WO2019150911A1 - Power conversion device, drive device, and power steering device - Google Patents

Abstract

Provided are a power conversion device with which it is possible, when one of two inverters has become inoperable due to abnormality in a drive system, to allow the one side to function as a neutral point, a drive device, and a power steering device. The power conversion device is provided with: a first inverter which is connected to one ends of windings; a second inverter connected to the other ends thereof; a first neutral point relay circuit which is connected to the one ends of the windings in parallel to the first inverter, and which switches connection/non-connection between the one ends; a second neutral point relay circuit which is connected to the other ends of the windings in parallel to the second inverter, and which switches connection/non-connection between the other ends; a first control circuit which controls the first inverter and the second neutral point relay circuit; and a second control circuit which controls the second inverter and the first neutral point relay circuit.

Description

Power conversion device, drive device, and power steering device

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

Conventionally, an inverter drive system that converts electric power of a motor by two inverters is known. There is also known an inverter driving system of a type in which an inverter is connected to each end of each winding of the motor and power is independently supplied to each winding. *

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

JP 2014-192950 A

In recent years, regarding power supply in a power conversion device, a drive device, and a power steering device, it is required to improve the continuity of power supply by making all or part of a drive system including a power supply and a control circuit redundant. In particular, in the above-described system in which power is supplied independently to each winding of the motor, there is a case where a mechanism is desired in which one of the two inverters functions as a neutral point when an abnormality occurs in one of the two inverters in order to continue power supply. is there. *

However, there has been no disclosure in the past regarding a specific configuration that allows one side of the inverter to function as a neutral point even when the drive system is abnormal. In this specification, “drive system abnormality” refers to various abnormalities such as an abnormality in the power supply only, an abnormality in the control circuit alone, an abnormality in both the power supply and the control circuit, and a state in which the control unit is stopped due to the power supply abnormality. Includes abnormal conditions. *

The present invention provides a power conversion device, a drive device, and a power steering device that can cause one of the two inverters to function as a neutral point even when one of the two inverters becomes inoperable due to an abnormality in the drive system. For the purpose.

One aspect of a power conversion device according to the present invention is a power conversion device that converts power from a power source into power supplied to a motor having n-phase (n is an integer of 3 or more) windings. A first inverter connected to one end of the wire, a second inverter connected to the other end with respect to the one end, connected to the one end of the winding in parallel with the first inverter, and the connection between the one end A first neutral point relay circuit for switching connection and a second neutral point connected to the other end of the winding in parallel with the second inverter and switching connection / disconnection between the other ends. A relay circuit; a first control circuit that controls the first inverter and the second neutral relay circuit; and a second control circuit that controls the second inverter and the first neutral relay circuit. . Also, an aspect of the drive device according to the present invention includes the power conversion device and a motor to which power converted by the power conversion device is supplied. *

Moreover, one aspect of the power steering device according to the present invention is driven by the power converter, a motor connected to the power converter and supplied with power converted by the power converter, and the motor. A power steering mechanism.

According to the present invention, even when one of the two inverters becomes inoperable due to an abnormality in the drive system, the one side can function as a neutral point.

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 the motor drive unit according to the present embodiment. FIG. 3 is a diagram showing current values flowing in the coils of the respective phases of the motor in a normal state. FIG. 4 is a diagram schematically illustrating a hardware configuration of the motor drive unit. FIG. 5 is a diagram schematically illustrating a hardware configuration of the first mounting board and the second mounting board. FIG. 6 is a diagram schematically illustrating a hardware configuration of a mounting board according to a modification of the present embodiment. FIG. 7 is a diagram schematically illustrating a hardware configuration of a mounting board according to another modification of the present embodiment. FIG. 8 is a diagram schematically showing the configuration of the power steering apparatus according to the present embodiment.

Hereinafter, embodiments of a power conversion device, a drive device, and a power steering device of the present disclosure will be described in detail with reference to the accompanying drawings. However, in order to avoid the following description from being unnecessarily redundant and to facilitate understanding by those skilled in the art, a more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. *

In this specification, electric power from a power source is converted into electric 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 using 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 an n-phase winding (n is an integer of 4 or more) such as four-phase or five-phase is also included in the scope of the present disclosure. . (Structure of Motor Drive Unit 1000) FIG. 1 is a diagram schematically showing a block configuration of the motor drive unit 1000 according to the present embodiment. The motor drive unit 1000 includes power supply apparatuses 101 and 102, a motor 200, and control circuits 301 and 302. *

In this specification, a motor driving unit 1000 including a 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 an apparatus for driving the motor 200 that does not include the motor 200 as a component. The motor drive unit 1000 that does not include the motor 200 corresponds to an example of the power conversion device of the present invention. *

The first power supply apparatus 101 includes a first inverter 111, a second neutral point relay circuit 121, a current sensor 401, and a voltage sensor 411. The second power supply apparatus 102 includes a second inverter 112, a first neutral point relay circuit 122, a current sensor 402 and a voltage sensor 412. *

