CN113044106A

CN113044106A - Circuit board

Info

Publication number: CN113044106A
Application number: CN202011560794.9A
Authority: CN
Inventors: 高村优介; 森川刚裕; 长内俊二郎
Original assignee: Nidec Elesys Corp
Current assignee: Nidec Elesys Corp
Priority date: 2019-12-26
Filing date: 2020-12-25
Publication date: 2021-06-29
Also published as: JP2021106448A

Abstract

The invention provides a circuit board for a motor control device, having a substitute unit for a power cut-off relay. A switch unit SW (7) for cutting off and energizing the power supply from the power generation unit (6) to the pre-driver unit (1) is arranged on a power supply path from the power generation unit (6) to the pre-driver unit (1). The control circuit includes a motor drive unit (INV) (5) for supplying power from an external power supply (BT) to a motor (15) and a pre-driver unit (pre-driver IC) (1) for outputting a drive signal to the INV (5), and when a failure or abnormality of the control circuit is detected, the control unit (3) sets SW (7) to a non-conduction state and cuts off power supply to the pre-driver unit (1).

Description

Circuit board

Technical Field

The present invention relates to a circuit board mounted on a motor control device such as an electric power steering device.

Background

An electric power steering apparatus includes an electric motor that generates an assist torque for a steering wheel operation by a driver of a vehicle such as an automobile, and a control device for the electric motor. The electric power steering apparatus includes an inverter control unit that receives a control signal from a control unit (CPU) and generates a motor drive signal (PWM signal), an inverter circuit (INV) that is connected to an external battery and supplies a drive current to each motor coil of the electric motor, and the like.

On a circuit board on which a control circuit of an electric power steering apparatus is mounted, a power supply relay is disposed on a power supply path from an external battery (power supply) to an inverter circuit toward a motor in order to prevent a dangerous behavior such as an overcurrent from flowing in the inverter circuit due to a failure such as a short circuit of a semiconductor switch (FET) constituting the inverter circuit, or to prevent an automatic steering from occurring.

Patent document 1 discloses an electronic control device that: an FET short-circuit detection unit for detecting FET short-circuit failure of the inverter is provided, and further, the function of diagnosing the failure of the FET short-circuit detection unit is used to prevent overcurrent from continuously flowing, thereby maintaining the safety of the system.

Patent document 1: japanese patent No. 6274365

The power supply relay for cutting off the overcurrent, which is disposed in the power supply line of the inverter, has high component cost. Therefore, in patent document 1, the above-described safety mechanism is constructed and the power supply relay is deleted, thereby realizing downsizing and cost reduction of the control device.

However, in the case where a power supply relay for overcurrent interruption is removed from a power supply line, if there is no other substitute function, there is a problem that an overcurrent continues to flow to the inverter or automatic steering occurs when an abnormality such as a short-circuit failure of an FET of the inverter occurs.

In the case of patent document 1, a failure of the short-circuit detection unit of the FET is diagnosed at the time of startup, but when a failure occurs in the short-circuit detection unit of the FET after the start of control, there is a possibility that the short-circuit failure of the FET in the short-circuit detection unit of the FET cannot be diagnosed normally. In this regard, there is a problem as a security mechanism.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object thereof is to provide a circuit board of a motor control device having a substitute unit that replaces a power shutoff relay disposed on a power supply line of an inverter circuit of the motor control device.

The above object is achieved by the following structure. That is, an exemplary 1 st invention of the present application is a circuit board including: a control unit that performs drive control on a drive target; an inverter unit having a plurality of high-potential-side drive elements and low-potential-side drive elements and supplying power from a main power supply to the drive target; a pre-driver IC that outputs a drive signal to the high-potential side drive element and the low-potential side drive element; a detection unit that detects a failure or abnormality of a plurality of control circuits including the pre-driver IC; and a stop unit that stops an operation of the pre-driver IC in response to the detected failure or abnormality, wherein the inverter unit receives power supply from the main power supply, and the pre-driver IC incorporates a 1 st voltage source that outputs a voltage corresponding to a drive signal of the high-potential-side drive element and a 2 nd voltage source that outputs a voltage corresponding to a drive signal of the low-potential-side drive element and different from the 1 st voltage source.

