WO2019058676A1

WO2019058676A1 - Malfunction diagnosis method, motor control method, power conversion device, motor module, and electric power steering device

Info

Publication number: WO2019058676A1
Application number: PCT/JP2018/023518
Authority: WO
Inventors: アハマッドガデリー
Original assignee: 日本電産株式会社
Priority date: 2017-09-25
Filing date: 2018-06-20
Publication date: 2019-03-28

Abstract

This malfunction diagnosis method involves executing, for each of a plurality of switching elements: a step for determining whether the voltage at the switching element when the switching element has been controlled to be in an on state is at least a prescribed voltage; a step for detecting, when the voltage at the switching element is at least the prescribed voltage, the amount of time that the voltage at the switching element is at least the prescribed voltage; a step for determining whether the detected amount of time is at least a prescribed about of time; a step for counting, when the detected amount of time is at least the prescribed amount of time, the number of times that the detected amount of time has been at least the prescribed amount of time; and a step for determining whether a counted total number of times is at least a prescribed number of times. Of n phases, the phases of windings that are connected to switching elements for which the counted total number of times is at least the prescribed number of times are determined to be malfunctioning phases.

Description

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

The present disclosure relates to a failure diagnosis method, a motor control 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 a device that drives a motor using the power conversion device as described above, when a failure occurs in the power conversion device, it is required to identify the failure location.

For example, when a failure occurs in a switching element included in the power conversion device, it is required to identify which of the plurality of switching elements has failed. Also, for example, when a failure occurs in a power conversion device that supplies power to a motor including a winding having n phases (n is an integer of 3 or more), which phase among a plurality of phases is specified is identified Is required.

Embodiments of the present disclosure provide a failure diagnosis method capable of identifying which one of a plurality of switching elements has failed when a failure occurs.

In addition, an embodiment of the present disclosure provides a failure diagnosis method capable of identifying which one of a plurality of phases has failed when a failure occurs.

An exemplary failure diagnosis method according to the present disclosure is a failure diagnosis method for diagnosing the presence or absence of a failure of a power conversion device that supplies electric power to a motor, wherein the power conversion device includes a plurality of switching elements, and the plurality of power conversion devices The switching element is connected to a winding of n phases (n is an integer of 3 or more) included in the motor, and in each of the plurality of switching elements, when the switching element is controlled to be in an on state Determining whether the generated voltage is equal to or higher than a predetermined voltage; and detecting, when the voltage generated at the switching element is equal to or higher than the predetermined voltage, a time when the voltage generated at the switching element is equal to or higher than the predetermined voltage And determining whether the detected time is a predetermined time or more, and the detected time is the predetermined time or more And counting the number of times the detected time is more than the predetermined time, and determining whether the total number counted is more than the predetermined number. It is determined that the phase of the winding to which the switching element whose total number of times is equal to or more than the predetermined number of times is connected is the phase that has failed.

According to an embodiment of the present disclosure, it is possible to identify which one of the plurality of switching elements has failed when a failure occurs.

Further, according to the embodiment of the present disclosure, when a failure occurs, it is possible to specify which phase among the plurality of phases has failed.

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. 3 exemplifies a current waveform (sine wave) obtained by plotting current values flowing in the A-phase, B-phase, and C-phase windings of motor 200 when inverter unit 100 is controlled according to three-phase conduction control. It is a graph. FIG. 4 is a functional block diagram illustrating functional blocks of the controller 340 for performing motor control in general. FIG. 5 is a flowchart showing an operation of diagnosing the presence or absence of a failure of the switching element using the value of the current flowing through the switching element. FIG. 6 is a diagram for explaining an example of the operation of diagnosing the presence or absence of a failure of the switching element using the value of the current flowing through the switching element. FIG. 7 is a diagram showing the relationship between the output value of the AND block 822, the output value of the integrator 831, and the output value of the comparator 841. FIG. 8 is a diagram showing the relationship between the output value of the AND block 822, the output value of the integrator 831, and the output value of the comparator 851. FIG. 9 is a flowchart showing an operation of diagnosing the presence or absence of a failure of the switching element using the value of the voltage applied to the switching element. FIG. 10 is a diagram for explaining an example of the operation of diagnosing the presence or absence of a failure of the switching element using the value of the voltage applied to the switching element. FIG. 11 is a diagram showing the controller 340 that diagnoses the presence or absence of a failure of the switching element using both the current value and the voltage value. FIG. 12 is a diagram showing an example of functional blocks of the failure diagnosis unit 800_IV. FIG. 13 is a diagram showing another example of functional blocks of the failure diagnosis unit 800_IV. FIG. 14 is a diagram showing the controller 340 that uses the current value to diagnose the presence or absence of a phase failure. FIG. 15 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P_I. FIG. 16 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P_IA. FIG. 17 is a diagram showing a controller 340 that diagnoses the presence or absence of a phase failure using a voltage value. FIG. 18 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P_V. FIG. 19 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P_VA. FIG. 20 shows a controller 340 that diagnoses the presence or absence of a phase failure using both current and voltage values. FIG. 21 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P_IV. FIG. 22 is a diagram showing another example of functional blocks of failure diagnosis unit 800P_IV. FIG. 23 is a circuit diagram schematically showing a circuit configuration of an inverter unit 100A having a single inverter 140 according to a modification of the first embodiment. FIG. 24 is a schematic view showing a typical configuration of the electric power steering apparatus 3000 according to the second embodiment.

Hereinafter, embodiments of a failure diagnosis method, a motor control method, a power conversion device, a motor module, and an electric power steering device according to the present disclosure will be described in detail with reference to the attached drawings. 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 conversion device for converting power from a power supply into power to be supplied to an n-phase motor having n-phase (n is an integer of 4 or more) windings such as four-phase or five-phase, and a motor used for the device Control methods are 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 power converter 1000 and motor 200. Power converter 1000 includes inverter unit 100 and control circuit 300. 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 converter.

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 turn-off) of each switching element (typically, semiconductor switching 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 switching 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 switching 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 drive circuit 350 includes a voltage detection circuit 380. The voltage detection circuit 380 detects, for example, the voltage applied to each of the plurality of switching elements included in the first and

second inverters

120 and 130. For example, when the switching element is a FET, the voltage detection circuit 380 detects the voltage between the source and drain of each FET.

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 switching element, a low side switching element and a shunt resistor. The A-phase leg has a high side switching element SW_A1H, a low side switching element SW_A1L, and a first shunt resistor S_A1. The B-phase leg has a high side switching element SW_B1H, a low side switching element SW_B1L, and a first shunt resistor S_B1. The C-phase leg has a high side switching device SW_C1H, a low side switching device SW_C1L, and a first shunt resistor S_C1.

As a switching 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 switching 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 switching element SW_B1L and the GND line GL. The first shunt resistor S_C1 is used to detect the C-phase current IC1 flowing through the C-phase winding M3, and is connected, for example, between the low side switching 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 switching element, a low side switching element and a shunt resistor. The A-phase leg has a high side switching element SW_A2H, a low side switching element SW_A2L, and a shunt resistor S_A2. The B-phase leg has a high side switching device SW_B2H, a low side switching device SW_B2L, and a shunt resistor S_B2. The C-phase leg has a high side switching device SW_C2H, a low side switching device 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 switching 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 switching 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 switching 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 switching element SW_A1H and the low side switching element SW_A1L) is connected to one end A1 of the A phase winding M1 of the motor 200, and the second inverter The 130 A-phase leg is connected to the other end A2 of the A-phase winding M1. The B-phase leg of the first inverter 120 is connected to one end B1 of the B-phase winding M2 of the motor 200, and the B-phase leg of the second inverter 130 is connected to the other end B2 of the winding M2. The C-phase leg of the first inverter 120 is connected to one end C1 of the C-phase winding M3 of the motor 200, and the C-phase leg of the second inverter 130 is connected to the other end C2 of the winding M3.

