.

According to an exemplary embodiment of the present disclosure, n-phase conduction control (typically, by appropriately determining the on / off states of the first phase separation relay circuit and the second phase separation relay circuit according to the control mode Three-phase energization control can be performed continuously. Thus, a power converter capable of improving a motor output in control at the time of abnormality, a motor module including the power converter, and an electric power steering apparatus including the motor module are provided.

FIG. 1 is a block diagram illustrating an exemplary block configuration of a motor module 1000 according to an exemplary embodiment 1. As shown in FIG. FIG. 2 is a circuit diagram showing a circuit configuration of the power conversion device 100 according to the exemplary embodiment 1. As shown in FIG. FIG. 3 is a schematic view showing the configuration of the bidirectional switch SW_2W. FIG. 4 is a block diagram showing a typical block configuration of control circuit 300. Referring to FIG. FIG. 5 is a graph illustrating a current waveform (sine wave) obtained by plotting current values flowing through the windings M1, M2, and M3 in accordance with the three-phase conduction control. FIG. 6 is a graph showing the relationship between the number of revolutions per unit time (rps) of the motor and the torque T (N · m). FIG. 7 is a circuit diagram showing a circuit configuration of a power conversion device 100A according to an exemplary embodiment 2. As shown in FIG. FIG. 8 is a schematic view showing a typical configuration of an electric power steering apparatus 2000 according to an exemplary embodiment 3. As shown in FIG.

Hereinafter, embodiments of a power conversion device, a motor module, and an electric power steering device of the present disclosure will be described in detail with reference to the accompanying drawings. However, in order to facilitate the understanding of the person skilled in the art, the following description may be omitted unnecessarily to avoid redundant description. For example, detailed description of already well-known matters and redundant description of substantially the same configuration may be omitted.

In the present specification, the implementation of the present disclosure will be exemplified taking a power conversion apparatus that converts power from a power supply into power supplied to a three-phase motor having three-phase (U-phase, V-phase, W-phase) windings. The form will be described. However, a power conversion device that converts power from a power supply to power supplied to an n-phase motor having n-phase (n is an integer of 4 or more) windings such as four-phase or five-phase is also within the scope of the present disclosure. .

(Embodiment 1)

[Structure of Motor Module 1000 and Power Converter 100]

FIG. 1 schematically shows a typical block configuration of a motor module 1000 according to the present embodiment.

Motor module 1000 typically includes power converter 100, motor 200, control circuit 300, and angle sensor 500. The angle sensor 500 may not be necessary depending on the motor control method (for example, sensorless control).

The motor module 1000 can be modularized and manufactured and sold as an electromechanical integrated motor having, for example, a motor, a sensor, a driver and a controller. In addition, a system for driving a motor, which can include components other than the motor among the components of the motor module can be referred to as a "motor drive system". The motor drive system can also be modularized and manufactured and sold.

Power converter 100 includes an inverter 110, a sub-inverter 120, a first phase separation relay circuit 130, a second phase separation relay circuit 140, and a current sensor 400. Power converter 100 can convert the power from power supply 101 (see FIG. 2) into the power to be supplied to motor 200. Inverter 110 is connected to motor 200. For example, the inverter 110 can convert DC power into three-phase AC power which is a pseudo-sine wave of U-phase, V-phase and W-phase. In the present specification, “connection” between components (components) mainly means electrical connection.

The motor 200 is, for example, a three-phase alternating current motor. The motor 200 has a U-phase winding M1, a V-phase winding M2, and a W-phase winding M3. One ends of the windings M1, M2 and M3 are Y-connected.

The control circuit 300 is configured of a microcontroller or the like. Control circuit 300 controls power conversion device 100 based on input signals from current sensor 400 and angle sensor 500. As the control method, there are, for example, vector control, pulse width modulation (PWM) or direct torque control (DTC).

The angle sensor 500 is, for example, a resolver or a Hall IC. The angle sensor 500 is also realized by a combination of an MR sensor having a magnetoresistive (MR) element and a sensor magnet. The angle sensor 500 detects the rotation angle (hereinafter referred to as “rotation signal”) of the rotor of the motor 200, and outputs a rotation signal to the control circuit 300.

A specific circuit configuration of power converter 100 will be described with reference to FIG.

FIG. 2 schematically shows the circuit configuration of the power conversion device 100 according to the present embodiment.

The power supply 101 generates a predetermined power supply voltage (for example, 12 V). For example, a DC power supply is used as the power supply 101. However, the power supply 101 may be an AC-DC converter or a DC-DC converter, or may be a battery (storage battery).

A fuse 102 is connected between the power supply 101 and the inverter 110. The fuse 102 can interrupt a large current that can flow from the power supply 101 to the inverter 110 or the sub-inverter 120. A relay or the like may be used instead of the fuse.

