JPWO2019159836A1 - Power converter, drive and power steering - Google Patents

Abstract

One aspect of the power conversion device is a power conversion that converts power from a power source into power supplied to a motor having windings of each phase having a first winding portion and a second winding portion connected in series. The device controls a first inverter that applies a drive voltage to one end of the first winding portion, a second inverter that applies a drive voltage to one end of the second winding portion, and the first inverter. The first control unit, the second control unit that controls the second inverter, and the winding of each phase at any position from the other end of the first winding portion to the other end of the second winding portion. It is equipped with a neutral point switch that switches between connection and non-connection between wires.

Description

The present invention relates to a power converter, a drive device and a power steering device.

Conventionally, an inverter drive system that converts the electric power of a motor by two inverters is known. Further, there is also known an inverter drive system in which an inverter is connected to both ends of each winding of the motor to supply electric power independently to each winding.

For example, Patent Document 1 discloses a power conversion device having two inverter units. In Patent Document 1, a failure of the switching element is detected by the failure detecting means. Then, when a failure occurs in the switching element, the on / off operation control of the switching element is switched from the normal control to the failure control in order to continue driving the rotary electric machine (motor), and the rotary electric machine is driven.

Japanese Unexamined Patent Publication No. 2014-192950

In recent years, with respect to the power supply in the power converter, the drive device, and the power steering device, it is required to improve the continuity of the power supply by making the drive system including the power supply and the control circuit redundant in whole or in part. In particular, a device capable of continuing power supply on one side of two inverters when control or operation becomes impossible due to a failure in the drive system or the like is desired.

Therefore, the present invention provides a power conversion device, a drive device, and a power steering device capable of continuing power supply by the other inverter even when control or operation of one side of the two inverters becomes impossible. The purpose is to do.

One aspect of the power conversion device according to the present invention is to transfer power from a power source to power supplied to a motor having windings of each phase having a first winding portion and a second winding portion connected in series. A power conversion device for conversion, the first inverter that applies a drive voltage to one end of the first winding portion, the second inverter that applies a drive voltage to one end of the second winding portion, and the first The first control unit that controls the inverter, the second control unit that controls the second inverter, and the other end of the first winding portion to the other end of the second winding portion are described above. It is equipped with a neutral point switch that switches between connection and non-connection between windings of each phase. Further, one aspect of the drive device according to the present invention includes the power conversion device and a motor to which the power converted by the power conversion device is supplied.

Further, one aspect of the power steering device according to the present invention includes the power conversion device, a motor to which the power converted by the power conversion device is supplied, and a power steering mechanism driven by the motor.

According to the present invention, even if control or operation of one side of the two inverters becomes impossible, the power supply can be continued by the other inverter.

FIG. 1 is a diagram schematically showing a block configuration of a motor drive unit according to the present embodiment. FIG. 2 is a diagram schematically showing a circuit configuration of a motor drive unit according to the present embodiment. FIG. 3 is a diagram showing a current value flowing through each coil of each phase of the motor in a normal state. FIG. 4 is a diagram schematically showing a hardware configuration of the motor drive unit. FIG. 5 is a diagram schematically showing a hardware configuration of a motor drive unit according to a modified example of the present embodiment. FIG. 6 is a diagram showing a modified example in which the circuit structure is different. FIG. 7 is a diagram showing another modified example having a different circuit structure. FIG. 8 is a diagram showing a modified example in which a neutral point switch is adopted as the neutral point mechanism. FIG. 9 is a diagram showing a modified example in which the configuration of the control circuit is different. FIG. 10 is a diagram schematically showing a hardware configuration of a motor drive unit according to a modification shown in FIG. 9. FIG. 11 is a diagram schematically showing the configuration of the power steering device according to the present embodiment.

Hereinafter, embodiments of the power conversion device, drive device, and power steering device of the present disclosure will be described in detail with reference to the accompanying drawings. However, in order to avoid unnecessarily redundant explanations below and facilitate understanding by those skilled in the art, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters and duplicate explanations for substantially the same configuration may be omitted.

In the present specification, power from a power source is converted into power supplied to a three-phase motor having three-phase (U-phase, V-phase, W-phase) windings (sometimes referred to as "coils"). An embodiment of the present disclosure will be described by taking a power conversion device as an example. However, a power conversion device that converts power from a power source into 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. .. (Structure of Motor Drive Unit 1000) FIG. 1 is a diagram schematically showing a block configuration of a motor drive unit 1000 according to the present embodiment. The motor drive unit 1000 includes power supply devices 101 and 102, a motor 200, and control circuits 301 and 302.

In the present specification, the motor drive unit 1000 including the motor 200 as a component will be described. The motor drive unit 1000 including the motor 200 corresponds to an example of the drive device of the present invention. However, the motor drive unit 1000 may be a device for driving the motor 200, in which the motor 200 is omitted as a component. The motor drive unit 1000 from which the motor 200 is omitted corresponds to an example of the power conversion device of the present invention.

The first power supply device 101 includes a first inverter 111, a current sensor 401, and a voltage sensor 411. The second power supply device 102 includes a second inverter 112, a current sensor 402, and a voltage sensor 412.

The motor drive unit 1000 can convert the electric power from the power source (reference numerals 403 and 404 in FIG. 2) into the electric power supplied to the motor 200 by the two electric power supply devices 101 and 102. For example, the first and second inverters 111 and 112 can convert DC power into three-phase AC power which is a pseudo sine wave of U-phase, V-phase and W-phase.

The motor 200 is, for example, a three-phase AC motor. The motor 200 has U-phase, V-phase and W-phase coils. The winding method of the coil is, for example, concentrated winding or distributed winding. The coils of each phase have a first coil portion 201 and a second coil portion 202 that are connected in series with each other. However, the first coil portion 201 and the second coil portion 202 may be two of the three or more coil portions provided.

