WO2019064749A1

WO2019064749A1 - Fault diagnosis method, power conversion device, motor module and electric power steering device

Info

Publication number: WO2019064749A1
Application number: PCT/JP2018/023722
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 and is used in a power conversion device which is provided with at least one H bridge and converts power from a power supply to power to be supplied to a motor having at least one-phase windings. The fault diagnosis method includes: an acquisition step for acquiring a current/voltage Ipeak_ref, Vpeak represented in a dq coordinate system, and acquires a voltage command value V_ref indicating a target voltage value imparted to the at least one-phase winding at the time of controlling the motor; and a diagnosis step for diagnosing a fault of the H bridge on the basis of the acquired current/voltage of the dq coordinate system.

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.

An exemplary fault diagnosis method of the present disclosure converts an electric power from a power supply into an electric power supplied to a motor having at least one phase winding, and uses the electric power conversion apparatus including at least one H bridge. A failure diagnosis method for diagnosing a failure, comprising obtaining a current / voltage represented in a dq coordinate system, and a voltage command value indicating a voltage value of a target to be applied to the at least one phase winding when controlling the motor And a diagnostic step of diagnosing the failure of the H bridge based on the magnitude of the voltage command value and the acquired current / voltage of the dq coordinate system.

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, comprising at least one H-bridge; Control circuit for controlling the switching operation of the switch elements of the two H bridges, said control circuit acquiring the current / voltage represented in the dq coordinate system, and controlling said motor at the time of said at least one phase winding The voltage command value indicating the voltage value of the target to be given is acquired, and the diagnosis of the failure of the H bridge is diagnosed based on the magnitude of the voltage command value and the acquired current / voltage of the dq coordinate system.

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 the winding of each phase of the motor and having n legs, and a second inverter connected to the other end of the winding of each phase of the motor and having n legs; Switching of the switch elements of the n H-bridges having the n-phase winding, the n-legs of the first inverter, and the n-legs of the second inverter, and the n H-bridges A control circuit for controlling the operation, wherein the control circuit obtains a current and a voltage represented in a dq coordinate system, and indicates each phase indicating a voltage value of a target to be applied to a winding of each phase when controlling the motor The voltage command value of each phase is acquired Decree value of the magnitude, and the failure of the H-bridge diagnosis for each phase based on the current and voltage of the dq coordinate system acquired.

According to an exemplary embodiment of the present disclosure, a failure diagnosis method capable of appropriately diagnosing a failure of an H bridge by referring to a voltage command value, a power converter, a motor module including the power converter, and the motor module An electric power steering apparatus comprising a 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. 5 is a functional block diagram illustrating functional blocks for performing failure diagnosis of the H bridge. FIG. 6 is a schematic diagram showing a circuit model for explaining the principle of performing a fault diagnosis of the H bridge by comparing the magnitudes of the system voltage and the voltage command value VA_ref. FIG. 7 is a functional block diagram illustrating another functional block for performing fault diagnosis of the H bridge. FIG. 8 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 energization control. Is a graph. FIG. 9A 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. 9B is obtained by plotting the current values flowing in 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. 9C is obtained by plotting current values flowing in the A-phase and B-phase windings of the motor 200 when the power converter 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. 10A 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. 10B is a graph showing the waveform of the simulation result of the A-phase current Ia. FIG. 10C is a graph showing the waveform of the simulation result of the B phase current Ib. FIG. 10D is a graph showing the waveform of the simulation result of the C-phase current Ic. FIG. 10E is a graph showing a waveform of a simulation result of the zero phase current Iz. FIG. 10F is a graph showing a waveform of a simulation result of voltage command value VA_ref. FIG. 10G is a graph showing a waveform of a simulation result of voltage command value VB_ref. FIG. 10H is a graph showing a waveform of a simulation result of voltage command value VC_ref. FIG. 10I is a graph showing a waveform (upper side) of a simulation result of a failure signal A_FD, a waveform (middle) of a simulation result of B_FD, and a waveform (lower side) of a simulation result of C_FD. FIG. 11 is a schematic view showing a typical configuration of an electric power steering apparatus 3000 according to an exemplary embodiment 2. As shown in FIG.