Although not shown, a coil is provided between the power supply 101 and the inverter 110. The coil functions as a noise filter and smoothes high frequency noise contained in the voltage waveform supplied to the inverter or high frequency noise generated by the inverter so as not to flow out to the power supply 101 side. In addition, a capacitor is connected to the power supply terminal of the inverter. The capacitor is a so-called bypass capacitor, which suppresses voltage ripple. The capacitor is, for example, an electrolytic capacitor, and the capacity and the number to be used are appropriately determined according to design specifications and the like.

The inverter 110 comprises a bridge circuit having three legs. Each leg has a high side switch element and a low side switch element. The U-phase leg has a high side switch element SW_AH and a low side switch element SW_AL. The V-phase leg has a high side switch element SW_BH and a low side switch element SW_BL. The W-phase leg has a high side switch element SW_CH and a low side switch element SW_CL. As a switch element, for example, a field effect transistor (typically, a MOSFET) in which a parasitic diode is formed, or a combination of an insulated gate bipolar transistor (IGBT) and a free wheeling diode connected in parallel thereto can be used.

The inverter 110 is, for example, a current sensor 400 (see FIG. 1) for detecting a current (sometimes referred to as “phase current”) flowing through the windings of each of the U, V and W phases. , Shunt resistance (not shown) on each leg. The current sensor 400 has a current detection circuit (not shown) that detects the current flowing in each shunt resistor. For example, a shunt resistor may be connected between the low side switch element and ground in each leg.

The number of shunt resistors is not limited to three. For example, it is possible to use two shunt resistors for U phase and V phase, two shunt resistors for V phase and W phase, or two shunt resistors for U phase and W phase. The number of shunt resistors to be used and the arrangement of the shunt resistors are appropriately determined in consideration of product cost, design specifications and the like.

The U-phase leg of inverter 110 (specifically, node na between high-side switch element SW_AH and low-side switch element SW_AL) is connected to the other end of U-phase winding M1 of motor 200. Similar to the node na, the node nb of the V-phase leg is connected to the other end of the V-phase winding M2, and the node nc of the W-phase leg is connected to the other end of the W-phase winding M3.

Sub-inverter 120 can be connected to the other end of windings M1, M2 and M3. The sub-inverter of the present disclosure may have at least one leg connected in parallel with the three legs of the inverter. In the circuit configuration shown in FIG. 2, the sub-inverter 120 has one leg D connected in parallel to the three legs of the inverter 110. The leg D has a high side switch element SW_DH and a low side switch element SW_DL. The leg D, like the leg of the inverter 110, can have a shunt resistance.

The node nd between the high side switch element SW_DH and the low side switch element SW_DL of the leg D can be connected to the windings M1, M2, and M3 via a second phase separation relay circuit 140 described later.

For example, the inverter 110 can be regarded as an inverter provided with four phase legs of A phase, B phase, C phase and D phase. The inverter 110 and the sub-inverter 120 can be manufactured as one bridge circuit comprising four legs including the leg D.

The first phase separation relay circuit 130 switches connection / disconnection between the power supply 101 and the inverter 110 for each phase. In other words, the first phase separation relay circuit 130 can switch connection / disconnection between the power supply 101 and the windings M1, M2 and M3 via the inverter 110 for each phase.

In the first phase separation relay circuit 130, in the inverter 110, three first phases connected between a node on the high side, which is a power supply line, and three high side switch elements SW_AH, SW_BH and SW_CH. It has three phase separation relays ISW_AH, ISW_BH and ISW_CH which are separation relays. The phase separation relay ISW_AH is in the U phase leg. The phase separation relay ISW_BH is in the V phase leg. The phase separation relay ISW_CH is in the W phase leg.

The first phase separation relay circuit 130 further includes three second phases connected between the low side node, which is the GND line, and the three low side switch elements SW_AL, SW_BL and SW_CL in the inverter 110. It has three phase separation relays ISW_AL, ISW_BL and ISW_CL which are separation relays. The phase separation relay ISW_AL is in the U phase leg. Phase separation relay ISW_BL is in the V phase leg. The phase separation relay ISW_CL is in the W phase leg.

For example, a semiconductor switch such as a MOSFET can be used as the phase separation relay. Other semiconductor switches such as thyristors and analog switch ICs or mechanical relays may be used. Also, a combination of IGBTs and diodes can be used.

In FIG. 2, a MOSFET having a parasitic diode inside is illustrated as a switch element of the inverter 110 and each phase separation relay. In each phase leg, the high side phase separation relay and the high side switch element are connected in series so that the forward current flows in the same direction to the internal parasitic diode. The low-side phase separation relay and the low-side switch element are connected in series such that the forward current flows in the same direction to the internal parasitic diode.

The second phase separation relay circuit 140 switches connection / disconnection between the power supply 101 and the windings M1, M2 and M3 via the sub-inverter 120. The second phase separation relay circuit 140 according to the present embodiment can switch connection / non-connection between the sub-inverter 120 and the windings M1, M2 and M3 for each phase.

