Patent ID: 6885927
Filing Date: 2005-04-26
Classification: B62D

Abstract:
1. An apparatus for controlling an electric power steering system comprising: a motor for providing assist steering torque for a steering line, said motor comprising a brushless motor; a sensor for detection of steering torque acting on said steering line and delivering a signal of steering torque; a device for detection of rotational phase of said motor and delivering a phase signal; a device for detection of current of said motor and delivering a signal of current; a current control unit for determining a signal for target current based upon at least said signal of steering torque, said current control unit comprising a first microcomputer; a drive control unit for determining a signal for motor control for controlling said motor based upon a deviation between said signal for target current and said signal of current, along with said phase signal, said drive control unit comprising a second microcomputer and a motor drive circuit for driving said motor based upon said signal for motor control; and wires electrically connecting said current control unit and drive control unit, wherein said drive control unit incorporates said signal of steering torque from said sensor for detection of steering torque, and if said first microcomputer fails, said second microcomputer determines a signal for target current based upon said signal of steering torque.