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. 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, 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. 1, for example, will be described. 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 is referred to as a failure of the A-phase H bridge BA.

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

First, the current / voltage represented in the dq coordinate system is acquired, and the voltage command value is acquired for each phase (acquisition step). The current and voltage expressed in the dq coordinate system are d axis voltage, q axis voltage, d axis current, q axis current, zero phase current, d axis current command value, q axis current command value and zero phase current command value Including. In the dq coordinate system, an axis corresponding to the zero phase is represented as the z axis. The voltage command value indicates the voltage value of the target to be applied to the winding, which is used when controlling the motor 200. The zero-phase current is also called z-axis current.

Next, the failure of the H bridge is diagnosed for each phase based on the magnitude of the voltage command value of each phase and the current / voltage of the acquired dq coordinate system (diagnosis step).

Next, a fault signal indicating a fault in the H bridge is generated, and a fault signal is output to the motor control unit 900 that controls the motor 200 (fault signal output step). For example, a fault signal is a signal that is asserted when a fault occurs.

The acquisition step, the diagnosis step, and the fault signal output step are repeatedly performed, for example, in synchronization with a cycle of measuring each phase current by the current sensor 150, that is, a 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. 5 exemplifies functional blocks for performing failure diagnosis of the H bridge.

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.

Fault diagnosis unit 800 obtains current peak command value Ipeak_ref and voltage peak value Vpeak expressed in the dq coordinate system, and obtains voltage command values VA_ref, VB_ref and VC_ref. The failure diagnosis unit 800 diagnoses a failure of the A-phase H bridge BA based on the magnitude of the voltage command value VA_ref, the acquired current peak command value Ipeak_ref and the voltage peak value Vpeak. The failure diagnosis unit 800 diagnoses a failure of the B-phase H bridge BB based on the magnitude of the voltage command value VB_ref, the acquired current peak command value Ipeak_ref and the voltage peak value Vpeak. The failure diagnosis unit 800 diagnoses a failure of the C-phase H bridge BC based on the magnitude of the voltage command value VC_ref, the acquired current peak command value Ipeak_ref and the voltage peak value Vpeak. The failure diagnosis unit 800 generates failure signals A_FD, B_FD and C_FD indicating the failure of the H bridge for each phase based on the diagnosis result, and outputs the generated signals to the 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 FIG. 5 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 includes, for example, gain unit 810, limit determination unit 820, LPF (low pass filter) 830, adder 840, multiplier 850,

absolute value units

860A, 860B, 860C,

adders

870A, 870B, 870C, signals. It has

generation units

880A, 880B and 880C.

The gain unit 810 multiplies the current peak command value Ipeak_ref by the gain R. The current peak command value Ipeak_ref indicates the peak value of the current amplitude in the dq coordinate system, and is specifically calculated based on the equation (1). Here, Idref indicates a d-axis current command value on the d-axis, Iqref indicates a q-axis current command value on the q-axis, and Izref indicates a zero-phase current command value. abs (X) indicates the absolute value of X. The gain R represents the electrical characteristics of the entire circuit system including the H bridge. For example, the gain R is determined in consideration of the influence of the dead time of the switch element and the like, and corresponds to the resistance [Ω] of the entire circuit.

Ipeak_ref = (2/3) ^1/2 (Idref ² + Iqref ² ) ^1/2 + abs (Izref) / 3 ^1/2 equation (1)

For example, the core of the controller 340 determines the current command values Idref, Iqref and Izref based on the rotational speed and the speed command value detected by the angle sensor 320, and outputs them to the fault diagnosis unit 800. A pre-operation unit to be described later calculates Ipeak_ref based on the current command values Idref, Iqref and Izref, and outputs the Ipeak_ref to the gain unit 810. The gain unit 810 outputs Ipeak_ref · R to the limit determination unit 820.

Limit determination unit 820 determines whether or not the magnitude of the product of current peak command value Ipeak_ref and gain R is within an allowable range. That is, the limit determination unit 820 determines whether Ipeak_ref · R is within the allowable range. The allowable range means the upper limit value of the input voltage in the normal operation.

