JP7420079B2 - motor control device - Google Patents

Description

The present invention relates to a motor control device installed in, for example, an electric power steering device.

2. Description of the Related Art An electric power steering device, which includes an electric motor that generates an auxiliary torque in response to a steering wheel operation by a driver of a vehicle such as an automobile, a control device for the electric motor, etc., is always in operation. Therefore, if a component that makes up the motor drive section breaks down during driving, control such as stopping the assist operation to the steering wheel is required.

For example, in the electric power steering apparatus of Patent Document 1, an inverter drive circuit (inverter drive IC), a central processing unit (CPU), It is a double inverter system that has two sets of three-phase inverter circuits that each have two systems of power supply circuits and drive three-phase windings individually.

That is, in the double inverter system, each of the two three-phase inverter circuits has a total of six switching elements for the upper and lower arms for independent U, V, and W phase drive, and each inverter circuit has two independent U, V, and W phase drives. It has a configuration in which the W-phase motor coil windings (total of 6 pieces) are energized.

In such a configuration, even if a failure occurs in the inverter drive circuit, three-phase inverter circuit, central processing unit (CPU), power supply circuit, etc. of one of the two systems, the inverter drive of the other system will continue to operate normally. Assist continues by driving the circuit, three-phase inverter circuit, central processing unit (CPU), power supply circuit, etc.

Japanese registered patent: Patent No. 6223593

The electric power steering device of Patent Document 1 has a double redundant system in which two control units with the same configuration are separated and arranged side by side, so that if an abnormality occurs in one control unit, the other control The unit is configured to supplement control.

Such a device configuration in which two systems are installed side by side not only complicates the device itself, but also inevitably increases the number of parts, which leads to an increase in cost. Furthermore, since supplementary control is performed by one of the control units during an abnormality, there is also a problem in that during an abnormality, only 50% of the normal output torque can be obtained.

The present invention has been made in view of the above-mentioned problems, and its purpose is to ensure that even if an abnormality occurs in one phase of the power supply circuit, control circuit, inverter circuit, etc. provided in correspondence with the phases, the motor can be operated by the other two phases. An object of the present invention is to provide a motor control device that can continue driving.

The following configuration is provided as a means for achieving the above object and solving the above problems. That is, a first exemplary invention of the present application is a motor control device for driving a multi-phase motor, comprising: a power supply circuit configured to be able to supply and cut off power for each of the plurality of phases; a motor control circuit provided for each of the plurality of phases, a full bridge inverter provided for each of the plurality of phases and receiving power for driving the motor from each of the power supply circuits, and the power supply circuit; the motor control circuit; and determining means for determining the presence or absence of a failure in the full-bridge inverter, and when the determining means determines the failure in one of the plurality of phases, The motor is continued to be driven by the power supply circuit, the motor control circuit, and the full bridge inverter corresponding to the motor. The motor is a three-phase motor, the power supply circuit has a configuration in which two or more power supply sources are divided into three phases, and the power supply circuit corresponding to two of the three phases is a power supply circuit that is connected to the two or more power supply sources. Each of the supply sources serves as a power supply, and a power supply circuit corresponding to one phase other than the two phases uses the two or more power supply sources as power supplies .

A second exemplary invention of the present application is a motor control device for electric power steering, in which the motor control device according to the first exemplary invention is used as an electric power steering device for assisting a driver of a vehicle or the like in steering operation. It is characterized by being a motor control device for steering.

A third exemplary invention of the present application is a motor control method in the motor control device according to the first exemplary invention , which determines the presence or absence of a failure in a power supply circuit provided for each of the plurality of phases. a first determination step of determining the presence or absence of a failure in a motor control circuit provided for each of the plurality of phases; and a second determination step of determining the presence or absence of a failure in a motor control circuit provided for each of the plurality of phases; and a third determination step of determining the presence or absence of a failure in the full-bridge inverter receiving power supply from the plurality of phases in the first determination step, the second determination step, or the third determination step. If a failure is determined in any one phase, the motor control device is configured to continue driving the motor by the power supply circuit, the motor control circuit, and the full-bridge inverter corresponding to the phases other than the one phase. It is characterized by controlling.

According to the present invention, even if a failure occurs in one phase of a component corresponding to multiple phases of a motor control device, the motor can continue to be rotated by the remaining phases. A motor drive output (torque output) of 67% or more can be secured.