The first inverter 111 applies a drive voltage to one end of the first coil unit 201, and the second inverter 112 applies a drive voltage to one end of the second coil unit 202. The other ends of the first coil portion 201 and the second coil portion 202 are connected to each other, and the coils of each phase are connected to each other by the bus bar 120 at the connection point between the first coil portion 201 and the second coil portion 202. In the present specification, the "connection" between parts (components) means an electrical connection unless otherwise specified. The bus bar 120 corresponds to an example of a neutral point mechanism in which coils of each phase are connected at any position from the other end of the first coil portion 201 to the other end of the second coil portion 202.

The control circuits 301 and 302 include microcontrollers 341 and 342 and the like, as will be described in detail later. The control circuits 301 and 302 control the drive voltages of the first inverter 111 and the second inverter 112 based on the input signals from the current sensors 401 and 402 and the angle sensors 321 and 322. The specific drive voltage will be described later. As the control method of the inverters 111 and 112 by the control circuits 301 and 302, for example, a control method selected from vector control and direct torque control (DTC) is used. A specific circuit configuration of the motor drive unit 1000 will be described with reference to FIG. FIG. 2 is a diagram schematically showing a circuit configuration of the motor drive unit 1000 according to the present embodiment.

The motor drive unit 1000 is connected to a power source. The power supply includes an independent first power supply 403 and a second power supply 404, respectively. The power supplies 403 and 404 generate a predetermined power supply voltage (for example, 12V). As the power supplies 403 and 404, for example, a DC power supply is used. However, the power supplies 403 and 404 may be an AC-DC converter or a DC-DC converter, or may be a battery (storage battery). In FIG. 2, as an example, the first power supply 403 for the first inverter 111 and the second power supply 404 for the second inverter 112 are shown, but the motor drive unit 1000 is common to the first inverter 111 and the second inverter 112. May be connected to a single power supply. Further, the motor drive unit 1000 may have a power supply inside. The motor drive unit 1000 includes a first inverter 111, a second inverter 112, a motor 200, and control circuits 301 and 302.

The motor drive unit 1000 includes a first system corresponding to the first coil portion 201 side of the motor 200 and a second system corresponding to the second coil portion 202 side of the motor 200. The first system includes a first inverter 111 and a first control circuit 301. The second system includes a second inverter 112 and a second control circuit 302. The inverter 111 and the control circuit 301 of the first system are supplied with electric power from the first power supply 403. The inverter 112 and the control circuit 302 of the second system are supplied with electric power from the second power supply 404. Since the drive system including the power supply and the control circuit is made redundant including the power supply, the power supply is continued by the other system even when the power supply in one system is abnormal, as will be described later.

The first inverter 111 includes a bridge circuit having three legs. Each leg includes a high-side switch element connected between the power supply and the first coil portion 201 of the motor 200 and a low-side switch element connected between the first coil portion 201 of the motor 200 and the ground. Specifically, the U-phase leg includes a high-side switch element 113H and a low-side switch element 113L. The V-phase leg includes a high-side switch element 114H and a low-side switch element 114L. The W-phase leg includes a high-side switch element 115H and a low-side switch element 115L. As the switch element, for example, a field effect transistor (MOSFET or the like) or an insulated gate bipolar transistor (IGBT or the like) is used. When the switch element is an IGBT, a diode (freewheel) is connected in antiparallel to the switch element.

The first inverter 111 uses shunt resistors 113R, 114R, and 115R as current sensors 401 (see FIG. 1) for detecting currents flowing in the windings of the U-phase, V-phase, and W-phase, respectively. Prepare for each leg. The current sensor 401 includes a current detection circuit (not shown) that detects the current flowing through each shunt resistor. For example, a shunt resistor may be connected between the low side switch elements 113L, 114L and 115L and the ground. The resistance value of the shunt resistor is, for example, about 0.5 mΩ to 1.0 mΩ.

The number of shunt resistors may be other than three. For example, two shunt resistors 113R and 114R for U-phase and V-phase, two shunt resistors 114R and 115R for V-phase and W-phase, or two shunt resistors 113R and 115R for U-phase and W-phase are used. May be done. The number of shunt resistors used and the arrangement of shunt resistors are appropriately determined in consideration of product cost, design specifications, and the like.

The second inverter 112 includes a bridge circuit having three legs. Each leg of the second inverter 112 is a high-side switch element connected between the power supply and the second coil portion 202 of the motor 200, and a low-side switch connected between the second coil portion 202 of the motor 200 and the ground. It is equipped with an element. Specifically, the U-phase leg includes a high-side switch element 116H and a low-side switch element 116L. The V-phase leg includes a high-side switch element 117H and a low-side switch element 117L. The W-phase leg includes a high-side switch element 118H and a low-side switch element 118L. Like the first inverter 111, the second inverter 112 includes, for example, shunt resistors 116R, 117R and 118R.

See FIG. 1 again. The control circuits 301 and 302 include, for example, power supply circuits 311, 312, angle sensors 321 and 322, input circuits 331 and 332, microcontrollers 341 and 342, drive circuits 351 and 352, and ROMs 361 and 362. .. The control circuits 301 and 302 are connected to the power supply devices 101 and 102. Then, the control circuits 301 and 302 control the first inverter 111 and the second inverter 112.

The control circuits 301 and 302 can realize closed loop control by controlling the position (rotation angle), rotation speed, current, and the like of the target rotor. The rotation speed is obtained by, for example, time-differentiating the rotation angle (rad), and is represented by the rotation speed (rpm) at which the rotor rotates in a unit time (for example, 1 minute). The control circuits 301 and 302 can also control the target motor torque. The control circuits 301 and 302 may be provided with a torque sensor for torque control, but torque control is possible even if the torque sensor is omitted. Further, a sensorless algorithm may be provided instead of the angle sensor. Further, the two control circuits 301 and 302 synchronize their control operations with each other by performing control in synchronization with the rotation of the motor. The power supply circuits 311 and 312 generate DC voltages (for example, 3V and 5V) required for each block in the control circuits 301 and 302.