It is preferable to subject the voltage peak value Vpeak to low-pass filter processing by the general purpose LPF 830 before performing the subsequent operation of adding the voltage peak value Vpeak. This makes it possible to acquire the voltage peak value Vpeak represented by only the fundamental wave.

The LPF 830 performs low-pass filter processing on the voltage peak value Vpeak. The voltage peak value Vpeak is calculated based on the equation (2). 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 (2)

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 a d-axis current Id, a q-axis current Iq and a zero-phase current Iz in the dq coordinate system, using Park conversion (dq coordinate conversion). 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 (2). 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-calculation unit acquires Vpeak and Ipeak_ref in synchronization with the cycle of measuring each phase current by the current sensor 150.

The adder 840 adds the output (Ipeak_ref · R) from the limit determination unit 820 and the output Vpeak from the LPF 830. The adder 840 outputs Ipeak_ref · R + Vpeak to the multiplier 850.

The multiplier 850 multiplies the output Ipeak_ref · R + Vpeak from the adder 840 by (−1). In the present specification, the output voltage (Ipeak_ref · R + Vpeak) from the adder 840 is referred to as “system voltage”. Multiplier 850 outputs the system voltage to A-phase adder 870A, B-phase adder 870B and C-phase adder 870C.

In the following, the process of H-bridge failure diagnosis will be described by taking the A-phase failure diagnosis as an example.

Failure diagnosis unit 800 diagnoses a failure of H bridge BA of A phase based on the comparison result of the system voltage and the magnitude of voltage command value VA_ref of A phase. If the magnitude of voltage command value VA_ref is larger than the system voltage, failure diagnosis unit 800 determines that A-phase H bridge BA is broken. When the magnitude of voltage command value VA_ref is equal to or less than the system voltage, failure diagnosis unit 800 determines that A-phase H bridge BA is not broken. In this embodiment, comparison between the system voltage and the voltage command value VA_ref of the A phase is realized using the multiplier 850, the absolute value unit 860A, and the adder 870A.

The adder 870A adds the output voltage from the multiplier 850 and the magnitude of the A-phase voltage command value VA_ref. The reason why the absolute value unit 860A takes the absolute value of the voltage command value VA_ref is to set the open failure of both the high side switch element and the low side switch element of the H bridge as a target of failure diagnosis.

Refer again to FIGS. 3A to 3C.

The voltage command value VA_ref of the A phase is a voltage command value VA1_ref for the high side switch device SW_A1H or low side switch device SW_A1L (a node between both switch devices) of the H bridge BA, the high side switch device SW_A2H or the low side switch device SW_A2L It is given by the difference with voltage command value VA2_ref for (a node between both switch elements). The B-phase voltage command value VB_ref and the C-phase voltage command value VC_ref are also given similarly to the A-phase voltage command value VA_ref. Voltage command values VA_ref, VB_ref and VC_ref are calculated based on equation (3).

VA_ref = VA1_ref-VA2_ref

VB_ref = VB1_ref-VB2_ref formula (3)

VC_ref = VC1_ref-VC2_ref

When the added value from adder 870A is larger than zero, signal generation unit 880A determines that H bridge BA is broken, generates failure signal A_FD, and outputs it to motor control unit 900. For example, the fault signal A_FD is assigned to a 1-bit signal, and the level of the fault signal A_FD in the normal state is set to the low level. When detecting a failure of the H bridge BA, the signal generation unit 880A generates a high level failure signal A_FD. In other words, the signal generation unit 880A asserts the fault signal A_FD.

The failure diagnosis unit 800 generates the failure signals B_FD and C_FD of the B phase and the C phase similarly to the A phase, and outputs them to the motor control unit 900.

FIG. 6 shows a circuit model for explaining the principle of performing fault diagnosis of the H bridge by comparing the magnitudes of the system voltage and the voltage command value VA_ref.

