WO2019064748A1

WO2019064748A1 - Fault diagnosis method, power conversion device, motor module and electric power steering device

Info

Publication number: WO2019064748A1
Application number: PCT/JP2018/023721
Authority: WO
Inventors: アハマッドガデリー
Original assignee: 日本電産株式会社
Priority date: 2017-09-28
Filing date: 2018-06-22
Publication date: 2019-04-04

Abstract

A fault diagnosis method of the present disclosure diagnoses a fault of an H bridge having 4 switch elements. The fault diagnosis method includes: an acquisition step for acquiring a current/voltage represented in a dq coordinate system, acquiring a first actual voltage indicating a voltage across terminals of one low side switch element and a second actual voltage indicating a voltage across terminals of the other low side switch element, and acquires a rotation speed of the motor; and a diagnosis step for diagnosing a fault of the 4 switch elements on the basis of the acquired current/voltage in the dq coordinate system, the first actual voltage, the second actual voltage, and the acquired rotation speed.

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.

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

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

Patent documents

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

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

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

In the above-described prior art, it has been required to properly detect the failure of the H bridge.

Embodiments of the present disclosure provide a fault diagnosis method capable of appropriately diagnosing a fault of the H bridge.

Exemplary fault diagnosis methods of the present disclosure convert power from a power supply into power supplied to a motor having at least one phase winding, each of which is a first high side switch element, a second high side switch element, A fault diagnostic method for diagnosing a fault in an H bridge, for use in a power converter comprising at least one H bridge having a first low side switch element and a second low side switch element, the current / voltage represented in the dq coordinate system And the first actual voltage indicating the voltage across the first low side switch element and the second actual voltage indicating the voltage across the second low side switch element, and the rotational speed of the motor Acquiring the current and voltage of the dq coordinate system, the first actual voltage, the second actual voltage, and the rotation speed. Including the first high side switching device, the second high side switching device, and a diagnostic step for diagnosing a failure of the first low side switching device and said second low-side switch elements.

An exemplary power converter of the present disclosure is a power converter that converts power from a power source to power supplied to a motor having at least one phase winding, each of which is a first high side switch element, 2) at least one H bridge having a high side switching device, a first low side switching device, and a second low side switching device, and a control circuit for controlling the switching operation of the switching devices of the at least one H bridge; The circuit acquires a current / voltage represented in a dq coordinate system, and acquires a first actual voltage indicating a voltage across the first low side switch element and a second actual voltage indicating a voltage across the second low side switch element. Current speed of the dq coordinate system, the first actual voltage, and the second actual voltage, which are obtained by acquiring the rotational speed of the motor. Preliminary on the basis of the rotational speed, the first high side switching device, the second high side switching device, for diagnosing a failure of the first low side switching device and said second low-side switch elements.

Another exemplary power converter of the present disclosure is a power converter that converts power from a power supply to 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 a winding of each phase of the motor and having n legs each including a first high side switching device and a first low side switching device, and the winding of each phase of the motor A second inverter connected to the end and having n legs each including a second high side switch element and a second low side switch element, a winding of the n phase, the n legs of the first inverter, And n H bridges having the n legs of the second inverter, and a control circuit for controlling the switching operation of the switch elements of the n H bridges, the control circuit having dq coordinates system Obtaining a current / voltage expressed in the equation, and acquiring a first actual voltage indicating the voltage across the first low side switch element and a second actual voltage indicating the voltage across the second low side switch element for each phase, Based on the current / voltage of the dq coordinate system, the first actual voltage, the second actual voltage, and the rotational speed acquired and acquired, the rotational speed of the motor, and the second high side switch element, the second Failures of the high side switching device, the first low side switching device, and the second low side switching device are diagnosed for each phase.

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

FIG. 1 is a block diagram schematically showing a typical block configuration of a motor module 2000 according to an exemplary embodiment 1. As shown in FIG. FIG. 2 is a circuit diagram schematically showing a circuit configuration of the inverter unit 100 according to the exemplary embodiment 1. As shown in FIG. FIG. 3A is a schematic view showing the configuration of the A-phase H bridge BA. FIG. 3B is a schematic view showing the configuration of the B-phase H bridge BB. FIG. 3C is a schematic view showing the configuration of the C-phase H bridge BC. FIG. 4 is a functional block diagram illustrating functional blocks of the controller 340 for performing motor control in general. FIG. 5A is a functional block diagram illustrating functional blocks for performing failure diagnosis of the A-phase H bridge BA. FIG. 5B is a functional block diagram illustrating functional blocks for performing failure diagnosis of B-phase H bridge BB. FIG. 5C is a functional block diagram illustrating functional blocks for performing failure diagnosis of the C-phase H bridge BC. FIG. 6 is a schematic diagram showing a look-up table 840 for determining the saturation voltage Vsat from the rotational speed ω and the current amplitude value. FIG. 7 exemplifies a current waveform (sine wave) obtained by plotting current values flowing in the A-phase, B-phase, and C-phase windings of the motor 200 when the power conversion device 1000 is controlled according to three-phase conduction control. Is a graph. FIG. 8A is obtained by plotting the current values flowing in the B-phase and C-phase windings of the motor 200 when the power converter 1000 is controlled according to the two-phase energization control when the A-phase H bridge BA fails. It is a graph which illustrates a current waveform. FIG. 8B can be obtained by plotting the current values flowing through the A-phase and C-phase windings of the motor 200 when the power converter 1000 is controlled according to the two-phase energization control when the B-phase H bridge BB fails. It is a graph which illustrates a current waveform. FIG. 8C is obtained by plotting the current values flowing in the A-phase and B-phase windings of the motor 200 when the power conversion apparatus 1000 is controlled according to the two-phase energization control when the C-phase H bridge BC fails. It is a graph which illustrates a current waveform. FIG. 9A is a graph showing a waveform (upper side) of a simulation result of motor rotation speed and a waveform (lower side) of a simulation result of rotor angle. FIG. 9B is a graph showing the waveform of the simulation result of the A-phase current Ia. FIG. 9C is a graph showing the waveform of the simulation result of the B phase current Ib. FIG. 9D is a graph showing the waveform of the simulation result of the C-phase current Ic. FIG. 9E is a graph showing the waveform of the simulation result of the zero phase current Iz. FIG. 9F shows waveforms of simulation results of the first actual voltage VA1 (upper side) and the second actual voltage VA2 (lower side) of the A phase when the high side switch element SW_A1H in the H bridge BA of the A phase has an open failure. It is a graph. FIG. 9G shows waveforms of simulation results of the first real voltage VB1 (upper side) and the second real voltage VB2 (lower side) of the B phase when the high side switch element SW_A1H in the H bridge BA of the A phase has an open failure. It is a graph. FIG. 9H shows waveforms of simulation results of the first actual voltage VC1 (upper side) and the second actual voltage VC2 (lower side) of the C phase when the high side switch element SW_A1H in the H bridge BA of the A phase has an open failure. It is a graph. FIG. 9I is a graph showing waveforms of simulation results of the first actual voltage VA1 (upper side) and the second actual voltage VA2 (lower side) of the A phase when the low side switch element SW_A1L in the H bridge BA of the A phase has an open failure. It is. FIG. 9J is a graph showing waveforms of simulation results of the first actual voltage VB1 (upper side) and the second actual voltage VB2 (lower side) of the B phase when the low side switch element SW_A1L in the H bridge BA of the A phase has an open failure. It is. FIG. 9K is a graph showing waveforms of simulation results of the first actual voltage VC1 (upper side) and the second actual voltage VC2 (lower side) of the C phase when the low side switch element SW_A1L in the H bridge BA of the A phase has an open failure. It is. FIG. 9L is a graph showing a waveform of a simulation result of the failure signal A_FD. FIG. 10 is a schematic view showing a typical configuration of an electric power steering apparatus 3000 according to the second embodiment.