The second phase separation relay circuit 140 is a three phase separation relay ISW_AD as three third phase separation relays, which switches connection / disconnection between the leg D of the sub-inverter 120 and the windings M1, M2 and M3. , ISW_BD and ISW_CD. One end of the phase separation relay ISW_AD is connected to the node nd of the leg D, and the other end is connected to the other end of the winding M1. One end of the phase separation relay ISW_BD is connected to the node nd of the leg D, and the other end is connected to the other end of the winding M2. One end of the phase separation relay ISW_CD is connected to the node nd of the leg D, and the other end is connected to the other end of the winding M3. Thus, one end of the three phase separation relays ISW_AD, ISW_BD and ISW_CD is commonly connected to the node nd of the leg D.

FIG. 3 schematically shows the configuration of the bidirectional switch SW_2W.

A bidirectional switch SW_2W as illustrated can be used as the three phase separation relays ISW_AD, ISW_BD, and ISW_CD. The bi-directional switch SW_2W can be configured by combining the two one-way switches SW_1W such that the internal diodes face in opposite directions.

FIG. 4 schematically shows a typical block configuration of the control circuit 300. As shown in FIG.

The control circuit 300 includes, for example, a power supply circuit 310, an input circuit 320, a controller 330, a drive circuit 340, and a ROM 350. Control circuit 300 is connected to power converter 100. The control circuit 300 controls the power conversion device 100, specifically, by controlling the inverter 110, the sub-inverter 120, the first phase separation relay circuit 130, and the second phase separation relay circuit 140 (see FIG. 1). The motor 200 can be driven. The control circuit 300 can achieve closed loop control by controlling the target position, rotational speed, and current of the rotor. A torque sensor may be used instead of the angle sensor 500 (see FIG. 1). In this case, the control circuit 300 can control the target motor torque.

The power supply circuit 310 generates DC voltages (for example, 3 V, 5 V) necessary for each block in the circuit.

Input circuit 320 receives a motor current value (hereinafter, referred to as “actual current value”) detected by current sensor 400. The input circuit 320 converts the level of the actual current value to the input level of the controller 330 as necessary, and outputs the actual current value to the controller 330. The input circuit 320 is typically an analog-to-digital converter.

The controller 330 is an integrated circuit that controls the entire motor module 1000, and is, for example, a microcontroller or a field programmable gate array (FPGA).

The controller 330 receives the rotation signal of the rotor detected by the angle sensor 500. The controller 330 sets a target current value in accordance with the actual current value, the rotation signal of the rotor, and the like, generates a PWM signal, and outputs the PWM signal to the drive circuit 340.

The controller 330 generates a PWM signal for controlling the switching operation (turn on or turn off) of each switch element in the inverter 110 and the sub-inverter 120 of the power conversion device 100. The controller 330 can further generate a signal that determines the on / off state of each phase separation relay in each phase separation relay circuit of the power conversion device 100.

The drive circuit 340 is typically a gate driver (or predriver). Drive circuit 340 generates a control signal (typically, a gate control signal) for controlling the switching operation of each switch element in inverter 110 and sub-inverter 120 in accordance with the PWM signal, and applies the control signal to each switch element. In the present embodiment, the drive circuit 340 generates on / off control signals (analog signals) according to signals from the controller 330 that determine the on / off state of each phase separation relay, and those control signals are It is possible to give to

When the drive target is a low voltage driveable motor, the gate driver may not be required. In that case, the function of the gate driver may be implemented in the controller 330.

The ROM 350 is, for example, a writable memory (for example, a PROM), a rewritable memory (for example, a flash memory), or a read only memory. The ROM 350 stores a control program including instructions for causing the controller 330 to control the power conversion apparatus 100. For example, the control program is temporarily expanded in a RAM (not shown) at boot time.

Control modes of the power conversion device 100 include control modes at normal and abnormal times. The control circuit 300 (mainly the controller 330) can switch the control of the power conversion device 100 from the control mode in the normal state to the control mode in the abnormal state. Depending on the control mode, the on / off states of the phase separation relays of the first phase separation relay circuit 130 and the second phase separation relay circuit 140 are determined.

Hereinafter, the electric power of power supply 101, inverter 110, sub-inverter 120, and windings M1, M2 and M3 in the on / off state and the on / off state of first phase separation relay circuit 130 and second phase separation relay circuit 140. Connection relationships will be described in detail.

In the present specification, “the first phase separation relay circuit 130 is turned on” means that all the phase separation relays ISW_AH, ISW_BH, ISW_CH, ISW_AL, ISW_BL and ISW_CL of the first phase separation relay circuit 130 are turned on. Do. "The first phase separation relay circuit 130 is turned off" means that all the phase separation relays ISW_AH, ISW_BH, ISW_CH, ISW_AL, ISW_BL and ISW_CL are turned off.