The control circuit 300 drives the motor 200 by performing three-phase conduction control using both the first and

second inverters

120 and 130. Specifically, the control circuit 300 performs three-phase conduction control by switching control of the switching element of the first inverter 110 and the switching element of the second inverter 140 in opposite phases (phase difference = 180 °). At this time, the fuses ISW_11, ISW_12, ISW_21, and ISW_22 are turned on. For example, focusing on the H bridge including the switching elements SW_A1L, SW_A1H, SW_A2L and SW_A2H, when the switching element SW_A1L turns on, the switching element SW_A2L turns off, and when the switching element SW_A1L turns off, the switching element SW_A2L turns on. Similarly, when the switching element SW_A1H is turned on, the switching element SW_A2H is turned off, and when the switching element SW_A1H is turned off, the switching element SW_A2H is turned on. The current output from the power supply 101 flows to the GND line GL through the high side switching element, the winding, and the low side switching element. The connection of the power conversion device 100 may be referred to as an open connection.

Here, an example of a current path flowing through the A-phase winding M1 will be described. When the switching element SW_A1H and the switching element SW_A2L are on and the switching element SW_A2H and the switching element SW_A1L are off, current flows in the order of the power supply 101, the switching element SW_A1H, the winding M1, the switching element SW_A2L, and the GND line GL. When the switching element SW_A2H and the switching element SW_A1L are on and the switching element SW_A1H and the switching element SW_A2L are off, current flows in the order of the power supply 101, the switching element SW_A2H, the winding M1, the switching element SW_A1L, and the GND line GL.

Note that part of the current flowing from the switching element SW_A1H to the winding M1 may flow to the switching element SW_A2H. That is, the current flowing from the switching element SW_A1H to the winding M1 may branch to the switching element SW_A2L and the switching element SW_A2H and flow. Similarly, part of the current flowing from the switching element SW_A2H to the winding M1 may flow to the switching element SW_A1H.

Next, an example of a current path flowing through the B-phase winding M2 will be described. When the switching element SW_B1H and the switching element SW_B2L are on and the switching element SW_B2H and the switching element SW_B1L are off, current flows through the power supply 101, the switching element SW_B1H, the winding M2, the switching element SW_B2L, and the GND line GL in this order. When the switching element SW_B2H and the switching element SW_B1L are on and the switching element SW_B1H and the switching element SW_B2L are off, current flows through the power supply 101, the switching element SW_B2H, the winding M2, the switching element SW_B1L, and the GND line GL in this order.

In the same manner as described above, a part of the current flowing from the switching element SW_B1H to the winding M2 may flow to the switching element SW_B2H. Further, part of the current flowing from the switching element SW_B2H to the winding M2 may flow to the switching element SW_B1H.

Next, an example of a current path flowing through the C-phase winding M3 will be described. When the switching element SW_C1H and the switching element SW_C2L are on and the switching element SW_C2H and the switching element SW_C1L are off, current flows in the order of the power supply 101, the switching element SW_C1H, the winding M3, the switching element SW_C2L, and the GND line GL. When the switching element SW_C2H and the switching element SW_C1L are on and the switching element SW_C1H and the switching element SW_C2L are off, current flows in the order of the power supply 101, the switching element SW_C2H, the winding M3, the switching element SW_C1L, and the GND line GL.

In the same manner as described above, a part of the current flowing from the switching element SW_C1H to the winding M3 may flow to the switching element SW_C2H. Further, part of the current flowing from the switching element SW_C2H to the winding M3 may flow to the switching element SW_C1H.

FIG. 3 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 inverter unit 100 is controlled according to three-phase energization control. ing. The horizontal axis indicates the motor electrical angle (deg), and the vertical axis indicates the current value (A). In the current waveform of FIG. 3, current values are plotted every 30 ° of electrical angle. I _pk represents the maximum current value (peak current value) of each phase. For example, the control circuit 300 can generate a PWM signal for obtaining the current waveform shown in FIG.

[2. Failure diagnosis]

Next, a failure diagnosis method according to the present embodiment will be described. Here, a method of diagnosing the presence or absence of a failure of the switching element will be described by taking the power conversion device 1000 shown in FIG. 1 as an example.

When the switching element is an FET, the failure is roughly classified into "open failure" and "short failure". "Open fault" refers to a fault in which the source-drain of the FET is open (in other words, the source-drain resistance is always in a high impedance state). "Short circuit failure" refers to a failure in which the source-drain of the FET is constantly shorted. In the failure diagnosis of the present embodiment, an open failure of the switching element is detected.

The algorithm for realizing the fault diagnosis method according to the present embodiment can be realized only by hardware such as a microcontroller, an application specific integrated circuit (ASIC) or an FPGA, or by a combination of hardware and software. It can be realized.

FIG. 4 exemplifies functional blocks of the controller 340 for performing motor control in general. FIG. 5 is a flowchart showing an example of failure diagnosis that the controller 340 executes.

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 failure diagnosis may be, for example, a module that configures a computer program for executing specific processing 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 receives the current value detected by the current sensor 150 via the input circuit 330 (FIG. 1). The current sensor 150 detects the current flowing in each phase using the above-described shunt resistor, so that the current flowing in each of the plurality of switching elements provided in the first and

second inverters

120 and 130 can be grasped. The voltage detection circuit 380 (FIG. 1) detects the voltage applied to each of the plurality of switching elements included in the first and

second inverters

120 and 130, for example, and outputs the voltage to the controller 340.

The controller 340 includes, for example, a fault diagnosis unit 800 and a motor control unit 900. The failure diagnosis unit 800 diagnoses the presence or absence of a failure using current and / or voltage information on each of the plurality of switching elements. The failure diagnosis unit 800 outputs a signal indicating the diagnosis result of the presence or absence of a failure to the motor control unit 900.

The motor control unit 900 generates, based on the diagnosis result, a PWM signal that controls the overall switching operation of the switching 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.

The motor control unit 900 switches control of the first and

second inverters

120 and 130 according to the diagnosis result. Specifically, the motor control unit 900 can determine the on / off operation of the switching elements of the first and

second inverters

120 and 130 based on the diagnosis result. The motor control unit 900 can further determine the on / off operation of the fuses ISW_11, ISW_12, ISW_21 and ISW_22 based on the diagnosis result.

In the present specification, each functional block may be referred to as a unit for convenience of explanation. Naturally, this notation is not 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 mentioned 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 illustrated functional blocks 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.

When no failure occurs in the plurality of switching elements included in the first and

second inverters

120 and 130, the control circuit 300 executes the above-described three-phase conduction control as a control mode in the normal state. In the three-phase energization control, each of the plurality of switching elements repeats switching between on and off. The failure diagnosis unit 800 includes 12 switching elements SW_A1H, SW_A1L, SW_B1H, SW_B1L, SW_C1H, SW_C1L, SW_A2H, SW_A2L, SW_A2L, SW_B2H, SW_B2L, SW_C2H, and 12 of the first and

second inverters

120 and 130. , Execute the fault diagnosis of the present embodiment.

[2-1. Failure diagnosis of switching element using current value]

The operation of detecting the current flowing through the switching element and diagnosing the presence or absence of a failure of the switching element will be described with reference to FIG. When the switching element is a FET, the current flowing through the switching element is a current flowing between the source and the drain of the FET. Here, fault diagnosis unit 800 that diagnoses the presence or absence of a fault of the switching element using the value of the current flowing through the switching element is expressed as fault diagnosis unit 800_I.

Here, an example of diagnosing the presence or absence of a failure of the switching element SW_A1H which is one of the plurality of switching elements provided in the first and

second inverters

120 and 130 will be described. This failure diagnosis may be repeatedly performed each time the switching element SW_A1H is turned on.