The motor drive unit 1000 can convert the power from the power source ( reference numerals 403 and 404 in FIG. 2) to the power to be supplied to the motor 200 by the two 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 that is a pseudo sine wave of U phase, V phase, and W phase. *

The first inverter 111 is connected to one end 210 of the coil of the motor 200, and the second inverter 112 is connected to the other end 220 of the coil of the motor 200. In this specification, “connection” between components (components) means electrical connection unless otherwise specified. *

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 control circuits 301 and 302 include microcontrollers 341 and 342, as will be described in detail later. The first control circuit 301 controls the first power supply apparatus 101 based on input signals from the current sensor 401 and the angle sensor 321. In addition, the second control circuit 302 controls the second power supply apparatus 102 based on input signals from the current sensor 402 and the angle sensor 322. As a control method of the power supply devices 101 and 102 in 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. However, FIG. 2 mainly shows the circuit configuration of the power supply apparatuses 101 and 102. *

The motor drive unit 1000 is connected to a power source. The power supply includes a first power supply 403 and a second power supply 404 that are independent of each other. The power supplies 403 and 404 generate a predetermined power supply voltage (for example, 12V). For example, a DC power supply is used as the power supplies 403 and 404. However, the power supplies 403 and 404 may be AC-DC converters, DC-DC converters, or batteries (storage batteries). In FIG. 2, the first power supply 403 for the first inverter 111 and the second power supply 404 for the second inverter 112 are shown as an example, 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 source. Further, the motor drive unit 1000 may include a power source therein. *

The motor drive unit 1000 includes coils 103 and 104, a capacitor 105, a first inverter 111, a second inverter 112, a first neutral point relay circuit 122, a second neutral point relay circuit 121, a motor 200, and control circuits 301 and 302. Is provided. *

The motor drive unit 1000 includes a first system corresponding to the one end 210 side of the coil (winding) of the motor 200 and a second system corresponding to the other end 220 side of the coil (winding) of the motor 200. The first system includes a first inverter 111, a first neutral relay circuit 122, and a first control circuit 301. The second system includes a second inverter 112, a second neutral relay circuit 121, and a second control circuit 302. The first system inverter 111 and the control circuit 301 are supplied with power from the first power supply 403. The second system inverter 112 and the control circuit 302 are supplied with 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, as described later, even when the power supply in one system is abnormal, the power supply is continued by the other system. *

The power supply apparatuses 101 and 102 have a configuration in which part of the above-described two systems is straddled. The first power supply apparatus 101 includes a first system inverter 111, a second system neutral point relay circuit 121, and a first system control circuit 301. The first system inverter 111 and the second system neutral point relay circuit 121 are controlled by the first system control circuit 301. The second power supply apparatus 102 includes a second system inverter 112, a first system first neutral point relay circuit 122, and a second system control circuit 302. The second system inverter 112 and the first system first neutral relay circuit 122 are controlled by the second system control circuit 302. *

Coils 103 and 104 are provided between the power supplies 403 and 404 and the inverters 111 and 112. The coils 103 and 104 function as a noise filter and smooth high frequency noise included in the voltage waveform supplied to each of the inverters 111 and 112. In addition, the coils 103 and 104 smooth the high frequency noise to prevent the high frequency noise generated by the inverters 111 and 112 from flowing out to the power sources 403 and 404. A capacitor 105 is connected to the power supply terminals of the inverters 111 and 112. The capacitor 105 is a so-called bypass capacitor and suppresses voltage ripple. The capacitor 105 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 first inverter 111 includes a bridge circuit having three legs. Each leg includes a high-side switch element connected between the power source and the motor 200 and a low-side switch element connected between 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.
Is provided. As the switch element, for example, a field effect transistor (MOSFET or the like) or an insulated gate bipolar transistor (IGBT) is used. When the switch element is an IGBT, a diode (freewheel) is connected in antiparallel with the switch element.

The first inverter 111 includes, for example, shunt resistors 113R, 114R, and 115R as current sensors 401 (see FIG. 1) for detecting currents flowing through 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 a current flowing through each shunt resistor. For example, a shunt resistor can be connected between the low side switch element and ground at each leg. 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. The number of shunt resistors to be used and the arrangement of the shunt resistors are appropriately determined in consideration of the product cost and design specifications. *

The second inverter 112 includes a bridge circuit having three legs. 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. Similar to the first inverter 111, the second inverter 112 includes, for example, shunt resistors 116R, 117R, and 118R. *

The first inverter 111 is connected to one end 210 of a coil (winding) of the motor 200. More specifically, the U-phase leg of the first inverter 111 (that is, the node between the high-side switch element and the low-side switch element) is connected to one end 210 of the U-phase coil of the motor 200. The V-phase leg of the first inverter 111 is connected to one end 210 of the V-phase coil. The W-phase leg of the first inverter 111 is connected to one end 210 of the W-phase coil. *

