WO2019220780A1

WO2019220780A1 - Failure diagnostic method, power converting device, motor module, and electric power steering device

Info

Publication number: WO2019220780A1
Application number: PCT/JP2019/013060
Authority: WO
Inventors: アハマッドガデリー
Original assignee: 日本電産株式会社
Priority date: 2018-05-15
Filing date: 2019-03-27
Publication date: 2019-11-21
Also published as: JPWO2019220780A1; CN112119580A

Abstract

This failure diagnostic method according to an embodiment of the present disclosure diagnoses a failure in a power converting device 1000 that converts power from a power source 101 into power to be supplied to a motor 200. The failure diagnostic method includes: an acquisition step for acquiring a first actual voltage VA1 which indicates the voltage at both ends of a first low-side switching element SW_A1L, a saturation voltage Vsat of the first low-side switching element, and a voltage peak value Vpeak determined on the basis of a d-axis voltage and a q-axis voltage in a dq-coordinate system; and a diagnosis step for diagnosing the presence of a failure of a second inverter 130 on the basis of the first actual voltage, the saturation voltage, and the voltage peak value.

Description

Failure diagnosis method, power conversion device, motor module, and electric power steering device

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

In recent years, an electromechanical integrated motor in which an electric motor (hereinafter simply referred to as “motor”), an inverter, and an ECU are integrated has been developed. Particularly in the in-vehicle field, high quality assurance is required from the viewpoint of safety. Therefore, a redundant design that can continue safe operation even when a part of the component fails is adopted. As an example of a redundant design, it is considered to provide two power conversion devices for one motor. As another example, it is considered to provide a backup microcontroller in the main microcontroller.

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

Patent Documents

2 and 3 also disclose a motor drive device having a first system and a second system.
Even if one system or one winding set fails, motor drive can be continued by a system that does not fail.

Japan Publication: JP-A-2016-34204 Japan publication: JP-A-2016-32977 Japanese publication: JP-A-2008-132919

In the above-described conventional technology, it has been required to appropriately detect the failure of the inverter.

The embodiment of the present disclosure provides a failure diagnosis method capable of appropriately diagnosing an inverter failure.

An exemplary failure diagnosis method of the present disclosure is a failure diagnosis method for diagnosing a failure in a power conversion device that converts electric power from a power source into electric power supplied to a motor having at least one phase winding, the electric power The converter is connected to one end of the at least one-phase winding, connected to a first inverter having a first high-side switch element and a first low-side switch element, and to the other end of the at least one-phase winding, A second inverter including a second high-side switch element and a second low-side switch element; and the first high-side switch element, the first low-side switch element, the second high-side switch element, and the second low-side switch element. An H-bridge, and the failure diagnosis method includes a first actual voltage indicating a voltage across the first low-side switch element. Obtaining a saturation voltage of the first low-side switch element and a voltage peak value determined based on a d-axis voltage and a q-axis voltage in a dq coordinate system; the first actual voltage; the saturation voltage; Diagnosing whether or not the second inverter has failed based on the voltage peak value.

An exemplary power conversion device of the present disclosure is a power conversion device that converts power from a power source into power supplied to a motor having at least one phase winding, the power conversion device including the at least one phase. A first inverter having a first high-side switch element and a first low-side switch element, and a second high-side switch element connected to the other end of the at least one-phase winding; A second inverter having two low-side switch elements; an H bridge including the first high-side switch element; the first low-side switch element; the second high-side switch element; and the second low-side switch element; A control circuit for controlling the operation of the second inverter, wherein the control circuit includes a first low-side switch element. Obtaining a first actual voltage indicating an end voltage, a saturation voltage of the first low-side switch element, and a voltage peak value determined based on a d-axis voltage and a q-axis voltage in a dq coordinate system; Based on the voltage, the saturation voltage, and the voltage peak value, the presence or absence of a failure of the second inverter is diagnosed.

According to an exemplary embodiment of the present disclosure, there is provided a failure diagnosis method capable of appropriately diagnosing an inverter failure, a power conversion device, a motor module including the power conversion device, and an electric power steering device including the motor module. Provided.

FIG. 1 is a block diagram schematically illustrating a motor module according to an embodiment. FIG. 2 is a circuit diagram schematically showing the inverter unit according to the embodiment. FIG. 3A is a schematic diagram showing an A-phase H-bridge. FIG. 3B is a schematic diagram showing a B-phase H-bridge. FIG. 3C is a schematic diagram showing a C-phase H-bridge. FIG. 4 is a functional block diagram showing a controller that performs overall motor control. FIG. 5 is a functional block diagram showing functional blocks for performing failure diagnosis of the second inverter. FIG. 6 is a functional block diagram showing functional blocks for performing failure diagnosis of the first inverter. FIG. 7 is a schematic diagram showing a lookup table for determining the saturation voltage Vsat from the rotation speed ω and the current amplitude value. FIG. 8 is a graph showing waveforms of simulation results of the actual voltage VA1 (upper side) and the actual voltage VA2 (lower side) when the low-side switch element SW_A1L has an open failure. FIG. 9 is a graph showing waveforms of simulation results of the actual voltage VB1 (upper side) and the actual voltage VB2 (lower side) when the low-side switch element SW_A1L has an open failure. FIG. 10 is a graph showing waveforms of simulation results of the actual voltage VC1 (upper side) and the actual voltage VC2 (lower side) when the low-side switch element SW_A1L has an open failure. FIG. 11 is a schematic diagram illustrating an electric power steering apparatus according to an exemplary embodiment.