An exemplary 2 nd invention of the present application is a motor control device having the circuit board of the exemplary 1 st invention mounted thereon, and having a DC motor as a driving target.

An exemplary 3 rd aspect of the present invention is an electric power steering motor control device that assists a steering wheel operation of a driver of a vehicle or the like, the electric power steering motor control device including: a DC motor for assisting steering of the driver; and means for driving and controlling the DC motor by the motor control device according to claim 2 as exemplified above.

An exemplary 4 th aspect of the present invention is an electric power steering system including the electric power steering motor control device according to the above exemplary 3 rd aspect.

An exemplary 5 th aspect of the present invention is a method for controlling a motor control device including a control unit, an inverter unit having a plurality of high-side and low-side drive elements and supplying power from a main power supply to a DC motor, and a pre-driver IC outputting drive signals to the high-side and low-side drive elements, the method comprising: detecting at least a runaway fault or an abnormal operation of the control unit, a runaway fault or an abnormal operation of the pre-driver IC, an on fault or an off fault of a driving element of the inverter unit, and a fault or an abnormal operation of a predetermined control circuit; and cutting off power supply to the pre-driver IC or inputting a reset signal to stop the operation of the pre-driver IC when the failure or abnormal operation is detected.

According to the present invention, by providing the stop portion that stops the supply of power from the main power supply to the pre-driver portion (pre-driver IC) instead of the power shutoff relay, it is possible to, for example, miniaturize the motor control device and reduce the cost.

Drawings

Fig. 1 shows a structure of a circuit board for a motor control device according to an embodiment of the present invention.

Fig. 2 is a flowchart illustrating an example of a failure diagnosis process of a circuit board for a motor control device according to the embodiment.

Fig. 3 schematically shows a power supply, a signal system, and the like of the motor control device corresponding to when the pre-driver section fails.

Fig. 4 schematically shows a power supply, a signal system, and the like of the motor control device corresponding to the case where the motor drive unit (INV) has a failure.

Fig. 5 schematically shows another example of a signal system and the like of the motor control device corresponding to the case where the motor drive unit (INV) has a failure.

Fig. 6 shows a schematic configuration of an electric power steering apparatus in which a motor control device having a circuit board according to an embodiment is mounted.

Description of the reference symbols

1: a pre-driver section (pre-driver IC); 2: a motor control device; 3: a control unit (CPU); 4: a motor current sensor section; 5: a motor drive unit (inverter circuit); 6: a power generation unit; 7: a switch unit (SW); 8: a power supply unit; 9: an ignition switch (IG-SW); 11: a PWM signal generation unit; 13a to 13 f: a driver (predriver); 15: an electric motor; 17: a pressure raising portion; 18: a failure detection unit; 25: a memory; 31: a diagnosis unit; 33: a reset section; 41a to 41 c: a current detection circuit (current sensor); 49a to 49 c: an amplifying circuit; 100: an electric power steering apparatus; 102: a steering wheel; 103: a rotating shaft; 104: a reduction gear; 105a, 105 b: a wheel; 106: a pinion gear; 107: a rack shaft; BT: an external battery.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a block diagram showing a configuration of a circuit board according to an embodiment of the present invention, and for example, shows a configuration of a circuit board of a motor Control device (Electronic Control Unit (ECU)) mounted on an electric power steering device.

In fig. 1, the motor control device 2 has the following components: a control unit (CPU)3 that controls the entire motor control device 2; a pre-driver unit (pre-driver IC)1 that generates a motor drive signal based on a control signal from the control unit 3 and functions as an FET drive circuit or the like; a motor drive unit (also referred to as an inverter circuit) 5 as a motor drive circuit that supplies a predetermined drive current to the electric motor 15; and a motor current sensor unit 4 that detects a motor current corresponding to each of the electric motors 15.

The control unit 3 is constituted by a microprocessor, for example. The control unit 3 outputs a PWM (pulse width modulation) signal based on the steering torque, a signal from a vehicle speed sensor, and the like to the pre-driver unit 1. The PWM signal generation unit 11 of the pre-driver unit 1 increases or decreases the duty ratio of the PWM control signal in accordance with the control signal from the control unit 3, thereby generating the on/off control signal of the semiconductor switching element of the motor drive unit 5.