When the first phase separation relay circuit 130 is turned on, the inverter 110 is electrically connected to the power supply 101. When the first phase separation relay circuit 130 is turned off, the inverter 110 is electrically separated from the power supply 101.

As described above, it is possible to switch between connection and disconnection of the power supply 101 and the three legs of the inverter 110 for each phase. For example, the U-phase leg is electrically separated from the power supply 101 by turning off the phase separation relays ISW_AH and ISW_AL. The V-phase and W-phase legs remain connected to the power supply 101.

In the present specification, “the second phase separation relay circuit 140 is turned on” means that all phase separation relays of the second phase separation relay circuit 140 are turned on. “The second phase separation relay circuit 140 is turned off” means that all phase separation relays of the second phase separation relay circuit 140 are turned off.

In the circuit configuration shown in FIG. 2, when the second phase separation relay circuit 140 is turned on, the sub inverter 120, more specifically, the leg D of the sub inverter 120 is connected to the windings M1, M2, and M3. When the second phase separation relay circuit 140 is turned off, the leg D is electrically separated from the windings M1, M2 and M3.

As described above, it is possible to switch connection / disconnection between the leg D of the sub-inverter 120 and the windings M1, M2 and M3 for each phase. For example, the leg D can be connected only to the winding M1 by turning on the phase separation relay ISW_AD and turning off the phase separation relays ISW_BD and ISW_CD.

[Operation of Power Converter 100]

Hereinafter, a specific example of the operation of the motor module 1000 will be described, and a specific example of the operation of the power conversion device 100 will be mainly described.

(1. Control when normal)

First, a specific example of a control method at the time of normal operation of the power conversion device 100 will be described.

In the present specification, “normal” indicates that the inverter 110, the sub-inverter 120, and the windings M1, M2 and M3 of the motor 200 do not have a failure. “Abnormal” mainly refers to occurrence of a failure in a switch element in the bridge circuit of the inverter 110. The failure of the switch element mainly refers to the open failure and the short failure of the semiconductor switch element (FET). "Open fault" refers to a fault in which the source-drain of FET is opened (in other words, resistance rds between source-drain becomes high impedance), and "short fault" is in the source-drain of FET Refers to a short circuit failure.

In the normal control mode, the control circuit 300 (mainly the controller 330) turns on the first phase separation relay circuit 130 and turns off the second phase separation relay circuit 140. The inverter 110 is connected to the power supply 101 by this control. In other words, windings M 1, M 2 and M 3 are electrically connected to power supply 101 via inverter 110. Also, leg D of sub-inverter 120 is electrically isolated from windings M1, M2 and M3. Power is not supplied from the power supply 101 to the motor 200 via the sub-inverter 120.

The control circuit 300 is capable of energizing the three-phase windings M1, M2 and M3 by controlling the switching operation of the switch element of the inverter 110. In the present specification, such energization control is referred to as “three-phase energization control”.

FIG. 5 exemplifies a current waveform (sine wave) obtained by plotting current values flowing in the windings M1, M2 and M3 in accordance with the three-phase conduction control. The horizontal axis indicates the motor electrical angle (deg), and the vertical axis indicates the current value (A). I _pk represents the maximum value (peak current value) of the phase current flowing in each phase. In a general Y-connection motor, the sum of the currents flowing through the three-phase windings in consideration of the current direction is “0” for each electrical angle.

The control circuit 300 controls the switching operation of each switch element of the inverter 110 so that, for example, the pseudo sine wave shown in FIG. 5 is obtained. Thereby, power conversion device 100 can receive power of control of control circuit 300 to energize windings M1, M2 and M3.

(2. Control at the time of abnormality)

When the power converter 100 is used for a long time, a switch element of the inverter 110 may fail. These failures are different from the manufacturing failures that can occur during manufacturing. When such a failure occurs, the above-described control at the normal time becomes impossible.

As an example of failure detection, the drive circuit 340 detects the failure of the switch element by monitoring the voltage Vds between the drain and the source of the switch element and comparing the predetermined threshold voltage with Vds. The threshold voltage is set in the drive circuit 340 by data communication with an external IC (not shown) and an external component, for example. The drive circuit 340 is connected to the port of the controller 330 and notifies the controller 330 of a failure detection signal. For example, when the drive circuit 340 detects a failure of the switch element, the drive circuit 340 asserts a failure detection signal. When the controller 330 receives the asserted fault detection signal, it can read out the internal data of the drive circuit 340 to determine which switch element among the plurality of switch elements in the inverter 110 is faulty. is there.

As another example of failure detection, the controller 330 can also detect a failure of the switch element based on the difference between the actual current value of the motor and the target current value. However, the failure detection is not limited to these methods, and a wide variety of known methods for failure detection can be used.

When the failure detection signal is asserted, the controller 330 switches control of the power conversion device 100 from normal control to abnormal control. For example, the timing at which control is switched from normal to abnormal is about 10 msec to 30 msec after the fault detection signal is asserted.