Hereinafter, embodiments of an inverter failure diagnosis method, a power conversion device, a motor module, and an electric power steering device according to 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 the present specification, implementation of the present disclosure will be described by taking, as an example, a power conversion device that converts power from a power source into power to be supplied to a three-phase motor having three-phase (A-phase, B-phase, and C-phase) windings. A form is demonstrated. However, a power conversion device that converts power from a power source into power to be supplied to an n-phase motor having n-phase (four or more) windings such as four-phase or five-phase, and an inverter used in the device The fault diagnosis method is also within the scope of the present disclosure.

(Embodiment 1)
[1. Structure of motor module 2000 and power conversion apparatus 1000]
FIG. 1 schematically shows a typical block configuration of a motor module 2000 according to the present embodiment.

The motor module 2000 typically includes a power converter 1000 having the inverter unit 100 and a control circuit 300 and a motor 200. The motor module 2000 is modularized and can be manufactured and sold as, for example, an electromechanically integrated motor having a motor, a sensor, a driver, and a controller.

The power conversion apparatus 1000 can convert power from the power source 101 (see FIG. 2) into power supplied to the motor 200. The power conversion apparatus 1000 is connected to the motor 200. For example, the power conversion apparatus 1000 can convert DC power into three-phase AC power that is pseudo-sine waves of A phase, B phase, and C phase. In this specification, “connection” between components (components) mainly means electrical connection.

The motor 200 is, for example, a three-phase AC motor. The motor 200 includes an A-phase winding M1, a B-phase winding M2, and a C-phase winding M3, and is connected to the first inverter 120 and the second inverter 130 of the inverter unit 100. More specifically, the first inverter 120 is connected to one end of each phase winding of the motor 200, and the second inverter 130 is connected to the other end of each phase winding.

The control circuit 300 includes, for example, a power supply circuit 310, an angle sensor 320, an input circuit 330, a controller 340, a drive circuit 350, and a ROM 360. Each component of the control circuit 300 is mounted on, for example, one circuit board (typically a printed board). The control circuit 300 is connected to the inverter unit 100 and controls the inverter unit 100 based on input signals from the current sensor 150 and the angle sensor 320. Examples of the control method include vector control, pulse width modulation (PWM), and direct torque control (DTC). However, the angle sensor 320 may be unnecessary depending on the motor control method (for example, sensorless control).

The control circuit 300 can realize the closed loop control by controlling the target position, rotation speed, current, and the like of the motor 200. Note that the control circuit 300 may include a torque sensor instead of the angle sensor 320. In this case, the control circuit 300 can control the target motor torque.

The power supply circuit 310 generates a power supply voltage (for example, 3V, 5V) necessary for each block in the circuit based on the voltage of the power supply 101, for example, 12V.

The angle sensor 320 is, for example, a resolver or a Hall IC. Alternatively, the angle sensor 320 is also realized by a combination of an MR sensor having a magnetoresistive (MR) element and a sensor magnet. The angle sensor 320 detects the rotation angle of the rotor (hereinafter referred to as “rotation signal”) and outputs the rotation signal to the controller 340.

The input circuit 330 receives the phase current detected by the current sensor 150 (hereinafter sometimes referred to as “actual current value”), and changes the level of the actual current value to the input level of the controller 340 as necessary. The actual current value is output to the controller 340. The input circuit 330 is, for example, an analog / digital (AD) conversion circuit.

The controller 340 is an integrated circuit that controls the entire power conversion apparatus 1000, and is, for example, a microcontroller or an FPGA (Field Programmable Gate Array). The controller 340 controls the switching operation (turn-on or turn-off) of each switch element (typically a semiconductor switch element) in the first and

second inverters

120 and 130 of the inverter unit 100. The controller 340 sets the target current value according to the actual current value and the rotation signal of the rotor, generates a PWM signal, and outputs it to the drive circuit 350.

The drive circuit 350 is typically a pre-driver (sometimes called a “gate driver”). The drive circuit 350 generates a control signal (gate control signal) for controlling the switching operation of each switch element in the first and

second inverters

120 and 130 of the inverter unit 100 according to the PWM signal, and supplies a control signal to the gate of each switch element. give. When the driving target is a motor that can be driven at a low voltage, the pre-driver is not necessarily required. In that case, the function of the pre-driver can be implemented in the controller 340.

The ROM 360 is, for example, a writable memory (for example, PROM), a rewritable memory (for example, flash memory), or a read-only memory. The ROM 360 stores a control program including a command group for causing the controller 340 to control the power conversion apparatus 1000. For example, the control program is temporarily expanded in a RAM (not shown) at the time of booting.