The memory 25 stores a motor control program executed by the control unit 3, and also stores programs necessary for executing a failure diagnosis process described later. The memory 25 is, for example, a Read Only Memory (ROM). The memory 25 may be a structure built in the CPU 3.

A power supply for driving the motor is supplied from the external battery BT to the motor driving unit 5 of the motor control device 2. That is, the motor control device 2 is configured such that a power supply relay for power interruption is not provided between the external battery BT and the motor drive unit 5, and the power from the battery BT is directly supplied to the motor drive unit 5.

The ignition switch (IG-SW)9 has one end connected to the external battery BT and the other end connected to the power supply generation unit 6. In the motor control device 2, the IG signal from the IG-SW 9 is used as a trigger signal to switch the electric motor 15 on/off, and when the IG-SW 9 is off, the steering assist function is stopped. Further, the engine start signal may be the trigger signal.

The motor drive unit (INV)5 is a FET bridge circuit including a plurality of semiconductor switching elements (FET 1 to FET 6). In fig. 1, the switching FET for supplying the driving current to the electric motor 15 is not shown. The electric motor 15 is a DC motor, for example, a three-phase brushless DC motor.

The FET bridge circuit is a three-phase (U-phase, V-phase, W-phase) inverter circuit. The semiconductor switching elements (FET 1 to FET 6) constituting the inverter circuit correspond to the electric motor 15, respectively.

The pre-driver unit 1 is a motor control integrated circuit (pre-driver IC) in which drivers (pre-drivers) 13a to 13f and the like for driving the semiconductor switching elements (FET 1 to FET 6) are integrated. The

drivers

13a, 13c, and 13e drive the high side (HiSide)

FETs

1, 3, and 5 of the motor drive unit 5, respectively, and the

drivers

13b, 13d, and 13f drive the low side (LoSide)

FETs

2, 4, and 6 of the motor drive unit 5, respectively.

That is,

FETs

1, 3, and 5 are high-side switching devices of U-phase, V-phase, and W-phase, respectively, and

FETs

2, 4, and 6 are low-side switching devices of U-phase, V-phase, and W-phase, respectively. Specifically,

FETs

1, 2 correspond to U, FETs 3, 4 correspond to V, and

FETs

5, 6 correspond to W.

The drain terminals of the

FETs

1, 3, and 5 are connected to the power supply side. Further, the source terminals of the

FETs

1, 3, and 5 are connected to the drain terminals of the

FETs

2, 4, and 6, respectively, and the source terminals of the

FETs

2, 4, and 6 are connected to the Ground (GND) side.

The switching element (FET) is also referred to as a power element. The Semiconductor device includes a Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET). In addition, a large-capacity, high-voltage switching element such as an IGBT (Insulated Gate Bipolar Transistor) may be used.

The power supply generation unit 6 (corresponding to the 1 st power supply generation unit described in claims) generates a system voltage VBAT of the circuit from the voltage + B input from the battery BT via the IG-SW 9. The power supply unit 8 (corresponding to the 2 nd power supply generation unit described in the claims) converts the voltage VBAT into a control voltage Vcc (+5V) of a logic level, and supplies the control voltage Vcc to a control circuit such as the control unit (CPU) 3. A switch unit (SW)7 is disposed on a power supply path from the power supply generation unit 6 to the pre-driver unit 1, and the switch unit (SW)7 receives a control signal from the control unit 3 and cuts off and energizes the power supply from the power supply generation unit 6 to the pre-driver unit 1.

Thus, the operation power supply (VBAT) of the pre-driver section 1 is supplied from the power supply generation section 6 via the switch Section (SW) 7. The switch unit (SW)7 is composed of, for example, a semiconductor switching element. By using the semiconductor switching element, the power consumption of the switch unit (SW)7 can be reduced and the size thereof can be reduced.

The power supply generation unit 6 is an IG switch circuit and is a self-holding OR circuit based on an IG signal from the IG-SW 9 and an instruction from the CPU3, but the detailed configuration thereof is omitted in fig. 1. In addition, the control voltage Vcc (+5V) of a logic level may be generated inside the pre-driver section 1.

