| 摘要 |
In control devices of electric power steering systems, steering characteristics are improved by control being carried out by means of a signal based on rotor speed or steering angle after failure of a torque sensor is detected. In the present invention, in a control device of an electric power steering system for controlling a motor applying a steering assist force to a steering mechanism on the basis of a current control value computed from a motor current value and a steering assist command value computed on the basis of a steering torque in a steering shaft, two over-current detecting circuits have different detection current values; when an over-current is detected by the circuit having the lower current detection value within the response time of current control, the duty of PWM for driving the motor is restricted, and when an over-current is detected by the circuit having the higher current detection value, motor current output is stopped and a relay is opened and the system is disengaged from the steering mechanism.
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