CN112805915A

CN112805915A - Motor control system, motor, and electric power steering device

Info

Publication number: CN112805915A
Application number: CN201980065306.6A
Authority: CN
Inventors: 山下佳明; 高村优介
Original assignee: Nidec Corp; Nidec Elesys Corp
Current assignee: Nidec Corp; Nidec Elesys Corp
Priority date: 2018-10-10
Filing date: 2019-10-08
Publication date: 2021-05-14
Also published as: WO2020075693A1; JPWO2020075693A1

Abstract

One embodiment of a motor control system according to the present invention is a motor control system that supplies electric power to a motor, and includes a first motor control unit and a second motor control unit, each of which includes a set of a power supply circuit that generates a constant voltage, an inverter circuit that drives a coil winding of the motor, a power relay circuit that cuts off the supply of electric power to the inverter circuit, and a CPU that calculates a control amount based on information from a sensor and outputs a control signal to the inverter circuit. The first motor control unit supplies power to a first coil winding that is one of the two independent coil windings, and the second motor control unit supplies power to a second coil winding that is the other of the two independent coil windings, and the first motor control unit has a first abnormality detection circuit that detects an abnormality of the second motor control unit, and the second motor control unit has a second abnormality detection circuit that detects an abnormality of the first motor control unit.

Description

Motor control system, motor, and electric power steering device

Technical Field

The invention relates to a motor control system, a motor and an electric power steering apparatus.

Background

As a conventional electric power steering apparatus, there is a configuration in which: the motor is provided with two groups of coil windings and a control unit which is provided with two groups of inverter circuits capable of independently driving the two groups of coil windings, and the two groups of inverter circuits are controlled to be driven by the group of continuous motor which is normally operated when abnormal. There is known an electric power steering apparatus in which a portion other than an inverter circuit of a control unit is also formed into a dual system in preparation for a failure (patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese granted patent: no. 3839358 publication

Disclosure of Invention

Technical problem to be solved by the invention

In patent document 1, the first ECU21 and the second ECU22 have the following mutual monitoring function: the actual rotational positions of the first motor 36 and the second motor 37, which are calculated by themselves, the detection values of the sensors of the systems themselves, other information necessary for motor control, and the error information α are always communicated with each other and exchanged. Here, when the ECUs communicate with each other to detect an abnormality, the ECU on the side where the abnormality occurs detects an abnormality in the circuit or the power supply, and then transmits the abnormality to the other ECU through communication. Further, since each system does not have a means for detecting an abnormality on the other side when an abnormality in communication of the ECU occurs, there are technical problems that the other side cannot be detected when a secondary failure related to an abnormality in the auxiliary system occurs, and that an abnormality in the ECU and an abnormality between the ECUs cannot be distinguished from each other.

Technical scheme for solving technical problem

One aspect of a motor control system according to the present invention is a motor control system that supplies electric power to a motor including: a rotor; a stator having two independent sets of coil windings; and a rotation angle sensor that acquires rotation angle information of the rotor, the motor control system including a first motor control unit and a second motor control unit, the first motor control unit and the second motor control unit each including a set of a power supply circuit that generates a constant voltage, an inverter circuit that drives a coil winding of the motor, a power supply relay circuit that cuts off power supply to the inverter circuit, and a CPU that calculates a control amount based on the information from the sensor and outputs a control signal to the inverter circuit. The first motor control unit supplies power to a first coil wire that is one of the two independent coil wires, the second motor control unit supplies power to a second coil wire that is the other of the two independent coil wires, the first motor control unit has a first abnormality detection circuit that detects an abnormality of the second motor control unit, and the second motor control unit has a second abnormality detection circuit that detects an abnormality of the first motor control unit.

One embodiment of the motor of the present invention includes: the motor control system; a rotor that rotates centering on a central axis; a rotation angle sensor that acquires rotation angle information of the rotor; and a stator that receives supply of electric power from the motor control system.

In addition, an embodiment of the electric power steering apparatus of the present invention includes: a motor controlled by the motor control system; a device control unit that manages an operation state of the electric power steering device; and a torque sensor.

Effects of the invention

According to the exemplary embodiment of the present invention, the motor control system can detect an abnormality without a time lag and can promptly perform a changeover to the control after a failure by directly monitoring the output abnormality of the other system. Thus, even if one system fails, the motor can maintain driving. Further, the electric power steering apparatus can assist steering without impairing the operability of the steering wheel of the driver.