The boosting unit 17 disposed in the pre-driver unit 1 boosts the power supply voltage VBAT (e.g., +14V) supplied via the switch unit 7 and outputs a boosted voltage VBC (e.g., + 28V). The boosting unit 17 is, for example, a DCDC converter that performs switching control of a built-in semiconductor switching element (FET) and boosts the supplied voltage VBAT to VBC.

The boosted voltage VBC is a drive power supply for the

drivers

13a, 13c, and 13e of the pre-driver section 1 that drive the high-side (HiSide)

FETs

1, 3, and 5, respectively. The power supply voltage VBAT is a drive power supply for the

drivers

13b, 13d, and 13f of the pre-driver section 1 that drive the low-side (LoSide)

FETs

2, 4, and 6, respectively.

The failure detection unit 18 of the predriver unit 1 includes voltage comparison circuits (comparators) corresponding to the U-phase MV terminal (MV 1), the V-phase MV terminal (MV 2), and the W-phase MV terminal (MV 3), respectively. Then, the voltage at the motor terminal (MV terminal) corresponding to each electric motor 15 is compared with the drain-source Voltage (VDS) of each FET composed of VIN and GND (VIN is the power supply voltage of the inverter circuit 5) by a comparator.

The diagnostic unit 31 of the control unit (CPU)3 determines whether the high side (HiSide) FET and the low side (LoSide) FET of each of the U-phase, V-phase, and W-phase have a short circuit or open circuit fault, and whether the voltage of the MV terminal of each phase is a normal value or an abnormal value, based on the comparison result from the fault detection unit 18.

In the motor current sensor unit 4, current detection circuits (current sensors) 41a to 41c corresponding to the respective low-side (LoSide)

FETs

2, 4, and 6 and the negative side (GND) of the power supply are arranged. These current detection circuits detect a direct current flowing through a shunt resistor for detecting a motor drive current using an amplifier circuit.

For example, the current detection circuit 41a includes a shunt resistor R1 and an amplifier circuit 49a, and the amplifier circuit 49a is configured by an operational amplifier or the like, and converts the potential difference (drop voltage) between both ends of the shunt resistor R1 based on the motor drive current into a current value to output as a current detection signal. Similarly, the current detection circuit 41b includes a shunt resistor R2 and an amplifier circuit 49b, and the current detection circuit 41c includes a shunt resistor R3 and an amplifier circuit 49 c.

The output signals (current detection signals) from the current detection circuits 41a to 41c are input to an a/D converter (ADC)44, and the analog current values detected by the current detection circuits 41a to 41c are converted into digital data by the a/D conversion function of the a/D converter (ADC)44, and are transmitted to the control unit (CPU) 3. The a/D converter 44 may be built in the CPU 3.

Next, the failure diagnosis of the circuit board of the motor control device of the present embodiment will be described.

< 1 st Fault diagnosis Structure example >

Fig. 2 is a flowchart showing an example of failure diagnosis processing in the motor control device 2 of fig. 1 as a first failure diagnosis configuration example 1.

In step S11 of fig. 2, the diagnostic unit 31 of the control unit (CPU)3 determines whether or not the pre-driver unit 1 is operating normally. For example, it is determined whether or not the PWM signal generation unit 11 of the pre-driver unit 1 outputs a PWM control signal in accordance with a control signal from the control unit 3, based on, for example, a current value detected by the motor current sensor unit 4.

When the PWM control signal is not normally output, the diagnosis unit 31 can determine that a failure has occurred in one or both of the PWM signal generation unit 11 and the drivers 13a to 13 f.

When the PWM signal generation unit 11 and the like of the pre-driver unit 1 normally operate, the diagnosis unit 31 of the control unit 3 determines whether or not the motor drive unit (INV)5 normally operates in step S13. For example, it is determined whether or not the high side (HiSide) FET and the low side (LoSide) FET of the motor drive unit (INV)5 normally operate, based on the drive signal (on/off signal) from the pre-driver unit 1.

Specifically, the motor instruction voltage and the phase voltage are compared based on the detection result of the voltage at the motor terminal (MV terminal) corresponding to each phase of the electric motor 15 in the failure detection unit 18, and if the difference between the motor instruction voltage and the phase voltage exceeds a predetermined threshold, it is determined that the FET of the phase has a short-circuit failure or an open-circuit failure.