A specific circuit configuration of the inverter unit 100 will be described with reference to FIG.

FIG. 2 schematically shows a circuit configuration of the inverter unit 100 according to the present embodiment.

The power supply 101 generates a predetermined power supply voltage (for example, 12V). As the power source 101, for example, a DC power source is used. However, the power source 101 may be an AC-DC converter, a DC-DC converter, or a battery (storage battery). The power source 101 may be a single power source common to the first and

second inverters

120 and 130 as shown in the figure, or may be a first power source (not shown) for the first inverter 120 and for the second inverter 130. A second power source (not shown) may be provided.

Although not shown, coils are provided between the power source 101 and the first inverter 120 and between the power source 101 and the second inverter 130. The coil functions as a noise filter, and smoothes the high frequency noise included in the voltage waveform supplied to each inverter or the high frequency noise generated by each inverter so as not to flow out to the power supply 101 side. A capacitor is connected to the power supply terminal of each inverter. The capacitor is a so-called bypass capacitor and suppresses voltage ripple. The capacitor is, for example, an electrolytic capacitor, and the capacity and the number to be used are appropriately determined according to design specifications.

The first inverter 120 has a bridge circuit composed of three legs. Each leg has a high-side switch element, a low-side switch element, and a shunt resistor. The A-phase leg includes a high-side switch element SW_A1H, a low-side switch element SW_A1L, and a first shunt resistor S_A1. The B-phase leg has a high-side switch element SW_B1H, a low-side switch element SW_B1L, and a first shunt resistor S_B1. The C-phase leg has a high-side switch element SW_C1H, a low-side switch element SW_C1L, and a first shunt resistor S_C1.

As the switch element, for example, a field effect transistor (typically MOSFET) having a parasitic diode formed therein, or a combination of an insulated gate bipolar transistor (IGBT) and a free-wheeling diode connected in parallel thereto can be used. .

The first shunt resistor S_A1 is used to detect the A-phase current IA1 flowing through the A-phase winding M1, and is connected, for example, between the low-side switch element SW_A1L and the GND line GL. The first shunt resistor S_B1 is used to detect the B-phase current IB1 flowing through the B-phase winding M2, and is connected between the low-side switch element SW_B1L and the GND line GL, for example. The first shunt resistor S_C1 is used to detect the C-phase current IC1 flowing through the C-phase winding M3, and is connected between, for example, the low-side switch element SW_C1L and the GND line GL. The three shunt resistors S_A1, S_B1, and S_C1 are connected in common with the GND line GL of the first inverter 120.

The second inverter 130 has a bridge circuit composed of three legs. Each leg has a high-side switch element, a low-side switch element, and a shunt resistor. The A-phase leg has a high-side switch element SW_A2H, a low-side switch element SW_A2L, and a shunt resistor S_A2. The B-phase leg has a high-side switch element SW_B2H, a low-side switch element SW_B2L, and a shunt resistor S_B2. The C-phase leg has a high-side switch element SW_C2H, a low-side switch element SW_C2L, and a shunt resistor S_C2.

The shunt resistor S_A2 is used to detect the A-phase current IA2, and is connected, for example, between the low-side switch element SW_A2L and the GND line GL. The shunt resistor S_B2 is used to detect the B-phase current IB2, and is connected between, for example, the low-side switch element SW_B2L and the GND line GL. The shunt resistor S_C2 is used to detect the C-phase current IC2, and is connected, for example, between the low-side switch element SW_C2L and the GND line GL. The three shunt resistors S_A2, S_B2, and S_C2 are connected in common with the GND line GL of the second inverter 130.

The current sensor 150 described above includes, for example, a shunt resistor S_A1, S_B1, S_C1, S_A2, S_B2, S_C2, and a current detection circuit (not shown) that detects a current flowing through each shunt resistor.

The A-phase leg of the first inverter 120 (specifically, a node between the high-side switch element SW_A1H and the low-side switch element SW_A1L) is connected to one end A1 of the A-phase winding M1 of the motor 200, and the second inverter The 130 A-phase leg is connected to the other end A2 of the A-phase winding M1. The B-phase leg of the first inverter 120 is connected to one end B1 of the B-phase winding M2 of the motor 200, and the B-phase leg of the second inverter 130 is connected to the other end B2 of the winding M2. The C-phase leg of the first inverter 120 is connected to one end C1 of the C-phase winding M3 of the motor 200, and the C-phase leg of the second inverter 130 is connected to the other end C2 of the winding M3.

FIG. 3A schematically shows the configuration of the A-phase H-bridge BA. FIG. 3B schematically shows the configuration of a B-phase H-bridge BB. FIG. 3C schematically shows the configuration of a C-phase H-bridge BC.

The inverter unit 100 includes A-phase, B-phase, and C-phase H-bridges BA, BB, and BC. The A-phase H bridge BA includes a high-side switch element SW_A1H and a low-side switch element SW_A1L in the leg on the first inverter 120 side, a high-side switch element SW_A2H, a low-side switch element SW_A2L in the leg on the second inverter 130 side, and a winding Has M1.

