Patent ID: 8381869
Filing Date: 2013-02-26
Classification: B62D,H02M,H02P

Abstract:
1. An electric power steering device, comprising: an electric motor that applies a steering assist torque to a steering mechanism; a booster circuit that boosts a voltage of an electric power supplied from a vehicle battery device and that supplies the boosted electric power to a motor drive circuit; a sub battery device connected to said booster circuit in parallel to said motor drive circuit, which sub battery device being charged by an output of said booster circuit and assists an electric power supply to said motor drive circuit by using charged electric energy; and a motor control unit that controls said motor drive circuit such that an amount of electric current depending on a steering operation of a steering wheel is supplied to said electric motor; wherein the electric power steering device further comprises: an estimation unit that estimates if there is a possibility that a backward electric current flows in said booster circuit toward said vehicle battery device; and a boosting control unit that stops the boosting operation of said booster circuit to prevent a backward electric current from flowing in said booster circuit when it is estimated by said estimation unit that there is a possibility that a backward electric current flows.