FIG. 1 is a block diagram showing a schematic configuration of a motor control device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating control operations corresponding to individual failures in the motor control device. FIG. 3 is a flowchart illustrating an example of failure handling processing of the motor control device. FIG. 4 is a diagram showing motor control corresponding to the failure of PrDr1/INV1. FIG. 5 is a diagram showing motor control in response to a failure of the power supply 1/CPU 1. FIG. 6 is a diagram showing motor control in response to an inter-CPU communication failure. FIG. 7 is a diagram showing motor control corresponding to the INV1 cutoff relay OFF failure. FIG. 8 is a diagram showing motor control in response to a short-circuit failure in the electrolytic capacitor C2 of INV2. FIG. 9 is a diagram showing motor control corresponding to a short-circuit failure of the electrolytic capacitor of INV1. FIG. 10 is a schematic configuration of an electric power steering device equipped with a motor drive device according to an embodiment.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of a motor control device according to this embodiment. In FIG. 1, a motor control device 20 drives an electric motor 15 having three-phase (U, V, W) motor coils 15a, 15b, and 15c that are not connected to each other.

A control unit 21 that controls the entire motor control device 20 uses three central control units (CPUs) 1 to 3 provided independently for each phase and a motor drive signal (PWM signal) based on control signals from each CPU 1 to 3. ), and three inverters provided independently for each phase to supply a predetermined drive current to each motor coil 15a, 15b, 15c of the electric motor 15. A motor drive section 27 having circuits (INV) 1 to 3 is provided.

The power supply unit 25 of the motor control device 20 includes power supply circuits 1 to 3, which are obtained by dividing two DC power supplies (not shown) connected to positive terminals +B1 and +B2 into three parts. That is, power for driving the motor is supplied from the power supply circuits 1 and 3 to the INVs 1 and 3 via the INV reverse connection protection relays 1 and 2, respectively. Further, power for driving the motor is supplied to the INV 2 from a power supply circuit 2 disposed on the output end side of each of the INV reverse connection protection relays 1 and 2.

INV1 to INV3 of the motor drive section 27 are full bridge inverters (also referred to as H bridges) corresponding to the U phase, V phase, and W phase, respectively. More specifically, in INV1, the source terminals of semiconductor switching elements FET1 and FET3 are respectively connected to the drain terminals of FET2 and FET4, and these FET1 to FET4 form an H bridge. An FET 13, which is a semiconductor relay (motor relay) capable of interrupting the U-phase current, is connected between the connection node between FET1 and FET2, the connection node between FET3 and FET4, and the motor coil 15a of the electric motor 15. , 14 are provided.

Similarly, INV2 also constitutes an H bridge with FETs 5 to 8, and FETs 15 and 16 capable of interrupting the V-phase current are provided between the connection nodes of FETs 5 and 6 and the connection nodes of FETs 7 and 8, respectively, and the motor coil 15b. is provided.

INV3 constitutes an H bridge with FETs 9 to 12, and FETs 17 and 18 capable of interrupting the W-phase current are provided between the connection nodes of FETs 9 and 10 and the connection nodes of FETs 11 and 12, respectively, and the motor coil 15c. The structure is as follows.

Among FET1 to FET12 constituting the motor drive unit 27, FET1, 3, 5, 7, 9, and 11 have their respective drain terminals connected to the power supply side (positive terminals +B1, +B2), and FETs 2, 4, 6, and 8 , 10 and 12 are connected to negative terminals -B1 and -B2 on the ground (GND) side.

The DC power supplied to INV1-3 is converted into three-phase AC power by the switching operation of each FET constituting these INV1-3, and the converted power is output to the motor coils 15a-15c of the electric motor 15, respectively. Ru.

Note that FET1 to FET18 are also called power elements, and are switching elements such as MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors).

Next, the control operation of the motor control device according to this embodiment will be explained. FIG. 2 is a diagram illustrating control operations corresponding to individual failures in the motor control device 20, and the same components as in FIG. 1 are given the same reference numerals. Further, FIG. 3 is a flowchart showing an example of failure handling processing of the motor control device.

During normal operation without failure, the motor control device 20 operates as shown in FIG. The INV3 reverse connection protection relay 38 becomes ON (conducting). Power is supplied from a battery or the like connected to the positive terminals +B1 and +B2, and INV1 to INV3 receive control signals from the control units 21a to 21c, respectively, and drive current is passed through the motor coils 15a to 15c to drive the electric motor. 15.

Note that the CPUs 1 to 3 forming the control units 21a to 21c operate by receiving power supply from the power supplies 1 to 3, respectively. The power supply 1 uses the power supplied from the positive terminal +B1 as its supply source, and the power supply 3 uses the power supplied from the positive terminal +B2 as its supply source. Further, the power source 2 uses power supplied from both positive terminals +B1 and +B2 as a power source.

