ANGULAR VELOCITY ESTIMATION METHOD OF DC MOTOR IN ELECTRONIC POWER STEERING SYSTEM CAPABLE OF EXPANDING ANGULAR VELOCITY ESTIMATION RANGE

摘要

PURPOSE: An angular velocity estimation method is provided to expand an angular velocity estimation range and reduce estimation error by estimating an angular velocity by varying motor resistance values in accordance with the size of motor current. CONSTITUTION: An angular velocity estimation method comprises a first step(S11 to S15) of judging a motor current by comparing sizes of a motor terminal voltage(VM+) and a motor terminal voltage(VM-) if a motor supply voltage(E) calculated as a difference between the motor terminal voltage(VM+) and the motor terminal voltage(VM-) is larger than zero, and estimating an angular velocity by varying motor resistance values in accordance with the size of the judged motor current; a second step(S21 to S25) of judging a motor current by comparing sizes of the motor terminal voltage(VM+) and the motor terminal voltage(VM-) if a motor supply voltage(E) is smaller than zero, and estimating an angular velocity by varying motor resistance values in accordance with the size of the judged motor current; and a third step(S31) of estimating the angular velocity of the DC motor as zero in case where estimation of motor supply voltage is impossible.