Patent ID: 6837331

Claim:
An electric power steering device, comprising: a steering unit equipped with a motor for providing a steering power assist; controlling means for controlling an output of said motor according to at least a signal of a steering torque generated at a steering shaft; wherein said controlling means includes: motor current command value calculating means for calculating a current command value of a current to be supplied to said motor; motor current detecting means for detecting a current that flows in said motor; current deviation calculating/proportionally integrating means for calculating each difference between a motor current command value and a detected motor current and integrating calculated difference proportionally for outputting a current control value; and fault determining means for determining that said motor current detecting means is defective when said detected motor current is not within a predetermined limit value; wherein said controlling means controls so that said motor current command value is set only for a time whose value is larger than said electrical time constant of said motor and smaller than said mechanical time constant of said motor to drive said motor with a voltage to be set based on the current control value output from said current deviation calculating/proportionally integrating means so as to enable said fault determining means to determine a fault of said motor current detecting means.