Drawings

Fig. 1 is a diagram showing a schematic configuration of an electric power steering apparatus according to an embodiment of the present invention.

Fig. 2 is a schematic view of a motor according to an embodiment of the present invention.

FIG. 3 is a flow chart of an embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of a motor control system, a motor having the motor control system, and an electric power steering apparatus having the motor according to the present disclosure will be described in detail with reference to the drawings. However, in the following description, in order to avoid unnecessary redundancy, it is easy for those skilled in the art to understand that detailed description other than the essential description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted.

Fig. 1 is a diagram showing an example of a schematic configuration of an electric power steering apparatus 10. The electric power steering system 10 is a device that assists a driver's steering wheel operation in a transportation apparatus such as an automobile. As shown in fig. 1, the electric power steering apparatus 10 includes a steering wheel (hereinafter also referred to as "steering wheel") 12, an electric power steering apparatus 20, and wheels 82.

The electric power steering apparatus 20 includes a torque sensor 22, a motor 7, and an apparatus control portion 80. The motor control system 30 is integrally mounted to the motor 7. The torque sensor 22 is mounted to the steering shaft 14. When the steering shaft 14 is rotated by the operation of the steering wheel 12 by the driver, the torque sensor 22 detects the torque applied to the steering shaft 14. A torque signal, which is a detection signal of the torque sensor 22, is output to the motor control system 30. The device control unit 80 manages the operating state of the power steering device 20. The control device unit 80 communicates and controls the operating state of other components such as an automobile.

The motor control system 30 controls the motor 7 by supplying a drive current to the motor 7. The motor control system 30 can drive the motor 7 using not only the torque signal but also other information such as the vehicle speed and the like to drive the motor 7.

The driving force generated from the motor 7 is transmitted to the wheels 82 via the gear box 84. Thereby, the steering angle of the wheel 82 changes. In this way, the electric power steering apparatus 20 increases the torque of the steering shaft 14 by the motor 7, and changes the steering angle of the wheels 82. Therefore, the driver can operate the steering wheel 12 with a light force.

Fig. 2 is a block diagram showing an example of the structure of the motor 7. As shown in fig. 2, the motor 7 includes a rotor (not shown) that rotates about a central axis, a stator 70, and a rotation angle sensor 761. The stator 70 includes: one winding group of the two independent coil windings, i.e., the first coil winding 71; and the other of the two independent sets of coil windings, i.e., the second coil winding 72. The first coil winding 71 includes a winding M1 of the U phase, a winding M2 of the V phase, and a winding M3 of the W phase. The second coil wire 72 includes a wire N1 of the U phase, a wire N2 of the V phase, and a wire N3 of the W phase. The rotation angle sensor 761 detects rotation angle information θ of the rotor.

The motor control system 30 includes a microcomputer, a drive circuit, and the like, and is configured as a dual system for driving and controlling the double-wound motor 7. By adopting the dual system configuration by the redundant design, even in the event of a failure of one system, the driving of the motor 7 can be continued by the other system, and therefore, an improvement in reliability can be achieved. The motor control system 30 includes: a first motor control unit 100 on the first system side; and a second motor control unit 200 on the second system side.

The first motor control section 100 includes: a first power supply circuit 101, the first power supply circuit 101 generating a constant voltage; a first inverter circuit 102, the first inverter circuit 102 being used for driving coil windings of the motor 7; a first power supply relay circuit 111 that interrupts power supply to the first inverter circuit 102, the first power supply relay circuit 111; a CPU1, the CPU1 outputting a control signal to the first inverter circuit 102; and a first anomaly detection circuit 104. Further, the second motor control section 200 includes: a second power supply circuit 201, the second power supply circuit 201 generating a constant voltage; a second inverter circuit 202, the second inverter circuit 202 being used for driving coil windings of the motor 7; a second power supply relay circuit 211 that interrupts power supply to the second inverter circuit 202, the second power supply relay circuit 211; a CPU2, the CPU2 outputting a signal to the second inverter circuit 202; and a second anomaly detection circuit 204. That is, the first motor control section and the second motor control section each include a set of a power supply circuit, an inverter circuit, a power supply relay circuit, a CPU, and an abnormality detection circuit.