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

In the present specification, the implementation of the present disclosure will be exemplified taking a power conversion device that converts power from a power supply into power supplied to a three-phase motor having three-phase (A-phase, B-phase, C-phase) windings. The form will be described. However, a power converter for converting power from a power supply into power for supplying to an n-phase motor having n-phase (n is an integer of 4 or more) windings such as four-phase or five-phase, and H used for the apparatus The fault diagnosis method of the bridge is also within the scope of the present disclosure.

(Embodiment 1)

[1. Structure of motor module 2000 and power converter 1000]

FIG. 1 schematically shows a typical block configuration of a motor module 2000 according to the present embodiment.

Motor module 2000 typically includes a power conversion device 1000 having an inverter unit 100 and a control circuit 300, and a motor 200. The motor module 2000 may be modularized and manufactured and sold as an electromechanical integrated motor having, for example, a motor, a sensor, a driver and a controller.

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

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

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, a single circuit board (typically, a printed circuit board). Control circuit 300 is connected to inverter unit 100, and controls inverter unit 100 based on input signals from current sensor 150 and angle sensor 320. As the control method, there are, for example, vector control, pulse width modulation (PWM) or direct torque control (DTC). However, depending on the motor control method (for example, sensorless control), the angle sensor 320 may not be necessary.

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

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

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 a rotation angle of the rotor (hereinafter referred to as “rotation signal”), and outputs a rotation signal to the controller 340.

The input circuit 330 receives the phase current detected by the current sensor 150 (hereinafter may be referred to as “actual current value”), and the level of the actual current value corresponds to the input level of the controller 340 as necessary. It converts and outputs an actual current value to the controller 340. The input circuit 330 is, for example, an analog-to-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 a field programmable gate array (FPGA). The controller 340 controls the switching operation (turn on or off) of each switch element (typically, semiconductor switch element) in the first and

second inverters

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

The drive circuit 350 is typically a predriver (sometimes referred to as 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 controls the gate of each switch element give. When the object to be driven is a low-voltage drivable motor, the pre-driver may not be required. In that case, the function of the pre-driver may be implemented in the controller 340.

The ROM 360 is, for example, a writable memory (for example, a PROM), a rewritable memory (for example, a flash memory), or a read only memory. The ROM 360 stores a control program including instructions 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 boot time.

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

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

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

second inverters

120, 130 as shown, or for the first power supply (not shown) for the first inverter 120 and for the second inverter 130. A second power source (not shown) of

The fuses ISW_ 11 and ISW_ 12 are connected between the power supply 101 and the first inverter 120. The fuses ISW_11 and ISW_12 can interrupt a large current that can flow from the power supply 101 to the first inverter 120. The fuses ISW 21 and ISW 22 are connected between the power supply 101 and the second inverter 130. The fuses ISW_ 21 and ISW_ 22 can interrupt a large current that can flow from the power supply 101 to the second inverter 130. A relay or the like may be used instead of the fuse.

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

The 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 has 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 a switch element, for example, a field effect transistor (typically, a MOSFET) in which a parasitic diode is formed, or a combination of an insulated gate bipolar transistor (IGBT) and a free wheeling diode connected in parallel thereto can be used. .

The first shunt resistor S_A1 is used to detect an 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, for example, between the low side switch element SW_B1L and the GND line GL. The first shunt resistor S_C1 is used to detect a C-phase current IC1 flowing through the C-phase winding M3, and is connected, for example, between the low side switch element SW_C1L and the GND line GL. The three shunt resistors S_A1, S_B1 and S_C1 are commonly connected to 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, for example, between 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 commonly connected to the GND line GL of the second inverter 130.

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

The A-phase leg of the first inverter 120 (specifically, the 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. 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 the B-phase H bridge BB. FIG. 3C schematically shows the configuration of the C-phase H bridge BC.