When the difference between the current value detected by the motor current sensor unit 4 (the detected current value of each phase) and the target current value of each phase exceeds a predetermined threshold value, it is determined that the FET of the phase has a short circuit or an open failure. Alternatively, if a through current flows between the high-side FET and the low-side FET and an excessive current exceeding a normal value is detected, it is determined as a short-circuit fault, and if no current flows at all, it is determined as an open-circuit fault.

When it is determined in step S13 that the FET of the motor drive unit (INV)5 is operating normally, the diagnostic unit 31 of the control unit 3 determines in step S15 whether or not there is a failure in another component of the motor control device 2. A unit for judging the runaway fault of the control unit (CPU)3 itself may be provided.

When there is no trouble such as a failure in another component or the like, the diagnostic unit 31 of the control unit 3 ends the failure diagnosis process. Thus, in the case of the electric power steering apparatus in which the motor control device having the circuit board of the present embodiment is mounted, the steering wheel is continuously assisted after the failure diagnosis is completed.

On the other hand, when it is determined in step S11 that PWM signal generation unit 11 of pre-driver unit 1 is out of control and does not operate normally as a logic unit, diagnostic unit 31 of control unit 3 transmits a drive stop signal (off signal) to switch unit (SW)7 in step S21. As a result, the switch unit (SW)7 is turned off (non-conductive), the power supply from the power generation unit 6 to the pre-driver unit 1 is cut off, and the pre-driver unit 1 stops operating (step S23).

Fig. 3 schematically shows a power supply and signal system of the motor control device corresponding to when the pre-driver section fails. When the pre-driver unit (pre-driver IC)1 fails, the control unit (CPU)3 transmits a drive stop signal (off signal) 51 to the switch unit (SW)7, thereby turning off the power supply to the pre-driver unit 1. In fig. 3, a state where the path is cut is indicated by a thick broken line.

Further, when the pre-driver unit 1 fails, as shown in fig. 3, the control unit (CPU)3 can stop the operation of the pre-driver unit 1 by interrupting the power supply to the pre-driver unit 1 by the drive stop signal 51 sent to the switch unit (SW)7 even if the control signal 53 continues to be output to the pre-driver unit 1. As a result, as shown by the thin broken line in fig. 3, the driving signal is not output from the pre-driver section 1 to the motor driving section (INV)5, and therefore, the safety mechanism of the motor control device can be ensured.

In step S15, when it is determined that a failure has occurred in another component of the motor control device 2, the power supply to the pre-driver unit 1 is cut off, and a drive signal is not output from the pre-driver unit 1 to the motor drive unit (INV)5, as in the case shown in fig. 3.

When determining in step S13 that the FET of the motor drive unit (INV)5 has not normally performed the on/off operation (on: energized state; off: non-energized state) due to a short-circuit fault or the like, the control unit (CPU)3 transmits a drive stop signal (off signal) 51 to the switch unit (SW)7 (step S21), and cuts off the power supply to the pre-driver unit 1 (step S23).

That is, when the motor drive unit (INV)5 fails, the control unit (CPU)3 transmits a drive stop signal (off signal) 51 to the switch unit (SW)7 to cut off the power supply to the pre-driver unit 1 as shown in fig. 4, and stops outputting the control signal to the pre-driver unit 1 as shown by a thin broken line in fig. 4. Accordingly, the safety mechanism of the motor control device can be ensured without outputting a drive signal from the pre-driver unit 1 to the motor drive unit (INV) 5.

< 2 nd Fault diagnosis Structure example >

In the 1 st failure diagnosis configuration example shown in fig. 3 and 4, a drive stop signal (off signal) is transmitted to the switch unit (SW)7, and the power supply to the pre-driver unit 1 is cut off to stop the operation of the pre-driver unit 1, but the configuration to stop the operation of the pre-driver unit is not limited to this.

As an example of the 2 nd failure diagnosis configuration, for example, the motor control device shown in fig. 5 is configured to directly input the power output (VBAT) from the power generation unit 6 to the pre-driver IC 1 without providing the switch unit (SW)7, unlike the examples shown in fig. 3 and 4.