The failure diagnosis unit 800_I detects the current flowing through the switching element SW_A1H when the switching element SW_A1H is controlled to the on state (step S101). For example, when the switching element SW_A1H and the switching element SW_A2L are on and the switching element SW_A2H and the switching element SW_A1L are off, current flows from the power supply 101, the switching element SW_A1H, the winding M1, the switching element SW_A2L, the shunt resistor S_A2, the GND line It flows in order of GL. The magnitude of the current flowing through the shunt resistor S_A2 corresponds to the magnitude of the current flowing through the switching element SW_A1H. The failure diagnosis unit 800_I can detect, for example, the magnitude of the current flowing through the switching element SW_A1H from the current flowing through the shunt resistor S_A2.

Next, the failure diagnosis unit 800_I determines whether the current flowing through the switching element SW_A1H is less than a predetermined current when the switching element SW_A1H is controlled to be in the on state (step S102). The predetermined current is, for example, 10 mA. Note that 10 mA is an example, and the embodiment of the present disclosure is not limited thereto.

In this example, when the switching element SW_A1H is not broken, that is, normal, a current of 10 mA or more flows in the switching element SW_A1H to which the gate control signal is supplied. When the switching element SW_A1H has an open failure, the current flowing through the switching element SW_A1H to which the gate control signal is supplied is less than 10 mA.

If the failure diagnosis unit 800_I determines that the detected current is not less than 10 mA, it determines that the switching element SW_A1H is normal (step S108). The failure diagnosis unit 800_I outputs a signal indicating that the switching element SW_A1H is normal to the motor control unit 900, and returns to the process of step S101.

If it is determined in step S102 that the detected current is less than 10 mA, the process proceeds to step S103. In step S103, when the switching element SW_A1H is controlled to be in the on state, the failure diagnosis unit 800_I detects the time when the current flowing through the switching element SW_A1H is less than 10 mA. Next, the failure diagnosis unit 800_I determines whether the detected time is equal to or longer than a predetermined time (step S104). The predetermined time is, for example, 50 μs. Note that 50 μs is an example, and the embodiment of the present disclosure is not limited thereto. The predetermined time may be set in accordance with the structure and rotational speed of motor 200.

Even when the switching element SW_A1H is normal, disturbance such as noise may cause the current flowing through the switching element SW_A1H in the on state to be less than 10 mA for a short time. If the switching element SW_A1H is determined to be abnormal based on an abnormal value caused by such noise, correct determination can not be made. Therefore, in the present embodiment, when the time when the current is less than 10 mA is short (for example, less than 50 μs), it is determined that the switching element SW_A1H is normal.

When it is determined that the detected time is not 50 μs or more, the failure diagnosis unit 800_I determines that the switching element SW_A1H is normal (step S108). The failure diagnosis unit 800_I outputs a signal indicating that the switching element SW_A1H is normal to the motor control unit 900, and returns to the process of step S101.

If it is determined in step S104 that the detected time is 50 μs or more, the process proceeds to step S105. In step S105, the failure diagnosis unit 800_I counts the number of times that the detected time is 50 μs or more. Next, the failure diagnosis unit 800_I determines whether the counted total number is equal to or more than a predetermined number (step S106). The predetermined number of times is, for example, three times. Note that three times is an example, and the embodiment of the present disclosure is not limited thereto. The predetermined number of times may be a plurality of times, may be two, or may be four or more.

If the detected time is 50 μs or more, the switching element SW_A1H may have an open failure, but it is not yet determined as a failure at a stage where it is detected only once. In the case where the switching element SW_A1H really has an open failure, each time the control circuit 300 supplies the gate control signal to the switching element SW_A1H, it is determined that the detected time is 50 μs or more in the process of step S104. When the determination that the detected time is 50 μs or more is performed a plurality of times (for example, three times), it is determined that the switching element SW_A1H has an open failure.

If it is determined in step S106 that the counted total number is not three or more, the failure diagnosis unit 800_I determines that the switching element SW_A1H is normal (step S108). The failure diagnosis unit 800_I outputs a signal indicating that the switching element SW_A1H is normal to the motor control unit 900, and returns to the process of step S101.

If it is determined in step S106 that the total number of times counted is three or more, it is determined that the switching element SW_A1H has an open failure (step S107). The failure diagnosis unit 800_I outputs a signal indicating that the switching element SW_A1H is broken to the motor control unit 900. After outputting a signal indicating that the switching element SW_A1H is broken to the motor control unit 900, the failure diagnosis unit 800_I may return to the process of step S101.

When receiving a signal indicating that the switching element SW_A1H is broken, the motor control unit 900 changes the control mode of the motor 200 from the normal control mode to the abnormal control mode.

The control mode at the time of abnormality is, for example, a control mode in which the neutral point of the winding is formed in the failed inverter, and the motor 200 is driven by the non-failed inverter. When the switching element SW_A1H is broken, the motor control unit 900 performs control to turn off the fuses ISW_11 and ISW_12. Accordingly, the first inverter 120 including the failed switching element SW_A1H is separated from the power supply and the GND. Then, for example, the switching elements SW_A1H, SW_B1H, and SW_C1H are turned off, and the switching elements SW_A1L, SW_B1L, and SW_C1L are turned on, whereby the first inverter 120 is configured with a neutral point. By using this neutral point, the motor 200 can be driven by the second inverter 130 which has not failed.

Further, the control mode at the time of abnormality may be two-phase energization control. When the switching element SW_A1H belonging to the A phase fails, the motor control unit 900 turns off all the switching elements SW_A1H, SW_A1L, SW_A2H, and SW_A2L belonging to the A phase. Then, two-phase conduction control is performed using switching elements SW_B1H, SW_B1L, SW_B2H, SW_B2L, SW_C1H, SW_C1L, SW_C2H, and SW_C2L belonging to the B phase and the C phase. In this way, the motor 200 can be driven using a phase that has not failed.

The control mode at the time of abnormality may be shutdown. The shutdown is control for stopping the operation of the motor 200.

The fault diagnosis unit 800 _I executes the same fault diagnosis as the fault diagnosis for the switching element SW_A1H with respect to switching elements other than the switching elements SW_A1H in the plurality of switching elements included in the first and

second inverters

120 and 130. .

In the failure diagnosis of the present embodiment, when a failure occurs in a switching element, it is possible to identify which of the plurality of switching elements has failed. By identifying the failed switching element, appropriate control can be performed according to the failure point.

Next, an example of the operation of detecting the current flowing through the detected switching element and diagnosing the presence or absence of a failure of the switching element will be described with reference to FIG.

The failure diagnosis unit 800_I illustrated in FIG. 6 is a failure diagnosis unit 800 that diagnoses the presence or absence of a failure of the switching element using the value of the current flowing through the detected switching element. Here, an example of diagnosing the presence or absence of a failure of the switching element SW_A1H which is one of the plurality of switching elements provided in the first and

second inverters

120 and 130 will be described.

The current value ("I" in FIG. 6) of the detected switching element SW_A1H is input to the failure diagnosis unit 800_I. Further, a gate control signal ("S" in FIG. 6) for turning on the switching element SW_A1H is input to the failure diagnosis unit 800_I. The absolute value block 811 obtains the absolute value of the detected current of the switching element SW_A1H. A comparator (Comparator) 812 compares the obtained absolute value with a predetermined current lower limit value. The current lower limit value corresponds to a predetermined current used in the process of step S102 shown in FIG. Note that 10 mA is an example, and the embodiment of the present disclosure is not limited thereto.

The comparator 812 outputs 1 when the absolute value of the current is 10 mA or more, and outputs 0 when it is less than 10 mA. The NOT block 821 performs the logical operation "NOT" and inverts the output value of the comparator 812.

The output value of the NOT block 821 and the gate control signal are input to the AND block 822. Here, a high level gate control signal for turning on the switching element SW_A1H is 1, and a low level gate control signal for turning off the switching element SW_A1H is 0. The AND block 822 performs a logical operation of "AND". The AND block 822 outputs 1 when both the output value of the NOT block 821 and the gate control signal are 1. That is, the AND block 822 outputs 1 when the current flowing through the switching element SW_A1H is less than the lower limit value when the switching element SW_A1H is controlled to be in the on state. Otherwise, the AND block 822 outputs 0.

