Patent ID: 8116945
Filing Date: 2012-02-14
Classification: B62D

Abstract:
1. An electric power steering device, comprising: a steering force assisting device having a motor that functions as a drive source and providing a steering system with an assist power for assisting a steering operation; and an oscillation detection part that detects an occurrence of an oscillation in the steering system; and a control device that controls an operation of the steering force assisting device through a supply of a drive power to the motor, the control device including: wherein: the motor control signal output part generates the motor control signal by executing current control on the basis of a rotational angle of the motor and, when the occurrence of the failure is detected, executes output of the motor control signal by means of two electrification phases other than a phase with the failure, when the occurrence of the failure is detected, the motor control signal output part performs a correction of the rotational angle and changes an amount of the correction of the rotational angle in accordance with a level of the oscillation detected, and when the occurrence of the failure is detected, the motor control signal output part executes the current control for supplying each of the electrification phases with a phase current that changes substantially in the form of a secant curve, a cosecant curve, or a tangent curve based on an asymptotic line, on which the rotational angle is a predetermined rotational angle corresponding to a phase with the failure, executes current restriction for restricting the phase current within a predetermined range, performs a correction of the rotational angle so that an angular phase is shifted in a direction of the steering operation, determines if the level of the oscillation detected exceeds a predetermined level, and performs a reduction of an amount of correction of the rotational angle when the level of the oscillation detected exceeds the predetermined level.