The angle sensors 321 and 322 are, for example, a resolver or a Hall IC. The angle sensors 321 and 322 are also realized by a combination of an MR sensor having a magnetoresistive (MR) element and a sensor magnet. The angle sensors 321 and 322 detect the rotation angle of the rotor of the motor 200, and output a rotation signal representing the detected rotation angle to the microcontrollers 341 and 342. Depending on the motor control method (for example, sensorless control), the angle sensors 321 and 322 may be omitted.

The voltage sensors 411 and 412 detect the voltage between each phase of the coil of the motor 200 at the connection points between the inverters 111 and 112 and the first coil unit 201 and the second coil unit 202, and input the detected voltage value into the input circuit 331. Output to 332.

The input circuits 331 and 332 receive the motor current value (hereinafter referred to as "actual current value") detected by the current sensors 401 and 402 and the voltage value detected by the voltage sensors 411 and 412. The input circuits 331 and 332 convert the actual current value and the voltage value level into the input levels of the microcontrollers 341 and 342 as needed, and output the actual current value and the voltage value to the microcontrollers 341 and 342. The input circuits 331 and 332 are analog-to-digital conversion circuits.

The microcontrollers 341 and 342 receive the rotation signal of the rotor detected by the angle sensors 321 and 322, and also receive the actual current value and the voltage value output from the input circuits 331 and 332. The microcontrollers 341 and 342 set a target current value according to the actual current value and the rotation signal of the rotor, generate a PWM signal, and output the generated PWM signal to the drive circuits 351 and 352. For example, the microcontrollers 341 and 342 generate a PWM signal for controlling the switching operation (turn-on or turn-off) of each switch element in the inverters 111 and 112 of the power supply devices 101 and 102.

Further, the microprocessors 341 and 342 can determine the control method for controlling the first inverter 111 and the second inverter 112 based on the received current value and voltage value.

The drive circuits 351 and 352 are typically gate drivers. The drive circuits 351 and 352 generate a control signal (for example, a gate control signal) for controlling the switching operation of each switch element in the first inverter 111 and the second inverter 112 according to the PWM signal, and generate the generated control signal for each switch element. Give to. Microcontrollers 341 and 342 may have the functions of drive circuits 351 and 352. In that case, the drive circuits 351 and 352 are omitted.

The ROMs 361 and 362 are, for example, a writable memory (for example, PROM), a rewritable memory (for example, a flash memory), or a read-only memory. The ROMs 361 and 362 store a control program including a group of instructions for causing the microprocessors 341 and 342 to control the power supply devices 101 and 102 (mainly the inverters 111 and 112). For example, the control program is temporarily expanded to RAM (not shown) at boot time. The control of the inverters 111 and 112 by the control circuits 301 and 302 (mainly the microprocessors 341 and 342) includes normal and abnormal control. Hereinafter, specific examples of the operation of the motor drive unit 1000 will be described, and specific examples of the operation of the inverters 111 and 112 will be mainly described.



(Control during normal operation)

A specific example of the normal control method of the inverters 111 and 112 will be described. Normal refers to a state in which both the two power supplies 403 and 404, the two inverters 111 and 112, and the two control circuits 301 and 302 operate correctly.

In the normal state, the control circuits 301 and 302 drive the motor 200 by controlling the three-phase energization using both the first inverter 111 and the second inverter 112. Specifically, the control circuits 301 and 302 perform three-phase energization control by switching control between the switch element of the first inverter 111 and the switch element of the second inverter 112.

Further, in the case of three-phase energization control, the control circuits 301 and 302 apply the drive voltage by the first inverter 111 and the second inverter 112 to the potential of the coil of each phase at the position where the coil of each phase of the motor 200 is connected to the bus bar 120. Control the drive voltage so that they have the same potential.

For example, focusing on the U-phase leg including the high-side switch elements 113H and 116H and the low-side switch elements 113L and 116L, the control circuits 301 and 302 can obtain a desired drive voltage for each of the high-side switch elements 113H and 116H. Switching control is performed by duty.

Specifically, when, for example, 6 V is required as the potential of the coil of each phase at the location connected to the bus bar 120, the control circuits 301 and 302 use the high side switch elements 113H and 116H at both ends of the coil of each phase. For example, switching control is performed with a duty at which driving voltages of 2V and 10V can be obtained. The potential difference between both ends of the coil changes according to the change in the current value flowing through the coil, but the potential of the coil of each phase at the position connected to the bus bar 120 is maintained at the common potential between the phases. However, if the potentials of the coils of each phase are the same as each other, the common potential may fluctuate with time.

In this way, the potentials of the coils of each phase at the points connected to the bus bar 120 become the same potentials, so that the same current as when the coils of each phase are insulated from each other flows through the coils of each phase. Become. That is, even if the coils of the respective phases are connected to each other by the bus bar 120, the currents of the respective phases flow independently, and the coils of the respective phases are prevented from being mixed with each other. Therefore, a switch for disconnecting the coils of each phase from each other is unnecessary. FIG. 3 is a diagram showing a current value flowing through each coil of each phase of the motor 200 in a normal state.

FIG. 3 plots the current values flowing through the U-phase, V-phase, and W-phase coils of the motor 200 when the first inverter 111 and the second inverter 112 are controlled according to the normal three-phase energization control. The obtained current waveform (sine wave) is illustrated. The horizontal axis of FIG. 3 indicates the motor electric angle (deg), and the vertical axis indicates the current value (A). I _pk represents the maximum current value (peak current value) of each phase. In addition to the sine wave illustrated in FIG. 3, the power supply devices 101 and 102 can also drive the motor 200 using, for example, a rectangular wave.

Table 1 shows the current values flowing through the terminals of each inverter for each electric angle in the sine wave of FIG. Specifically, Table 1 shows the current values at every 30 ° of electric angles flowing through the connection points between the first inverter 111 and the first coil portion 201 of the U-phase, V-phase, and W-phase coils. Table 1 shows the current values flowing at the connection points between the second inverter 112 and the second coil portion 202 of the U-phase, V-phase, and W-phase coils for each electric angle of 30 °. Here, with respect to the first inverter 111, the direction of the current flowing from the first coil portion 201 side to the second coil portion 202 side of the motor 200 is defined as a positive direction. Further, with respect to the second inverter 112, the direction of the current flowing from the second coil portion 202 side of the motor 200 to the first coil portion 201 side is defined as a positive direction. Therefore, the phase difference between the current of the first inverter 111 and the current of the second inverter 112 is 180 °. In Table 1, the magnitude of the current value _{I 1} is ^{[(3) 1/2} / 2] _* is _{I pk,} the magnitude of the current value _{I 2} is _{I pk} / 2.