Therefore, the path to the motor coil 15a during normal operation of the motor control device 20 is as shown by the thick line A in FIG. A drive current is supplied through the path of terminal -B1.

Further, the drive current is transmitted to the motor coil 15c through the path shown by the bold line C in FIG. Supplied.

On the other hand, the drive current to the motor coil 15b is supplied from a power source separated from the two power sources as described above. That is, as shown by thick line B in FIG. 2, the path is positive terminal +B1 → power coil 51 → INV1 power relay 31 → INV1 reverse connection protection relay 37 → INV1 cutoff relay 35, and positive terminal +B2 → power coil 53 → INV3 power relay The current that merges through the path 33→INV3 reverse connection protection relay 38→INV3 cutoff relay 36 is supplied through the path INV2 power relay 32→INV2. The current supplied to INV2 is then divided into negative terminal -B1 and negative terminal -B2.

Although not shown, each of the CPUs 1 to 3 has a corresponding current sensor and an angle sensor, and each of them independently detects the current value and rotation angle of each phase of the electric motor 15. The CPUs 1 to 3 perform control according to individual failures, as shown in FIG. 3, according to programs stored in a memory (not shown) such as a ROM. Each CPU not only controls itself but also monitors the entire control system, including the control operations of other CPUs, through real-time mutual communication between the CPUs.

Connected to the CPUs 1 and 3 are CANs (Controller Area Networks) 1 and 2 and TSs (Torque Sensors) 1 and 2 that exchange various information about the vehicle. Since the CPUs 1 to 3 are configured to be able to communicate with each other as described above, the information obtained by the CPUs 1 and 3 from the CAN etc. via the thick dotted lines D and E in FIG. 2 is transmitted through the thick dotted line F in FIG. The data is sent to the CPU 2 via the communication path shown in .

The CPUs 1 to 3 perform processing based on the steering torque detection values from the TSs 1 and 2, the vehicle speed values from the CANs 1 and 2, etc., and apply PWM (pulse width modulation) to the predriver sections (PrDr) 1 to 3, which function as FET drive circuits. ) outputs a signal. PrDr1-3 increase/decrease the duty of the PWM control signal according to commands from CPU1-3 to generate ON/OFF control signals for the respective semiconductor switching elements INV1-INV3.

Further, PrDr1 to PrDr3 have an abnormality monitoring function for each of the high-potential side drive element (FET) and the low-potential side drive element (FET) of the full-bridge inverter. This makes it possible to quickly and easily determine whether there is a phase-related failure in the full-bridge inverter. As a result, smooth motor drive control can be continued by switching to another INV without a failure.

Next, control operations corresponding to individual failures in the motor control device 20 will be explained.

<When power supply 2/CPU2/PrDr2/INV2 fails>
When CPU1 or CPU3 determines a failure in power supply 2, CPU2, PrDr2, or INV2 through mutual communication between CPUs (step S19 in FIG. 3), the power supply path leading to INV2 and the operating power supply of CPU2 A power supply route to a certain power source 2 is cut off. Specifically, the INV1 cutoff relay 35, INV3 cutoff relay 36, and INV2 power supply relay 32 shown in FIG. 2 are turned off (cut off). As a result, the path shown by thick line B in FIG. 2 is cut off, and power is supplied to INV1 and INV 3 through the paths shown by thick lines A and C (step S21 in FIG. 3).

As shown by thick dotted lines D and E in FIG. 21a, 21c) drives the motor 15 (step S29 in FIG. 3).

In this way, even if one of the three phases fails, the motor drive control is continued using the other two normal phases using two power supplies, which increases the torque output by more than 67% of the normal state ( motor drive output).

Therefore, as will be described later, when the motor control device 20 is installed in an electric power steering device, even if the above-mentioned failure occurs, the assist does not stop and the assist can continue.

Regarding the failure of PrDr2/INV2, the CPU2 detects that the motor coil 15b is not energized based on the current detection value by the current sensor (shunt resistor) provided for each phase, and , or the failure of PrDr2/INV2 is notified to CPU1 or CPU3 through communication between CPU2 and CPU3.

On the other hand, a failure of the power supply 2/CPU 2 is detected based on a situation in which the CPU 1 or the CPU 3 communicating with the CPU 2, for example, does not receive normal information from the CPU 2 or the communication with the CPU 2 is interrupted.