The B-phase H-bridge BB includes a high-side switch element SW_B1H and a low-side switch element SW_B1L in the leg on the first inverter 120 side, a high-side switch element SW_B2H, a low-side switch element SW_B2L in the leg on the second inverter 130 side, and a winding Has M2.

The C-phase H-bridge BC includes a high-side switch element SW_C1H and a low-side switch element SW_C1L in the leg on the first inverter 120 side, a high-side switch element SW_C2H, a low-side switch element SW_C2L in the leg on the second inverter 130 side, and a winding M3.

The control circuit 300 (specifically, the controller 340) can identify a faulty inverter of the first inverter 120 and the second inverter 130 by executing an inverter fault diagnosis described below. The details of inverter failure diagnosis will be described below.

[2. (Inverter failure diagnosis method)
A specific example of a failure diagnosis method for diagnosing an inverter failure, for example, used in the power conversion apparatus 1000 shown in FIG. 1 will be described with reference to FIGS. The failure diagnosis method of the present disclosure can be suitably used for a power conversion device including at least one H bridge, for example, a full bridge type power conversion device. In the present specification, the failure of the inverter indicates an open failure of the switch element. An open failure is a failure in which the switch element always has a high impedance. In this specification, for example, an open failure occurring in the high-side switch element SW_A1H or SW_A1L of the first inverter 120 may be referred to as a failure of the first inverter 120.

In the failure diagnosis, for example, the current and voltage expressed in the dq coordinate system, the actual voltage indicating the voltage across the low-side switch element, and the rotational speed ω of the motor are acquired. The current and voltage expressed in the dq coordinate system include a d-axis voltage Vd, a q-axis voltage Vq, a d-axis current Id, and a q-axis current Iq. In the dq coordinate system, the axis corresponding to the zero phase is represented as the z axis. The rotation speed ω is represented by a rotation speed (rpm) at which the rotor of the motor rotates per unit time (for example, 1 minute) or a rotation speed (rps) at which the rotor rotates at unit time (for example, 1 second).

The actual voltage of the switch element will be described with reference to FIGS. 3A to 3C.

A first actual voltage and a second actual voltage are defined for each of the A-phase, B-phase, and C-phase H-bridges BA, BB, and BC. The first actual voltage indicates the voltage across the first low-side switch element in the leg on the first inverter 120 side in the H bridge of each phase. In other words, the first actual voltage corresponds to the node potential between the first high-side switch element and the first low-side switch element in the leg on the first inverter 120 side. The second actual voltage indicates the voltage across the second low-side switch element in the leg on the second inverter 130 side. In other words, the second actual voltage corresponds to the node potential between the second high-side switch element and the second low-side switch element in the leg on the second inverter 130 side. The voltage across the switch element is equal to the voltage Vds between the source and drain of the FET that is the switch element.

For the A-phase H bridge BA, the first actual voltage indicates the voltage VA1 across the low-side switch element SW_A1L shown in FIG. 3A, and the second actual voltage points across the voltage VA2 across the low-side switch element SW_A2L shown in FIG. 3A. . For the B-phase H-bridge BB, the first actual voltage indicates the voltage VB1 across the low-side switch element SW_B1L shown in FIG. 3B, and the second actual voltage indicates the voltage VB2 across the low-side switch element SW_B2L shown in FIG. 3B. . For the C-phase H-bridge BC, the first actual voltage indicates the voltage VC1 across the low-side switch element SW_C1L illustrated in FIG. 3C, and the second actual voltage indicates the voltage VC2 across the low-side switch element SW_C2L illustrated in FIG. 3C. .

Next, based on the acquired current and voltage in the dq coordinate system, the first actual voltage, the second actual voltage, and the rotation speed, the inverter failure is diagnosed.

When it is determined that the inverter has failed, a failure signal indicating the failure of the inverter is generated and output to a motor control unit described later. For example, a failure signal is a signal that is asserted when a failure occurs.

The above-described failure diagnosis is repeatedly executed in synchronization with, for example, a period in which each phase current is measured by the current sensor 150, that is, an AD conversion period.

The algorithm for realizing the fault diagnosis method according to the present embodiment can be realized only by hardware such as an application specific integrated circuit (ASIC) or FPGA, or can be realized by a combination of a microcontroller and software. Can do. In the present embodiment, the operation subject of failure diagnosis is the controller 340 of the control circuit 300.

FIG. 4 exemplifies functional blocks of the controller 340 for performing overall motor control. FIG. 5 illustrates functional blocks for performing failure diagnosis of the second inverter 130. FIG. 6 illustrates functional blocks for performing failure diagnosis of the first inverter 120.

In this specification, each block in the functional block diagram is shown not in hardware units but in functional block units. The software used for motor control and failure diagnosis may be a module constituting a computer program for executing specific processing corresponding to each functional block, for example. Such a computer program is stored in the ROM 360, for example. The controller 340 can read out commands from the ROM 360 and sequentially execute each process.