The output value of the AND block 822 and the output value of the comparator 841 are input to the OR block 832. The OR block 832 performs the logical operation of “OR”. The initial value output by the comparator 841 is zero. The OR block 832 outputs 1 when at least one of the output value of the AND block 822 and the output value of the comparator 841 is 1. The OR block 832 outputs 0 when both the output value of the AND block 822 and the output value of the comparator 841 are 0. The NOT block 833 performs the logical operation “NOT” and inverts the output value of the OR block 832.

An integrator (Integrator) 831 integrates and outputs the output value of the AND block 822. The comparator 841 compares the output value of the integrator 831 with the first reference value. The comparator 851 compares the output value of the integrator 831 with the second reference value.

FIG. 7 is a diagram showing the relationship between the output value of the AND block 822, the output value of the integrator 831, and the output value of the comparator 841. The horizontal axis of FIG. 7 represents time. The first reference value is a value corresponding to a predetermined time used in the process of step S104 shown in FIG. For example, the output value of the integrator 831 corresponding to the predetermined time 50 μs is set to 10. When the output value of the integrator 831 is represented by a voltage, for example, when the integrator 831 is hardware, the output value “10” corresponds to, for example, 1.0 V of the output voltage of the integrator 831.

As described above, even when the switching element SW_A1H is normal, disturbance such as noise may cause the current flowing through the switching element SW_A1H in the on state to be less than 10 mA for a short time. In the example of FIG. 7, the portion where the AND block 822 outputs 1 for 10 μs corresponds to noise. The integrator 831 outputs a value obtained by integrating the output value of the AND block 822 for a period of 10 μs. In the example of FIG. 7, the integrator 831 outputs 2. The comparator 841 outputs 0 because the output value “2” of the integrator 831 is less than the first reference value “10”.

When the switching element SW_A1H is turned off, the AND block 822 outputs 0. The OR block 832 outputs 0 when both the output value of the AND block 822 and the output value of the comparator 841 are 0. In response to this, the NOT block 833 outputs "1". The integrator 831 resets the integrated value when 1 is input from the NOT block 833.

On the other hand, when the time when the AND block 822 outputs 1 becomes 50 μs or more, the value integrated by the integrator 831 becomes 10 or more. The comparator 841 outputs 1 because the output value of the integrator 831 is equal to or greater than the first reference value “10”.

Since the output value of the comparator 841 becomes 1, the OR block 832 outputs 1 and the NOT block 833 outputs 0 even if the switching element SW_A1H is turned off. When 0 is input from the NOT block 833, the integrator 831 continues integration while maintaining the integrated value. Reset of integrated value is not performed.

FIG. 8 is a diagram showing the relationship between the output value of the AND block 822, the output value of the integrator 831, and the output value of the comparator 851. The horizontal axis of FIG. 8 represents time. The second reference value is a value corresponding to a predetermined number of times used in the process of step S106 shown in FIG. For example, the output value of the integrator 831 corresponding to three counts is set to 30.

When the output value of the comparator 841 becomes 1, the integrator 831 continues to integrate the output value of the AND block 822. The comparator 851 outputs 0 while the output value of the integrator 831 is less than the second reference value “30”. The comparator 851 outputs 1 when the output value of the integrator 831 becomes equal to or greater than the second reference value “30”. The output value “1” of the comparator 851 becomes a signal indicating that the switching element SW_A1H is broken, and is input to the motor control unit 900.

While the output value of the integrator 831 is less than the second reference value “30”, the comparator 851 outputs 0. The output value “0” of the comparator 851 becomes a signal indicating that the switching element SW_A1H is normal, and is input to the motor control unit 900.

When the output value of the integrator 831 is less than the second reference value “30” even if a predetermined time (for example, several seconds) elapses after the output value of the comparator 841 becomes 1, the integrator 831 may reset the integrated value. When the AND block 822 outputs 1 for 50 μs or more, the switching element SW_A1H may be out of order. However, when it is not continuous that the AND block 822 outputs 1 for 50 μs or more, the switching element SW_A1H may be regarded as not having a fault, and the integrator 831 may be reset to continue fault diagnosis.

Thus, the failure diagnosis unit 800_I can diagnose the presence or absence of a failure of the switching element using the value of the current flowing through the detected switching element.

second inverters

120 and 130. .

[2-2. Failure diagnosis of switching element using voltage value]

Next, the operation of detecting the voltage applied to the switching element and diagnosing the presence or absence of a failure of the switching element will be described with reference to FIG. Here, fault diagnosis unit 800 that diagnoses the presence or absence of a fault of the switching element using the value of the voltage applied to the switching element is expressed as fault diagnosis unit 800_V. FIG. 9 is a flowchart showing an operation of diagnosing the presence or absence of a failure of the switching element using the value of the voltage applied to the switching element. When the switching element is an FET, the voltage applied to the switching element is the voltage between the source and drain of the FET. The operations of steps S105 to S108 shown in FIG. 9 are similar to the operations of steps S105 to S108 shown in FIG.

second inverters

The failure diagnosis unit 800_V detects the source-drain voltage of the switching element SW_A1H when the switching element SW_A1H is controlled to be in the on state (step S111). For example, the failure diagnosis unit 800_V can detect the source-drain voltage of the switching element SW_A1H using the output signal of the voltage detection circuit 380 (FIG. 1).

Next, the failure diagnosis unit 800_V determines whether the voltage between the source and drain of the switching element SW_A1H when the switching element SW_A1H is controlled to be in the ON state is equal to or higher than a predetermined voltage (step S112). The predetermined voltage is, for example, 0.5V. In addition, 0.5 V is an example, and the embodiment of the present disclosure is not limited thereto.

In this example, when the switching element SW_A1H is not broken, that is, normal, the source-drain voltage of the switching element SW_A1H supplied with the gate control signal is less than 0.5V. When the switching element SW_A1H has an open failure, the source-drain voltage of the switching element SW_A1H to which the gate control signal is supplied is 0.5 V or more.

If failure diagnosis unit 800_V determines that the detected voltage is not 0.5 V or more, it determines that switching element SW_A1H is normal (step S108). Failure diagnosis unit 800_V outputs a signal indicating that switching element SW_A1H is normal to motor control unit 900, and returns to the process of step S111.

If it is determined in step S112 that the detected voltage is 0.5 V or more, the process proceeds to step S113. In step S113, when the switching element SW_A1H is controlled to be in the on state, the failure diagnosis unit 800_V detects the time when the source-drain voltage of the switching element SW_A1H is 0.5 V or more. Next, fault diagnosis unit 800_V determines whether the detected time is equal to or longer than a predetermined time (step S114). The predetermined time is, for example, 50 μs. Note that 50 μs is an example, and the embodiment of the present disclosure is not limited thereto.

Even when the switching element SW_A1H is normal, the source-drain voltage of the on-state switching element SW_A1H may be 0.5 V or more for a short time due to disturbance such as noise. If the switching element SW_A1H is determined to be abnormal based on an abnormal value caused by such noise, correct determination can not be made. Therefore, in the present embodiment, when the time during which the voltage is 0.5 V or more is short (for example, less than 50 μs), it is determined that the switching element SW_A1H is normal.

If failure diagnosis unit 800_V determines that the detected time is not 50 μs or more, it determines that switching element SW_A1H is normal (step S108). Failure diagnosis unit 800_V outputs a signal indicating that switching element SW_A1H is normal to motor control unit 900, and returns to the process of step S111.

If it is determined in step S114 that the detected time is 50 μs or more, the process proceeds to step S105. The operations in steps S105 to S108 shown in FIG. 9 are the same as the operations in steps S105 to S108 shown in FIG. 5, and therefore, the detailed description thereof will not be repeated.