<When PrDr1/INV1 fails>
FIG. 4 shows the motor control device 20 when the power supply path to INV1 is cut off in response to a failure of PrDr1 or INV1 (step S23 in FIG. 3). Specifically, the INV1 power relay 31, the INV1 cutoff relay 35, and the INV1 reverse connection protection relay 37 are turned off (cut off). When PrDr1/INV1 malfunctions, for example, the CPU1 detects that the motor coil 15a is not energized based on the current detected value by a current sensor (shunt resistor) provided for each phase, and then Alternatively, the notification is sent to CPU2 or CPU3 through communication between CPU1 and CPU3.

As a result, power is supplied to the INVs 2 and 3 through the paths indicated by thick lines B' and C in FIG. 4, and the motors are continued to be driven by the control units 21b and 21c (step S25 in FIG. 3). At this time, CPU2 receives various vehicle information from TS1/CAN1 through communication with CPU1, as shown by thick dotted lines D and F in FIG. Receive various vehicle information directly from.

In this way, even if PrDr1 or INV1 fails, the CPU 2 can obtain the target torque etc. through communication with the normal CPU 1 corresponding to the failed phase. In addition, by configuring the power supply paths B' and C in which one power source is branched into two, which is unrelated to the interruption of the power supply path, the motor can be continued to be driven by the normal two-phase control units 21b and 21c ( Step S29 in FIG. 3). As a result, it is possible to obtain a torque output that is 67% or more of the normal torque output.

<When power supply 1/CPU 1 fails>
When the power supply 1 or the CPU 1 fails (step S23 in FIG. 3), the control unit 21a does not operate as shown in FIG. 5, and the control signal to the INV1 is interrupted, so FET1 to FET4 forming the INV1 are turned off. . Further, the INV1 power relay 31, INV1 cutoff relay 35, and INV1 reverse connection protection relay 37 are turned off (cut off) to cut off the power supply path leading to the INV1. A failure of the power supply 1 or the CPU 1 is detected when the CPU 2 or the CPU 3 becomes unable to communicate with the CPU 1.

When the power supply 1/CPU 1 fails, power is supplied to the INVs 2 and 3 through the paths indicated by thick lines B' and C in FIG. 5, and the motors are continued to be driven by the control units 21b and 21c (step S25 in FIG. 3). At this time, as shown by the thick dotted line E in FIG. 5, the CPU 3 receives various vehicle information directly from the TS2/CAN2, and as shown by the thick dotted line G in FIG. Receive various information about the vehicle.

Therefore, even if the power supply 1 or the CPU 1 fails, as a result of the INV control by the two normal CPUs 2 and 3 (i.e., the control units 21b and 21c), the motor continues to be driven and the target torque etc. can be secured (Fig. 3 step S29). In addition, the normal two-phase control units 21b and 21c continue to drive the motors by the power supply paths B' and C, which branch one power source into two that are not related to the interruption of the power supply path. % or more torque output can be obtained.

Note that the CPUs 1 to 3 described above may each have the same configuration and may have a safety mechanism such as a dual-core lockstep system that executes the same processing while mutually synchronizing. For example, if the CPU 1 goes out of control, the operation of the CPU 1 may be reset or stopped by a safety mechanism of the CPU 1.

<Communication failure between CPUs>
Even if each of CPUs 1 to 3 is operating normally, for example, if CPUs 2 and 3 become unable to communicate with CPU 1, CPUs 2 and 3 will detect a communication failure between CPU 1 and CPU 2 or between CPU 1 and CPU 3. (Step S11 in FIG. 3). In this case, since the individual CPUs 1 to 3 are operating normally, the CPU 1 receives various vehicle information directly from the TS1/CAN1, as shown by the thick dotted line D in FIG. Further, the CPU 3 receives various vehicle information directly from TS2/CAN2 (thick dotted line E in FIG. 6), and the CPU 2 receives various vehicle information from TS2/CAN2 through normal communication with the CPU 3. receive (thick dotted line G in FIG. 6).

Therefore, when the control units 21a to 21c operate normally, motor drive current is supplied to INVs 1 to 3 via the power supply paths A, B, and C indicated by bold lines in FIG. 6, and motor drive is continued. (Steps S13 and S29 in FIG. 3). Thereby, even if a communication failure occurs between the CPU 1 and the CPUs 2 and 3, it is possible to obtain 100% torque output, which is the same as during normal operation.

<TS1/CAN1 failure>
If TS1 or CAN1 fails (step S11 in FIG. 3), CPU1 cannot receive various vehicle information from TS1/CAN1. In this case, the CPU 1 detects a TS1/CAN1 failure through a predetermined failure diagnosis, and notifies the CPUs 2 and 3 of this through inter-CPU communication.