The second inverter 112 is connected to the other end 220 of the coil (winding) of the motor 200. More specifically, the U-phase leg of the second inverter 112 is connected to the other end 220 of the U-phase coil of the motor 200. The V-phase leg of the second inverter 112 is connected to the other end 220 of the V-phase coil. The W-phase leg of the second inverter 112 is connected to the other end 220 of the W-phase coil. *

The first neutral point relay circuit 122 is connected to one end 210 of the coil of the motor 200 in parallel with the first inverter 111. The first neutral point relay circuit 122 can switch connection / disconnection between the one ends 210 of the coils of the motor 200. *

The first neutral point relay circuit 122 has three first neutral point relays 123, 124, and 125 each having one end connected in common to the node N1 and the other end connected to a coil of each phase of the motor 200. Have More specifically, first neutral relay 123 is connected to node N1 and one end 210 of the U-phase coil. First neutral point relay 124 is connected to node N1 and one end 210 of the V-phase coil. First neutral point relay 125 is connected to node N1 and one end 210 of the W-phase coil. *

The second neutral point relay circuit 121 is connected to the other end 220 of the coil of the motor 200 in parallel with the second inverter 112. The second neutral point relay circuit 121 can switch connection / disconnection between the other ends 220 of the coils of the motor 200. *

The second neutral point relay circuit 121 has three second neutral point relays 126, 127, and 128, one end of which is commonly connected to the node N 2 and the other end is connected to a coil of each phase of the motor 200. Have Specifically, second neutral point relay 126 is connected to node N2 and the other end 220 of the U-phase coil. Second neutral point relay 127 is connected to node N2 and other end 220 of the V-phase coil. Second neutral point relay 128 is connected to node N2 and other end 220 of the W-phase coil. As the neutral point relay described above, for example, a semiconductor switch element such as a MOSFET or a mechanical relay is used. *

Refer to FIG. 1 again. The control circuits 301 and 302 include, for example, power supply circuits 311 and 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 apparatuses 101 and 102. The control circuits 301 and 302 control the power supply apparatuses 101 and 102. Specifically, as described above, the first control circuit 301 controls the first inverter 111 and the second neutral point relay circuit 122. The second control circuit 302 controls the second inverter 112 and the first neutral point relay circuit 121. *

The control circuits 301 and 302 can realize closed-loop control by controlling the target rotor position (rotation angle), rotation speed, current, and the like. The rotation speed is obtained, for example, by differentiating the rotation angle (rad) with time, and is represented by the number of rotations (rpm) at which the rotor rotates per 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 include 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. The two control circuits 301 and 302 synchronize their control operations 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) necessary for the respective blocks in the control circuits 301 and 302. *

The angle sensors 321 and 322 are, for example, resolvers or Hall ICs. 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 not be required. *

The voltage sensors 411 and 412 detect the voltage at one end of the neutral point relay circuits 121 and 122 connected to the coil of the motor 200 and output the detected voltage values to the input circuits 331 and 332. *

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

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

Further, the microcontrollers 341 and 342 can generate a signal for determining the on / off state of the neutral point relay circuits 121 and 122 according to the received voltage value. *

The drive circuits 351 and 352 are, for example, 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 and second inverters 111 and 112 according to the PWM signal, and generate the generated control signal for each switch element. To give. Furthermore, the drive circuits 351 and 352 are connected to the neutral point relay circuits 121 and 122 according to signals from the microcontrollers 341 and 342 that determine the on / off states of the neutral point relay circuits 121 and 122, respectively. It is possible to generate a control signal for turning on / off the sex point relay and to supply the generated control signal to each neutral point relay. The microcontrollers 341 and 342 may have the functions of the 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 command group for causing the microcontrollers 341 and 342 to control the power supply apparatuses 101 and 102. For example, the control program is temporarily expanded in a RAM (not shown) at the time of booting. *

Control of the power supply apparatuses 101 and 102 includes normal and abnormal control. The control circuits 301 and 302 (mainly the microcontrollers 341 and 342) can switch the control of the power supply apparatuses 101 and 102 from normal control to abnormal control. The on / off states of the first neutral point relay circuit 122 and the second neutral point relay circuit 121 are determined according to the type of control. Hereinafter, a specific example of the operation of the motor drive unit 1000 will be described, and a specific example of the operation of the power supply apparatus 100 will be mainly described. *

(Control during normal operation)



A specific example of a control method when the power supply apparatuses 101 and 102 are normal will be described. Normal indicates a state in which both of the two power supplies 403 and 404, the two inverters 111 and 112, and the two control circuits 301 and 302 operate correctly.