The pre-driver section (pre-driver IC)1 shown in fig. 5 has an input terminal (not shown) for a reset signal. Therefore, for example, when the control unit (CPU)3 detects a failure of the motor drive unit (INV)5, the reset unit 33 (see fig. 1) outputs a reset signal 52 of a logic low level to the pre-driver IC 1. As a result, the reset terminal of the pre-driver IC 1 becomes the reset level, and the operation of the pre-driver section 1 can be stopped.

In this way, in the example shown in fig. 5, the control unit (CPU)3 controls the reset terminal of the pre-driver unit 1 to stop the operation of the pre-driver unit 1. Specifically, the booster circuit (not shown) in the pre-driver section 1 is stopped by resetting, and the supply of the drive power to both the drive driver of the high-side (HiSide) FET and the drive driver of the low-side (los) FET is stopped. Accordingly, the motor control device can be shifted to the safe state because the drive signal is not output to the motor drive unit (INV) 5.

By the above-described failure diagnosis process, the drive of the motor to be driven can be stopped in accordance with a runaway fault of the predriver IC 1, an on fault or an off fault of the drive element of the inverter unit 5, or the like (including a runaway fault of the control unit (CPU)3 in some cases).

In addition, a warning display corresponding to the above-described failure determination result may be performed. As the warning display, for example, it is conceivable to display a warning indicating that a failure has occurred in the predriver IC 1, the inverter unit 5, or the like by lighting or blinking a lamp provided on a panel of the vehicle.

Fig. 6 is a schematic configuration of an electric power steering apparatus in which a motor control device (electronic control unit) having a circuit board according to an embodiment of the present invention is mounted. The electric power steering apparatus 100 shown in fig. 6 includes a motor control device 2, a steering wheel 102 as a steering member, a rotary shaft 103 connected to the steering wheel 102, a pinion gear 106, a rack shaft 107, and the like.

The rotary shaft 103 is engaged with a pinion gear 106 provided at the front end thereof. The rotational motion of the rotary shaft 103 is converted into a linear motion of the rack shaft 107 by the pinion gear 106, and the pair of

wheels

105a and 105b provided at both ends of the rack shaft 107 are steered to an angle corresponding to the displacement amount of the rack shaft 107.

A torque sensor 109 that detects a steering torque when the steering wheel 102 is operated is provided on the rotary shaft 103, and the detected steering torque is transmitted to the motor control device 2. The motor control device 2 generates a motor drive signal based on a signal such as a steering torque acquired by the torque sensor 109 and a vehicle speed from a vehicle speed sensor (not shown), and outputs the signal to the electric motor 15.

An assist torque for assisting steering of the steering wheel 102 is output from the electric motor 15 to which the motor drive signal is input, and the assist torque is transmitted to the rotary shaft 103 via the reduction gear 104. As a result, the rotation of the rotary shaft 103 is assisted by the torque generated by the electric motor 15, thereby assisting the steering wheel operation of the driver.

As described above, the circuit board for the motor control device of the present embodiment has the following structure: instead of a power supply interruption relay for interrupting the power supply to the drive circuit for driving the motor, a switch unit for interrupting and energizing the power supply from the main power supply to the pre-driver unit is added as an alternative means.

In this way, by adopting a configuration in which the main power supply and the pre-driver unit are connected via the cut-off unit (switch unit) and the power cut-off relay for the drive circuit for driving the motor is not provided, it is possible to delete not only the power cut-off relay but also the drive circuit for the power cut-off relay. As a result, not only can the motor control device be downsized and cost reduced, but also the motor control circuit board can be downsized and cost reduced in the electric power steering system mounted with the motor control device.

Further, by performing the above-described failure determination only by the motor current sensor portion, it is possible to use a pre-driver portion (pre-driver IC) that does not include a short-circuit detection portion, and thus it is possible to further reduce the cost.

Thus, when an abnormality (failure) is detected, the cutoff unit (switch unit) is operated to cut off the power supply to the pre-driver IC and stop the operation of the motor to be driven, so that the cutoff unit (switch unit) functions as a substitute unit for the power relay, thereby ensuring a safety mechanism of the motor control device.