CPU3, which learned of the failure of TS1/CAN1 from the notification from CPU1, receives various vehicle information directly from TS2/CAN2, and also transmits various vehicle information from TS2/CAN2 to CPUs 1 and 2 through inter-CPU communication. Send.

Therefore, even if a TS1/CAN1 failure occurs, motor drive current is supplied to INV1 to INV3 through the same paths as the thick lines A, B, and C in FIG. 2, and the motor drive is continued by the control units 21a to 21c. . As a result, it is possible to obtain 100% torque output according to the target torque, similar to the normal state.

<INV1 cutoff relay OFF failure>
When the INV1 cutoff relay 35 becomes OFF failure (non-conducting state) (step S15 in FIG. 3), as shown in FIG. →The path leading to INV2 via INV2 power relay 32 is cut off.

In this case, power supply current is supplied to INV2 via the path (thick line B' in FIG. 7) leading to INV2 via positive terminal + B2 → INV3 power relay 33 → INV3 reverse connection protection relay 38 → INV3 cutoff relay 36 → INV2 power relay 32. be done. Further, in FIG. 7, the motor drive current is supplied to INV1 through the path indicated by thick line A, and the motor drive current is supplied to INV3 through the path indicated by thick line C (step S17 in FIG. 3). Therefore, the motor drive is continued by the control units 21a to 21c (step S29 in FIG. 3), and 100% torque output according to the target torque can be obtained as in the normal state.

The INV1 cutoff relay OFF failure is detected by the CPU 2 during initial diagnosis, for example, based on the current detection result from a current sensor provided corresponding to the CPU 2. This detection result is notified from CPU 2 to CPUs 1 and 3 through inter-CPU communication.

<INV1 cutoff relay ON failure>
When the INV1 cutoff relay 35 becomes ON failure (continuous state), the positive terminal +B2 → INV3 power relay 33 → INV3 reverse connection protection relay 38 → INV3 cutoff relay 36 → INV2 power relay A power supply current is supplied to INV2 by a path to INV2 through INV2.

Further, a motor drive current is supplied to INV1 through a path similar to the path shown by thick line A in FIG. 7, and a motor drive current is supplied to INV3 through a path similar to the path shown by thick line C in FIG. Then, as a result of the motor drive control performed by the control units 21a to 21c, 100% torque output according to the target torque can be obtained as in the normal state.

The INV1 cutoff relay ON failure is also detected by the CPU 2 during initial diagnosis, for example, based on the current detection result from a current sensor provided corresponding to the CPU 2. This detection result is notified from CPU 2 to CPUs 1 and 3 through inter-CPU communication.

Note that when the motor control device 20 is installed in an electric power steering device, when the IG-ON is turned on again, an ON failure of the INV1 cutoff relay 35 is detected, for example, by initial diagnosis, and the relays (FET5 to FET8) constituting the INV2 are turned on. Turn OFF to put INV2 in a non-drive state. As a result, since the motor is driven by the drivable two-phase INVs 1 and 3, it is possible to obtain a torque output of 67% or more compared to the normal state.

<INV2 electrolytic capacitor short circuit failure>
FIG. 8 shows the motor control device 20 that responds to a short-circuit failure of the electrolytic capacitor C2 of INV2. When the electrolytic capacitor C2 is short-circuited, the potential at the connection point of the drain terminals of FETs 5 and 7 connected to the power supply side among the relays (FETs) forming the H bridge of INV2 becomes GND level. This potential level drop is detected by a voltage drop detection section 42 that is a motor current potential detection section provided in the INV2 power supply relay 32, and the voltage drop detection section 42 immediately turns the INV2 power supply relay 32 OFF (non-conducting state). ).

As a result, the power supply path to INV2 is cut off. Further, as shown in FIG. 8, the FETs 5 to 8 forming the H bridge of the INV2 are turned OFF (non-conductive state) by the CPU 2, for example.

Here, the presence or absence of an abnormality in the voltage supplied to the motor is directly detected by the voltage drop detection section 42 as described above in response to a power short circuit due to a short circuit failure of the electrolytic capacitor C2 or the like. By doing this, compared to the case where a voltage drop is detected by a CPU operated by software, the hardware called the voltage drop detection section 42 can quickly cut off the power supply path to the part where the short circuit failure has occurred. , it is possible to instantly avoid the effects of power short circuits on other parts.