At an electrical angle of 0 °, the U-phase coil has a current of "0". _{At an electric angle of 0 °, a current of magnitude I 1} flows from the second inverter 112 to the first inverter 111 in the V-phase coil, and a magnitude I 1 flows from the first inverter 111 to the second inverter 112 in the W-phase coil. ₁ current flows.

_{At an electric angle of 30 °, a current of magnitude I 2} flows from the first inverter 111 to the second inverter 112 in the U-phase coil, and a magnitude I 2 flows from the second inverter 112 to the first inverter 111 in the V-phase coil. _{A current of pk flows, and a current of magnitude I 2} flows from the first inverter 111 to the second inverter 112 in the W-phase coil.

_{At an electric angle of 60 °, a current of magnitude I 1} flows from the first inverter 111 to the second inverter 112 in the U-phase coil, and a magnitude I 1 flows from the second inverter 112 to the first inverter 111 in the V-phase coil. ₁ current flows. At an electric angle of 60 °, the current of the W-phase coil becomes “0”.

_{At an electric angle of 90 °, a current of magnitude I pk} flows from the first inverter 111 to the second inverter 112 in the U-phase coil, and a magnitude I pk from the second inverter 112 to the first inverter 111 in the V-phase coil. _{The current of 2 flows, and the current of magnitude I 2} flows from the second inverter 112 to the first inverter 111 in the W-phase coil.

_{At an electric angle of 120 °, a current of magnitude I 1} flows from the first inverter 111 to the second inverter 112 in the U-phase coil, and a magnitude I 1 flows from the second inverter 112 to the first inverter 111 in the W-phase coil. ₁ current flows. At an electric angle of 120 °, the current of the V-phase coil becomes “0”.

_{At an electric angle of 150 °, a current of magnitude I 2} flows from the first inverter 111 to the second inverter 112 in the U-phase coil, and a magnitude I 2 flows from the first inverter 111 to the second inverter 112 in the V-phase coil. _{A current of 2 flows, and a current of magnitude I pk} flows from the second inverter 112 to the first inverter 111 in the W-phase coil.

At an electric angle of 180 °, the current of the U-phase coil becomes “0”. _{At an electric angle of 180 °, a current of magnitude I 1} flows from the first inverter 111 to the second inverter 112 in the V-phase coil, and a magnitude I 1 flows from the second inverter 112 to the first inverter 111 in the W-phase coil. ₁ current flows.

_{At an electric angle of 210 °, a current of magnitude I 2} flows from the second inverter 112 to the first inverter 111 in the U-phase coil, and a magnitude I 2 flows from the first inverter 111 to the second inverter 112 in the V-phase coil. _{A current of pk flows, and a current of magnitude I 2} flows from the second inverter 112 to the first inverter 111 in the W-phase coil.

_{At an electric angle of 240 °, a current of magnitude I 1} flows from the second inverter 112 to the first inverter 111 in the U-phase coil, and a magnitude I 1 flows from the first inverter 111 to the second inverter 112 in the V-phase coil. ₁ current flows. At an electric angle of 240 °, the current of the W-phase coil becomes “0”.

_{At an electric angle of 270 °, a current of magnitude I pk} flows from the second inverter 112 to the first inverter 111 in the U-phase coil, and a magnitude I pk from the first inverter 111 to the second inverter 112 in the V-phase coil. _{The current of 2 flows, and the current of magnitude I 2} flows from the first inverter 111 to the second inverter 112 in the W-phase coil.

_{At an electric angle of 300 °, a current of magnitude I 1} flows from the second inverter 112 to the first inverter 111 in the U-phase coil, and a magnitude I 1 flows from the first inverter 111 to the second inverter 112 in the W-phase coil. ₁ current flows. At an electric angle of 300 °, the current of the V-phase coil becomes “0”.

_{At an electric angle of 330 °, a current of magnitude I 2} flows from the second inverter 112 to the first inverter 111 in the U-phase coil, and a magnitude I 2 flows from the second inverter 112 to the first inverter 111 in the V-phase coil. _{A current of 2 flows, and a current of magnitude I pk} flows from the first inverter 111 to the second inverter 112 in the W-phase coil.

In the current waveform shown in FIG. 3, the total sum of the currents flowing through the three-phase coils in consideration of the direction of the current is "0" for each electric angle. However, according to the circuit configurations of the power supply devices 101 and 102, the current flowing through the three-phase coils is controlled independently. Therefore, the control circuits 301 and 302 can also control the total current to be a value other than "0". (Control at the time of abnormality) A specific example of the control method of the first inverter 111 and the second inverter 112 at the time of abnormality will be described.

The abnormality refers to a state in which one or more of the two power supplies 403 and 404, the two inverters 111 and 112, and the two control circuits 301 and 302 have failed. The abnormalities are roughly classified into the abnormalities of the first system and the abnormalities of the second system. The abnormalities of each system include an abnormality due to a failure of the inverters 111 and 112 and an abnormality in the upstream portion including the power supplies 403 and 404 and the control circuits 301 and 302.

"Upstream abnormality" is controlled according to an abnormality of power supplies 403 and 404 only, an abnormality of control circuits 301 and 302 only, an abnormality of both power supplies 403 and 404 and control circuits 301 and 302, and an abnormality of power supplies 403 and 404. The circuits 301 and 302 also include various abnormal states such as a state in which the operation is stopped. Failures of the inverters 111 and 112 include disconnection, short circuit, and failure of the switch element in the inverter circuit.

As a control method in the event of an abnormality due to a failure of the inverters 111 and 112, for example, the control method described in Japanese Patent Application Laid-Open No. 2014-192950 is used. In the following, a control method at the time of abnormality in the upstream portion will be described.