Under normal conditions, the control circuits 301 and 302 turn off the first neutral point relay circuit 122 and turn off the second neutral point relay circuit 121. Thereby, the coils of each phase of the motor 200 are disconnected from each other. *

When the first neutral point relay circuit 122 is turned off, the one ends 210 of the coils of the respective phases of the motor 200 are insulated from each other. “The first neutral relay circuit 122 is turned off” means that the first neutral relays 123, 124, and 125 are all turned off. *

When the second neutral relay circuit 121 is turned off, the other ends 220 of the coils of the respective phases of the motor 200 are insulated from each other. “The second neutral point relay circuit 121 is turned off” means that the second neutral point relays 126, 127, and 128 are all turned off. *

In this connected state, the control circuits 301 and 302 drive the motor 200 by performing three-phase energization control using both the first inverter 111 and the second inverter 112. As an example, the control circuits 301 and 302 can perform three-phase energization control by switching control of the switch element of the first inverter 111 and the switch element of the second inverter 112 with a duty that varies periodically. The duty cycle variation in each of the first inverter 111 and the second inverter 112 can be switched by the control circuits 301 and 302. For example, the control circuits 301 and 302 may be switched to a period variation in which the first inverter 111 and the second inverter 112 have opposite phases (phase difference = 180 °). FIG. 3 is a diagram showing current values flowing in the coils of the respective phases of the motor 200 in a normal state. *

FIG. 3 shows the current obtained by plotting the current values flowing through the U-phase, V-phase and W-phase coils of the motor 200 when the power supply devices 101 and 102 are controlled according to the normal three-phase energization control. A waveform (sine wave) is illustrated. The horizontal axis in FIG. 3 represents the motor electrical angle (deg), and the vertical axis represents the current value (A). _Ipk represents the maximum current value (peak current value) of each phase. Note that the power supply devices 101 and 102 can drive the motor 200 using, for example, a rectangular wave in addition to the sine wave illustrated in FIG.

Table 1 shows the value of current flowing through the terminals of each inverter for each electrical angle in the sine wave of FIG. Table 1 specifically shows a current value at every electrical angle of 30 ° flowing at a connection point between the first inverter 111 and one end 210 of each of the U-phase, V-phase, and W-phase coils. Table 1 shows current values for each electrical angle of 30 ° flowing through the connection points between the second inverter 112 and the other ends 220 of the U-phase, V-phase, and W-phase coils. Here, for the first inverter 111, the direction of current flowing from one end 210 to the other end 220 of the motor 200 is defined as a positive direction. For the second inverter 112, the direction of current flowing from the other end 220 of the motor 200 to the one end 210 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] * I _pk , and the magnitude of the current value I ₂ is I _pk / 2.

At an electrical angle of 0 °, the current of the U-phase coil is “0”. At an electrical angle of 0 °, a current of magnitude I ₁ flows from the second inverter 112 to the first inverter 111 through the V-phase coil, and a magnitude I from the first inverter 111 to the second inverter 112 flows through the W-phase coil. ₁ current flows.

In the electrical angle 30 °, the coils of the U-phase current of magnitude _{I 2} flows through the second inverter 112 from the first inverter 111, the coil of the V phase magnitude I from the second inverter 112 to the first inverter 111 _pk of current flows, the coil of the W-phase current having a magnitude _{I 2} flows from the first inverter 111 to the second inverter 112.

At an electrical angle of 60 °, a current of magnitude I ₁ flows from the first inverter 111 to the second inverter 112 through the U-phase coil, and a magnitude I from the second inverter 112 to the first inverter 111 flows through the V-phase coil. ₁ current flows. At an electrical angle of 60 °, the current of the W-phase coil is “0”.

At an electrical angle of 90 °, a current of magnitude I _pk flows from the first inverter 111 to the second inverter 112 through the U-phase coil, and a magnitude I from the second inverter 112 to the first inverter 111 flows through the V-phase coil. _second current flows to the coil of the W-phase current having a magnitude _{I 2} flows from the second inverter 112 to the first inverter 111.

At an electrical angle of 120 °, a current of magnitude I ₁ flows from the first inverter 111 to the second inverter 112 through the U-phase coil, and a magnitude I from the second inverter 112 to the first inverter 111 flows through the W-phase coil. ₁ current flows. At an electrical angle of 120 °, the current of the V-phase coil is “0”.

At an electrical angle of 150 °, a current of magnitude I ₂ flows from the first inverter 111 to the second inverter 112 through the U-phase coil, and a magnitude I from the first inverter 111 to the second inverter 112 flows through the V-phase coil. ₂ current 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 electrical angle of 180 °, the current of the U-phase coil is “0”. At an electrical angle of 180 °, a current of magnitude I ₁ flows from the first inverter 111 to the second inverter 112 through the V-phase coil, and a magnitude I from the second inverter 112 to the first inverter 111 flows through the W-phase coil. ₁ current flows.

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

At an electrical angle of 240 °, a current of magnitude I ₁ flows from the second inverter 112 to the first inverter 111 through the U-phase coil, and a magnitude I from the first inverter 111 to the second inverter 112 flows through the V-phase coil. ₁ current flows. At an electrical angle of 240 °, the current of the W-phase coil is “0”.