Therefore, by turning off the INV2 power relay 32 when a short-circuit failure occurs in the electrolytic capacitor C2, power is supplied to the INV1 and INV3 through the paths shown by thick lines A and C in FIG. At this time, the CPUs 1 and 3 receive various vehicle information from the TS1/CAN1 and TS2/CAN2, respectively (thick dotted lines D and E in FIG. 8), so the motor drive is continued by the control units 21a and 21c.

As a result, even if an electrolytic capacitor short-circuit failure (power supply short-circuit) occurs in one of the three phases, the motor can continue to be driven by the two-phase control unit that does not have a short-circuit failure. Torque output can be obtained.

Regarding the short-circuit failure of the electrolytic capacitor C2, as described above, the voltage drop detection section 42 detects a drop in the potential of the power supply path, and after the INV2 power relay 32 is turned OFF, the CPU 2, for example, Based on the current detected value by the provided current sensor (shunt resistor), it is detected that the motor coil 15b is not energized. Then, through inter-CPU communication, the CPU 2 notifies the CPU 1 or the CPU 3 of the occurrence of the failure.

<INV1 electrolytic capacitor short circuit failure>
If the electrolytic capacitor C1 of INV1 has a short-circuit failure, as shown in Figure 9, the connection point of the drain terminals of FETs 1 and 3 connected to the power supply side among the relays (FETs) that make up the H bridge of INV1. The potential becomes GND level. The decrease in the potential level is detected by a voltage drop detection section 41 provided in the INV1 cutoff relay 35, and the voltage drop detection section 41 immediately turns the INV1 cutoff relay 35 OFF (non-conductive state).

Furthermore, since the potential of the positive terminal +B1 temporarily decreases, the power supply 1 becomes unable to generate the operating power for the CPU 1. As a result, the CPU 1 becomes inactive (reset), and the INV1 power relay 31 and the INV1 reverse connection protection relay 37 are turned off (non-conductive), so the power supply path to the INV1 is cut off. At the same time, FETs 1 to 4 forming the H bridge of INV1 are also turned off (non-conductive).

In this manner, the voltage drop detection section 41 directly detects whether or not there is an abnormality in the voltage supplied to the motor in response to a short circuit in the power supply due to a short-circuit failure of the electrolytic capacitor C1 or the like. By doing this, compared to detecting a voltage drop using a CPU operated by software, the hardware called the voltage drop detection unit 41 can quickly cut off the power supply path to the part where the short-circuit failure has occurred, and the power supply You can instantly prevent the effects of short circuits from affecting other parts.

Therefore, by turning off the INV1 cutoff relay 35, INV1 power supply relay 31, and INV1 reverse connection protection relay 37 at the time of a short-circuit failure of the electrolytic capacitor C1, power is supplied to INV2 and 3 through the paths shown by thick lines B' and C in FIG. is supplied. At this time, the CPU 3 receives various vehicle information directly from the TS2/CAN2 (thick dotted line E in FIG. 9), and the CPU 2 receives various vehicle information from the TS2/CAN2 through communication with the CPU 3 (see FIG. 9 thick dotted line G). As a result, the motor drive is continued by the control units 21b and 21c.

Therefore, even if a short-circuit failure (power supply short-circuit) occurs in the electrolytic capacitor C1, the motor continues to be driven by the two-phase control unit that does not have short-circuit failures, so it is possible to obtain a torque output of 67% or more compared to normal conditions. .

Note that the CPU 1 notifies the CPUs 2 and 3 through inter-CPU communication that the FETs 1 to 4 of the INV1 are turned off under the control of the CPU 1 and that the CPU 1 is reset.

<Ground fault of power supply positive terminal + B1>
As another failure process in step S27 in FIG. 3, for example, if the power supply positive terminal +B1 (power connector) has a ground fault, FET1 connected to the power supply side among the FETs forming the H bridge of INV1. , 3 is the same as the above-mentioned "electrolytic capacitor short-circuit failure of INV1" in that the potential at the connection point of the drain terminals of INV1 becomes the GND level.

Therefore, in the event of a ground fault at the power supply positive terminal +B1, a drop in the potential level at the connection point of the drain terminals of FETs 1 and 3 is detected by the voltage drop detection unit 41 provided in the INV1 cutoff relay 35, and the voltage drop detection unit 41 , immediately turn the INV1 cutoff relay 35 OFF (non-conductive state).

Furthermore, due to the potential drop of the positive terminal +B1, the power supply 1 is no longer able to generate operating power for the CPU 1. As a result, the CPU 1 becomes inactive (reset), the INV1 power relay 31 and the INV1 reverse connection protection relay 37 become OFF (non-conductive), and the power supply path to the INV1 is cut off. At the same time, FETs 1 to 4 forming the H bridge of INV1 are also turned off (non-conductive).