As an example of abnormality detection, the control circuits 301 and 302 (mainly the microcontrollers 341 and 342) analyze the voltage value detected by the voltage sensors 411 and 412 and the actual current value detected by the current sensors 401 and 402. This detects an abnormality in the other system with respect to the system to which the self belongs among the two systems.

The control circuits 301 and 302 can confirm the behavior of the inverters 111 and 112 on the other side via the voltage sensors 411 and 412 and the current sensors 401 and 402 under their control. Specifically, the voltage at the connection point between the inverters 111 and 112 under one's control and the motor 200 affects not only the behavior of the inverters 111 and 112 on the own side but also the behavior of the inverters 111 and 112 on the other side. Be affected. Further, the current flowing from the lower arm of the inverters 111 and 112 under one's control to the ground is also affected not only by the behavior of the inverters 111 and 112 on the own side but also by the behavior of the inverters 111 and 112 on the other side. .. The voltage sensors 411 and 412 detect the voltage affected as described above at the connection point, and the current sensors 401 and 402 detect the current affected as described above by the shunt resistors 113R, ..., 118R in FIG. To do.

As another example of abnormality detection, the microprocessors 341 and 342 can also detect an abnormality by analyzing the difference between the actual current value of the motor and the target current value. However, the control circuits 301 and 302 are not limited to these methods, and known methods related to abnormality detection can be widely used.

Control circuit 301,
When the microcontrollers 341 and 342 detect an abnormality, the 302 switches the control of the inverters 111 and 112 from the normal control to the abnormal control. For example, the timing for switching the control from the normal time to the abnormal time is about 10 msec to 30 msec after the abnormality is detected.

When an abnormality occurs, the control circuits 301 and 302 use only their own inverters 111 and 112 to perform drive control using the bus bar 120 as a neutral point. For example, when the first control circuit 301 detects an abnormality, the first control circuit 301 energizes the first coil portion 201 of the coil of the motor 200 by controlling the first inverter 111 for three-phase energization.

As described above, in the normal state, the potential at each location where each coil is connected to the bus bar 120 is controlled to a common potential in order to avoid mixing the currents of the coils of each phase via the bus bar 120. Therefore, the bus bar 120 connects the coils of each phase even in the normal state, and it is not necessary to change the connection between the coils even in the transition to the abnormal time.

When the first control circuit 301 detects an abnormality, it means that an abnormality has occurred in the second system. When the abnormality of the second system is an abnormality of the upstream portion, the second inverter 112 is in an inoperable or uncontrollable state. Even in such a case, since the bus bar 120 can be used as a neutral point, the power supply to the motor 200 is continued by the inverter 111 on the first system side.

When the second control circuit 302 detects an abnormality, the second control circuit 302 energizes the second coil portion 202 of the coil of the motor 200 by controlling the second inverter 112 for three-phase energization.

When the second control circuit 302 detects an abnormality, it means that an abnormality has occurred in the first system. When the abnormality of the first system is an abnormality of the drive system, the first inverter 111 is in an inoperable or uncontrollable state. Even in such a case, since the bus bar 120 can be used as a neutral point, the power supply to the motor 200 is continued by the inverter 112 on the second system side.

In the present embodiment, each switch included in the first inverter 111 is a switch that is naturally turned off when the control by the first control circuit 301 is lost, and each switch included in the second inverter 112 is , It is a switch that is naturally turned off when the control by the second control circuit 302 is lost. By using such a switch for the inverters 111 and 112, when one of the control circuits 301 and 302 fails, the inverters 111 and 112 on the failed side are naturally electrically disconnected from the coil of the motor.

As a specific three-phase energization control in the event of an abnormality, the control circuits 301 and 302 perform switching operations in the switching elements of the inverters 111 and 112 by PWM control so as to obtain a waveform similar to the current waveform shown in FIG. 3, for example. To control.

Table 2 shows the current values flowing through the terminals of the second inverter 112 for each electrical angle when, for example, the second inverter 112 is controlled by three-phase energization control so as to obtain a waveform similar to the current waveform shown in FIG. Illustrate to. Specifically, Table 2 shows the current values flowing at the connection points between the second inverter 112 and the second coil portions 202 of each of the U phase, the V phase, and the W phase for each electric angle of 30 °. The definition of the current direction is as described above.

_{For example, at an electric angle of 30 °, a current of magnitude I 2} flows from the first inverter 111 to the second inverter 112 in the U-phase coil, and a large current flows from the second inverter 112 to the first inverter 111 in the V-phase coil. A current of I _{pk flows, and a current of magnitude I 2} flows from the first inverter 111 to the second inverter 112 in the W-phase coil. _{At an electric angle of 60 °, a current of magnitude I 1} flows from the first inverter 111 to the second inverter 112 in the U-phase coil, and a magnitude I 1 flows from the second inverter 112 to the first inverter 111 in the V-phase coil. ₁ current flows. At an electric angle of 60 °, the current of the W-phase coil becomes “0”. The sum of the current flowing into the neutral point and the current flowing out from the neutral point is always "0" for each electric angle.

As shown in Tables 1 and 2, the motor current flowing through the motor 200 during normal and abnormal control is the same for each electrical angle. However, since the current flows through only one of the first coil unit 201 and the second coil unit 202 at the time of abnormality, the motor torque at the time of abnormality is smaller than the motor torque at the time of normal operation.

When the abnormal location at the time of abnormality is one switch element in the inverters 111 and 112, for example, the neutralization of the inverters 111 and 112 by the control method described in Japanese Patent Application Laid-Open No. 2014-192950 can be performed. It is possible. However, in order to realize this control method, a special gate driver in which the voltage of the control signal is different from that in the normal state is required. In contrast to such a control method, the control in which the bus bar 120 is used as the neutral point can be executed with a control signal having the same voltage as in the normal state, so that a special gate driver is not required.

Further, since it is desirable to avoid the use of the inverters 111 and 112 including the failed switch element, the control in which the bus bar 120 is used as the neutral point is superior in this respect as well.