The controller 340 includes, for example, a failure diagnosis unit 800 and a motor control unit 900. As described above, the failure diagnosis of the present disclosure can be suitably combined with motor control (for example, vector control), and can be incorporated into a series of processes of motor control.

Failure diagnosis unit 800 obtains d-axis current Id, q-axis current Iq, d-axis voltage Vd, q-axis voltage Vq, and rotation speed ω of motor 200 in the dq coordinate system. The fault diagnosis unit 800 further obtains the first actual voltages VA1, VB1, VC1, and the second actual voltages VA2, VB2, and VC2.

For example, the failure diagnosis unit 800 may include a pre-computation unit (not shown) that acquires Vpeak. The pre-computation unit uses the Clark transformation to convert the three-phase currents Ia, Ib and Ic obtained based on the measured values of the current sensor 150 into the currents Iα and β on the α axis in the αβ fixed coordinate system. Convert to current Iβ. The pre-arithmetic unit converts the currents Iα and Iβ into a d-axis current Id and a q-axis current Iq in the dq coordinate system by using park conversion (dq coordinate conversion). The pre-calculation unit acquires the d-axis voltage Vd and the q-axis voltage Vq based on the currents Id and Iq, and calculates the voltage peak value Vpeak from the acquired Vd and Vq based on the following formula (1). Alternatively, the pre-computation unit can also receive Vd and Vq necessary for calculating Vpeak from the motor control unit 900 that performs vector control. For example, the pre-computation unit acquires Vpeak in synchronization with the period in which each phase current is measured by the current sensor 150.
Vpeak = (2/3) ^1/2 (Vd ² + Vq ² ) ^1/2 formula (1)

Failure diagnosis unit 800 refers to look-up table 840 (FIG. 7) and determines saturation voltage Vsat based on currents Id, Iq and rotation speed ω.

FIG. 7 schematically shows a look-up table (LUT) 840 that determines the saturation voltage Vsat from the rotational speed ω and the current amplitude value. The LUT 840 associates the relationship between the saturation voltage Vsat and the input of the current amplitude value (Id ² + Iq ² ) ^1/2 determined based on the d-axis current and the q-axis current and the rotational speed ω of the motor 200.

The rotation speed ω is calculated based on, for example, a rotation signal from the angle sensor 320. Alternatively, the rotational speed ω can be estimated using, for example, a known sensorless control method. The actual voltage of each switch element is measured by a drive circuit (predriver) 350, for example.

Table 1 illustrates the configuration of the LUT 840 that can be used for failure diagnosis. In motor control, Id is generally treated as zero. Therefore, the current amplitude value is equal to Iq. Table 1 lists Iq (A). The saturation voltage Vsat is determined from the acquired current amplitude value Iq and the rotational speed ω. Alternatively, for example, a value set in advance before driving may be used as the saturation voltage Vsat. For example, a constant value (for example, about 0.1 V) depending on the system may be used as the saturation voltage Vsat.

Failure diagnosis unit 800 diagnoses the presence or absence of an inverter failure based on the above-described actual voltage, voltage peak value Vpeak, and saturation voltage Vsat.

The failure diagnosis unit 800 generates a failure signal 1_FD indicating a failure of the first inverter 120 and a failure signal 2_FD indicating a failure of the second inverter 130 based on the diagnosis result, and outputs them to the motor control unit 900.

The motor control unit 900 generates a PWM signal that controls the overall switching operation of the switch elements of the first and

second inverters

120 and 130 using, for example, vector control. The motor control unit 900 outputs a PWM signal to the drive circuit 350.

When the failure signal is asserted and it is difficult to continue the torque assist of the motor 200, the motor control unit 900 stops the torque assist of the motor 200, for example. In this case, power conversion device 1000 may output a notification signal for alerting a human to a notification device (not shown). For example, the notification device alerts a person using at least one of light, sound, and display. Thereby, a human can recognize that the torque assist of the motor 200 has stopped. When the motor 200 is mounted on the electric power steering apparatus, the driver of the automobile can recognize that the torque assist of the motor that assists the steering operation has stopped. The driver can stop the car on the road shoulder, for example, according to the alert by the notification device.

In this specification, for convenience of explanation, each functional block may be expressed as a unit. Naturally, these notations are not used with the intention of restricting each functional block to hardware or software.

When each functional block is implemented as software in the controller 340, the execution subject of the software may be the core of the controller 340, for example. As described above, the controller 340 can be realized by an FPGA. In that case, all or some of the functional blocks may be realized by hardware.

By distributing processing using a plurality of FPGAs, it is possible to distribute the computation load of a specific computer. In that case, all or some of the functional blocks shown in FIG. 4 to FIG. 6 may be distributed and implemented in a plurality of FPGAs. The plurality of FPGAs are communicably connected to each other by, for example, an in-vehicle control area network (CAN), and can transmit and receive data.