If one of the three legs of inverter 110 fails, control circuit 300 controls one of phase separation relays ISW_AH, ISW_BH and ISW_CH in first phase separation relay circuit 130 in an abnormal control. Of the phase separation relay connected to the failed leg of the inverter 110 and the phase separation relay connected to the broken leg of the phase separation relays ISW_AL, ISW_BL and ISW_CL, and the remaining 4 Turn on the phase separation relays. Furthermore, control circuit 300 turns on the phase separation relay connected to the other end of the winding connected to the failed leg among phase separation relays ISW_AD, ISW_BD and ISW_CD in second phase separation relay circuit 140. And turn off the other two phase separation relays. In this specification, failure of a switch element of a leg may be referred to as “leg failure”.

Under the control of control circuit 300, power conversion device 100 uses three legs other than the failed leg of the three legs of inverter 110 and three legs D of sub-inverter 120 to form a three-phase winding. The wire can be energized.

Hereinafter, an exemplary failure pattern will be described, and a control method of the phase separation relay in each phase separation relay circuit will be described in detail.

Refer again to FIG.

For example, consider the case where the high side switch element SW_AH in the U phase leg of the inverter 110 has an open failure. In that case, in the first phase separation relay circuit 130, the control circuit 300 turns off the phase separation relays ISW_AH, ISW_AL of the U phase leg including the failed switch element, and four of the V phase and W phase legs. The phase separation relays ISW_BH, ISW_BL, ISW_CH and ISW_CL are turned on. Further, in the second phase separation relay circuit 140, control circuit 300 turns on phase separation relay ISW_AD connected to winding M1, and turns off phase separation relays ISW_BD and ISW_CD connected to windings M2 and M3. Do.

By these controls, the failed U-phase leg is electrically isolated from the power supply 101. Windings M 2 and M 3 are connected to power supply 101 via V-phase and W-phase legs of inverter 110. On the other hand, U-phase winding M 1 is connected to leg D of sub-inverter 120 instead of U-phase leg of inverter 110. In this connection state, control circuit 300 can continue three-phase conduction control using the V-phase leg of inverter 110, the W-phase leg, and leg D of sub-inverter 120. That is, the leg D of the sub-inverter 120 can function as the U-phase leg of the inverter 110.

For example, consider a case where the high side switch element SW_BH in the V phase leg of the inverter 110 has an open failure. In that case, in the first phase separation relay circuit 130, the control circuit 300 turns off the phase separation relays ISW_BH and ISW_BL of the V phase leg including the failed switch element, and four of the U and W phase legs. The phase separation relays ISW_AH, ISW_AL, ISW_CH and ISW_CL are turned on. Furthermore, in the second phase separation relay circuit 140, control circuit 300 turns on phase separation relay ISW_BD connected to winding M2, and turns off phase separation relays ISW_AD, ISW_CD connected to windings M1 and M3. Do. With these controls, three-phase conduction control can be continued using the U-phase leg of the inverter 110, the W-phase leg, and the leg D of the sub-inverter 120. That is, the leg D of the sub-inverter 120 can function as the V-phase leg of the inverter 110.

For example, in an inverter having a four-phase leg that drives a four-phase AC motor, when a one-phase leg fails, the leg D of the sub-inverter 120 can be used as the leg of the broken phase. Thus, the present disclosure can also be suitably used to drive a multiphase motor having four or more phase windings.

According to this embodiment, in the control at the time of abnormality, by substituting the leg D of the sub-inverter 120, it is possible to continuously carry out three-phase conduction control using three legs.

FIG. 6 shows the relationship between the number of revolutions per unit time (rps) of the motor and the torque T (N · m). The horizontal axis of the graph indicates the rotational speed, and the vertical axis indicates the value of the normalized torque. The rotation speed Wmn represents the maximum rotation speed. Wcn represents the number of revolutions at a change point at which the torque rapidly changes in the motor output characteristic.

The so-called TN curve shown in FIG. 6 shows the characteristics of the motor output obtained in the normal control and the motor output obtained in the abnormal control. The torque value obtained by the control at the time of abnormality is a value normalized by the torque value obtained by the control at the normal time. Also, as a comparative example, FIG. 6 shows motor output characteristics in control at the time of abnormality obtained by the control method disclosed in Patent Documents 1 (Japanese Patent Application Laid-Open No. 2016-34204) and 4 (Japanese Patent No. 5797751). .

In the motor drive device of Patent Document 1, the motor is driven using one of the first system and the second system which has not failed in the control at the time of abnormality. The maximum value of the phase current in abnormal control is reduced to about 50% compared to that in normal control, so the torque obtained in abnormal control is also reduced to about 50% compared to that in normal control. . On the other hand, since the maximum value of the phase voltage applied to the windings of each phase does not change in the normal and abnormal control, the maximum rotation speed Wmn is maintained.