(Hardware configuration of motor drive unit 1000)



Next, the hardware configuration of the motor drive unit 1000 will be described. FIG. 4 is a diagram schematically showing a hardware configuration of the motor drive unit 1000.

The motor drive unit 1000 includes the above-mentioned motor 200, a first mounting board 1001, a second mounting board 1002, a housing 1003, and connectors 1004 and 1005 as hardware configurations.

From the motor 200, one end 210 of the first coil portion 201 and one end 220 of the second coil portion 202 extend toward the protruding mounting substrates 1001 and 1002. Both one end 210 of the first coil portion 201 and one end 220 of the second coil portion 202 are connected to one of the first mounting board 1001 and the second mounting board 1002, and are connected to one end 210 of the first coil portion 201. Both one end 220 of the second coil portion 202 penetrates one of the first mounting board 1001 and the second mounting board 1002 and is connected to the other. Specifically, both one end 210 of the first coil portion 201 and one end 220 of the second coil portion 202 are connected to, for example, the second mounting board 1002. Further, both one end 210 of the first coil portion 201 and one end 220 of the second coil portion 202 penetrate the second mounting board 1002 and are connected to the first mounting board 1001.

The other end 230 of the first coil portion 201 and the other end 240 of the second coil portion 202 also protrude from the motor 200. The other end 230 of the first coil portion 201 is connected to the other end 240 of the second coil portion 202, and the connection points of the respective phases are connected to each other by the bus bar 120. In an embodiment of the drive device of the present invention, the bus bar 120 may be provided inside the motor 200 or may be provided on the output side (lower side of FIG. 4) of the motor 200. When the neutral point mechanism is the bus bar 120, the degree of freedom in arranging the neutral point mechanism is high, and by extension, the degree of freedom in designing the drive device is high.

The board surfaces of the first mounting board 1001 and the second mounting board 1002 face each other. The rotation axis of the motor 200 extends in the direction in which the substrate surfaces face each other. The positions of the first mounting board 1001, the second mounting board 1002, and the motor 200 are fixed to each other by being housed in the housing 1003.

A connector 1004 to which the power cord from the first power supply 403 is connected is attached to the first mounting board 1001. A connector 1005 to which the power cord from the second power supply 404 is connected is attached to the second mounting board 1002.

The first inverter 111 is mounted on the first mounting board 1001, and the second inverter 112 is mounted on the second mounting board 1002. By distributing such elements to the two mounting boards 1001 and 1002, the wiring of the inverters 111 and 112 to the one end 210 of the first coil portion 201 and the one end 220 of the second coil portion 202 is simplified and an efficient element is used. Arrangement is possible.

The first control circuit 301 is also mounted on the first mounting board 1001. The second control circuit 302 is also mounted on the second mounting board 1002. Since the control circuits 301 and 302 are mounted on the same mounting board as the element to be controlled by the control circuits 301 and 302, the wiring for control is housed in the board. Therefore, efficient element arrangement is possible.

When viewed in the opposite directions of the first mounting board 1001 and the second mounting board 1002, the first inverter 111 on the first mounting board 1001 and the second inverter 112 on the second mounting board 1002 are arranged symmetrically with each other. Is. Further, when viewed in the opposite directions of the first mounting board 1001 and the second mounting board 1002, the control circuit 301 on the first mounting board 1001 and the control circuit 302 on the second mounting board 1002 are arranged symmetrically with each other. Is. With such a symmetrical arrangement, the board design can be standardized for the two mounting boards 1001 and 1002. (Modification Example) FIG. 5 is a diagram schematically showing a hardware configuration of the motor drive unit 1000 according to the modification of the present embodiment.

The modified example shown in FIG. 5 is an example of a neutral point mechanism in which the coils of each phase are connected at any position from the other end 230 of the first coil portion 201 to the other end 240 of the second coil portion 202. , A neutral point circuit 125 provided on the substrate is provided. Specifically, the neutral point circuit 125 is formed on the second mounting board 1002 by a wiring pattern. The neutral point circuit 125 may be formed on the first mounting board 1001, or may be formed on a board different from the first mounting board 1001 and the second mounting board 1002. When the neutral point mechanism is a neutral point circuit on the substrate, the neutral point mechanism is formed outside the motor 200, so that the motor 200 can be miniaturized. Further, when the neutral point mechanism is a neutral point circuit on the substrate, the first one is similar to the connection to the mounting substrates 1001 and 1002 at one end 210 of the first coil portion 201 and the one end 220 of the second coil portion 202. Since the other end 230 of the coil portion 201 and the other end 240 of the second coil portion 202 are connected to the neutral point circuit 125, the assembly process is facilitated.

The neutral point mechanism may have a structure other than the bus bar and the neutral point circuit. As long as it is connected as a neutral point mechanism, for example, a structure in which the leader wires of the coils are welded to each other may be used. FIG. 6 is a diagram showing a modified example in which the circuit structure is different.

In the modified example shown in FIG. 6, a first open relay 131 is provided between one end of the first coil portion 201 and the first inverter 111, and a second open relay 131 is provided between one end of the second coil portion 202 and the second inverter 112. Two open relays 132 are provided. The first open relay 131 switches between connection and non-connection between one end of the first coil unit 201 and the first inverter 111. The second open relay 132 switches between connection and non-connection between one end of the second coil portion 202 and the second inverter 112. Further, the first control circuit 301 controls the first inverter 111 and the first open relay 131, and the second control circuit 302 controls the second inverter 112 and the second open relay 132.

The open relays 131 and 132 are naturally turned off when the control signal is stopped. By providing the open relays 131 and 132, the inverters 111 and 112 of the system in which the abnormality has occurred are separated from the motor 200. As a result, power loss is suppressed. Further, by sharing the control of the inverters 111 and 112 and the open relays 131 and 132 by the two control circuits 301 and 302, even if one of the control circuits 301 and 302 has an abnormality, the other control circuit The power supply can be continued by 301 and 302. FIG. 7 is a diagram showing another modified example having a different circuit structure.