The failure diagnosis unit 800 includes a failure diagnosis unit 801 for diagnosing the presence or absence of a failure in the second inverter 130 and a failure diagnosis unit 802 for diagnosing the presence or absence of a failure in the first inverter 120 shown in FIGS.

Fault diagnosis units

801 and 802 have substantially the same functional blocks, but input actual voltages are different from each other.

Each of the

fault diagnosis units

801 and 802 includes

absolute value calculators

811, 814, and 817,

multipliers

812, 813, 815, 816, 818, and 819,

adders

831, 832, and 833, and

comparators

851 and 852. , 853 and a logic circuit OR871.

First, diagnosis processing for the presence or absence of a failure of the second inverter 130 will be described.

The absolute value calculator 811 of the failure diagnosis unit 801 calculates the absolute value of the actual voltage VA1. The multiplier 812 multiplies the voltage peak value Vpeak by a constant “−1/2”. The multiplier 813 multiplies the saturation voltage Vsat by a constant “−1”. The adder 831 adds the output values of the absolute value calculator 811 and the

multipliers

812 and 813, and calculates the failure diagnosis voltage VA1_FD represented by the following formula (2).
VA1_FD = | VA1 | − [(Vpeak / 2) + Vsat] Equation (2)

The comparator 851 compares “VA1_FD” with “zero”. When VA1_FD is equal to or smaller than zero (VA1_FD ≦ 0), the comparator 851 outputs “0” indicating that the actual voltage VA1 is normal to the logic circuit OR871. When VA1_FD is larger than zero (VA1_FD> 0), the comparator 851 outputs “1” indicating that the actual voltage VA1 is abnormal to the logic circuit OR871.

Similarly, the absolute value calculator 814 of the failure diagnosis unit 801 calculates the absolute value of the actual voltage VB1. The multiplier 815 multiplies the voltage peak value Vpeak by a constant “−1/2”. The multiplier 816 multiplies the saturation voltage Vsat by a constant “−1”. The adder 832 adds the output values of the absolute value calculator 814 and the

multipliers

815 and 816 to calculate a failure diagnosis voltage VB1_FD represented by the following equation (3).
VB1_FD = | VB1 | − [(Vpeak / 2) + Vsat] Equation (3)

The comparator 852 compares “VB1_FD” with “zero”. When VB1_FD is equal to or less than zero, the comparator 852 outputs “0” indicating that the actual voltage VB1 is normal to the logic circuit OR871. When VB1_FD is greater than zero, the comparator 852 outputs “1” indicating that the actual voltage VB1 is abnormal to the logic circuit OR871.

The absolute value calculator 817 of the failure diagnosis unit 801 calculates the absolute value of the actual voltage VC1. The multiplier 818 multiplies the voltage peak value Vpeak by a constant “−1/2”. The multiplier 819 multiplies the saturation voltage Vsat by a constant “−1”. The adder 833 adds the output values of the absolute value calculator 817 and the

multipliers

818 and 819 to calculate a failure diagnosis voltage VC1_FD represented by the following formula (4).
VC1_FD = | VC1 | − [(Vpeak / 2) + Vsat] Equation (4)

The comparator 853 compares “VC1_FD” with “zero”. When VC1_FD is equal to or smaller than zero, the comparator 853 outputs “0” indicating that the actual voltage VC1 is normal to the logic circuit OR871. When VC1_FD is larger than zero, the comparator 853 outputs “1” indicating that the actual voltage VC1 is abnormal to the logic circuit OR871.

The logic circuit OR871 takes the logical sum of the output signals of the

comparators

851, 852, 853. The logic circuit OR871 outputs a logical sum to the motor control unit 900 as a failure signal 2_FD indicating whether or not the second inverter 130 has failed.

When the output signals of the

comparators

851, 852, and 853 are all “0”, the logic circuit OR871 outputs “0” indicating that the second inverter 130 is normal as the failure signal 2_FD. When at least one of the output signals of the

comparators

851, 852, and 853 is “1”, the logic circuit OR871 outputs “1” indicating that the second inverter 130 has failed as the failure signal 2_FD.

For example, when the low-side switch element SW_A2L has an open failure, no current flows through the switch element. As a result, under the influence of the counter electromotive force of the motor 200, the lower peak value (negative value) of the actual voltage VA2 increases and the absolute value thereof decreases. When an open failure has not occurred in the low-side switch element SW_A2L, VA1≈ [(Vpeak / 2) + Vsat], and the magnitude of the actual voltage VA1 is equal to | (Vpeak / 2) + Vsat |. On the other hand, when an open failure occurs in the low-side switch element SW_A2L, this balance is lost. For example, since no current flows through the switch element SW_A2L, an extra voltage is applied to the switch element SW_A1L. The actual voltage VA1 increases and VA1_FD> 0.

The failure diagnosis unit 802 shown in FIG. 6 performs the same processing as the failure diagnosis unit 801, and diagnoses the presence or absence of a failure of the first inverter 120. Instead of the actual voltages VA1, VB1, and VC1, actual voltages VA2, VB2, and VC2 are input to the failure diagnosis unit 802. Since the other processing of the failure diagnosis unit 802 is the same as that of the failure diagnosis unit 801, detailed description is omitted here.