The first power supply circuit 101 is a power supply for driving each circuit element of the first motor control unit 100. For example, the first power supply circuit 101 supplies power to the coil windings of the motor, the respective elements of the first inverter circuit 102, and the CPU 1. Since the second power supply circuit 201 has the same function as the first power supply circuit 101, the description thereof is omitted.

The first motor control portion 100 supplies power to the first coil winding 71. The second motor control portion 200 supplies electric power to the second coil wire 72. The first inverter circuit 102 is connected to the first coil winding 71. The second inverter circuit 202 is connected to the second coil wire 72. Each

inverter circuit

102, 202 includes a bridge circuit composed of three bridge arms including a high-side switching element and a low-side switching element. The first inverter circuit 102 and the second inverter circuit 202 have three

shunt resistors

81 and 82, respectively. A shunt resistor is provided on the low side of the low-side switching element of one of the arms. Each shunt resistor is connected to each coil winding, and therefore functions as a current sensor.

The first power relay circuit 111 is connected to the high side of the first inverter circuit 102. The first power relay circuit 111 controls the supply of electric power to the first inverter circuit 102 by turning on/off the switching elements. The second power relay circuit 211 has the same configuration as the first inverter circuit, and therefore, the description thereof is omitted.

The CPU1 includes a microcontroller, an input/output circuit, an AD converter, a load driving circuit, a ROM (Read On Memory), a communication module, and the like. The CPU1 controls the driving of the motor 7 based on the torque instruction of the torque sensor 22. The CPU1 calculates a control amount based on the rotation angle information θ output from the rotation angle sensor 761, and outputs a control signal to the first inverter circuit 102. Similarly, the CPU2 calculates a control amount based on the rotation angle information θ output from the rotation angle sensor 761, and outputs a control signal to the second inverter circuit 202.

The first motor control section 100 and the second motor control section 200 each include a communication section. The first motor control section 100 includes a first communication section 91, and the first motor control section 200 includes a second communication section 92. The CPU1 communicates with the apparatus control section 80 via the first communication section 91. Similarly, the CPU2 communicates with the apparatus control unit 80 via the second communication unit 92. The communication unit may be, for example, a communication cable provided separately from the CPU, or may be a communication module provided in the CPU. The communication unit is connected to communicate with the CPU. The communication unit communicates communication data with the device control unit 80 according to a communication protocol such as CAN (Controller Area Network). The communication unit is wired or wireless.

The first abnormality detection circuit 104 and the second abnormality detection circuit 204 are formed of circuits such as comparators. The abnormality detection circuit detects the current values output from the

shunt resistors

81 and 82. The abnormality detection circuit determines an abnormality of the switching element when the abnormality exceeds or does not exceed a predetermined threshold. At this time, the CPU communicates with the apparatus control unit 80 via the communication unit to determine the abnormality. The abnormality detection circuit is not limited to detecting the current values output from the

shunt resistors

81 and 82. For example, the abnormality detection circuit may detect the voltages of the

shunt resistors

81 and 82. Further, the abnormality detection circuit is not limited to detecting the states of the

shunt resistors

81, 82. The abnormality detection circuit may also detect the driving state of other components. For example, the abnormality detection circuit may detect a voltage value or a current value between motor terminals, or may detect a current value or a voltage value of the power supply circuit.

Here, referring to fig. 3, in the present embodiment, a case is considered in which an abnormality occurs in which a current value equal to or greater than a threshold value flows through the U-phase winding M1 in the first coil winding 71. (step 1: S1) the first abnormality detection circuit 104 determines the phase in which the abnormal current flows based on the current value of the shunt resistor 81. (step S2: S2) first motor control unit 100 determines whether or not first inverter current 102 can be normally driven. (step 3: S3) in step 2, when the first motor control unit 100 determines that the first inverter circuit 102 is abnormal, the first motor control unit 100 controls the switch of the first power supply relay circuit 111 to interrupt the supply of electric power. (step 4: S4) the second abnormality detection circuit 204 determines that the first inverter circuit 102 is not driven based on the current value of the shunt resistor 81. (step 5: S5) the CPU2 notifies the device control section 80 of the determined abnormal state via the second communication section 92. (step 6: S6) the device control section 80 outputs a command for compensating the output of the first motor control section 100 to the CPU 2. According to the present embodiment, since the output abnormality of the other system can be directly monitored, the abnormality detection and the control after the transition to the failure can be performed without a time lag. In the present embodiment, the second abnormality detection circuit 204 is configured to monitor only the output of the first inverter circuit 102. Therefore, detection of an abnormality related to an output abnormality of other system and the number of AD ports can be saved.