In the example of FIG. 9, when it is determined in step S108 that the switching element SW_A1H is normal, the failure diagnosis unit 800_V outputs a signal indicating that the switching element SW_A1H is normal to the motor control unit 900, and step S111. Return to the processing of When it is determined in step S107 that the switching element SW_A1H has an open failure, the failure diagnosis unit 800_V outputs a signal indicating that the switching element SW_A1H is broken to the motor control unit 900. After outputting a signal indicating that the switching element SW_A1H is broken to the motor control unit 900, the failure diagnosis unit 800_I may return to the process of step S111.

The fault diagnosis unit 800 _V executes the same fault diagnosis as the fault diagnosis for the switching element SW_A1H with respect to the switching elements other than the switching elements SW_A1H in the plurality of switching elements included in the first and

second inverters

120 and 130. .

Next, an example of the operation of detecting the voltage applied to the switching element and diagnosing the presence or absence of a failure of the switching element will be described using FIG.

The failure diagnosis unit 800 _V illustrated in FIG. 10 is a failure diagnosis unit 800 that diagnoses the presence or absence of a failure of the switching element using the value of the voltage applied to the detected switching element. Here, an example of diagnosing the presence or absence of a failure of the switching element SW_A1H which is one of the plurality of switching elements provided in the first and

second inverters

120 and 130 will be described.

The source-drain voltage ("V" in FIG. 10) of the detected switching element SW_A1H is input to the failure diagnosis unit 800_V. Further, a gate control signal ("S" in FIG. 10) for turning on the switching element SW_A1H is input to the failure diagnosis unit 800_V. The absolute value block 813 obtains the absolute value of the detected source-drain voltage of the switching element SW_A1H. The comparator 814 compares the obtained absolute value with a predetermined voltage lower limit value. The voltage lower limit value corresponds to a predetermined voltage used in the process of step S112 shown in FIG. In addition, 0.5 V is an example, and the embodiment of the present disclosure is not limited thereto.

The comparator 814 outputs 1 when the absolute value of the voltage is 0.5 V or more, and outputs 0 when the absolute value of the voltage is less than 0.5 V. The output of the comparator 814 and the gate control signal are input to the AND block 822. The AND block 822 outputs 1 when both the output value of the comparator 814 and the gate control signal are 1. That is, the AND block 822 outputs 1 when the voltage between the source and the drain of the switching element SW_A1H when the switching element SW_A1H is controlled to be in the ON state is equal to or more than the lower limit value. Otherwise, the AND block 822 outputs 0. The output of the AND block 822 is input to the integrator 831 and the OR block 832.

The operations of the integrator 831, the OR block 832, the NOT block 833, the comparator 841, and the comparator 851 are the same as the operations described with reference to FIGS. 6 to 8, and therefore the repeated detailed description thereof is omitted here. Do.

When the output value of the comparator 841 becomes 1, the integrator 831 continues to integrate the output value of the AND block 822. The comparator 851 outputs 0 while the output value of the integrator 831 is less than the second reference value “30”. The comparator 851 outputs 1 when the output value of the integrator 831 becomes equal to or greater than the second reference value “30”.

As described above, the failure diagnosis unit 800_V can diagnose the presence or absence of a failure of the switching element using the value of the voltage applied to the detected switching element.

second inverters

120 and 130. .

[2-3. Failure diagnosis of switching element using both current value and voltage value]

Next, an operation of diagnosing the presence or absence of a failure of the switching element using both the value of the current flowing through the switching element and the value of the voltage applied to the switching element will be described. In this example, as shown in FIG. 11, the controller 340 includes a failure diagnosis unit 800_IV as the failure diagnosis unit 800. The failure diagnosis unit 800_IV diagnoses the presence or absence of a failure of the switching element using both the value of the current flowing through the switching element and the value of the voltage applied to the switching element.

FIG. 12 shows an example of functional blocks of the failure diagnosis unit 800_IV. The failure diagnosis unit 800_IV shown in FIG. 12 includes a failure diagnosis unit 800_I, a failure diagnosis unit 800_V, and an OR block 861.

The failure diagnosis unit 800_I performs the diagnosis using the current value described with reference to FIGS. 5 to 8. However, in this example, in step S108 shown in FIG. 5, the failure diagnosis unit 800_I determines that the current flowing through the switching element SW_A1H is normal. In this case, the failure diagnosis unit 800_I outputs a signal (for example, “0”) indicating that the current flowing through the switching element SW_A1H is normal to the OR block 861, and returns to the process of step S101. Further, in step S107 shown in FIG. 5, the failure diagnosis unit 800_I determines that the current flowing through the switching element SW_A1H is abnormal. The failure diagnosis unit 800_I outputs a signal (for example, “1”) indicating that the current flowing through the switching element SW_A1H is abnormal to the OR block 861.

Further, in this example, the output value “0” of the comparator 851 shown in FIG. 6 is a signal indicating that the current flowing through the switching element SW_A1H is normal. The output value “1” of the comparator 851 is a signal indicating that the current flowing through the switching element SW_A1H is abnormal. The output of the comparator 851 is input to the OR block 861.

Thus, the failure diagnosis unit 800_I shown in FIG. 12 determines the presence or absence of an abnormality in the current flowing through the switching element.

Failure diagnosis unit 800_V performs a diagnosis using voltage values described with reference to FIGS. 9 and 10. However, in this example, in step S108 shown in FIG. 9, the failure diagnosis unit 800_V determines that the voltage applied to the switching element SW_A1H is normal. In this case, the failure diagnosis unit 800_V outputs a signal (for example, “0”) indicating that the voltage applied to the switching element SW_A1H is normal to the OR block 861, and returns to the process of step S111. Further, in step S107 shown in FIG. 9, the fault diagnosis unit 800_V determines that the voltage applied to the switching element SW_A1H is abnormal. The failure diagnosis unit 800_V outputs a signal (eg, “1”) indicating that the voltage applied to the switching element SW_A1H is abnormal to the OR block 861.

Further, in this example, the output value “0” of the comparator 851 shown in FIG. 10 is a signal indicating that the voltage applied to the switching element SW_A1H is normal. The output value “1” of the comparator 851 is a signal indicating that the voltage applied to the switching element SW_A1H is abnormal. The output of the comparator 851 is input to the OR block 861.

As described above, the failure diagnosis unit 800 _V illustrated in FIG. 12 determines whether or not the voltage applied to the switching element is abnormal.

The OR block 861 determines that the switching element SW_A1H is normal if both of the signals output from the failure diagnosis units 800_I and 800_V are normal. When it is determined that the switching element SW_A1H is normal, the OR block 861 outputs a signal (for example, “0”) indicating that the switching element SW_A1H is normal to the motor control unit 900.

The OR block 861 determines that the switching element SW_A1H is out of order if at least one of the signals output from the failure diagnosis units 800_I and 800_V indicates an abnormality. If it is determined that the switching element SW_A1H is faulty, the OR block 861 outputs a signal (for example, “1”) indicating that the switching element SW_A1H is faulty to the motor control unit 900. When receiving a signal indicating that the switching element SW_A1H is broken, the motor control unit 900 changes the control mode of the motor 200 from the normal control mode to the abnormal control mode.

In the example shown in FIG. 12, the fault diagnosis unit 800_IV performs fault diagnosis using both of the detected current value and voltage value. Then, when at least one of the detected current value and voltage value is abnormal, it is determined that the switching element is broken. For example, when the current sensor 150 breaks down, the current flowing through the switching element can not be detected. Even in this case, the detected voltage value can be used to diagnose the presence or absence of a fault. Also, for example, when the voltage detection circuit 380 fails, the voltage applied to the switching element can not be detected, but in this case as well, the presence or absence of the failure can be diagnosed using the detected current value.