At an electrical angle of 270 °, a current of magnitude I _pk flows from the second inverter 112 to the first inverter 111 through the U-phase coil, and a magnitude I from the first inverter 111 to the second inverter 112 flows through the V-phase coil. ₂ 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 electrical angle of 300 °, a current of magnitude I ₁ flows from the second inverter 112 to the first inverter 111 through the U-phase coil, and a magnitude I from the first inverter 111 to the second inverter 112 flows through the W-phase coil. ₁ current flows. At an electrical angle of 300 °, the current of the V-phase coil is “0”.

At an electrical angle of 330 °, a current of magnitude I ₂ flows from the second inverter 112 to the first inverter 111 through the U-phase coil, and a magnitude I from the second inverter 112 to the first inverter 111 flows through the V-phase coil. ₂ current 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 sum of the currents flowing through the three-phase coils in consideration of the current direction is “0” for each electrical angle. However, according to the circuit configuration of the power supply devices 101 and 102, the current flowing through the three-phase coil is controlled independently. Therefore, the control circuits 301 and 302 can also perform control such that the sum of currents is a value other than “0”. *

(Control in case of abnormality)



A specific example of a control method when the power supply apparatus 100 is abnormal will be described. 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 abnormality is roughly classified into an abnormality of the first system and an abnormality of the second system. Further, the abnormality of each system includes an abnormality due to a failure of the inverters 111 and 112 and an abnormality of the drive system. As described above, “drive system abnormality” refers to various abnormalities such as an abnormality in the power supply only, an abnormality in the control circuit only, an abnormality in both the power supply and the control circuit, and a state in which the control unit is stopped due to the power supply abnormality. Includes state. Further, the failure of the inverters 111 and 112 includes disconnection, short circuit, switch element failure, and the like in the inverter circuit.

As an example of abnormality detection, the control circuits 301 and 302 (mainly the microcontrollers 341 and 342) analyze the voltage values detected by the voltage sensors 411 and 412 so that the counterpart to the system to which the self belongs. Detect abnormalities in the side system. The control circuits 301 and 302 can check the voltages at the counterpart inverters 111 and 112 via the voltage sensors 411 and 412 and the neutral point relay circuits 121 and 122 under their control. Specifically, the neutral point relay circuits 121 and 122 are connected to the inverters 111 and 112 via one end 210 and the other end 220 of the motor coil, and the voltage sensors 411 and 412 are connected to the one end 210 and the other end 220. Detect voltage. *

As another example of abnormality detection, the microcontrollers 341 and 342 can also detect an abnormality by analyzing a 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 widely known methods relating to abnormality detection can be used. *

When the microcontrollers 341 and 342 detect an abnormality, the control circuits 301 and 302 switch the control of the power supply apparatuses 101 and 102 from normal control to abnormal control. For example, the timing for switching control from normal to abnormal is about 10 msec to 30 msec after the abnormality is detected. *

The control circuits 301 and 302 turn on the neutral point relay circuits 121 and 122 of the counterpart system when an abnormality occurs. Note that the control circuits 301 and 302 may turn on the neutral point switches 131 and 132 even in a specific case other than when an abnormality occurs. For example, when the first control circuit 301 detects an abnormality, the first control circuit 301 turns on the second neutral point relay circuit 121. *

When the second neutral relay circuit 121 is turned on, the other ends 220 of the three-phase coils of the motor 200 are connected to each other. As a result, the coil of the motor 200 is Y-connected. Then, the node N2 in the second neutral point relay circuit 121 functions as a neutral point. “The second neutral point relay circuit 121 is turned on” means that the second neutral point relays 126, 127, and 128 in the second neutral point relay circuit 121 are all turned on. In this connected state, the first control circuit 301 can energize the coil of the motor 200 by performing three-phase energization control of the first inverter 111. *

If the first control circuit 301 detects an abnormality, it means that an abnormality has occurred in the second system. When the abnormality in the second system is an abnormality in the drive system, the second control circuit 302 has lost control of the second inverter 112 (a state in which the second control circuit 302 has failed). Even in such a case, since the first control circuit 301 controls the second neutral point relay circuit 121, a neutral point is formed on the second system side. Then, power supply to the motor 200 is continued by the inverter 111 on the first system side. *

Further, the second inverter 112 is cut off from the power from the power source 404 when the second control circuit 302 fails. Specifically, all the switch elements in the second inverter 112 are automatically turned off at the normal time when there is no control signal. For this reason, current does not flow from the power supply 404 to the second inverter 112, and power loss is suppressed. When the second control circuit 302 detects an abnormality, the second control circuit 302 turns on the first neutral point relay circuit 122. *