In the present embodiment, a case is considered in which the first inverter 102 cannot be driven due to an abnormality in voltage or the like. In this case, step 1, step 2 and step 3 are omitted regardless of the above example. (step 4: S4) the second abnormality detection circuit 204 determines that the first inverter circuit 102 is not driven based on the signal of the shunt resistor 81. (step 5: S5) the CPU2 notifies the device control section 80 of the determined abnormal state via the second communication section 92. (step 6: S6) the device control section 80 outputs a command for compensating the output of the first motor control section 100 to the CPU 2.

In addition, in the present embodiment, in step 3, the first motor control unit 100 controls the switch of the first power supply relay circuit 111, but the second motor control unit 200 may control the switch, or the device control unit 80 may control the switch. In the above example, the case where an overcurrent occurs in any phase is considered, but a communication abnormality in the communication unit is also conceivable. In this case, the other normal motor control unit may determine the operating state of one inverter circuit based on the detection values of the

shunt resistors

81 and 82. That is, in step 1, the second abnormality detection circuit 204 may determine the phase in which the abnormal current flows based on the current value of the shunt resistor 81. Subsequently, the normal CPU may control one power relay circuit, or the apparatus control unit 80 may control one power relay circuit. According to the above configuration, even if any phase of the coil winding fails, the switching after the failure can be performed quickly when a communication abnormality occurs in one CPU.

The first inverter circuit 102 and the second inverter circuit 202 may include three motor relays that control power supply to each phase of the coil winding. Each motor relay is connected between each corresponding high-side switching element and each phase of the coil winding. The motor relays can stop the supply of electric power to the specific phase when an abnormality occurs in one phase. Therefore, even in the case where one phase fails, the output of the motor 30 can be suppressed from being greatly reduced. In the present embodiment, in step 1, after the phase in which the abnormal current flows is identified, the motor control unit controls the switching of the motor relay, and stops the supply of the electric power to the phase in which the abnormal current flows.

The first motor control part 100 and the second motor control part 200 further include insulating elements, respectively. The first motor control portion 100 includes a first insulating member 51. The second motor control portion 200 includes a second insulating member 52. The first insulating element 51 is connected between the first abnormality detection circuit 104 and the shunt resistor 81 of the second inverter circuit 202. Further, the second insulating element 52 is connected between the second abnormality detection circuit 204 and the shunt resistor 82 of the first inverter circuit 102. According to the above configuration, for example, when a steep inrush current flows through the first motor control unit 100, the inrush current also flows through the second motor control unit 200 or the CPU2 via the second abnormality detection circuit 204, and the entire motor control system 30 can be prevented from becoming functionally incomplete. In the case where GND (ground) is not shared with the first motor control unit 100, the second motor control unit 100 differs from the GND of the first motor control unit 100 in the GND of the second abnormality detection circuit 204. Therefore, the GND of the second abnormality detection circuit 204 is shared with the first motor control unit 100 via the second insulating element 52, and therefore the accuracy of measuring the current value of the shunt resistance can be improved.

The electric power steering apparatus 20 is configured to include the apparatus control unit 80, but is not limited thereto. The device control unit 80 may be a control device that controls other components such as a vehicle.

In the present embodiment, the first motor control unit 100 and the second motor control unit 200 may be formed in a first circuit board or may be formed in different circuit boards. The first power supply circuit 101 and the second power supply circuit 201 may be provided outside the motor 7 as a structure different from the first motor control unit 100 and the second motor control unit 200.

In the present embodiment, the abnormality detection circuit detects an abnormality using a shunt resistor, but the present invention is not limited to this. For example, the abnormality detection circuit may monitor a current value or a voltage value using an a/D converter. The abnormality detection circuit may monitor the state of the output port of the CPU. More specifically, the first motor control section 100 includes a pre-driver PrDr1 for driving the switching element. Further, the second motor control portion 200 includes a pre-driver PrDr2 for driving the switching element. The CPU1 outputs a control signal such as a PWM signal to the predr 1 or the first inverter circuit 102. Here, the second abnormality detection circuit 204 may determine whether or not an abnormality occurs by monitoring a control signal such as a PWM signal output from the CPU 1. According to this configuration, since the second abnormality detection circuit 204 can monitor the digital signal, it is possible to detect with high accuracy even when the first motor control unit and the second motor control unit do not share the GND. Similarly, the first abnormality detection circuit 104 may monitor a control signal output from the CPU2 to the predr 2 or the second inverter circuit 202. In addition, the above-described respective configurations can be appropriately combined within a range not contradictory to each other.