FIG. 13 shows another example of the functional block of the fault diagnosis unit 800_IV. The fault diagnosis unit 800_IV shown in FIG. 13 includes a fault diagnosis unit 800_I, a fault diagnosis unit 800_V, and an AND block 862.

The operation of fault diagnosis units 800_I and 800_IV shown in FIG. 13 is similar to the operation of fault diagnosis units 800_I and 800_IV shown in FIG. In the example shown in FIG. 13, the output of each of the fault diagnosis units 800 _I and 800 _IV is input to an AND block 862.

The AND block 862 determines that the switching element SW_A1H is normal if at least one of the signals output from the failure diagnosis units 800_I and 800_V is normal. When it is determined that the switching element SW_A1H is normal, the AND block 862 outputs a signal (for example, “0”) indicating that the switching element SW_A1H is normal to the motor control unit 900.

The AND block 862 determines that the switching element SW_A1H is out of order if both of the signals output from the failure diagnosis units 800_I and 800_V indicate an abnormality. If it is determined that the switching element SW_A1H has a failure, the AND block 862 outputs a signal (for example, “1”) indicating that the switching element SW_A1H has a failure to the motor control unit 900. When receiving a signal indicating that the switching element SW_A1H is broken, the motor control unit 900 changes the control mode of the motor 200 from the normal control mode to the abnormal control mode.

In the example illustrated in FIG. 13, the failure diagnosis unit 800 _IV performs failure diagnosis using both of the detected current value and voltage value. Then, when both of the detected current value and voltage value are abnormal, it is determined that the switching element is broken. Determining a failure when both the current value and the voltage value are abnormal can increase the reliability of the determination of the failure.

In the above description, the method of diagnosing the presence or absence of a failure of the switching element has been described by taking the power conversion device 1000 as an example. The failure diagnosis method for diagnosing the presence or absence of a failure of a switching element according to an embodiment of the present disclosure can be applied to various devices other than the power conversion device 1000. For example, these failure diagnosis methods can be applied to various converters such as a DC-DC converter, and various power generation systems such as a wind power generation system. The failure diagnosis method for diagnosing the presence or absence of a failure of a switching element according to an embodiment of the present disclosure can be applied to an electric device including a switching element in which switching between on and off is repeated.

[2-4. Failure diagnosis of phase using current value]

Next, a failure diagnosis method for diagnosing the presence or absence of a phase failure according to the present embodiment will be described. Here, a method of diagnosing the presence or absence of a phase failure will be described using the power conversion device 1000 shown in FIG. 1 as an example.

The plurality of switching elements included in the first and

second inverters

120 and 130 are connected to the A-phase winding M1, the B-phase winding M2, and the C-phase winding M3 included in the motor 200. When a failure occurs, if it is possible to specify which of the A phase, B phase, and C phase the failure has occurred, appropriate control can be performed according to the location of the failure. For example, if it is possible to specify that a failure has occurred in the A phase, it is possible to perform two-phase current control using the remaining B phase and C phase.

In this example, as shown in FIG. 14, the controller 340 includes a fault diagnosis unit 800P_I as the fault diagnosis unit 800. The failure diagnosis unit 800P_I diagnoses the presence or absence of a phase failure using the value of the current flowing through the switching element.

FIG. 15 shows an example of a functional block of the failure diagnosis unit 800P_I. Fault diagnosis unit 800P_I shown in FIG. 15 includes fault diagnosis units 800P_IA, 800P_IB, and 800P_IC. Failure diagnosis unit 800P_IA performs failure diagnosis of phase A using the value of the current flowing through the switching element belonging to phase A. Failure diagnosis unit 800P_IB performs failure diagnosis of phase B using the value of the current flowing through the switching element belonging to phase B. Failure diagnosis unit 800P_IC performs failure diagnosis on the C phase using the value of the current flowing through the switching element belonging to the C phase.

FIG. 16 shows an example of functional blocks of the failure diagnosis unit 800P_IA. Fault diagnosis unit 800P_IA shown in FIG. 16 includes fault diagnosis units 800_I1H, 800_I1L, 800_I2H, 800_I2L, and an OR block 870_I.

In the example illustrated in FIG. 2, the switching elements SW_A1H, SW_A1L, SW_A2H, and SW_A2L are connected to the A-phase winding M1.

The current I_A1H flowing through the switching element SW_A1H and the gate control signal S_A1H for turning on the switching element SW_A1H are input to the failure diagnosis unit 800_I1H. The current I_A1L flowing through the switching element SW_A1L and the gate control signal S_A1L for turning on the switching element SW_A1L are input to the failure diagnosis unit 800_I1L. The current I_A2H flowing through the switching element SW_A2H and the gate control signal S_A2H for turning on the switching element SW_A2H are input to the failure diagnosis unit 800_I2H. The current I_A2L flowing through the switching element SW_A2L and the gate control signal S_A2L for turning on the switching element SW_A2L are input to the failure diagnosis unit 800_I2L.

The failure diagnosis unit 800_I1H performs the failure diagnosis using the current value described with reference to FIGS. 5 to 8. When it is determined in step S108 in FIG. 5 that the switching element SW_A1H is normal, the failure diagnosis unit 800_I1H outputs a signal (for example, “0”) indicating that the switching element SW_A1H is normal to the OR block 870_I. It returns to the process of step S101. If it is determined in step S107 that the switching element SW_A1H has a failure, the failure diagnosis unit 800_I1H outputs a signal (for example, “1”) indicating that the switching element SW_A1H has a failure to the OR block 870_I.

Similar to the failure diagnosis unit 800_I1H, the failure diagnosis units 800_I1L, 800_I2H, and 800_I2L also perform failure diagnosis on the switching elements SW_A1L, SW_A2H, and SW_A2L. The output of each of the four fault diagnosis units 800_I1H, 800_I1L, 800_I2H and 800_I2L is input to the OR block 870_I.

The OR block 870_I determines that the phase A is normal if all of the outputs of the four fault diagnosis units 800_I1H, 800_I1L, 800_I2H and 800_I2L indicate normal. If it is determined that the A phase is normal, the OR block 870_I outputs a signal (for example, “0”) indicating that the A phase is normal to the motor control unit 900.

The OR block 870 _I determines that a failure has occurred in the A phase when any of the output signals of the four failure diagnosis units 800 _I 1 H, 800 _ I 1 L, 800 _ I 2 H, and 800 _ I 2 L indicates a failure. If it is determined that a failure occurs in phase A, OR block 870 _I outputs a signal (for example, “1”) indicating that a failure occurs in phase A to motor control unit 900.

Similar to the fault diagnosis unit 800P_IA, the fault diagnosis units 800P_IB and 800P_IC shown in FIG. 15 also diagnose the presence or absence of a B phase and a C phase fault. Fault diagnosis units 800P_IB and 800P_IC output a signal indicating the result of fault diagnosis to motor control unit 900.

The motor control unit 900 can determine the presence or absence of a failure of the A phase, the B phase, and the C phase from the output signals of the failure diagnosis units 800P_IA, 800P_IB, and 800P_IC. Also, when a failure occurs, the motor control unit 900 can identify which phase the failure has occurred from the output signals of the failure diagnosis units 800P_IA, 800P_IB, and 800P_IC. By identifying the failed phase, the motor control unit 900 can perform appropriate control according to the failure point. For example, the motor control unit 900 can perform two-phase conduction control using the remaining two phases other than the failure phase.

[2-5. Failure diagnosis of phase using voltage value]

Next, a failure diagnosis method for diagnosing the presence or absence of a phase failure using a voltage value will be described. Here, a method of diagnosing the presence or absence of a phase failure will be described using the power conversion device 1000 shown in FIG. 1 as an example.

In this example, as shown in FIG. 17, the controller 340 includes a fault diagnosis unit 800P_V as the fault diagnosis unit 800. The failure diagnosis unit 800P_V diagnoses the presence or absence of a phase failure using the value of the voltage applied to the switching element.