In the motor drive device of Patent Document 4, it is possible to independently control the current flowing through the three-phase winding in the control at the normal time. On the other hand, in the control at the time of abnormality, the motor is driven substantially only by the inverter on one side using the neutral point of the failed inverter. Since the maximum value of the phase voltage applied to the windings of each phase is reduced to about 58% compared to that at normal time, the maximum rotational speed obtained by control at normal time is the maximum rotational speed Wmn at normal time It falls to about 58% compared with. As a result, the high speed rotation area is reduced to the low speed side, and the motor can not be driven at a higher speed. On the other hand, since the maximum value of the phase current of the motor does not change in the normal and abnormal control, the torque is maintained.

According to the present embodiment, the same three-phase energization control as in the normal state can be performed even in the abnormal state. Therefore, in the control at the abnormal time, the same torque as the control at the normal time can be obtained. Furthermore, since the maximum value of the phase voltage applied to the windings of each phase does not change in the normal and abnormal control, the maximum rotational speed Wmn can be maintained, and the rotational speed Wcn can be maintained. Can. That is, the motor output characteristics do not change between normal and abnormal control.

Summarizing the above, as shown in FIG. 6, the torque, the maximum number of revolutions Wmn of the motor and the number of revolutions Wcn of the motor can be maintained at the same values as in the normal state in the control at the time of abnormality. As a result, it is possible to improve the motor output, that is, the drive range of the motor. In particular, higher torque can be obtained in the high speed rotation region. Motor output characteristics in control at the time of abnormality can be further improved.

Second Embodiment

[Structure of Power Converter 100A]

The structures of the sub-inverter 120 and the second phase separation relay circuit 140 of the power conversion device 100A according to the present embodiment are different from those of the power conversion device 100 according to the first embodiment. Hereinafter, the description common to the first embodiment will be omitted, and the difference will be mainly described.

FIG. 7 schematically shows the circuit configuration of the power conversion device 100A according to the present embodiment.

Similar to inverter 110, sub-inverter 120 has three legs of U-phase leg, V-phase leg and W-phase leg. The U-phase leg has a high side switch element SW_DAH and a low side switch element SW_DAL. The V-phase leg has a high side switch element SW_DBH and a low side switch element SW_DBL. The W-phase leg has a high side switch element SW_DCH and a low side switch element SW_DCL.

The three legs of sub-inverter 120 are connected to the other ends of windings M1, M2 and M3. Specifically, the node nda between the high side switch element SW_DAH and the low side switch element SW_DAL of the U phase leg is connected to the other end of the winding M1 together with the node na of the inverter 110. Node ndb of the V-phase leg is connected to the other end of winding M2 together with node nb of inverter 110. The node ndc of the W-phase leg is connected to the other end of the winding M3 together with the node nc of the inverter 110.

The second phase separation relay circuit 140 switches connection / disconnection between the power supply 101 and the sub-inverter 120. The second phase separation relay circuit 140 has a phase separation relay ISW_DH which is a third phase separation relay and a phase separation relay ISW_DL which is a fourth phase separation relay. The phase separation relay ISW_DH is connected between the high side node ndh connecting the three high side switch elements SW_DAH, SW_DBH and SW_DCH of the sub-inverter 120 and the power supply 101. The phase separation relay ISW_DL is connected between a low side node ndl connecting the three low side switch elements SW_DAL, SW_DBL and SW_DCL of the sub-inverter 120 and GND.

[Operation of Power Converter 100A]

In normal control, the control circuit 300 turns on the first phase separation relay circuit 130 and turns off the second phase separation relay circuit 140 as described in the first embodiment. Thus, the inverter 110 is connected to the power supply 101, and the sub-inverter 120 is separated from the power supply 101. Control circuit 300 performs three-phase conduction control using inverter 110.

If one of the three legs of inverter 110 fails, control circuit 300 controls one of phase separation relays ISW_AH, ISW_BH and ISW_CH in first phase separation relay circuit 130 in an abnormal control. Of the phase separation relay connected to the failed leg of the inverter 110 and the phase separation relay connected to the broken leg among the phase separation relays ISW_AL, ISW_BL and ISW_CL, and the other four Turn on the phase separation relay of Control circuit 300 further turns on phase separation relays ISW_DH and ISW_DL of second phase separation relay circuit 140.

Control circuit 300 includes two legs other than the broken leg of the three legs of inverter 110 and the other end of the winding connected to the broken leg of the three legs of sub-inverter 120. The three-phase conduction control can be performed using the legs connected together.

Hereinafter, an exemplary failure pattern will be described, and the control method of the power conversion device 100A will be described in detail.

