Patent ID: 9065375
Filing Date: 2015-06-23
Classification: B62D

Abstract:
1. An electric power steering device, comprising: steering torque detection means for detecting a steering torque input from a steering wheel; a motor provided in a steering mechanism; a motor drive circuit comprising a switching element for controlling energization of the motor; control amount calculation means for calculating a control amount of the motor based on the steering torque detected by the steering torque detection means; switch control means for controlling the switching element of the motor drive circuit in accordance with the control amount calculated by the control amount calculation means, thereby generating a steering assist torque from the motor; internal resistance value measurement means for energizing the motor so as not to rotate the steering wheel, thereby measuring an internal resistance value of an energization path that is a circuit through which a current flows, including motor drive circuit and the motor; semi-abnormal state detection means for detecting a semi-abnormal state relating to an internal resistance of the energization path, in which the internal resistance value measured by the internal resistance value measurement means becomes a semi-abnormal value that exceeds a normal range and is out of an abnormal range in which the motor is intended to be stopped; and semi-abnormal occasion control amount limiting means for limiting, when the semi-abnormal state is detected, the control amount of the motor so that the energization of the motor for generating the steering assist torque is limited as compared to a case where the internal resistance value falls within the normal range.