In the modified example shown in FIG. 7, two bus bars 121 and 122 are used as a neutral point mechanism in which the coils of each phase are connected at any position from the other end of the first coil portion 201 to the other end of the second coil portion 202. Is provided. The first bus bar 121 connects the other ends of each phase of the first coil portion 201. The second bus bar 122 connects the other ends of each phase of the second coil portion 202. Between the first bus bar 121 and the second bus bar 122, intermediate open relays 133 and 134 for switching connection / non-connection between the other end of the first coil portion 201 and the other end of the second coil portion 202 are provided. Be done. Although one intermediate open relay may be used, in the modified example shown in FIG. 7, the first intermediate open relay 133 on the first inverter 111 side and the first intermediate open relay 112 side connected to each other as intermediate open relays are connected in series. Two intermediate open relays 134 are provided.

When the intermediate open relays 133 and 134 are turned on, the first coil portion 201 and the second coil portion 202 are connected in series. Therefore, the circuit structure shown in FIG. 7 is electrically equivalent to the circuit structure shown in FIG. Become. In the event of an abnormality, the first coil portion 201 and the second coil portion 202 are separated by the intermediate open relays 133 and 134. As a result, power loss is suppressed.

Even in the case of the modification shown in FIG. 7, under normal conditions, the potential of the coils of each phase at the location connected to the bus bar 120 is maintained at the common potential between the phases, and the currents are mixed between the coils of each phase. Is prevented. As a result, even in the case of the modified example shown in FIG. 7, a switch for switching the connection state between the coils between the normal state and the abnormal time is unnecessary.

In the modified example shown in FIG. 7, the first control circuit 301 controls the first inverter 111 and the first intermediate open relay 133, and the second control circuit 302 has the second inverter 112 and the second intermediate open relay 134. To control. By sharing the control of the inverters 111 and 112 and the intermediate open relays 133 and 134 by the two control circuits 301 and 302, even if one of the control circuits 301 and 302 has an abnormality, the other control circuit 301 , 302 enables the continuation of power supply.

As the neutral point mechanism, in addition to the neutral point connection connected as in the bus bar 120 shown in FIG. 4 and the neutral point circuit 125 shown in FIG. 5, the coils can be switched between connection and non-connection. A gender switch may be adopted. FIG. 8 is a diagram showing a modified example in which a neutral point switch is adopted as the neutral point mechanism.

In the modified example shown in FIG. 8, the neutrality of switching the connection / non-connection between the windings (coils) of each phase at any position from the other end of the first coil portion 201 to the other end of the second coil portion 202. As a point switch, a neutral point switch 127 composed of three switch elements is provided. Such a neutral point switch 127 is opened at the time of normal operation to disconnect the coils of the motor, and is closed at the time of abnormality described above to connect the coils of the motor. Therefore, under normal conditions, even if the coils of the motor 200 are controlled to have different potentials, current leakage between the coils is prevented and the degree of freedom of control is high. Further, in the event of an abnormality, the motor 200 can continue to be driven by one of the normal first system and the second system, which functions in the same manner as the above-mentioned neutral point connection.

The other end of the first coil portion 201 and the other end of the second coil portion 202 are connected to each other by a conducting wire. Therefore, the other end of the first coil portion 201 and the other end of the second coil portion 202 are always conductive in the same phase. Therefore, the separation switch that separates the first coil portion 201 and the second coil portion 202 is omitted, and the circuit configuration is simple.

Control signals are input to the neutral point switch 127 from both of the two control circuits 301 and 302, and the neutral point switch 127 can be controlled by only one of these control signals. That is, the neutral point switch 127 can be controlled by each of the first control circuit 301 and the second control circuit 302. With such control, the neutral point switch 127 can be controlled even if one of the two control circuits 301 and 302 fails. FIG. 9 shows a modified example in which the configuration of the control circuit is different.

In the modified example shown in FIG. 9, a third control circuit 303 for controlling the neutral point switch 127 is provided. Since the control circuits 301 and 302 for controlling the inverters 111 and 112 and the control circuit 303 for controlling the neutral point switch 127 are separate, the control of the neutral point switch is simplified. FIG. 10 is a diagram schematically showing a hardware configuration of the motor drive unit 1000 according to the modified example shown in FIG.

The neutral point switch 127 is provided on the second mounting board 1002, for example, and a third control circuit 303 for controlling the neutral point switch 127 is also provided on the second mounting board 1002. The neutral point switch 127 may be formed on the first mounting board 1001, or may be formed on a board different from the first mounting board 1001 and the second mounting board 1002. Further, it is preferable that the neutral point switch 127 and the third control circuit 303 are provided on the same mounting board because wiring and the like are simplified, but they may be provided on separate boards.



(Embodiment of Power Steering Device)

Vehicles such as automobiles are generally equipped with a power steering device. The power steering device generates an auxiliary torque for assisting the steering torque of the steering system generated by the driver operating the steering handle. The auxiliary torque is generated by the auxiliary torque mechanism, and the burden on the driver's operation can be reduced. For example, the auxiliary torque mechanism includes a steering torque sensor, an ECU, a motor, a deceleration mechanism, and the like. The steering torque sensor detects the steering torque in the steering system. The ECU generates a drive signal based on the detection signal of the steering torque sensor. The motor generates an auxiliary torque according to the steering torque based on the drive signal, and transmits the auxiliary torque to the steering system via the reduction mechanism.

The motor drive unit 1000 of the above embodiment is suitably used for a power steering device. FIG. 11 is a diagram schematically showing the configuration of the power steering device 2000 according to the present embodiment. The electric power steering device 2000 includes a steering system 520 and an auxiliary torque mechanism 540.

The steering system 520 is, for example, a steering handle 521, a steering shaft 522 (also referred to as a "steering column"), free shaft joints 523A, 523B, and a rotating shaft 524 (also referred to as a "pinion shaft" or "input shaft"). ) Is provided.