FIG. 18 shows an example of a functional block of the failure diagnosis unit 800P_V. The fault diagnosis unit 800P_V illustrated in FIG. 18 includes fault diagnosis units 800P_VA, 800P_VB, and 800P_VC. Failure diagnosis unit 800P_VA performs failure diagnosis of A phase using the value of the voltage applied to the switching element belonging to A phase. Failure diagnosis unit 800P_VB performs failure diagnosis of phase B using the value of the voltage applied to the switching element belonging to phase B. Failure diagnosis unit 800P_VC performs failure diagnosis of phase C using the value of the voltage applied to the switching element belonging to phase C.

FIG. 19 shows an example of a functional block of the failure diagnosis unit 800P_VA. Failure diagnosis unit 800P_VA shown in FIG. 19 includes failure diagnosis units 800_V1H, 800_V1L, 800_V2H, 800_V2L, and an OR block 870_V.

The voltage V_A1H applied to the switching element SW_A1H and the gate control signal S_A1H are input to the failure diagnosis unit 800_V1H. The voltage V_A1L applied to the switching element SW_A1L and the gate control signal S_A1L are input to the failure diagnosis unit 800_V1L. The voltage V_A2H applied to the switching element SW_A2H and the gate control signal S_A2H are input to the failure diagnosis unit 800_V2H. The voltage V_A2L applied to the switching element SW_A2L and the gate control signal S_A2L are input to the failure diagnosis unit 800_V2L.

The failure diagnosis unit 800_V1H performs the failure diagnosis using the voltage value described with reference to FIGS. 9 and 10. When it is determined in step S108 in FIG. 9 that the switching element SW_A1H is normal, the failure diagnosis unit 800_V1H outputs a signal (for example, “0”) indicating that the switching element SW_A1H is normal to the OR block 870_V. It returns to the process of step S111. When it is determined in step S107 in FIG. 9 that the switching element SW_A1H is in failure, the failure diagnosis unit 800_V1H outputs a signal (for example, “1”) indicating that the switching element SW_A1H is in failure to the OR block 870_V. Do.

Similar to the failure diagnosis unit 800_V1H, the failure diagnosis units 800_V1L, 800_V2H, and 800_V2L also perform failure diagnosis on the switching elements SW_A1L, SW_A2H, and SW_A2L. The outputs of the four fault diagnosis units 800_V1H, 800_V1L, 800_V2H and 800_V2L are input to the OR block 870_V.

The OR block 870 _V determines that the phase A is normal when all of the output signals of the four fault diagnosis units 800 _V 1 H, 800 _ V 1 L, 800 _ V 2 H, and 800 _ V 2 L indicate normal. If it is determined that the A phase is normal, the OR block 870 _V outputs a signal (for example, “0”) indicating that the A phase is normal to the motor control unit 900.

The OR block 870 _V determines that a failure has occurred in the A phase when any of the output signals of the four failure diagnosis units 800 _V 1 H, 800 _ V 1 L, 800 _ V 2 H, and 800 _ V 2 L indicates a failure. If it is determined that a failure has occurred in phase A, OR block 870 _V outputs a signal (for example, “1”) indicating that a failure has occurred in phase A to motor control unit 900.

Similarly to the fault diagnosis unit 800P_VA, the fault diagnosis units 800P_VB and 800P_VC shown in FIG. 18 also diagnose the presence or absence of a B phase and a C phase fault. Fault diagnosis units 800P_VB and 800P_VC output a signal indicating the result of fault diagnosis to motor control unit 900.

The motor control unit 900 can determine the presence or absence of a failure of the A phase, the B phase, and the C phase from the output signals of the failure diagnosis units 800P_VA, 800P_VB, and 800P_VC. Also, when a failure occurs, the motor control unit 900 can identify which phase the failure has occurred from the output signals of the failure diagnosis units 800P_VA, 800P_VB, and 800P_VC. By identifying the failed phase, the motor control unit 900 can perform appropriate control according to the failure point. For example, the motor control unit 900 can perform two-phase conduction control using the remaining two phases other than the failure phase.

[2-6. Failure diagnosis of phase using both current value and voltage value]

Next, a failure diagnosis method for diagnosing the presence or absence of a phase failure using both the current value and the voltage value will be described. In this example, as shown in FIG. 20, the controller 340 includes a fault diagnosis unit 800P_IV as the fault diagnosis unit 800. Failure diagnosis unit 800P_IV diagnoses the presence or absence of a phase failure using both the value of the current flowing through the switching element and the value of the voltage applied to the switching element.

FIG. 21 shows an example of a functional block of the failure diagnosis unit 800P_IV. Failure diagnosis unit 800P_IV shown in FIG. 21 includes failure diagnosis units 800P_IA and 800P_VA, and an OR block 881A.

Failure diagnosis unit 800P_IA performs the diagnosis using the current value described with reference to FIGS. 15 and 16. Failure diagnosis unit 800P_VA performs a diagnosis using voltage values described with reference to FIGS. 18 and 19.

The OR block 881A determines that the A phase is normal if both of the signals output from the fault diagnosis units 800P_IA and 800P_VA indicate that the signals are normal. If it is determined that the A phase is normal, the OR block 881A outputs a signal (for example, “0”) indicating that the A phase is normal to the motor control unit 900.

The OR block 881A determines that the A phase is broken when at least one of the signals output from the failure diagnosis units 800P_IA and 800P_VA indicates that it is abnormal. If it is determined that the A phase is broken, the OR block 881A outputs a signal (for example, “1”) indicating that the A phase is broken to the motor control unit 900.

Fault diagnosis unit 800P_IV further includes fault diagnosis units 800P_IB and 800P_VB, and an OR block 881B.

Failure diagnosis unit 800P_IB performs the diagnosis using the current value described with reference to FIGS. 15 and 16. Failure diagnosis unit 800P_VB performs diagnosis using voltage values described with reference to FIGS. 18 and 19.

The OR block 881B determines that the B phase is normal if both of the signals output from the failure diagnosis units 800P_IB and 800P_VB are normal. If it is determined that the B phase is normal, the OR block 881B outputs a signal indicating that the B phase is normal to the motor control unit 900.

The OR block 881B determines that the B phase is broken when at least one of the signals output from the failure diagnosis units 800P_IB and 800P_VB is abnormal. If it is determined that the B phase is broken, the OR block 881B outputs a signal indicating that the B phase is broken to the motor control unit 900.

Failure diagnosis unit 800P_IV further includes failure diagnosis units 800P_IC and 800P_VC, and an OR block 881C.

Failure diagnosis unit 800P_IC performs the diagnosis using the current value described with reference to FIGS. 15 and 16. Failure diagnosis unit 800P_VC performs diagnosis using voltage values described with reference to FIGS. 18 and 19.

The OR block 881 C determines that the C phase is normal if both of the signals output from the failure diagnosis units 800 P_IC and 800 P_VC indicate that they are normal. If it is determined that the C phase is normal, the OR block 881C outputs a signal indicating that the C phase is normal to the motor control unit 900.

The OR block 881 C determines that the C phase is broken when at least one of the signals output from the failure diagnosis units 800 P_IC and 800 P_VC indicates an error. If it is determined that the C phase is broken, the OR block 881C outputs a signal indicating that the C phase is broken to the motor control unit 900.

The motor control unit 900 can determine the presence or absence of a failure of the A phase, the B phase, and the C phase from the output signals of the OR blocks 881A, 881B, and 881C. If a failure occurs, the motor control unit 900 can identify which phase the failure has occurred. By identifying the failed phase, the motor control unit 900 can perform appropriate control according to the failure point. For example, the motor control unit 900 can perform two-phase conduction control using the remaining two phases other than the failure phase.