In this manner, in the case of a ground fault at the power supply positive terminal +B1, the voltage drop detection section 41 directly detects whether or not there is an abnormality in the voltage supplied to the motor. As a result, the power supply can be cut off more quickly than when a voltage drop is detected by the CPU, and the influence of a ground fault in the connector on other parts can be instantly avoided.

Therefore, by turning the INV1 cutoff relay 35 and the INV1 power relay 31 into the OFF state, power is supplied to INV2 and 3 via the paths shown by thick lines B' and C, as in the case of the INV1 electrolytic capacitor short-circuit failure shown in FIG. is supplied.

At this time, the CPU 3 receives various types of vehicle information directly from the TS2/CAN2, and the CPU 2 receives various types of vehicle information from the TS2/CAN2 through communication with the CPU3. As a result, the motor drive is continued by the control units 21b and 21c.

Therefore, even if a ground fault occurs at the power supply positive terminal +B1, by continuing to drive the motor using the two-phase control unit that is not related to the ground fault, it is possible to obtain a torque output of 67% or more compared to normal conditions. can.

Note that the CPU 1 notifies the CPUs 2 and 3 through inter-CPU communication that the FETs 1 to 4 of the INV1 are turned off and the CPU 1 is reset.

FIG. 10 is a schematic diagram of an electric power steering device equipped with a motor control device according to an embodiment of the present invention. The electric power steering device 1 in FIG. 10 includes a motor control device 20 as an electronic control unit (ECU), a steering handle 2 as a steering member, a rotating shaft 3 connected to the steering handle 2, a pinion gear 6, It is equipped with a rack shaft 7 and the like.

The rotating shaft 3 meshes with a pinion gear 6 provided at its tip. The pinion gear 6 converts the rotational motion of the rotary shaft 3 into a linear motion of the rack shaft 7, and the pair of wheels 5a, 5b provided at both ends of the rack shaft 7 move at an angle corresponding to the amount of displacement of the rack shaft 7. is steered.

The rotating shaft 3 is provided with a torque sensor 9 that detects steering torque when the steering handle 2 is operated, and the detected steering torque is sent to the motor control device 20. The motor control device 20 generates a motor drive signal based on signals such as steering torque obtained from the torque sensor 9 and vehicle speed from a vehicle speed sensor (not shown), and outputs the signal to the electric motor 15 .

The electric motor 15 to which the motor drive signal is input outputs an auxiliary torque for assisting the steering of the steering wheel 2, and the auxiliary torque is transmitted to the rotating shaft 3 via the reduction gear 4. As a result, the rotation of the rotating shaft 3 is assisted by the torque generated by the electric motor 15, thereby assisting the driver's steering operation.

By installing the motor control device 20, in the motor control device for electric power steering, even if a failure occurs in one phase of multiple phases, the motor is driven by the remaining phases, and the assist will not stop due to a single failure. It becomes possible to continue. That is, it is possible to continue assisting by the two-phase degenerate motor drive, and it is possible to continue assisting the vehicle driver in steering operation.

Furthermore, in an electric power steering system, it is possible to quickly determine whether or not there is a failure in the power supply circuit, motor control circuit, and full-bridge inverter with a simple configuration. As a result, if an abnormality is detected during steering assist, the failure can be determined in a short time, and the power supply circuit, motor control circuit, and full-bridge inverter that correspond to the non-faulty phase continue to operate, thereby shortening the steering assist stop time. can do. Furthermore, it is possible to shorten the startup time of the electric power steering motor control device and hasten the time until the start of steering assist.

As explained above, in a motor control device that drives a three-phase motor, there is a power supply circuit configured to be able to supply and cut off power for each phase, a motor control circuit provided for each phase, and a motor control device that drives a three-phase motor from each power supply circuit. A full-bridge inverter is installed for each phase that receives power for driving the motor, and if there is a failure in any one of the three phases, the power supply circuit corresponding to the two phases excluding the phase determined to be failed, and the motor The motor continues to be driven by the control circuit and full bridge inverter.

In this way, by performing failure-free two-phase motor drive control, it is possible to continue rotating the three-phase motor. As a result, by continuing to drive the motor using two phases at the time of failure, it is possible to secure a motor drive output (torque output) that is 67% or more of the normal state. Furthermore, if three-phase control is possible even in the event of a failure, 100% motor drive output can be obtained, which is the same as in normal times.

That is, when a failure occurs in the motor control device, a predetermined torque output can be ensured by controlling the power supply relay, cutoff relay, etc. in accordance with the failure location. Further, even if any failure occurs, control can be performed so that the motor can be driven in two phases or three phases using two power supplies or one power supply.