Further, the failure diagnosis voltage may be obtained by a method other than the above calculation. For example, the failure diagnosis voltage VA1_FD may be obtained from the calculation of the following equation (5).
VA1_FD = VA1 ² − [(Vpeak / 2) + Vsat] ² formula (5)

Further, for example, the failure diagnosis voltage VA1_FD may be obtained by the calculation of the following equation (6).
VA1_FD = [VA1 + (Vpeak / 2) + Vsat] [VA1- (Vpeak / 2) −Vsat] Equation (6)

Even if these calculations are used, it is possible to diagnose the presence or absence of an inverter failure in the same manner as described above.

Hereinafter, the validity of the algorithm used for the failure diagnosis according to the present disclosure will be shown using the “Rapid Control Prototyping (RCP) System” of dSPACE and the Matlab / Simlink of MathWorks. For this verification, a model of a surface magnet type (SPM) motor used in an electric power steering (EPS) apparatus, which is controlled by vector control, was used. In the verification, the q-axis current command value Iq_ref was set to 3A, and the d-axis current command value Id_ref and the zero-phase current command value Iz_ref were set to 0A. The rotation speed ω of the motor was set to 1200 rpm. In the simulation, an open failure occurs in the low-side switch element SW_A1L of the first inverter 120 at time 1.641s.

8 to 10 show the simulation results of the waveform of each signal. The vertical axis of each graph represents voltage (V), and the horizontal axis represents time (s).

FIG. 8 shows waveforms of the actual voltage VA1 (upper side) and the actual voltage VA2 (lower side) when the low-side switch element SW_A1L has an open failure. FIG. 9 shows waveforms of the actual voltage VB1 (upper side) and the actual voltage VB2 (lower side) when the low-side switch element SW_A1L has an open failure. FIG. 10 shows waveforms of the actual voltage VC1 (upper side) and the actual voltage VC2 (lower side) when the low-side switch element SW_A1L has an open failure.

After the low-side switch element SW_A1L has an open failure at time 1.641s, it can be seen that the lower peak value of the actual voltage VA1 increases as shown in FIG. It can also be seen that the upper peak value of the actual voltage VA2 is increasing. That is, the absolute value of the upper peak value of the actual voltage VA2 increases. As shown in FIGS. 9 and 10, the actual voltages VB1, VB2, VC1, and VC2 have a small degree of change.

Even in normal operation, it may occur that the actual voltage becomes slightly higher than Vpeak / 2. However, in this embodiment, the value obtained by adding the saturation voltage Vsat to Vpeak / 2 is compared with the actual voltage. For this reason, it can be determined that a failure has occurred only when an actual voltage that has changed significantly, such as the actual voltage VA2 shown in FIG. When the actual voltage is higher than Vpeak / 2 in the normal operation, the failure determination accuracy can be improved by not determining the failure.

As described above, the failure diagnosis of the present disclosure can be realized by a simple algorithm. For this reason, for example, an advantage of reducing the circuit size or the memory size can be obtained in mounting 340 to the controller.

The failure diagnosis method of the present disclosure can be suitably used for a full bridge type power conversion device. The full bridge includes a one-phase H-bridge structure, for example, the circuit structure shown in FIG. 3A. By utilizing the above-described failure diagnosis method for full bridge failure diagnosis, a full bridge failure can be detected.

In the present embodiment, the above-described failure diagnosis need not be performed for all three phases, and the failure diagnosis may be performed only for one phase or two phases. For example, when failure diagnosis is performed only for the A phase, only the process related to the A phase among the processes described with reference to FIGS. 5 and 6 may be performed, and the process related to the B phase and the C phase may not be performed.

(Embodiment 2)
FIG. 11 schematically shows a typical configuration of the electric power steering apparatus 3000 according to the present embodiment.

A vehicle such as an automobile generally has an electric power steering device. The electric power steering apparatus 3000 according to the present embodiment includes a steering system 520 and an auxiliary torque mechanism 540 that generates auxiliary torque. The electric power steering device 3000 generates auxiliary torque that assists the steering torque of the steering system that is generated when the driver operates the steering wheel. The burden on the driver's operation is reduced by the auxiliary torque.

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

universal shaft joints

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

tie rods

527A and 527B, and a knuckle. 528A and 528B, and left and

right steering wheels

529A and 529B.

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

The ECU 542 includes, for example, the controller 340 and the drive circuit 350 according to the first embodiment. In an automobile, an electronic control system with an ECU as a core is constructed. In the electric power steering apparatus 3000, for example, a motor drive unit is constructed by the ECU 542, the motor 543, and the inverter 545. The motor module 2000 according to the first embodiment can be suitably used for the system.

The embodiment of the present disclosure is also suitably used for motor control systems such as X-by-wire such as shift-by-wire, steering-by-wire, and brake-by-wire, and a traction motor. For example, an EPS that implements a fault diagnosis method according to an embodiment of the present disclosure is an autonomous driving vehicle that corresponds to levels 0 to 5 (standards for automation) defined by the Japanese government and the US Department of Transportation's Road Traffic Safety Administration (NHTSA). Can be mounted.