For example, consider the case where the high side switch element SW_AH in the U phase leg of the inverter 110 has an open failure. In that case, in the first phase separation relay circuit 130, the control circuit 300 turns off the phase separation relays ISW_AH, ISW_AL of the U phase leg including the failed switch element, and four of the V phase and W phase legs. The phase separation relays ISW_BH, ISW_BL, ISW_CH and ISW_CL are turned on. Control circuit 300 further turns on phase separation relays ISW_DH and ISW_DL of second phase separation relay circuit 140.

By these controls, the failed U-phase leg is electrically isolated from the power supply 101. Windings M2 and M3 are connected to power supply 101 via V-phase and W-phase legs. Winding M 1 is connected to power supply 101 via the U-phase leg of sub-inverter 120 instead of the U-phase leg of inverter 110. In this connection state, control circuit 300 can continue three-phase conduction control using the V-phase leg of W, the U-phase leg of sub-inverter 120, and the V-phase leg of inverter 110. That is, the U-phase leg of sub-inverter 120 can be functioned as the U-phase leg of inverter 110.

For example, consider a case where two switch elements of the high side switch element SW_AH of the U phase leg of the inverter 110 and the high side switch element SW_BH of the V phase leg have an open failure. In that case, in the first phase separation relay circuit 130, the control circuit 300 turns off the four phase separation relays ISW_AH, ISW_AL, ISW_BH and ISW_BL of the U phase leg including the failed switch element and the V phase leg, and , W phase leg phase separation relays ISW_CH, ISW_CL are turned on. Control circuit 300 further turns on phase separation relays ISW_DH and ISW_DL of second phase separation relay circuit 140.

By these controls, the failed U-phase leg and V-phase leg are electrically isolated from the power supply 101. Winding M3 is connected to power supply 101 via the W-phase leg. Windings M 1 and M 2 are connected to power supply 101 via the U-phase leg and V-phase leg of sub-inverter 120 instead of the U-phase leg and V-phase leg of inverter 110. In this connection state, control circuit 300 can continue the three-phase conduction control using the W-phase leg of inverter 110, the U-phase leg and the V-phase leg of sub-inverter 120. That is, the U-phase leg and the V-phase leg of the sub-inverter 120 can function as the U-phase leg and the V-phase leg of the inverter 110.

If all three legs of the inverter 110 fail, the control circuit 300 can continue the three-phase conduction control using the three legs of the sub-inverter 120 instead of the inverter 110.

According to the present embodiment, as in the first embodiment, three-phase energization control can be continuously performed by using the leg of the sub-inverter 120 in control at the time of abnormality, and further, a motor in control at the time of abnormality Output characteristics can be further improved.

(Embodiment 3)

FIG. 8 schematically shows a typical configuration of the electric power steering apparatus 2000 according to the present embodiment.

Vehicles such as automobiles generally have an electric power steering (EPS) device. The electric power steering apparatus 2000 according to the present embodiment has a steering system 520 and an auxiliary torque mechanism 540 that generates an auxiliary torque. Electric power steering apparatus 2000 generates an assist torque that assists a steering torque of a steering system generated by a driver operating a steering wheel. The assist torque reduces the burden on the driver's operation.

The steering system 520 includes, for example, a steering handle 521, a steering shaft 522,

free shaft joints

523A and 523B, a rotating shaft 524, a rack and pinion mechanism 525, rack shafts 526, left and right ball joints 552A and 552B,

tie rods

527A and 527B, knuckles And 528A, 528B, and left and

right steering wheels

529A, 529B.

The auxiliary torque mechanism 540 includes, for example, a steering torque sensor 541, an electronic control unit (ECU) 542 for a car, a motor 543, a reduction mechanism 544, and the like. The steering torque sensor 541 detects a steering torque in the steering system 520. The ECU 542 generates a drive signal based on a detection signal of the steering torque sensor 541. The motor 543 generates an auxiliary torque corresponding to the steering torque based on the drive signal. The motor 543 transmits the generated assist torque to the steering system 520 via the reduction mechanism 544.

The ECU 542 includes, for example, the controller 330 and the drive circuit 340 according to the first embodiment. In automobiles, an electronic control system is built around an ECU. In the electric power steering apparatus 2000, for example, a motor drive unit is constructed by the ECU 542, the motor 543 and the inverter 545. The motor module 1000 according to Embodiment 1 or 2 can be suitably used for the unit.

Embodiments of the present disclosure are also suitably used in motor control systems such as shift by wire, steering by wire, X by wire such as brake by wire, and traction motors. For example, a motor control system according to an embodiment of the present disclosure may be mounted on an autonomous vehicle that complies with levels 0 to 4 (standards of automation) defined by the Japanese government and the United States Department of Transportation Road Traffic Safety Administration (NHTSA).

Embodiments of the present disclosure can be widely used in a variety of devices equipped with various motors, such as vacuum cleaners, dryers, ceiling fans, washing machines, refrigerators, and electric power steering devices.