When the first neutral point relay circuit 122 is turned on, the one ends 210 of the three-phase coils of the motor 200 are connected to each other. As a result, the coil of the motor 200 is Y-connected. Then, the node N1 in the first neutral point relay circuit 122 functions as a neutral point. “The first neutral point relay circuit 122 is turned on” means that all the first neutral point relays 123, 124, and 125 in the first neutral point relay circuit 122 are turned on. In this connected state, the second control circuit 302 can energize 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 in the first system is an abnormality in the drive system, the first control circuit 301 is in a state where it cannot control the first inverter 111 (failed state). Even in the case described above, since the second control circuit 302 controls the first neutral point relay circuit 122, a neutral point is formed on the first system side. Then, power supply to the motor 200 is continued by the inverter 112 on the second system side. *

Further, the first inverter 111 is cut off from the power from the power supply 403 when the first control circuit 301 fails. Specifically, all the switch elements in the first inverter 111 are automatically turned off at the normal time when there is no control signal. For this reason, current does not flow from the power source 403 to the first inverter 111, and power loss is suppressed. *

As specific three-phase energization control at the time of abnormality, the control circuits 301 and 302 are configured to perform switching operations in the switching elements of the inverters 111 and 112, for example, by PWM control that can obtain a waveform similar to the current waveform shown in FIG. To control. *

Table 2 shows the values of the current flowing through the terminals of the second inverter 140 for each electrical angle when the second inverter 112 is controlled by, for example, three-phase energization control such that a waveform similar to the current waveform shown in FIG. 3 is obtained. It is illustrated in Table 2 specifically shows the current value at every electrical angle of 30 ° flowing through the connection point between the second inverter 112 and the other end 220 of each of the U-phase, V-phase, and W-phase coils. The definition of the current direction is as described above. *

For example, at an electrical 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 of the current from the second inverter 112 to the first inverter 111 flows in the V-phase coil. the current flow _{I pk,} the coil of the W-phase current having a magnitude _{I 2} flows from the first inverter 111 to the second inverter 112. At an electrical angle of 60 °, a current of magnitude I ₁ flows from the first inverter 111 to the second inverter 112 through the U-phase coil, and a magnitude I from the second inverter 112 to the first inverter 111 flows through the V-phase coil. ₁ current flows. At an electrical angle of 60 °, the current of the W-phase coil is “0”. The sum of the current flowing into the neutral point and the current flowing out of the neutral point is always “0” for each electrical 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. For this reason, in the control at the time of abnormality, the torque of the motor in the control at the time of normal is maintained. *

In addition, when the abnormal part at the time of abnormality is one switch element in the inverters 111 and 112, the inverters 111 and 112 are determined to be neutral points by a control method described in, for example, Japanese Patent Application Laid-Open No. 2014-192950. Is possible. However, in order to realize this control method, a special gate driver is required in which the ON voltage of the control signal is different between when it is normal and when it is abnormal. In contrast to such a control method, the neutral point relay circuits 121 and 122 only need to be turned on when there is an abnormality, so that only one on-voltage of the control signal is required and no special driver is required. Further, since it is desirable to avoid the use of the inverters 111 and 112 including the switch element in which a failure has occurred, the method in which the neutral point is formed by the neutral point relay circuits 121 and 122 is superior also in this respect. (Hardware Configuration of Motor Drive Unit 1000) Next, a 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. As shown in FIG. *

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

From the motor 200, one end 210 and the other end 220 of the coil protrude and extend toward the mounting boards 1001 and 1002. Both one end 210 and the other end 220 of the coil are connected to one of the first mounting substrate 1001 and the second mounting substrate 1002, and both the one end 210 and the other end 220 are connected to the first mounting substrate 1001 and the second mounting substrate 1002. One side of the mounting substrate 1002 passes through and is connected to the other side. Specifically, both one end 210 and the other end 220 of the coil are connected to the second mounting substrate 1002, for example. Further, both the one end 210 and the other end 220 of the coil penetrate the second mounting substrate 1002 and are connected to the first mounting substrate 1001. *

The first mounting substrate 1001 and the second mounting substrate 1002 face each other. The rotation axis of the motor 200 extends in the direction in which the substrate surfaces face each other. The first mounting substrate 1001, the second mounting substrate 1002, and the motor 200 are housed in the housing 1003 so that their positions are fixed. *

A connector 1004 to which a power cord from the first power supply 403 is connected is attached to the first mounting board 1001. A connector 1005 to which a power cord from the second power supply 404 is connected is attached to the second mounting board 1002. FIG. 5 is a diagram schematically showing the hardware configuration of the first mounting board 1001 and the second mounting board 1002. *

A first inverter 111 and a second neutral relay circuit 121 are mounted on the first mounting board 1001. A second inverter 112 and a first neutral relay circuit 122 are mounted on a second mounting board 1002 that is different from the first mounting board 1001. Since the circuits of each system made redundant in the first system and the second system are distributed to the two mounting boards 1001 and 1002, efficient element arrangement with the same circuit scale is possible on the two mounting boards. It becomes. *