The inverter unit 100 includes A-phase, B-phase and C-phase H bridges BA, BB, 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 in the leg on the second inverter 130 side, a low side switch element SW_A2L, and a winding It 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 a leg on the first inverter 120 side, a high side switch element SW_B2H in a leg on the second inverter 130 side, a low side switch element SW_B2L, and a winding It has M2. The C-phase H bridge BC includes a high side switching device SW_C1H and a low side switching device SW_C1L in the leg on the first inverter 120 side, a high side switching device SW_C2H in the leg on the second inverter 130 side, a low side switching device SW_C2L, and a winding It has M3.

The control circuit 300 (specifically, the controller 340) can identify the failed H bridge from among the three-phase H bridges by performing the failure diagnosis of the H bridge described below. Furthermore, the control circuit 300 can identify an open failure switch element from among the four switch elements of the failed H bridge. For example, when the control circuit 300 identifies a failed H bridge, it is possible to switch to motor control in which a two-phase winding is energized using a two-phase H bridge other than the failed H bridge. In the present specification, energization of a three-phase winding is referred to as "three-phase energization control", and energization of a two-phase winding is referred to as "two-phase energization control".

[2. Failure diagnosis method of H bridge]

With reference to FIGS. 4 to 6, for example, a specific example of a failure diagnosis method for diagnosing a failure of the H bridge, which is used for the power conversion device 1000 shown in FIG. However, as will be described later, the failure diagnosis method of the present disclosure can be suitably used for a power converter including at least one H bridge, for example, a full bridge type power converter. Here, the failure of the H bridge will be described. The failure of the H bridge refers to the open failure of the switch element. In this specification, for example, the occurrence of an open failure in the high-side switch element SW_A1H of the A-phase H bridge BA may be referred to as a failure of the A-phase H bridge BA.

According to the H-bridge failure diagnosis method of the present disclosure, it is possible to identify an open-failed switch element among the four switch elements of the failed H-bridge. In that respect, the H-bridge failure diagnosis method includes a method of identifying an open failure switch element.

The outline of the failure diagnosis method for diagnosing the failure of the H bridge is as follows.

First, a current / voltage expressed in the dq coordinate system is acquired, and a first actual voltage indicating a voltage across the first low side switch element and a second actual voltage indicating a voltage across the second low side switch element are And the motor rotation speed ω (acquisition step). The current / voltage represented in the dq coordinate system includes the d-axis voltage Vd, the q-axis voltage Vq, the d-axis current Id and the q-axis current Iq. In the dq coordinate system, an axis corresponding to the zero phase is represented as az axis. The rotational speed ω is represented by the number of revolutions (rpm) at which the rotor of the motor rotates per unit time (for example, one minute) or the number of revolutions (rps) at which the rotor rotates per unit time (for example, one second).

The first actual voltage and the second actual voltage will be described with reference to FIGS. 3A to 3C.

A first actual voltage and a second actual voltage are defined for the A-phase, B-phase and C-phase H bridges BA, BB and BC, respectively. 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 switching device and the first low side switching device 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 switching device and the second low side switching device 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 which 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 indicates 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 device SW_B1L shown in FIG. 3B, and the second actual voltage indicates the voltage VB2 across the low side switch device 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 shown in FIG. 3C, and the second actual voltage indicates the voltage VC2 across the low-side switch element SW_C2L shown in FIG. 3C. .

Next, based on the acquired current / voltage in the dq coordinate system, the first actual voltage, the second actual voltage, and the rotation speed, the first high side switch element, the second high side switch element, the first low side switch element, The failure of the second low side switch element is diagnosed for each phase (diagnosis step).

Next, the failure signal indicating the failure of the H bridge is phase-by-phase based on the diagnosis result of the open failure of each of the first high side switching device, the second high side switching device, the first low side switching device and the second low side switching device. And output to a motor control unit described later (fault signal generation step). For example, a fault signal is a signal that is asserted when a fault occurs.

The above acquisition step, diagnosis step and fault signal generation step are repeatedly performed, for example, in synchronization with the cycle of measuring each phase current by the current sensor 150, that is, the cycle of AD conversion.

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 an FPGA, for example, or realized by a combination of a microcontroller and software. Can. 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 motor control in general. FIG. 5A illustrates functional blocks for performing failure diagnosis of the A-phase H bridge BA. FIG. 5B illustrates functional blocks for performing failure diagnosis of the B-phase H bridge BB. FIG. 5C illustrates functional blocks for performing failure diagnosis of the C-phase H bridge BC.

In the present specification, each block in the functional block diagram is shown not in hardware but in functional block. The software used for motor control and fault diagnosis of the H bridge may be, for example, a module constituting a computer program for executing a specific process corresponding to each functional block. Such computer programs are stored, for example, in the ROM 360. The controller 340 can read an instruction from the ROM 360 and sequentially execute each process.

The controller 340 includes, for example, a fault diagnosis unit 800 and a motor control unit 900. Thus, the fault 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.

The failure diagnosis unit 800 obtains, as input signals, a voltage peak value Vpeak expressed in the dq coordinate system, a current amplitude value (Id ² + Iq ² ) ^1/2, and a rotational speed ω of the motor 200. The failure diagnosis unit 800 refers to the look-up table 840 to determine the saturation voltage Vsat based on the acquired current amplitude value and rotational speed ω. The fault diagnosis unit 800 further obtains the first actual voltages VA1, VB1, VC1, and the second actual voltages VA2, VB2, and VC2.

The failure diagnosis unit 800 diagnoses a failure of the A-phase H bridge BA based on the acquired voltage peak value Vpeak, the saturation voltage Vsat, the first actual voltage VA1 and the second actual voltage VA2. The failure diagnosis unit 800 diagnoses a failure of the B-phase H bridge B based on the acquired voltage peak value Vpeak, the saturation voltage Vsat, the first actual voltage VB1 and the second actual voltage VB2. The failure diagnosis unit 800 diagnoses a failure of the C-phase H bridge BC based on the acquired voltage peak value Vpeak, the saturation voltage Vsat, the first actual voltage VC1 and the second actual voltage VC2.

