DRIVE CONTROL DEVICE AND DRIVE CONTROL METHOD FOR MOTOR

• US 20140265965A1
• Filed: 09/26/2013
• Published: 09/18/2014
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: Aoyagi, Hiroshi, SAKASHITA, Tomio
• Granted Patent: US 9,143,075 B2
• Time in Patent Office: Days
• US Class Current: 318/400.26
• CPC Class Codes: B62D 5/04 electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: B62D 5/0487 detecting motor faults B62D5/0496 takes precedence
• CPC Class Codes: H02M 1/084 using a control circuit common to several phases of a multi-phase system
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: H02P 3/18 for stopping or slowing an ac motor
• CPC Class Codes: H02P 6/14 Electronic commutators

Abstract

The present invention provides a motor drive control device provided with a shutoff circuit employing semiconductor relays and configured to drive a motor by a duty ratio control of an inverter, which stably drives the motor even in an operation state that drive duty ratio of phases are uneven. In the motor drive control device, output lines of three phases of the inverter circuit are connected to phases of the motor and further connected to a booster circuit, an output boosted by the booster circuit at a time of drive of the motor is distributed to semiconductor relays connected to respective phases of the motor, and furthermore, a switching circuit for stopping actuation of the booster circuit to shut off drive of the motor, is interposed in a line for supplying an electric power to the booster circuit.

Claims

1. A motor drive control device including an inverter circuit of n (which is equal to or greater than 3) phases of which output lines of respective phases are connected to respective phases of an n phase motor, and which controls drive of the motor based on an output signal of the inverter circuit;

the motor drive control device comprising;

a booster circuit which is connected to output lines of at least (n−

1) phases of the inverter circuit and boosts outputs of the output lines;

semiconductor relays which are interposed in respective phases of the motor connected to the output lines of at least (n−

1) phases of the inverter circuit and which are adapted to receive the outputs boosted by the booster circuit and distributed as relay drive signals at a time of driving the motor; and

a switching circuit which stops actuation of the booster circuit and turns off the semiconductor relays to shut off the drive of the motor.

2. The motor drive control device according to claim 1,

wherein the booster circuit includes:

at least (n−

1) pieces of diodes interposed in a power supply line for the booster circuit at a position on the upstream side of connecting points with output lines of the inverter circuit of at least (n−

1) phases; and

a capacitor for storing electric charge which has one end connected to the output end of the diodes, and the other end of the capacitor is connected to a neutral point to which the phases of the motor are connected.

3. The motor drive control device according to claim 1,

wherein the switching circuit is interposed in the power supply line for the booster circuit.

4. The motor drive control device according to claim 1,

wherein the switching circuit is interposed in a line for discharging the electric charge stored in the capacitor.

5. The motor drive control device according to claim 2,

wherein the booster circuit includes:

a zener diode which is connected in parallel with the capacitor and limits a voltage between the terminals of the capacitor to be at most a predetermined voltage.

6. The motor drive control device according to claim 2,

wherein the booster circuit further includes:

at least (n−

1) pieces of upstream side capacitors for storing electric charge interposed in the output lines of at least (n−

1) phases of the inverter circuit on the upstream side of the connecting points with the diodes; and

downstream side diodes of at least (n−

1) phases connected to the downstream side of the capacitors, and the output terminals of the downstream side diodes are connected together at a connecting point, and the output at the connecting point is distributed to the semiconductor relays.

7. The motor drive control device according to claim 1,

wherein the semiconductor relays are interposed between the output sides of the respective phases of the motor connected to the output lines of at least (n−

1) phases of the inverter circuit, and a neutral point to which the phases of the motor are connected.

8. The motor drive control device according to claim 1,

wherein the semiconductor relays are interposed between the output lines of at least (n−

1) phases of the inverter circuit, and the at least (n−

1) phases of the motor.

9. The motor drive control device according to claim 1,

wherein the output lines of all of three phases U, V and W of the inverter are connected to the booster circuit.

10. The motor drive control device according to claim 1,

wherein the output lines of two of three phases U, V and W of the inverter are connected to the booster circuit.

11. The motor drive control device according to claim 1,

wherein the motor is a motor for driving an electric power steering device of a vehicle.

12. A motor drive control device including an inverter circuit of n (which is equal to or greater than 3) phases of which output lines of respective phases are connected to respective phases of an n phase motor, and which controls drive of the motor based on an output signal of the inverter circuit;

the motor drive control device comprising;

booster means which is connected to output lines of at least (n−

1) phases of the inverter circuit and boosts outputs of the output lines;

semiconductor relays which are interposed in respective phases of the motor connected to the output lines of at least (n−

1) phases of the inverter circuit and which are adapted to receive the outputs boosted by the booster means and distributed as relay drive signals at a time of driving the motor; and

switching means which stops actuation of the booster means and shuts off the drive of the motor.

13. A motor drive control method for controlling drive of the motor based on an output signal of an inverter circuit, in which output lines of the inverter circuit of n (which is equal to or greater than 3) phases are connected to respective phases of an n phase motor,

the motor drive control method comprising the following steps:

boosting outputs of at least (n−

1) phases of the inverter circuit by a booster circuit at a time of driving the motor;

distributing the outputs boosted by the booster circuit to semiconductor relays which are interposed in respective phases of the motor connected to the output lines of at least (n−

1) phases of the inverter circuit, as relay drive signals; and

stopping actuation of the booster circuit to shut off the drive of the motor.