As described above, the gain R corresponds to the resistance [Ω] of the entire circuit. In the circuit model shown in FIG. 6, a current command value IPeak_ref is a current flowing through the entire circuit, a gain R is an internal resistance of the circuit, and Vpeak is an input voltage. The failure diagnosis unit 800 diagnoses a failure of the H bridge BA based on the voltage command value VA_ref, the input voltage Vpeak and the voltage drop (Ipeak_ref · R) of the internal resistance R.

If the H bridge BA has not failed, the difference between Vpeak + Ipeak_ref · R and the voltage command value VA_ref (Vpeak + Ipeak_ref · R-VA_ref) becomes zero or less. That is, the relationship of Vpeak + Ipeak_ref · R ≒ VA_ref holds.

When H bridge BA fails, voltage command value VA_ref rises. Therefore, the difference (Vpeak + Ipeak_ref · R-VA_ref) does not become zero, but Vpeak + Ipeak_ref · R <VA_ref, and the balance is broken.

FIG. 7 shows a modification of the functional block for performing fault diagnosis of the H bridge.

In this modification,

subtractors

890A, 890B and 890C are used instead of the multiplier 850 and the

adders

870A, 870B and 870C. If the difference value obtained by subtracting the system voltage from the magnitude of voltage command value VA_ref of phase A is greater than zero, failure diagnosis unit 800 determines that H bridge BA is broken. Failure diagnosis unit 800 determines that H bridge BA has not failed if the difference value is less than or equal to zero. The failure diagnosis unit 800 can determine the B phase and the C phase in the same manner as the A phase.

A look-up table (LUT) 801 can be used instead of the gain unit 810 and the limit determination unit 820. The LUT 801 is a table that relates the relationship between the current peak command value Ipeak_ref and the input of the speed indicating the rotational speed of the motor 200, and the output voltage Vsat. The failure diagnosis unit 800 refers to the LUT 801 to determine the output voltage Vsat based on the acquired current peak command value Ipeak_ref and the rotation speed speed. The failure diagnosis unit 800 may acquire the system voltage by performing an operation of adding the voltage peak value Vpeak to the determined output voltage Vsat.

FIG. 8 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 energization control. Do. FIG. 9A 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. 8 and FIG. 9, 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. 9B 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 FIG. 9C is obtained by plotting current values flowing in the A-phase and B-phase windings of the motor 200 when the power converter 1000 is controlled according to the two-phase energization control when the C-phase H bridge BC fails. 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 verification, the current command value Iqref was set to 3A, and Idref and Iz_ref were set to 0A. The rotational speed of the motor was set to 1190 rpm, and 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.

The simulation result of the waveform of each signal is shown to FIGS. 10A to 10I.

FIG. 10A shows a waveform (upper side) of the motor rotational speed and a 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.

10B shows the waveform of the A-phase current Ia, FIG. 10C shows the waveform of the B-phase current Ib, and FIG. 10D shows the waveform of the C-phase current Ic. The vertical axis shows the current (A). In the waveform of each phase, the waveform of the actual current value and the waveform of the current command value are shown.

FIG. 10E shows the waveform of the zero phase current Iz. The vertical axis shows the current (A).

FIG. 10F shows the waveform of voltage command value VA_ref, FIG. 10G shows the waveform of voltage command value VB_ref, and FIG. 10H shows the waveform of voltage command value VC_ref. The vertical axis represents voltage (V).

FIG. 10I shows the waveform of failure signal A_FD (upper side), the waveform of B_FD (middle) and the waveform of C_FD (lower side). 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, it can be seen that the voltage command value VA_ref rises as shown in FIG. 10F. As shown in FIGS. 10G and 10H, voltage command values VB_ref and VC_ref do not rise. Further, as shown in FIG. 10I, 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 appropriate in synchronization with the rise of the voltage command value VA_ref. It can be seen that it is asserted to. The fault signals B_FD and C_FD are not asserted.

According to the present embodiment, the H bridge of the failed phase can be identified by comparing the magnitude relationship between Vpeak + Ipeak_ref · R and V_ref. 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.

The full bridge type power converter includes one H bridge and a control circuit 300 that controls the switching operation of the switch element of the H bridge. The control circuit 300 acquires the current / voltage represented in the dq coordinate system, acquires the voltage command value indicating the voltage value of the target applied to the winding at the time of control of the motor, and acquires the magnitude and acquisition of the voltage command value. The fault of the full bridge is diagnosed based on the current and voltage of the dq coordinate system.