The embodiment of the present disclosure can be widely used in various devices including various motors such as a vacuum cleaner, a dryer, a ceiling fan, a washing machine, a refrigerator, and an electric power steering device.

100: Inverter unit, 101: Power supply, 120: First inverter, 130: Second inverter, 140: Inverter, 150: Current sensor, 200: Motor, 300: Control circuit, 310: Power supply circuit, 320: Angle sensor, 330 : Input circuit, 340: microcontroller, 350: drive circuit, 360: ROM, 1000: power conversion device, 2000: motor module, 3000: electric power steering device

Claims

A failure diagnosis method for diagnosing a failure of a power conversion device that converts power from a power source into power supplied to a motor having at least one phase winding,
The power converter is
A first inverter connected to one end of the at least one phase winding and comprising a first high-side switch element and a first low-side switch element;
A second inverter connected to the other end of the at least one-phase winding and comprising a second high-side switch element and a second low-side switch element;
An H bridge including the first high-side switch element, the first low-side switch element, the second high-side switch element, and the second low-side switch element;
With
The failure diagnosis method includes:
A first actual voltage indicating a voltage across the first low-side switch element; a saturation voltage of the first low-side switch element; and a voltage peak value determined based on a d-axis voltage and a q-axis voltage in a dq coordinate system. An acquisition step to acquire,
A diagnostic step of diagnosing the presence or absence of a failure of the second inverter based on the first actual voltage, the saturation voltage, and the voltage peak value;
A fault diagnosis method including:
The diagnosis step includes a step of diagnosing the presence or absence of a failure of the second inverter based on the first failure diagnosis voltage VA1_FD represented by the following equation:
VA1_FD = | VA1 | − [(Vpeak / 2) + Vsat]
2. The failure diagnosis method according to claim 1, wherein VA 1 indicates the first actual voltage, Vpeak indicates the voltage peak value, and Vsat indicates the saturation voltage.
The diagnosis step includes a step of diagnosing the presence or absence of a failure of the second inverter based on the first failure diagnosis voltage VA1_FD represented by the following equation:
VA1_FD = VA1 2 -[(Vpeak / 2) + Vsat] 2
2. The failure diagnosis method according to claim 1, wherein VA 1 indicates the first actual voltage, Vpeak indicates the voltage peak value, and Vsat indicates the saturation voltage.
The diagnosis step includes a step of diagnosing the presence or absence of a failure of the second inverter based on the first failure diagnosis voltage VA1_FD represented by the following equation:
VA1_FD = [VA1 + (Vpeak / 2) + Vsat] [VA1- (Vpeak / 2) −Vsat]
2. The failure diagnosis method according to claim 1, wherein VA 1 indicates the first actual voltage, Vpeak indicates the voltage peak value, and Vsat indicates the saturation voltage.
When the first failure diagnosis voltage VA1_FD is less than or equal to zero, the second inverter is diagnosed as normal;
5. The failure diagnosis method according to claim 2, wherein when the first failure diagnosis voltage VA 1 _FD is greater than zero, the second inverter is diagnosed as having failed.
The failure according to any one of claims 1 to 5, further comprising a step of outputting a failure signal indicating that the second inverter has failed when the second inverter is diagnosed as having failed. Diagnostic method.
7. The failure diagnosis method according to claim 1, wherein the saturation voltage is determined based on a d-axis current, a q-axis current in the dq coordinate system, and a rotation speed of the motor.
In the acquisition step, the saturation voltage is determined using a lookup table that associates the saturation voltage with the input of the current value determined based on the d-axis current and the q-axis current and the rotational speed of the motor. The failure diagnosis method according to any one of claims 1 to 7.
The motor has n-phase windings (n is an integer of 3 or more),
The power conversion device has n H bridges,
The failure diagnosis method according to claim 1, wherein the acquisition step and the diagnosis step are executed in each of the n H bridges.
A power conversion device that converts electric power from a power source into electric power to be supplied to a motor having at least one phase winding,
The power converter is
A first inverter connected to one end of the at least one phase winding and comprising a first high-side switch element and a first low-side switch element;
A second inverter connected to the other end of the at least one-phase winding and comprising a second high-side switch element and a second low-side switch element;
An H bridge including the first high-side switch element, the first low-side switch element, the second high-side switch element, and the second low-side switch element;
A control circuit for controlling the operation of the first and second inverters;
With
The control circuit includes:
A first actual voltage indicating a voltage across the first low-side switch element; a saturation voltage of the first low-side switch element; and a voltage peak value determined based on a d-axis voltage and a q-axis voltage in a dq coordinate system. Earn,
A power converter that diagnoses the presence or absence of a failure of the second inverter based on the first actual voltage, the saturation voltage, and the voltage peak value.
A motor,
The power conversion device according to claim 10;
A motor module comprising:
An electric power steering apparatus comprising the motor module according to claim 11.