The failure diagnosis unit 800 generates failure signals A_FD, B_FD and C_FD indicating a failure of the H bridge for each phase based on the diagnosis result, and outputs the signals to a motor control unit 900 that controls the motor 200.

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. Further, the motor control unit 900 can switch the motor control from the three-phase energization control to the two-phase energization control, for example, when a failure signal is asserted.

In the present specification, each functional block may be referred to as a unit for convenience of explanation. Naturally, these notations should not be used with the intention of limiting interpretation of 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, for example, the core of the controller 340. As described above, controller 340 may be implemented by an FPGA. In that case, all or part of the functional blocks can be realized in hardware.

By distributing the processing using a plurality of FPGAs, the computing load of a specific computer can be distributed. In that case, all or part of the functional blocks shown in FIG. 4 and FIGS. 5A to C may be distributed and implemented in a plurality of FPGAs. The plurality of FPGAs are communicably connected to one another by, for example, a vehicle-mounted control area network (CAN), and can transmit and receive data.

The failure diagnosis unit 800 is a failure diagnosis unit 800A (see FIG. 5A) for diagnosing a failure of the A-phase H bridge BA, and a failure diagnosis unit 800B for diagnosing a failure of the B-phase H bridge BB (FIG. 5B). And a failure diagnosis unit 800C (see FIG. 5C) for diagnosing a failure of the C-phase H bridge BC. The failure diagnosis units 800A, B, C are configured by substantially the same functional blocks. However, the input signals of the first actual voltage and the second actual voltage are different among the blocks. Hereinafter, the fault diagnosis of the H-bridge will be described in detail with reference to FIG. 5A, taking the fault diagnosis of the A-phase H bridge BA as an example.

The fault diagnosis unit 800A is a low side fault diagnosis

unit including multipliers

810, 811, adders 812, 813_1, 813_2, signal generation units 814_1 and 814_2,

multipliers

820, 821, adders 822, 823_1, 823_2, signal generation. It has a high side fault diagnosis unit including units 824_1 and 824_2, and a logic circuit OR 830.

The low side fault diagnosis unit identifies open faults of the low side switch elements SW_A1L and SW_A2L. The high side fault diagnosis unit identifies open faults of the high side switch elements SW_A1H and SW_A2H.

First, the high side fault diagnosis unit will be described.

The high side fault diagnosis unit performs a first fault diagnosis for diagnosing an open fault of the high side switch element SW_A1H based on the voltage peak value Vpeak, the saturation voltage Vsat and the first actual voltage VA1, a voltage peak value Vpeak, a saturation voltage Vsat and A second failure diagnosis for diagnosing an open failure of the high side switch element SW_A2H is performed based on the second actual voltage VA2.

The multiplier 820 multiplies the voltage peak value Vpeak by a constant "1/2". The voltage peak value Vpeak is calculated based on the equation (1). Here, Vd indicates the d-axis voltage in the dq coordinate system, and Vq indicates the q-axis voltage.

Vpeak = (2/3) ^1/2 (Vd ² + Vq ² ) ^1/2 equation (1)

For example, the failure diagnosis unit 800 may have a pre-operation unit (not shown) for acquiring Vpeak. The pre-arithmetic unit uses three-phase currents Ia, Ib and Ic obtained based on the measurement values of the current sensor 150 using Clarke transformation to generate currents I _α and β on the α axis in the αβ fixed coordinate system. Current _I.sub..beta . The pre-arithmetic unit further converts the currents I _α and I _β into the d-axis current Id and the q-axis current Iq in the dq coordinate system, using Park transformation (dq coordinate transformation). The pre-arithmetic unit acquires the d-axis voltage Vd and the q-axis voltage Vq based on Id and Iq, and calculates the voltage peak value Vpeak from the acquired Vd and Vq based on Expression (1). Alternatively, the pre-arithmetic unit can also receive Vd and Vq necessary for calculation of Vpeak from the motor control unit 900 performing vector control. For example, the pre-arithmetic unit acquires Vpeak in synchronization with the cycle of measuring each phase current by the current sensor 150.

The multiplier 821 multiplies the saturation voltage Vsat by a constant "1".

FIG. 6 schematically shows a look-up table (LUT) 840 for determining the saturation voltage Vsat from the rotational speed ω and the current amplitude value. The LUT 840 relates 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.

Id and Iq are input from, for example, a pre-operation unit. 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, for example, using a known sensorless control method.

Table 1 illustrates the configuration of the LUT 840 that can be used for the H-bridge failure diagnosis method. In motor control, Id is generally treated as zero. Therefore, it becomes equal to current amplitude value = Iq. In Table 1, Iq (A) is described. Thus, the saturation voltage Vsat is determined from the acquired current amplitude value Iq and the rotational speed ω. Alternatively, a constant value (for example, about 0.1 V) depending on the system can be used as the saturation voltage Vsat.

Refer again to FIG. 5A.

The adder 822 adds the output Vsat of the multiplier 821 to the output Vpeak / 2 of the multiplier 820.

The adder 823_1 calculates the first failure diagnosis voltage VA1H_FD by adding the first actual voltage VA1 to the output (Vpeak / 2) + Vsat from the adder 822 in the first failure diagnosis (Equation (2)) . The adder 823_2 calculates the second fault diagnosis voltage VA2H_FD by adding the second actual voltage VA2 to the output (Vpeak / 2) + Vsat from the adder 822 in the second fault diagnosis (Equation (3)) . The first actual voltage VA1 and the second actual voltage VA2 are measured by, for example, a drive circuit (predriver) 350.

VA1H_FD = VA1 + [(Vpeak / 2) + Vsat] Formula (2)

VA2H_FD = VA2 + [(Vpeak / 2) + Vsat] Formula (3)

In the first failure diagnosis, the signal generation unit 824_1 diagnoses an open failure of the high side switch element SW_A1H based on the first failure diagnosis voltage VA1H_FD. Specifically, when the first failure diagnosis voltage VA1H_FD is less than zero (VA1H_FD <0), the signal generation unit 824_1 identifies an open failure of the high side switch element SW_A1H. When the first failure diagnosis voltage VA1H_FD is greater than or equal to zero (VA1H_FD ≧ 0), the signal generation unit 824_1 determines that an open failure has not occurred in the high side switch element SW_A1H.

