Actuator controller and actuator control method

Patent metadata

Field	Value
Publication number	US-9712103-B2
Application number	US-201415117303-A
Country	US
Kind code	B2
Filing date	Sep 19, 2014
Priority date	Feb 21, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

The controller for an actuator that is driven by a brushless motor estimates the temperature of the magnet in the brushless motor on the basis of an electric current value and a rotation speed thereof which are obtained by supplying power to rotate the brushless motor in a reverse direction, and limits current flowing through the brushless motor during forward rotation so as to prevent the magnet temperature from rising beyond an allowable maximum temperature. Limiting the current flowing through the brushless motor on the basis of the estimated magnet temperature makes it possible to drive the brushless motor while preventing the magnet temperature from rising beyond the allowable maximum temperature without providing the brushless motor with any temperature sensor for detecting the magnet temperature therein.

First claim

The invention claimed is:

1. A controller for an actuator that is driven by a brushless motor for driving an electric oil pump, wherein, according to a temperature of a magnet in the brushless motor estimated on the basis of a saturation rotation speed and a phase current value during saturation rotation of the brushless motor which are obtained by supplying power thereto while the electric oil pump is caused to run idle with oil drained out of an oil pipe by rotating the brushless motor in a direction reversal of a rotational direction thereof for driving the actuator, the actuator controller limits current flowing through the brushless motor while the brushless motor is driving the actuator.

2. The actuator controller according to claim 1 , wherein the actuator controller limits the current flowing through the brushless motor first by calculating the temperature of the magnet in the brushless motor on the basis of temperature-torque characteristics thereof, and then by limiting a control variable in accordance with the calculated temperature and demagnetization characteristics of the magnet.

3. The actuator controller according to claim 2 , wherein the temperature of the magnet is calculated at at least one of time points of: just before a drive request for the brushless motor is issued, just after the brushless motor is rotated for a predetermined time period, and just after the brushless motor operates for a predetermined control variable.

4. The actuator controller according to claim 2 , wherein the actuator controller corrects, on the basis of a learned value, the temperature of the magnet calculated as a tentative value.

5. The actuator controller according to claim 2 , wherein
the control variable corresponds to a duration of driving the brushless motor, and
the actuator controller limits the current flowing through the brushless motor by stopping driving the brushless motor.

6. The actuator controller according to claim 1 , wherein the actuator is for driving an accessory of a vehicle, and stops limiting the current flowing through the brushless motor in response to a request from the vehicle.

7. A method for controlling an actuator that is driven by a brushless motor for driving an electric oil pump, comprising the steps of:
rotating the brushless motor in a direction reversal of a rotational direction thereof for driving the actuator;
supplying power to the brushless motor while the electric oil pump is running idle with oil drained out of an oil pipe; and
limiting current flowing through the brushless motor while the brushless motor is driving the actuator, according to a temperature of a magnet in the brushless motor estimated on the basis of a saturation rotation speed and a phase current value during saturation rotation of the brushless motor which are obtained by performing the step of supplying power.

8. The actuator control method according to claim 7 , wherein the step of limiting the current includes the steps of:
calculating the temperature of the magnet in the brushless motor on the basis of temperature-torque characteristics thereof; and
limiting a control variable in accordance with the calculated temperature and demagnetization characteristics of the magnet.

9. The actuator control method according to claim 8 , wherein the step of calculating the temperature of the magnet is carried out at least one of time points of: just before a drive request for the brushless motor is issued, just after the brushless motor is rotated for a predetermined time period, and just after the brushless motor operates for a predetermined control variable.

10. The actuator control method according to claim 8 , further comprising the step of correcting, on the basis of a learned value, the temperature of the magnet calculated as a tentative value.

11. The actuator control method according to claim 10 , wherein the learned value is updated at predetermined timing.

12. The actuator control method according to claim 8 , wherein
the control variable corresponds to a duration of driving the brushless motor, and
the actuator controller limits the current flowing through the brushless motor by stopping driving the brushless motor.

13. The actuator control method according to claim 7 , further comprising the steps of:
learning and storing a temperature correction value; and
correcting, with the stored temperature correction value, a control variable for limiting the current flowing through the brushless motor.

14. The actuator control method according to claim 7 , wherein the actuator is for driving an accessory of a vehicle, and the step of limiting the current is carried out in response to a request from the vehicle.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Miyamoto Shogo

Classifications

• F04B2203/0205

  Temperature · CPC title

• F04B2203/0209

  Rotational speed · CPC title

• F16H61/0025

  Supply of control fluid; Pumps therefor · CPC title

• F04B2203/0201

  Current · CPC title

• F04B17/03

  driven by electric motors · CPC title