A first control circuit 301 is also mounted on the first mounting substrate 1001. A second control circuit 302 is also mounted on the second mounting substrate 1002. Since the control circuits 301 and 302 are mounted on the same mounting board as the inverters 111 and 112 and the neutral point relay circuits 121 and 122 to be controlled by the control circuits 301 and 302, wiring for control is provided in the board. Fits in. Therefore, efficient element arrangement is possible. *

The first inverter 111 on the first mounting board 1001 and the first neutral relay circuit 122 on the second mounting board 1002 are mutually opposite when viewed in the opposing direction of the first mounting board 1001 and the second mounting board 1002. It is mounted at the overlapping position. When the second neutral relay circuit 121 on the first mounting board 1001 and the second inverter 112 on the second mounting board 1002 are viewed in the opposite direction of the first mounting board 1001 and the second mounting board 1002. Are mounted at positions that overlap each other. Such a circuit arrangement enables an efficient element arrangement in which the wiring path to the one end 210 and the other end 220 of the coil is simplified. *

When viewed in the opposite direction of the first mounting board 1001 and the second mounting board 1002, the first inverter 111 and the second mounting board 1 on the first mounting board 1001.
The second inverter 112 on 002 is symmetrical to each other. Further, when viewed in the opposing direction of the first mounting board 1001 and the second mounting board 1002, the second neutral point relay circuit 121 on the first mounting board 1001 and the first neutrality on the second mounting board 1002 are used. The point relay circuit 122 is symmetrical to each other. Such a symmetrical arrangement enables common board design for the two mounting boards 1001 and 1002.



(Modification)



FIG. 6 is a diagram schematically illustrating a hardware configuration of a mounting board according to a modification of the present embodiment.

In the modification shown in FIG. 6, one double-sided mounting substrate 1006 is provided. The first inverter 111 and the second neutral point relay circuit 121 are mounted on one of the front and back surfaces of the double-sided mounting substrate 1006. The second inverter 112 and the first neutral point relay circuit 122 are mounted on the other surface with respect to one surface. A first control circuit 301 is also mounted on one of the front and back surfaces. A second control circuit 302 is also mounted on the other surface. Since the circuits of each system made redundant in the first system and the second system are distributed to both the front and back surfaces of the double-sided mounting substrate, an efficient element arrangement in which the circuit scale is equalized on both the front and back surfaces is possible. *

The specific circuit arrangement on both the front and back sides of the double-sided mounting board 1006 is the same as the circuit arrangement on the first mounting board 1001 shown in FIG. This is the same as the circuit arrangement on the second mounting substrate 1002 shown in FIG. For this reason, an efficient element arrangement in which the wiring path to the one end 210 and the other end 220 of the coil is simplified is possible, and the board design can be made common to both the front and back sides of the double-sided mounting board 1006. FIG. 7 is a diagram schematically showing a hardware configuration of a mounting board according to another modification of the present embodiment. *

In the hardware configuration shown in FIG. 7, a third mounting board 1007 is provided in addition to the first mounting board 1001 and the second mounting board 1002. The third mounting substrate 1007 is located between the first mounting substrate 1001 and the second mounting substrate 1002. The control circuits 301 and 302 are mounted on the third mounting board 1007, and the inverters 111 and 112 and the neutral point relay circuits 121 and 122 are the first mounting board as in the hardware configuration shown in FIG. 1001 and the second mounting substrate 1002 are mounted. With such a hardware configuration, since the power circuit and the control circuit are separated, the safety can be improved and the power supply wiring can be simplified. *

(Embodiment of power steering device)



A vehicle such as an automobile generally includes a power steering device. The power steering device generates an auxiliary torque for assisting a steering torque of a steering system that is generated when a driver operates a steering wheel. The auxiliary torque is generated by the auxiliary torque mechanism, and the burden on the operation of the driver can be reduced. For example, the auxiliary torque mechanism includes a steering torque sensor, an ECU, a motor, a speed reduction mechanism, and the like. The steering torque sensor detects 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 auxiliary torque corresponding to the steering torque based on the drive signal, and transmits the auxiliary torque to the steering system via the speed reduction mechanism.

The motor drive unit 1000 of the above embodiment is suitably used for a power steering apparatus. FIG. 8 is a diagram schematically showing the configuration of the power steering apparatus 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 also referred to as, for example, a steering handle 521, a steering shaft 522 (also referred to as “steering column”), universal joints 523A, 523B, and a rotating shaft 524 (“pinion shaft” or “input shaft”). 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, knuckle 528A and 528B, and left and right steering wheels (for example, left and right front wheels) 529A, 529B. *

The steering handle 521 is connected to the rotating shaft 524 via a steering shaft 522 and universal shaft joints 523A and 523B. A rack shaft 526 is connected to the rotation shaft 524 via a rack and pinion mechanism 525. The rack and pinion mechanism 525 includes a pinion 531 provided on the rotation 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 through a ball joint 552A, a tie rod 527A, and a knuckle 528A in this order. Similarly 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 viewed from the driver sitting on the seat, respectively. *

According to the steering system 520, a steering torque is generated by the driver operating the steering handle 521, and is transmitted to the left and right steering wheels 529A and 529B via the rack and pinion mechanism 525. Accordingly, 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 gives auxiliary torque to the steering system 520 from the steering handle 521 to the left and right steering wheels 529A and 529B. The auxiliary torque may be referred to as “additional torque”.