The signal generation unit 824_1 generates a first failure signal A1H_FD indicating an open failure of the high side switch element SW_A1H based on the diagnosis result in the first failure diagnosis. For example, the first failure signal A1H_FD can be assigned to a 1-bit signal. When the open failure does not occur in the high side switch element SW_A1H, the level of the first failure signal A1H_FD is Low. When the signal generation unit 824_1 identifies the open failure of the high side switch element SW_A1H, it asserts the first failure signal A1H_FD.

For example, when the high side switch element SW_A1H is in open failure, no current flows in the switch element. As a result, under the influence of the back electromotive force of the motor 200, the upper peak value (positive value) of the first actual voltage decreases. When no open failure occurs in the high side switch element SW_A1H, VA1 ≒ − [(Vpeak / 2) + Vsat], and the magnitude of the first actual voltage VA1 is equal to | (Vpeak / 2) + Vsat |. On the other hand, when an open failure occurs in the high side switch element SW_A1H, this balance is broken. In order to lower VA1, the first failure diagnosis voltage VA1H_FD becomes <0. The present disclosure uses this phenomenon to identify the open failure of the switch element.

As in the first fault diagnosis, in the second fault diagnosis, the signal generation unit 824_2 diagnoses an open fault of the high side switch element SW_A2H based on the second fault diagnosis voltage VA2H_FD. Specifically, when the second failure diagnosis voltage VA2H_FD is less than zero (VA2H_FD <0), the signal generation unit 824_2 specifies an open failure of the high side switch element SW_A2H. When the second failure diagnosis voltage VA2H_FD is greater than or equal to zero (VA2H_FD ≧ 0), the signal generation unit 824_2 determines that an open failure has not occurred in the high side switch element SW_A2H.

The signal generation unit 824_2 generates a second failure signal A2H_FD indicating an open failure of the high side switch element SW_A2H based on the diagnosis result in the second failure diagnosis. For example, the second failure signal A2H_FD can be assigned to a 1-bit signal. When the open failure does not occur in the high side switch element SW_A2H, the level of the second failure signal A2H_FD is Low. When the signal generation unit 824_2 identifies the open failure of the high side switch element SW_A2H, it asserts the second failure signal A2H_FD.

Next, the low side fault diagnosis unit will be described.

The low side fault diagnosis unit performs third fault diagnosis that diagnoses an open fault of the low side switch element SW_A1L based on the voltage peak value Vpeak, the saturation voltage Vsat and the first actual voltage VA1, and the voltage peak value Vpeak, the saturation voltage Vsat and the second fault diagnosis unit. A fourth failure diagnosis is performed to diagnose an open failure of the low side switch element SW_A2L based on the actual voltage VA2.

The multiplier 810 multiplies the voltage peak value Vpeak by a constant “−1⁄2”. The multiplier 811 multiplies the saturation voltage Vsat by a constant “−1”. In view of the fact that the current flowing between the low side switch element and the high side switch element is reversed, the low side fault diagnosis unit has the opposite sign of the

multipliers

810 and 811 of the high side fault diagnosis unit. A constant is used.

The adder 812 adds the output (-Vsat) of the multiplier 811 to the output (-Vpeak / 2) of the multiplier 810.

The adder 813_1 calculates the third fault diagnosis voltage VA1L_FD by adding the first actual voltage VA1 to the output from the adder 812:-[(Vpeak / 2) + Vsat] in the third fault diagnosis (formula (4)). The adder 813_2 calculates the fourth failure diagnosis voltage VA2L_FD by adding the second actual voltage VA2 to the output from the adder 812:-[(Vpeak / 2) + Vsat] in the fourth failure diagnosis. (5). VA1L_FD = VA1-[(Vpeak / 2) + Vsat] formula (4) VA2L_FD = VA2-[(Vpeak / 2) + Vsat] formula (5)

In the third failure diagnosis, the signal generation unit 814_1 diagnoses an open failure of the low side switch element SW_A1L based on the third failure diagnosis voltage VA1L_FD. Specifically, when the third failure diagnosis voltage VA1L_FD is larger than zero (VA1L_FD> 0), the signal generation unit 814_1 identifies an open failure of the low side switch element SW_A1L. When the third failure diagnosis voltage VA1L_FD is equal to or less than zero (VA1L_FD ≦ 0), the signal generation unit 814_1 determines that the open failure does not occur in the low side switch element SW_A1L.

The signal generation unit 814_1 generates a third failure signal A1L_FD indicating an open failure of the low side switch element SW_A1L based on the diagnosis result in the third failure diagnosis. For example, the third fault signal A1L_FD can be assigned to a 1-bit signal. When no open failure occurs in the low side switch element SW_A1L, the level of the third failure signal A1L_FD is Low. The signal generation unit 814_1 asserts the third failure signal A1L_FD upon identifying the open failure of the low side switch element SW_A1L.

For example, when the low side switch element SW_A1L is in open failure, no current flows in the switch element. As a result, under the influence of the back electromotive force of the motor 200, the lower peak value (negative value) of the first actual voltage increases and its absolute value decreases. When no open failure occurs in the low side switch element SW_A1L, VA1 ≒ [(Vpeak / 2) + Vsat], and the magnitude of the first 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_A1L, this balance is broken. The third failure diagnosis voltage VA1L_FD> 0 is obtained in order to increase VA1.