The steering system 520 includes, for example, a rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A and 552B, tie rods 527A and 527B, knuckles 528A and 528B, and left and right steering wheels (for example, left and right front wheels) 529A. It is equipped with 529B.

The steering handle 521 is connected to the rotating shaft 524 via the steering shaft 522 and the universal shaft joints 523A and 523B. A rack shaft 526 is connected to the rotating shaft 524 via a rack and pinion mechanism 525. The rack and pinion mechanism 525 has a pinion 531 provided on the rotating shaft 524 and a rack 532 provided on the rack shaft 526. The right steering wheel 529A is connected to the right end of the rack shaft 526 via a ball joint 552A, a tie rod 527A, and a knuckle 528A in this order. Similar to the right side, the left steering wheel 529B is connected to the left end of the rack shaft 526 via a ball joint 552B, a tie rod 527B and a knuckle 528B in this order. Here, the right side and the left side correspond to the right side and the left side as seen from the driver sitting in the seat, respectively.

According to the steering system 520, steering torque is generated when the driver operates the steering handle 521, and is transmitted to the left and right steering wheels 529A and 259B via the rack and pinion mechanism 525. As a result, the driver can operate the left and right steering wheels 529A and 529B.

The auxiliary torque mechanism 540 includes, for example, a steering torque sensor 541, an ECU 542, a motor 543, a speed reduction mechanism 544, and a power supply device 545. The auxiliary torque mechanism 540 applies auxiliary torque to the steering system 520 from the steering handle 521 to the left and right steering wheels 529A and 259B. The auxiliary torque is sometimes referred to as "additional torque".

As the ECU 542, for example, the control circuits 301 and 302 shown in FIG. 1 and the like are used. Further, as the power supply device 545, for example, the power supply devices 101 and 102 shown in FIG. 1 and the like are used. Further, as the motor 543, for example, the motor 200 shown in FIG. 1 or the like is used. When the ECU 542, the motor 543, and the power supply device 545 form a unit generally referred to as a "mechanical-electric integrated motor", the unit has, for example, the hardware configuration shown in FIGS. The motor drive unit 1000 is preferably used. Among the elements shown in FIG. 11, the mechanism composed of the elements excluding the ECU 542, the motor 543, and the power supply device 545 corresponds to an example of the power steering mechanism driven by the motor 543.

The steering torque sensor 541 detects the steering torque of the steering system 520 applied by the steering handle 521. The ECU 542 generates a drive signal for driving the motor 543 based on a detection signal (hereinafter referred to as "torque signal") from the steering torque sensor 541. The motor 543 generates an auxiliary torque according to the steering torque based on the drive signal. The auxiliary torque is transmitted to the rotating shaft 524 of the steering system 520 via the reduction mechanism 544. The reduction mechanism 544 is, for example, a worm gear mechanism. Auxiliary torque is further transmitted from the rotating shaft 524 to the rack and pinion mechanism 525.

The power steering device 2000 is classified into a pinion assist type, a rack assist type, a column assist type, and the like, depending on where the auxiliary torque is applied to the steering system 520. FIG. 11 shows a pinion-assisted power steering device 2000. However, the power steering device 2000 is also applied to a rack assist type, a column assist type, and the like.

Not only a torque signal but also, for example, a vehicle speed signal can be input to the ECU 542. The microcontroller of the ECU 542 can vector-control or PWM-control the motor 543 based on a torque signal, a vehicle speed signal, or the like.

The ECU 542 sets the target current value at least based on the torque signal. It is preferable that the ECU 542 sets the target current value in consideration of the vehicle speed signal detected by the vehicle speed sensor and further in consideration of the rotation signal of the rotor detected by the angle sensor. The ECU 542 can control the drive signal of the motor 543, that is, the drive current so that the actual current value detected by the current sensor (see FIG. 1) matches the target current value.

According to the power steering device 2000, the left and right steering wheels 529A and 529B can be operated by the rack shaft 526 by utilizing the combined torque obtained by adding the auxiliary torque of the motor 543 to the steering torque of the driver. In particular, by using the motor drive unit 1000 of the above-described embodiment for the above-mentioned mechanical / electrical integrated motor, appropriate current control can be performed in both normal and abnormal times. As a result, the power assist in the power steering device is continued in both the normal state and the abnormal time.

Here, a power steering device is mentioned as an example of the usage in the power conversion device and the drive device of the present invention, but the usage method of the power conversion device and the drive device of the present invention is not limited to the above, and the pump and the compressor It can be used in a wide range.

The embodiments and modifications described above should be considered exemplary in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims.

Claims (8)

A power conversion device that converts electric power from a power source into electric power supplied to a motor having windings of each phase having a first winding portion and a second winding portion connected in series.



A first inverter that applies a drive voltage to one end of the first winding portion,



A second inverter that applies a drive voltage to one end of the second winding portion,



The first control unit that controls the first inverter and



A second control unit that controls the second inverter,



A neutral point switch that switches between connection and non-connection between the windings of each phase at any position from the other end of the first winding portion to the other end of the second winding portion.



A power converter equipped with. The power conversion device according to claim 1, wherein the other end of the first winding portion and the other end of the second winding portion are always conductive in the same phase. Each switch included in the first inverter is a switch that is turned off when the control by the first control unit is lost.



The power conversion device according to claim 2, wherein each switch included in the second inverter is a switch that is turned off when the control by the second control unit is lost. The power conversion device according to any one of claims 1 to 3, wherein the neutral point switch is controllable by each of the first control unit and the second control unit. The power conversion device according to any one of claims 1 to 3, further comprising a third control unit that controls the neutral point switch. The first inverter and the first control unit are supplied with electric power from the first power source.



The power conversion device according to any one of claims 1 to 5, wherein power is supplied from the second power source to the second inverter and the second control unit. The power conversion device according to any one of claims 1 to 6.



A motor to which the electric power converted by the electric power converter is supplied, and



A drive device equipped with. The power conversion device according to any one of claims 1 to 6.



A motor to which the electric power converted by the electric power converter is supplied, and



The power steering mechanism driven by the motor and



An electric power steering device equipped with.

Images