100, 100A: power converter, 101: power supply, 102: fuse, 110: inverter, 120: sub-inverter, 130: first phase separation relay circuit, 140: second phase separation relay circuit, 200: motor, 300: control Circuit 310: power supply circuit 320: input circuit 330: microcontroller 340: drive circuit 350: ROM 400: current sensor 500: angle sensor 1000: motor module 2000: electric power steering apparatus

Claims

A power conversion apparatus for converting power from a power supply into power supplied to a motor having n-phase (n is an integer of 3 or more) windings, one end of which is Y-connected,

An inverter connected to the other end of the n-phase winding and having n legs each including a low side switch element and a high side switch element;

A first phase separation relay circuit that switches connection / disconnection between the power supply and the n-phase winding via the inverter between the phases;

A sub-inverter having at least one leg connected in parallel with the n legs of the inverter, the sub-inverter connected to the other end of the n-phase winding;

A second phase separation relay circuit that switches connection / disconnection between the power supply and the n-phase winding via the sub-inverter;

Power converter comprising:
The power converter according to claim 1, wherein the second phase separation relay circuit switches connection / non-connection between the sub-inverter and the n-phase winding.
The second phase separation relay circuit according to claim 2, further comprising: n third phase separation relays for switching connection / disconnection between said at least one leg of said sub-inverter and said n-phase winding. Power converter.
The at least one leg of the sub-inverter is a single leg including a low side switch element and a high side switch element,

One end of the n third phase separation relays is commonly connected to a node connecting the low side switch element and the high side switch element of the one leg,

The power conversion device according to claim 3, wherein the other end of the n third phase separation relays is connected to the other end of the n-phase winding.
The power conversion device according to claim 3, wherein each of the n third phase separation relays is a bidirectional switch.
The power converter according to claim 1, wherein the second phase separation relay circuit switches connection / non-connection between the power supply and the sub-inverter.
The at least one leg of the sub-inverter is n legs each including a low side switch element and a high side switch element,

The power converter according to claim 6, wherein the n legs of the sub-inverter are connected to the other end of the n-phase winding.
The second phase separation relay circuit is

A first node connecting n high-side switch elements of the n legs and a third phase separation relay connected between the power supplies;

The power converter according to claim 7, further comprising: a second node connecting n low-side switch elements of the n legs and a fourth phase separation relay connected between the ground and the second node.
The first phase separation relay circuit is

In the inverter, n first phase separation relays connected between a node on the high side connecting the n legs of the inverter and n high side switch elements;

In the inverter, n second phase separation relays connected between a low side node connecting the n legs of the inverter and n low side switch elements;

The power converter device according to any one of claims 1 to 8, which has
The power conversion control mode has a normal control mode and an abnormal control mode.

The power conversion device according to any one of claims 1 to 9, wherein, in the normal control mode, the first phase separation relay circuit is turned on and the second phase separation relay circuit is turned off.
The power conversion control mode has a normal control mode and an abnormal control mode.

The first phase separation relay circuit is

In the inverter, n first phase separation relays connected between a node on the high side connecting the n legs of the inverter and n high side switch elements;

In the inverter, n second phase separation relays connected between a low side node connecting the n legs of the inverter and n low side switch elements;

Have

When one of the n legs of the inverter fails, in the control at the time of the abnormality,

The first phase separation relay connected to the failed leg of the inverter among the n first phase separation relays and the failed leg among the n second phase separation relays, The second phase separation relay is turned off, and the other n-1 first phase separation relays and the second phase separation relay are turned on,

Of the n third phase separation relays, the third phase separation relay connected to the other end of the winding connected to the failed leg is turned on, and the other n-1 third phase separations are performed. The power converter according to claim 4, wherein the relay is turned off.
The n-phase winding is energized using n-1 legs other than the failed leg of the n legs of the inverter and one leg of the sub-inverter. Power converter according to claim 1.
The power conversion control mode has a normal control mode and an abnormal control mode.

The first phase separation relay circuit is

In the inverter, n first phase separation relays connected between a node on the high side connecting the n legs of the inverter and n high side switch elements;

In the inverter, n second phase separation relays connected between a low side node connecting the n legs of the inverter and n low side switch elements;

Have

When one of the n legs of the inverter fails, in the control at the time of the abnormality,

The first phase separation relay connected to the failed leg of the inverter among the n first phase separation relays and the failed leg among the n second phase separation relays, The second phase separation relay is turned off, and the other n-1 first phase separation relays and the second phase separation relay are turned on,

The power converter according to claim 8, wherein the second phase separation relay circuit is turned on.
A winding connected to n-1 legs other than the failed leg of the n legs of the inverter and the failed leg of the inverter of the n legs of the sub-inverter The power converter according to claim 13, wherein the n-phase winding is energized using a leg connected to the other end.
Motor,

The power converter according to any one of claims 1 to 14,

A control circuit that controls the power converter;

Motor module having
An electric power steering apparatus comprising the motor module according to claim 15.