As in the third fault diagnosis, in the fourth fault diagnosis, the signal generation unit 814_2 diagnoses an open fault of the low-side switch element SW_A2L based on the fourth fault diagnostic voltage VA2L_FD. Specifically, when the fourth failure diagnosis voltage VA2L_FD is larger than zero (VA2L_FD> 0), the signal generation unit 814_2 identifies an open failure of the low side switch element SW_A2L. When the fourth failure diagnosis voltage VA2L_FD is less than or equal to zero (VA2L_FD ≦ 0), the signal generation unit 814_2 determines that the open failure does not occur in the low side switch element SW_A2L.

The signal generation unit 814_2 generates a fourth failure signal A2L_FD indicating an open failure of the low side switch element SW_A2L based on the diagnosis result in the fourth failure diagnosis. For example, the fourth failure signal A2L_FD can be assigned to a 1-bit signal. When the open failure does not occur in the low side switch element SW_A2L, the level of the fourth failure signal A2L_FD is Low. When the signal generation unit 814_2 identifies the open failure of the low side switch element SW_A2L, it asserts a fourth failure signal A2L_FD.

As described above, the failure diagnosis unit 800A can specify the open failure switch element among the high side switch elements SW_A1H and SW_A2H, and the low side switch elements SW_A1L and SW_A2L.

The logic circuit OR 830 logically ORs the first to fourth failure signals A1H_FD, A2H_FD, A1L_FD and A2L_FD. The logic circuit OR 830 outputs a logical sum to the motor control unit 900 as a failure signal A_FD indicating a failure of the A-phase H bridge BA. For example, the failure signal A_FD can be assigned to a 1-bit signal. When at least one of the high side switch elements SW_A1H and SW_A2H and the low side switch elements SW_A1L and SW_A2L is open, the failure signal A_FD is asserted.

When the failure diagnosis unit 800B identifies at least one open failure of the high side switch devices SW_B1H and SW_B2H, and the low side switch devices SW_B1L and SW_B2L, the failure diagnosis unit 800B asserts the failure signal B_FD. When the failure diagnosis unit 800C identifies at least one open failure of the high side switch devices SW_C1H and SW_C2H, and the low side switch devices SW_C1L and SW_C2L, the failure diagnosis unit 800C asserts the failure signal C_FD.

FIG. 7 exemplifies a current waveform (sine wave) obtained by plotting current values flowing in the A-phase, B-phase, and C-phase windings of the motor 200 when the power conversion device 1000 is controlled according to three-phase conduction control. Do. FIG. 8A is obtained by plotting the current values flowing in the B-phase and C-phase windings of the motor 200 when the power converter 1000 is controlled according to the two-phase energization control when the A-phase H bridge BA fails. The current waveform is illustrated. The horizontal axis indicates the motor electrical angle (deg), and the vertical axis indicates the current value (A). In the current waveforms of FIG. 7 and FIG. 8A, current values are plotted at every electrical angle of 30 °. I _pk represents the maximum current value (peak current value) of each phase.

As a reference, when the B-phase H bridge BB fails, FIG. 8B plots the current values flowing in the A-phase and C-phase windings of the motor 200 when the power conversion device 1000 is controlled according to the two-phase energization control. The current waveform obtained by In FIG. 8C, when the C-phase H bridge BC fails, it is obtained by plotting the current values flowing in the A-phase and B-phase windings of the motor 200 when the power conversion device 1000 is controlled according to the two-phase energization control. The current waveform is illustrated.

Motor control unit 900 performs three-phase energization control when normal, that is, when the levels of failure signals A_FD, B_FD and C_FD are all low. On the other hand, for example, when the failure signal A_FD is asserted, the motor control unit 900 performs two-phase energization to energize the windings M2 and M3 using the two-phase H bridges BB and BC other than the failed H bridge BA. Control can be performed. Thus, even if one of the three phases of the H bridge is broken, power conversion device 1000 can continue motor driving.

The following shows the results of verification of the validity of the algorithm used for fault diagnosis of the H bridge according to the present disclosure, using dSPACE's "Rapid Control Prototyping (RCP) system" and Matlab / Simulink from MathWorks. For this verification, a model of a surface magnet type (SPM) motor used in an electric power steering (EPS) device, which is controlled by vector control, is used. In the verification, the q-axis current command value Iqref is set to 3A, and the d-axis current command value Idref and the zero-phase current command value Iz_ref are set to 0A.

The motor rotational speed ω was set to 1190 rpm, and a simulation was performed in which an open failure was generated at time 1.543 s in the high side switch element SW_A1H of the A-phase H bridge BA. Also, a simulation was performed in which an open failure was generated at time 1.641 s in the low-side switch element SW_A1L of the A-phase H bridge BA.

The simulation result of the waveform of each signal is shown to FIG. 9A-FIG. 9L.

FIG. 9A shows the waveform (upper side) of the rotational speed ω of the motor and the waveform (lower side) of the rotor angle. The upper vertical axis of the graph indicates the rotational speed (rpm), and the lower vertical axis indicates the rotor angle (rad). The horizontal axis shows time (s). The horizontal axis of all the waveforms of this simulation result indicates time.

FIG. 9B shows the waveform of the A phase current Ia, FIG. 9C shows the waveform of the B phase current Ib, and FIG. 9D shows the waveform of the C phase current Ic. The vertical axis shows the current (A). In the waveforms of the respective phases, waveforms of actual current values and waveforms of current command values are shown.

FIG. 9E shows the waveform of the zero phase current Iz. The vertical axis shows the current (A).

FIG. 9F shows the waveforms of the first actual voltage VA1 (upper side) and the second actual voltage VA2 (lower side) of the A phase when the high side switch element SW_A1H in the A bridge H of the A phase has an open failure. FIG. 9G shows waveforms of the first actual voltage VB1 (upper side) and the second actual voltage VB2 (lower side) of the B phase when the high side switch element SW_A1H in the A bridge H of the A phase is open-circuited. FIG. 9H shows waveforms of the first actual voltage VC1 (upper side) and the second actual voltage VC2 (lower side) of the C phase when the high side switch element SW_A1H in the H bridge BA of the A phase has an open failure. The vertical axis represents voltage (V).