As the ECU 542, for example, control circuits 301 and 302 shown in FIG. Further, as the power supply device 545, for example, the power supply devices 101 and 102 shown in FIG. As the motor 543, for example, the motor 200 shown in FIG. When the ECU 542, the motor 543, and the power supply device 545 constitute a unit generally referred to as “mechanical and integrated motor”, the unit may be a motor drive having a hardware configuration shown in FIG. The unit 1000 is preferably used. Of the elements shown in FIG. 8, the mechanism constituted by elements excluding the ECU 542, the motor 543, and the power supply device 545 corresponds to an example of a 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 from the steering torque sensor 541 (hereinafter referred to as “torque signal”). The motor 543 generates an auxiliary torque corresponding 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 speed reduction mechanism 544. The speed reduction mechanism 544 is, for example, a worm gear mechanism. The 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 a place where an assist torque is applied to the steering system 520. FIG. 8 shows a pinion assist type power steering apparatus 2000. However, the power steering device 2000 is also applied to a rack assist type, a column assist type, and the like. *

The ECU 542 can receive not only a torque signal but also a vehicle speed signal, for example. The microcontroller of the ECU 542 can vector-control the motor 543 based on a torque signal, a vehicle speed signal, or the like. *

The ECU 542 sets a target current value based on at least the torque signal. The ECU 542 preferably sets the target current value in consideration of the vehicle speed signal detected by the vehicle speed sensor and the rotor rotation signal 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 apparatus 2000, the left and right steering wheels 529A and 529B can be operated by the rack shaft 526 using the combined torque obtained by adding the assist 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-described electromechanical integrated motor, appropriate current control can be performed at both normal and abnormal times. As a result, the power assist in the power steering device is continued both in the normal time and in the abnormal time.

Claims (8)

1. A power conversion device that converts power from a power source into power supplied to a motor having an n-phase (n is an integer of 3 or more) winding,
   
   
   
   A first inverter connected to one end of the winding;
   
   
   
   A second inverter connected to the other end with respect to the one end;
   
   
   
   A first neutral point relay circuit that is connected to the one end of the winding in parallel with the first inverter and that switches connection / disconnection between the one ends;
   
   
   
   A second neutral point relay circuit that is connected to the other end of the winding in parallel with the second inverter and that switches connection / disconnection between the other ends;
   
   
   
   A first control circuit for controlling the first inverter and the second neutral relay circuit;
   
   
   
   A second control circuit for controlling the second inverter and the first neutral relay circuit;
   
   
   
   A power conversion device comprising:
2. The power source includes a first power source and a second power source independent of each other,
   
   
   
   The first control circuit and the first inverter are supplied with power from the first power source,
   
   
   
   The power converter according to claim 1, wherein the second control circuit and the second inverter are supplied with power from the second power source.
3. A first mounting board on which the first inverter and the second neutral relay circuit are mounted;
   
   
   
   3. The power conversion device according to claim 1, further comprising a second mounting board different from the first mounting board on which the second inverter and the first neutral relay circuit are mounted.
4. The first inverter and the second neutral point relay circuit are mounted on one surface of both the front and back surfaces, and the second inverter and the first neutral point relay circuit are mounted on the other surface with respect to the one surface. The power converter according to claim 1, further comprising a double-sided mounting board.
5. The first inverter is cut off from the power from the power source when the first control circuit fails.
   
   
   
   5. The power conversion device according to claim 1, wherein the second inverter is in a cut-off state with respect to power from the power source when the second control circuit fails. 6.
6. The power conversion device according to any one of claims 1 to 5,
   
   
   
   A motor connected to the power converter and supplied with power converted by the power converter;
   
   
   
   A drive device comprising:
7. The power converter includes a first mounting board on which the first inverter and the second neutral relay circuit are mounted, and a first mounting board on which the second inverter and the first neutral relay circuit are mounted. A second mounting board different from the mounting board,
   
   
   
   In the motor, both the one end and the other end of the winding are connected to one of the first mounting board and the second mounting board, and the both pass through the one and connect to the other. The drive device according to claim 6.
8. The power conversion device according to any one of claims 1 to 5,
   
   
   
   A motor to which power converted by the power converter is supplied;
   
   
   
   A power steering mechanism driven by the motor;
   
   
   
   A power steering apparatus comprising:

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