Steering controlling device

• US 7,514,889 B2
• Filed: 06/14/2007
• Issued: 04/07/2009
• Est. Priority Date: 07/10/2001
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kifuku, Takayuki
• Primary Examiner(s): Ro; Bentsu
• Assistant Examiner(s): DINH, THAI T
• Application Number:
  US11/763,061
• Publication Number:
  US 20070235249A1
• Time in Patent Office: 663 Days
• Field of Search: 318/138, 318/254, 318/439, 318/432, 318/434, 318560-609, 318700-800, 180/443
• US Class Current: 318/432
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input

Abstract

A steering controlling device comprising a power source, a motor connected to a steering system, a motor driving circuit converting a power source voltage to a predetermined voltage and applying the voltage to the motor, and a controlling means for controlling the motor driving circuit, wherein the controlling means controls the motor driving circuit so as to boost the power source voltage when a rotational speed of the motor is a predetermined value or more, whereby a sufficient motor output torque is obtainable under various steering conditions in use of a converter, an efficiency is improved by suppressing a frequency of operating the converter, and an appropriate fail safe treatment is conducted when the converter is disordered.

Claims

1. A steering controlling device comprising:

a power source;

a motor connected to a steering system;

a motor driving circuit converting a power source voltage to a predetermined voltage and applying the converted voltage to the motor;

a means for controlling the motor driving circuit, wherein the controlling means controls the motor driving circuit to boost the power source voltage when a rotational speed of the motor is greater than a predetermined value;

wherein the motor driving circuit includes at least a first converter connected to the power source and a bridge circuit connected to the motor; and

a second converter boosting an output voltage from the first converter in order to drive switching elements, forming the bridge circuit.

2. The steering controlling device according to claim 1, wherein the controlling means controls the motor driving circuit by controlling an electric current of the motor to be a predetermined target value and boosting the power source voltage when a voltage applied to the motor exceeds a predetermined value to drive the motor.

3. The steering controlling device according to claim 1,

wherein the motor driving circuit is controlled to boost the power source voltage in order to drive the motor when a condition for boosting the power source voltage is satisfied for a predetermined time or more.

4. The steering controlling device according to claim 1,

wherein the motor uses a magnetic field by a permanent magnet.

5. The steering Controlling device according to claim 1,

wherein the switching elements on a side of the power source are driven by the second converter.

6. The steering controlling device according to claim 1,

wherein the controlling means monitors an input voltage to the first converter or an output voltage from the first converter.

7. The steering controlling device according to claim 1,

wherein the controlling means controls an output voltage from the first converter to be a predetermined target value.

8. The steering controlling device according to claim 7,

wherein the controlling means controls the boosted voltage to be a predetermined value or less.

9. The steering controlling device according to claim 1,

wherein a duty ratio of driving the switching elements of the bridge circuit is 100% when the first converter is operated to boost the voltage.

10. The steering controlling device according to claim 1,

wherein the diodes forming the first converter are parasitic diodes of MOSFET.

11. The steering controlling device according to claim 1,

wherein the controlling means controls the electric current of the motor to be a predetermined target value by driving at least one of the first converter and the bridge circuit by pulse.

12. The steering device according to claim 1, wherein the controlling means operates the rotational speed of the motor based an electric current and an impressed voltage of the motor.