Furthermore, in a motor control device, a control unit (CPU) corresponding to each motor control circuit is provided, and through communication between the control units, abnormalities in the control unit of the communication partner are monitored. If an abnormality occurs in the control unit corresponding to one phase, the motor control circuit corresponding to three phases to drive and control the full-bridge inverter.

Therefore, due to real-time communication between the control units, the normal control unit can obtain the target torque etc. in place of the abnormal control unit and continue the operation of all three-phase full bridge inverters, so there is no such thing as a control unit failure. The motor drive output at the time of failure can be set to 100%, which is the same as when it is normal. At the same time, since the presence or absence of a failure in other phases can be determined through communication between control units, it is possible to quickly determine a failure and take measures to deal with the failure.

In addition, two DC power supplies are divided into three parts to form a three-phase power supply circuit, and motor drive power is supplied from these power supply circuits to each of the inverter circuits 1 to 3. Compared to conventional double inverter systems that drive system inverters, the torque output available in the event of a failure can be increased. On the other hand, compared to the case where three power supply sources corresponding to three phases are provided, the device configuration can be simplified and the device cost can be reduced.

15 Electric motor 15a to 15c Motor coil 20 Motor control device 21, 21a to 21c Control section 25 Power supply section 27 Motor drive section 31 INV1 power relay 32 INV2 power relay 33 INV3 power relay 35 INV1 cutoff relay 36 INV3 cutoff relay 37 INV1 reverse connection protection Relay 38 INV3 reverse connection protection relay 41 to 43 Voltage drop detection section 51, 53 Power coil

Claims (8)

A motor control device that drives a multi-phase motor,
a power supply circuit configured to be able to supply and cut off power for each of the plurality of phases;
a motor control circuit provided for each of the plurality of phases;
a full-bridge inverter provided for each of the plurality of phases and receiving power for driving the motor from each of the power supply circuits;
determining means for determining whether there is a failure in the power supply circuit, the motor control circuit, and the full-bridge inverter;
Equipped with
When the determining means determines that the failure has occurred in any one of the plurality of phases, the motor is driven by the power supply circuit, the motor control circuit, and the full-bridge inverter corresponding to the phases other than the one phase. continue ,
The motor is a three-phase motor, the power supply circuit has a configuration in which two or more power supply sources are divided into three phases, and the power supply circuit corresponding to two of the three phases is a power supply circuit that is connected to the two or more power supply sources. A motor control device characterized in that each of the supply sources serves as a power supply, and a power supply circuit corresponding to one phase other than the two phases uses the two or more power supply sources as power supplies . The determining means has a control unit provided corresponding to each of the motor control circuits, and determines whether or not there is a failure corresponding to each phase based on a notification result through communication between the control units. The motor control device according to claim 1. An abnormality in a control unit of a communication partner is monitored through communication between the control units, and if an abnormality occurs in a control unit corresponding to any one of the plurality of phases, a control unit corresponding to a phase other than the one phase is detected. 3. The motor control device according to claim 2, wherein the full-bridge inverter is driven and controlled via the motor control circuit corresponding to the plurality of phases based on a notification result obtained through communication between the motor control circuits. The motor control device according to claim 1, further comprising means for detecting an abnormality in the power supply voltage supplied to the motor and stopping power supply from the power supply circuit related to the abnormality. 2. The motor control device according to claim 1, wherein the motor control circuit includes means for monitoring ON failures and OFF failures of each of the plurality of drive elements constituting the full bridge inverter. A motor control device for electric power steering, characterized in that the motor control device according to any one of claims 1 to 5 is used as a motor control device for electric power steering that assists a driver of a vehicle in steering operation. . An electric power steering system comprising the electric power steering motor control device according to claim 6 . A motor control method in a motor control device according to any one of claims 1 to 7, comprising :
a first determination step of determining the presence or absence of a failure in a power supply circuit provided for each of the plurality of phases;
a second determination step of determining the presence or absence of a failure in the motor control circuit provided for each of the plurality of phases;
a third determination step of determining the presence or absence of a failure in a full-bridge inverter that is provided for each of the plurality of phases and receives power supply from each of the power supply circuits;
Equipped with
If a failure is determined in any one of the plurality of phases in the first determination step, the second determination step, or the third determination step, the power supply circuit corresponding to the phase other than the one phase. . A motor control method, comprising controlling the motor control device so that the motor control circuit and the full-bridge inverter continue to drive the motor.

Images