FIG. 9I shows waveforms of the first actual voltage VA1 (upper side) and the second actual voltage VA2 (lower side) of the A phase when the low side switch element SW_A1L in the H bridge BA of the A phase has an open failure. FIG. 9J shows the waveforms of the first actual voltage VB1 (upper side) and the second actual voltage VB2 (lower side) of the B phase when the low side switch element SW_A1L in the H bridge BA of the A phase has an open failure. FIG. 9K shows waveforms of the first actual voltage VC1 (upper side) and the second actual voltage VC2 (lower side) of the C phase when the low side switch element SW_A1L in the H bridge BA of the A phase has an open failure. The vertical axis represents voltage (V).

FIG. 9L shows the waveform of the failure signal A_FD. The vertical axis indicates the failure signal level.

After the open failure of the high-side switch element SW_A1H of the A-phase H bridge BA at time 1.543 s, as shown in FIG. 9F, it can be seen that the upper peak value of the first actual voltage VA1 decreases. Further, it can be seen that the lower peak value of the second actual voltage VA2 is decreasing (the absolute value of the lower peak value is increased). As shown in FIGS. 9G and 9H, the first actual voltages VB1 and VC1 and the second actual voltages VB2 and VC2 do not change. Further, as shown in FIG. 9L, after 3.2 ms have elapsed since the open failure of the high-side switch element SW_A1H of the A-phase H bridge BA, the fault signal A_FD is properly reduced with the drop of the first actual voltage VA1. It can be seen that it is asserted. The fault signals B_FD and C_FD are not asserted.

After the open failure of the low-side switch element SW_A1L of the A-phase H bridge BA at time 1.641 s, it can be seen that the lower peak value of the first actual voltage VA1 is rising as shown in FIG. 9I. Further, it can be seen that the upper peak value of the second actual voltage VA2 is rising (the absolute value of the upper peak value is increased). As shown in FIGS. 9J and 9K, the first actual voltages VB1 and VC1 and the second actual voltages VB2 and VC2 do not change.

In this embodiment, an open failure switch element can be identified among the four switch elements of the H bridge. In addition, the failed H bridge of the three-phase H bridge can be identified. The fault diagnosis of the present disclosure can be realized by a simple algorithm. Therefore, for example, advantages such as circuit size reduction or memory size reduction can be obtained in the implementation of the controller 340.

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

For example, a full bridge type power converter controls the switching operation of the H bridge BA having the high side switch element SW_A1H, the high side switch element SW_A2H, the low side switch element SW_A1L and the low side switch element SW_A2L, and the switch elements of the H bridge BA And a control circuit 300. The control circuit 300 acquires the current / voltage represented in the dq coordinate system, and acquires the first actual voltage VA1 indicating the voltage across the low side switch element SW_A1L and the second actual voltage VA2 indicating the voltage across the low side switch element SW_A2L. To obtain the rotational speed ω of the motor. The control circuit 300 controls the high side switch element SW_A1H, the high side switch element SW_A2H, and the low side switch element based on the acquired current / voltage in the dq coordinate system, the first actual voltage VA1, the second actual voltage VA2 and the rotational speed ω. Diagnose open faults of SW_A1L and low side switch element SW_A2L.

Second Embodiment

FIG. 10 schematically shows a typical configuration of the electric power steering apparatus 3000 according to the present embodiment.

Vehicles such as automobiles generally have an electric power steering device. The electric power steering apparatus 3000 according to the present embodiment has a steering system 520 and an auxiliary torque mechanism 540 that generates an auxiliary torque. Electric power steering apparatus 3000 generates an assist torque that assists the steering torque of the steering system generated by the driver operating the steering wheel. The assist torque reduces the burden on the driver's operation.

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

free shaft joints

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

tie rods

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

right steering wheels

529A, 529B.

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

The ECU 542 includes, for example, the controller 340 and the drive circuit 350 according to the first embodiment. In automobiles, an electronic control system is built around an ECU. 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 by Embodiment 1 can be used suitably for the system.

Embodiments of the present disclosure are also suitably used in motor control systems such as shift by wire, steering by wire, X by wire such as brake by wire, and traction motors. For example, an EPS implementing a failure diagnosis method according to an embodiment of the present disclosure is an autonomous vehicle corresponding to levels 0 to 4 (standards of automation) defined by the Government of Japan and the Road Traffic Safety Administration (NHTSA) of the US Department of Transportation. It can be loaded.

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

100: inverter unit, 101: power supply, 120: first inverter, 130: second inverter, 140: inverter, 150: current sensor, 200: motor, 300: control circuit, 310: power circuit, 320: angle sensor, 330 : Input circuit, 340: Micro controller, 350: Drive circuit, 360: ROM, 1000: Power converter, 2000: Motor module, 3000: Electric power steering device

Claims

The power from the power supply is converted into power to be supplied to a motor having at least one phase winding, each of which is a first high side switching device, a second high side switching device, a first low side switching device and a second low side switching device What is claimed is: 1. A fault diagnostic method for diagnosing a fault in an H bridge, for use in a power conversion device comprising at least one H bridge having:

acquiring a current / voltage expressed in a dq coordinate system, and acquiring a first actual voltage indicating a voltage across the first low side switch element and a second actual voltage indicating a voltage across the second low side switch element And an acquiring step of acquiring the rotational speed of the motor,

The first high side switch element, the second high side switch element, and the first low side based on the acquired current / voltage of the dq coordinate system, the first actual voltage, the second actual voltage, and the rotational speed. A diagnosis step of diagnosing a failure of the switch element and the second low side switch element.
In the acquisition step, a voltage peak value determined based on the d-axis voltage and the q-axis voltage in the dq coordinate system, and a d-axis current in the dq coordinate system, the q-axis current, and the rotation speed are determined. To achieve the saturation voltage,

The diagnostic step

A first failure diagnosis for diagnosing an open failure of the first high side switch element based on the voltage peak value, the saturation voltage and the first actual voltage;