Further, since the power supply to the pre-driver IC is cut off by operating the cutting unit (switching unit) and the operation of the pre-driver IC itself and the motor driving are stopped, it is not necessary to perform control for invalidating the output signal from the pre-driver IC when an abnormality (failure) is detected.

In addition, not only when the motor Control device (Electronic Control Unit: ECU) is activated, but also when the ECU executes Control, it is possible to continuously cope with a failure of the motor Control device.

On the other hand, when a pre-driver IC having a reset terminal is used and a failure of a motor drive unit (INV) is detected, a reset signal of a logic low level is output from a reset unit in a control unit (CPU) to the pre-driver IC, and the reset terminal of the pre-driver IC is set to a reset level.

By not providing the switch unit (SW) for cutting off the power supply to the pre-driver unit and stopping the operation of the pre-driver unit constituting the motor control device by the reset signal, the safety state of the motor control device can be ensured and the cost of the circuit board can be further reduced.

Claims

1. A circuit board, having:

a control unit that performs drive control on a drive target;

an inverter unit having a plurality of high-potential-side drive elements and low-potential-side drive elements and supplying power from a main power supply to the drive target;

a pre-driver IC that outputs a drive signal to the high-potential side drive element and the low-potential side drive element;

a detection unit that detects a failure or abnormality of a plurality of control circuits including the pre-driver IC; and

a stop unit that stops the operation of the pre-driver IC in accordance with the detected failure or abnormality,

the inverter unit receives power supply from the main power supply, and the predriver IC incorporates a 1 st voltage source that outputs a voltage corresponding to a drive signal of the high-potential-side drive element and a 2 nd voltage source that outputs a voltage corresponding to a drive signal of the low-potential-side drive element and different from the 1 st voltage source.

2. The circuit board of claim 1,

the circuit board further has:

a 1 st power supply generation unit that generates a power supply for the circuit system from the main power supply; and

a 2 nd power supply generation unit that generates a control power supply from the power supply for the circuit system,

the 1 st power generation unit is activated or deactivated in response to a trigger signal input from the outside.

3. The circuit board of claim 2,

the trigger signals are an ignition-on signal and an ignition-off signal from an ignition switch.

4. The circuit board of claim 2,

the stop unit is a cut-off unit that cuts off power supply to the pre-driver IC,

the 1 st power supply generation unit supplies the power supply for the circuit system to the pre-driver IC via the disconnection unit in a non-disconnected state, and the 2 nd power supply generation unit supplies the power supply for control to the control unit.

5. The circuit board of claim 2,

the stop unit is a reset unit that outputs a reset signal for resetting the operation of the pre-driver IC from the control unit,

the 1 st power generation unit directly supplies the power for the circuit system to the pre-driver IC, and the 2 nd power generation unit supplies the power for control to the control unit.

6. The circuit board according to any one of claims 1 to 5,

the failure or abnormality includes at least an abnormality of the control unit, an abnormality detected by a predetermined sensor unit, an abnormality of the pre-driver IC, an abnormality of the power supply generation unit, and an abnormality of the inverter unit.

7. The circuit board of claim 4,

the cut-off portion is a semiconductor switching element.

8. A motor control device having the circuit board according to any one of claims 1 to 7 mounted thereon, wherein a DC motor is used as the driving object.

9. A motor control device for electric power steering for assisting a steering wheel operation of a driver of a vehicle or the like,

the motor control device for electric power steering includes:

a DC motor for assisting steering of the driver; and

a unit that drive-controls the DC motor by the motor control device according to claim 8.

10. An electric power steering system having the motor control device for electric power steering according to claim 9.

11. A control method of a motor control device having a control section, an inverter section having a plurality of high-potential side driving elements and low-potential side driving elements and supplying power from a main power supply to a DC motor, and a pre-driver IC outputting drive signals to the high-potential side driving elements and the low-potential side driving elements,

the control method of the motor control device comprises the following steps:

detecting at least a runaway fault or an abnormal operation of the control unit, a runaway fault or an abnormal operation of the pre-driver IC, an on fault or an off fault of a driving element of the inverter unit, and a fault or an abnormal operation of a predetermined control circuit; and

when the failure or the abnormal operation is detected, the power supply to the pre-driver IC is cut off, or a reset signal is input to stop the operation of the pre-driver IC.