Second Embodiment

FIG. 11 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

What is claimed is: 1. A fault diagnostic method for diagnosing H-bridge failure, comprising: converting power from a power source into power to be supplied to a motor having at least one phase winding, for use in a power converter comprising at least one H bridge;

acquiring a current / voltage represented in a dq coordinate system, and acquiring a voltage command value indicating a voltage value of a target to be applied to the at least one phase winding when controlling the motor;

Diagnosing the failure of the H bridge based on the magnitude of the voltage command value and the acquired current / voltage of the dq coordinate system;

Failure diagnosis method including:
In the acquisition step, three command values of 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, a q axis current, and a zero phase current in the dq coordinate system And the current peak command value determined based on

In the diagnosis step, a system voltage determined based on the voltage peak value, the current peak command value, and a gain representing an electrical characteristic of the entire circuit system including the H bridge, and a magnitude of the voltage command value The failure diagnosis method according to claim 1, wherein the failure of the H bridge is diagnosed based on the comparison result of
In the diagnosis step, when the magnitude of the voltage command value is larger than the system voltage, it is determined that the H bridge is broken, and the magnitude of the voltage command value is equal to or less than the system voltage. The fault diagnostic method according to claim 2, wherein it is determined that the H bridge is not faulty.
The method according to claim 1, further comprising: a fault signal output step of generating a fault signal indicating a fault of the H bridge upon determining that the H bridge is faulty in the diagnosis step, and outputting the fault signal to a control unit that controls the motor. The failure diagnosis method according to 3.
5. The system according to any one of claims 2 to 4, wherein the acquiring step includes acquiring the system voltage by performing an operation of adding the voltage peak value to a product of the current peak command value and the gain. Failure diagnosis method described.
The acquisition step determines whether or not the magnitude of the product of the current peak command value and the gain is within an allowable range, and the voltage peak value is calculated before performing an operation of adding the voltage peak value. The fault diagnosis device according to claim 5, wherein the low pass filter processing is performed.
The acquisition step is

The output voltage is calculated based on the acquired current peak command value and the number of revolutions of the motor with reference to a lookup table that relates the relationship between the current peak instruction value and the input of the number of revolutions of the motor and the output voltage. Decide

The fault diagnosis method according to any one of claims 2 to 4, comprising acquiring the system voltage by performing an operation of adding the voltage peak value to the determined output voltage.
The fault diagnosis apparatus according to claim 7, wherein the acquiring step low-pass-filters the voltage peak value before performing an operation of adding the voltage peak value.
In the diagnosis step, when the difference value obtained by subtracting the system voltage from the magnitude of the voltage command value is larger than zero, it is determined that the H bridge is broken, and the difference value is less than or equal to zero. The failure diagnosis method according to any one of claims 5 to 8, wherein it is determined that the H bridge has not failed.
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,

By executing the fault diagnosis method according to any one of claims 1 to 9, the H bridge fault is determined based on the magnitude of the voltage command value of each phase and the acquired current / voltage of the dq coordinate system. Failure diagnosis method to diagnose every phase.
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,

With at least one H bridge,

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

Equipped with

The control circuit

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

Obtaining a voltage command value indicating a voltage value of a target applied to the at least one phase winding when controlling the motor;

A power converter that diagnoses a failure of the H bridge based on the magnitude of the voltage command value and the acquired current / voltage of the dq coordinate system.
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;

A second inverter connected to the other end of the windings of each phase of the motor and having n legs;

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;

Equipped with

The control circuit

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

The voltage command value of each phase indicating the voltage value of the target applied to the winding of each phase when controlling the motor is obtained,

A power conversion device that diagnoses a failure of an H bridge for each phase based on the magnitude of the voltage command value of each phase and the acquired current / voltage of the dq coordinate system.
A motor module, comprising: a motor; and the power conversion device according to claim 11.
An electric power steering apparatus comprising the motor module according to claim 13.