A second fault diagnosis for diagnosing an open fault of the second high side switch element based on the voltage peak value, the saturation voltage and the second actual voltage;

A third fault diagnosis that diagnoses an open fault of the first low side switch element based on the voltage peak value, the saturation voltage, and the first actual voltage;

The fault diagnosis method according to claim 1, further comprising: a fourth fault diagnosis that diagnoses an open fault of the second low side switch element based on the voltage peak value, the saturation voltage, and the second actual voltage.
In the acquisition step, the current value determined based on the d-axis current and the q-axis current and the rotational speed of the motor are acquired with reference to a lookup table that relates the relationship between the saturation voltage The fault diagnosis method according to claim 2, wherein the saturation voltage is determined based on the d-axis current, the q-axis current, and the rotation speed.
In the first fault diagnosis, a first fault diagnostic voltage VA1H_FD is calculated based on the equation (1), and an open fault of the first high side switch element is diagnosed based on the first fault diagnostic voltage VA1H_FD,

In the second fault diagnosis, a second fault diagnostic voltage VA2H_FD is calculated based on the equation (2), and an open fault of the second high side switch element is diagnosed based on the second fault diagnostic voltage VA2H_FD,

In the third fault diagnosis, a third fault diagnostic voltage VA1L_FD is calculated based on the equation (3), and an open fault of the first low side switch element is diagnosed based on the third fault diagnostic voltage VA1L_FD,

In the fourth fault diagnosis, a fourth fault diagnostic voltage VA2L_FD is calculated based on the equation (4), and an open fault of the second low side switch element is diagnosed based on the fourth fault diagnostic voltage VA2L_FD,

VA1H_FD = VA1 + [(Vpeak / 2) + Vsat] Formula (1)

VA2H_FD = VA2 + [(Vpeak / 2) + Vsat] Formula (2)

VA1L_FD = VA1-[(Vpeak / 2) + Vsat] formula (3)

VA2L_FD = VA2-[(Vpeak / 2) + Vsat] formula (4)

The fault diagnostic method according to claim 3, wherein Vpeak indicates the voltage peak value, Vsat indicates the saturation voltage, VA1 indicates the first actual voltage, and VA2 indicates the second actual voltage.
In the first failure diagnosis, when the first failure diagnosis voltage VA1H_FD is less than zero, an open failure of the first high side switch element is specified;

In the second failure diagnosis, when the second failure diagnosis voltage VA2H_FD is less than zero, an open failure of the second high side switch element is identified,

In the third fault diagnosis, when the third fault diagnosis voltage VA1L_FD is larger than zero, an open fault of the first low side switch element is identified,

The failure diagnosis method according to claim 4, wherein in the fourth failure diagnosis, an open failure of the second low side switch element is identified when the fourth failure diagnosis voltage VA2L_FD is larger than zero.
Generating a first failure signal indicating an open failure of the first high side switch element based on a diagnosis result in the first failure diagnosis;

Generating a second failure signal indicating an open failure of the second high side switch element based on the diagnosis result in the second failure diagnosis;

Generating a third failure signal indicating an open failure of the first low side switch element based on a diagnosis result in the third failure diagnosis;

The fault signal generating step according to any one of claims 2 to 5, further comprising a fourth fault signal generating step indicating a fourth fault signal indicating an open fault of said second low side switch element based on a diagnosis result in said fourth fault diagnosis. Failure diagnosis method.
The fault diagnostic method according to claim 6, wherein in the fault signal generating step, a logical sum of the first to fourth fault signals is output to a control unit that controls the motor.
The first inverter connected to one end of the n-phase winding and the n-phase are converted into power to be supplied to a motor having an n-phase (n is an integer of 3 or more) windings from a power source. The n-phase winding, n legs of the first inverter, and n legs of the second inverter, for use in a power conversion device including a second inverter connected to the other end of the winding A failure diagnosis method for diagnosing failure of an H bridge in each H bridge phase by phase,

A failure diagnosis method of diagnosing a failure of an H bridge on a phase-by-phase basis by executing the failure diagnosis method according to claim 7 on the n H bridges.
What is claimed is: 1. A power conversion device for converting power from a power supply into power supplied to a motor having at least one phase winding,

At least one H-bridge, each having a first high side switch element, a second high side switch element, a first low side switch element and a second low side switch element;

A control circuit that controls the switching operation of the switch element of the at least one H bridge;

The control circuit

acquire the current and voltage represented in the dq coordinate system,

A first actual voltage indicating a voltage across the first low side switch element and a second actual voltage indicating a voltage across the second low side switch element are obtained.

Obtain the rotational speed of the motor,

The first high side switch element, the second high side switch element, and the first low side based on the acquired current / voltage of the dq coordinate system, the first actual voltage, the second actual voltage, and the rotational speed. A power conversion device that diagnoses a failure of a switch element and the second low side switch element.
A power converter that converts power from a power supply 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 a winding of each phase of the motor and having n legs each including a first high side switching device and a first low side switching device;

A second inverter having n legs connected to the other ends of the windings of each phase of the motor and each including a second high side switch element and a second low side switch element;

N H-bridges comprising the n-phase winding, the n legs of the first inverter, and the n legs of the second inverter;

A control circuit that controls the switching operation of the switch elements of the n H bridges,

The control circuit

acquire the current and voltage represented in the dq coordinate system,

A first actual voltage indicating a voltage across the first low side switching device and a second actual voltage indicating a voltage across the second low side switching device are obtained for each phase,

Obtain the rotational speed of the motor,

The first high side switch element, the second high side switch element, and the first low side based on the acquired current / voltage of the dq coordinate system, the first actual voltage, the second actual voltage, and the rotational speed. The power converter device which diagnoses the failure of a switch element and said 2nd low side switch element for every phase.
A motor module, comprising: a motor; and the power conversion device according to claim 9.
An electric power steering apparatus comprising the motor module according to claim 11.