(symbol description)

10 an electric power steering system; 20 an electric power steering apparatus; 30 motor control systems; 7 a motor; 70 a stator; 71 a first coil winding; 72 second coil winding; 100 a first motor control unit; 101 a first power supply circuit; 102 a first inverter circuit; 111 a first power relay circuit; 200 a second motor control unit; 201 a second power supply circuit; 202 a second inverter circuit; 211 second power relay circuit.

Claims

1. A motor control system that supplies electric power to a motor, the motor comprising:

a rotor;

a stator having two independent sets of coil windings; and

a rotation angle sensor that acquires rotation angle information of the rotor,

the motor control system includes a first motor control section and a second motor control section, the first motor control section and the second motor control section respectively including a set of a power supply circuit, an inverter circuit, a power supply relay circuit, and a CPU,

the power supply circuit generates a constant voltage,

the inverter circuit is used for driving coil windings of the motor,

the power supply relay circuit cuts off the supply of electric power to the inverter circuit,

the CPU calculates a control amount based on information from the sensor and outputs a control signal to the inverter circuit,

the first motor control part supplies power to a first coil wire that is one of the two independent sets of coil wires,

the second motor control portion supplies electric power to a second coil wire that is the other of the two independent sets of coil wires,

the first motor control unit has a first abnormality detection circuit for detecting an abnormality in the second motor control unit,

the second motor control unit has a second abnormality detection circuit that detects an abnormality of the first motor control unit.

2. The motor control system of claim 1,

the first abnormality detection circuit detects an abnormality of the second coil wire, and the second abnormality detection circuit detects an abnormality of the first coil wire.

3. The motor control system of claim 1 or 2,

a first inverter circuit as the inverter circuit of the first motor control section and a second inverter circuit as the inverter circuit of the second motor control section each include a bridge circuit,

the bridge circuit is formed by three legs including high-side switching elements and low-side switching elements,

the first inverter circuit and the second inverter circuit each have three shunt resistors,

the first abnormality detection circuit detects a signal of a shunt resistance of the second inverter,

the second abnormality detection circuit detects a signal of a shunt resistance of the first inverter.

4. The motor control system of any one of claims 1 to 3,

the first motor control unit and the second motor control unit each further include a communication unit that outputs an abnormality determination result to the device control unit.

5. The motor control system of any one of claims 1 to 4,

the first abnormality detection circuit detects abnormality of the first coil winding, the first motor control unit controls switching of the first power supply relay circuit, the second abnormality detection circuit detects abnormality of the second coil winding, and the second motor control unit controls switching of the second power supply relay circuit.

6. The motor control system of any one of claims 1 to 5,

the first motor control unit controls the switch of the second power supply relay circuit, and the second motor control unit controls the switch of the first power supply relay circuit.

7. The motor control system of any one of claims 1 to 6,

the first motor control unit and the second motor control unit each further include an insulating element connected between the first abnormality detection circuit or the second abnormality detection circuit and the shunt circuit.

8. The motor control system of any one of claims 1 to 7,

the first inverter circuit and the second inverter circuit each include three motor relays, and the three motor relays are connected between each corresponding high-side switching element and each phase of the coil winding, and stop supplying power to each phase of the coil winding.

9. A motor, comprising:

the motor control system of any one of claims 1 to 8;

a rotor that rotates centering on a central axis;

a rotation angle sensor that acquires rotation angle information of the rotor; and

a stator that receives a supply of electric power from the motor control system.

10. An electric power steering apparatus comprising:

a device control unit that manages an operation state of the electric power steering device; the motor of claim 9; and a torque sensor.

11. The electric power steering apparatus according to claim 10,

the device control unit controls switching of the first power supply relay circuit and the second power supply relay circuit.

12. The electric power steering apparatus according to claim 10 or 11,

the device control unit outputs an instruction to increase an output to the normal first motor control unit or the second motor control unit when receiving a notification that either one of the first motor control unit and the second motor control unit is abnormal.