In the example illustrated in FIG. 21, the failure diagnosis unit 800P_IV performs failure diagnosis using both of the detected current value and voltage value. For example, when the current sensor 150 breaks down, the current flowing through the switching element can not be detected. Even in this case, the detected voltage value can be used to diagnose the presence or absence of a fault. Also, for example, when the voltage detection circuit 380 fails, the voltage applied to the switching element can not be detected, but in this case as well, the presence or absence of the failure can be diagnosed using the detected current value.

FIG. 22 shows another example of the functional block of the failure diagnosis unit 800P_IV. Compared to the failure diagnosis unit 800_IV shown in FIG. 21, the failure diagnosis unit 800_IV shown in FIG. 22 includes AND

blocks

882A, 882B and 882C instead of the OR blocks 881A, 881B and 881C.

In the example shown in FIG. 22, the outputs of fault diagnosis units 800P_IA and 800P_VA are input to AND block 882A. The outputs of fault diagnosis units 800P_IB and 800P_VB are input to AND block 882B. The outputs of fault diagnosis units 800P_IC and 800P_VC are input to AND block 882C.

The AND block 882A determines that the A phase is normal if at least one of the signals output from the failure diagnosis units 800P_IA and 800P_VA indicates that the signal is normal. If it is determined that the A phase is normal, the AND block 882A outputs a signal (for example, “0”) indicating that the A phase is normal to the motor control unit 900.

The AND block 882A determines that the A phase is broken when both of the signals output from the failure diagnosis units 800P_IA and 800P_VA indicate that it is abnormal. If it is determined that the A phase is broken, the AND block 882A outputs a signal (for example, “1”) indicating that the A phase is broken to the motor control unit 900.

The AND block 882B determines that the B phase is normal if at least one of the signals output from the failure diagnosis units 800P_IB and 800P_VB is normal. If it is determined that the B phase is normal, the AND block 882B outputs a signal indicating that the B phase is normal to the motor control unit 900.

The AND block 882B determines that the B phase is broken when both of the signals output from the failure diagnosis units 800P_IB and 800P_VB are abnormal. When it is determined that the B phase is broken, the AND block 882B outputs a signal indicating that the B phase is broken to the motor control unit 900.

The AND block 882C determines that the C phase is normal if at least one of the signals output from the failure diagnosis units 800P_IC and 800P_VC indicates that it is normal. If it is determined that the C phase is normal, the AND block 882C outputs a signal indicating that the C phase is normal to the motor control unit 900.

The AND block 882C determines that the C phase is in failure if both of the signals output from the failure diagnosis units 800P_IC and 800P_VC indicate an abnormality. If it is determined that the C phase is broken, the AND block 882 C outputs a signal indicating that the C phase is broken to the motor control unit 900.

The motor control unit 900 can determine the presence or absence of a failure of the A phase, the B phase, and the C phase from the output signals of the OR blocks 882A, 882B, 882C. If a failure occurs, the motor control unit 900 can identify which phase the failure has occurred. By identifying the failed phase, the motor control unit 900 can perform appropriate control according to the failure point.

In the example shown in FIG. 22, the failure diagnosis unit 800P_IV performs failure diagnosis using both of the detected current value and voltage value. Determining a failure when both the current value and the voltage value are abnormal can increase the reliability of the determination of the failure.

The failure diagnosis method according to the embodiment of the present disclosure is not limited to the power conversion device 1000 including the inverter unit 100 having three H bridges as shown in FIG. 2, and a motor in which one ends of the windings are Y-connected It can also be suitably used for a power converter to be driven.

FIG. 23 schematically shows a circuit configuration of an inverter unit 100A having a single inverter 140 according to a modification of the present embodiment.

In this example, the inverter unit 100A is connected to a motor 200 having three-phase windings whose one ends are Y-connected. The failure diagnosis method according to the embodiment is applicable to, for example, a motor using a three-phase current, and is also applicable to a motor having a winding in which one end is delta-connected. The A phase leg of the inverter 140 has a low side switch element SW_AL, a high side switch element SW_AH, and a shunt resistor S_A. The B-phase leg has a low side switch element SW_BL, a high side switch element SW_BH, and a shunt resistor S_B. The C-phase leg has a low side switch element SW_CL, a high side switch element SW_CH, and a shunt resistor S_C.

The controller 340 can diagnose the presence or absence of a failure of a plurality of switching elements included in the inverter 140 in the same manner as the failure diagnosis method described above. Further, the controller 340 can diagnose the presence or absence of a failure in the A phase, the B phase, and the C phase in the same manner as the failure diagnosis method described above.

When no failure occurs in the inverter 140, the controller 340 controls the motor 200 by, for example, three-phase conduction control. When a failure occurs in the inverter 140, the controller 340 performs control to stop the driving of the motor 200, for example.

As such, the controller 340 can change the control of the motor 200 depending on whether the inverter 140 is normal or abnormal.

Second Embodiment

FIG. 24 schematically shows a typical configuration of an electric power steering apparatus 3000 according to this 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 a 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 motor control 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, 100A: 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: microcontroller, 350: drive circuit, 360: ROM, 1000: power converter, 2000: motor module, 3000: electric power steering device

Claims

A failure diagnosis method for diagnosing the presence or absence of a failure of a power conversion device that supplies power to a motor, comprising:

The power converter includes a plurality of switching elements,

The plurality of switching elements are connected to windings of n phases (n is an integer of 3 or more) included in the motor,

In each of the plurality of switching elements,

Determining whether a voltage generated in the switching element when the switching element is controlled to an on state is equal to or higher than a predetermined voltage;

Detecting a time period in which the voltage generated in the switching element is equal to or higher than the predetermined voltage when the voltage generated in the switching element is equal to or higher than the predetermined voltage;

Determining whether the detected time is a predetermined time or more;

Counting the number of times the detected time is greater than or equal to the predetermined time if the detected time is greater than or equal to the predetermined time;

Determining whether the counted total number is equal to or greater than a predetermined number;

Run

The failure diagnosis method determines the phase of the winding to which the switching element having the total counted number of the n phases is equal to or more than the predetermined number is connected.
The failure diagnosis method according to claim 1, further comprising the step of determining that the switching element is normal if the voltage generated in the switching element is not higher than the predetermined voltage.
The failure diagnosis method according to claim 1, further comprising the step of determining that the switching element is normal if the detected time is not a predetermined time or more.
The failure diagnosis method according to any one of claims 1 to 3, further comprising the step of determining that the switching element is normal if the counted total number is not more than the predetermined number.
The switching element is a transistor,

The failure diagnosis method according to any one of claims 1 to 4, wherein the voltage generated in the switching element is a source-drain voltage of the transistor.
A motor control method for executing the failure diagnosis method according to any one of claims 1 to 5, comprising:

When it is determined that the switching element has not failed, the motor is controlled in the first control mode,

And controlling the motor in a second control mode different from the first control mode when it is determined that the switching element is broken.
A power converter for supplying power to a motor, wherein

With multiple switching elements,

A control circuit that controls an on / off switching operation of the plurality of switching elements;

Equipped with

The plurality of switching elements are connected to windings of n phases (n is an integer of 3 or more) included in the motor,

The control circuit determines, in each of the plurality of switching elements, whether a voltage generated in the switching element when the switching element is controlled to be in an on state is equal to or higher than a predetermined voltage.

When the voltage generated in the switching element is equal to or higher than the predetermined voltage, the time when the voltage generated in the switching element is equal to or higher than the predetermined voltage is detected.

It is determined whether the detected time is a predetermined time or more,

When the detected time is equal to or longer than the predetermined time, the number of times the detected time is equal to or longer than the predetermined time is counted,

It is determined whether the counted total number is equal to or greater than a predetermined number,

The power conversion device, wherein the control circuit determines that the phase of the winding to which the switching element having the total counted number of the n phases is equal to or more than the predetermined number is the phase that has failed.
Motor,

A power converter according to claim 7;

Motor module comprising:
An electric power steering apparatus comprising the motor module according to claim 8.