| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an electric power steering system in which steering feeling can be improved without using an angle sensor. SOLUTION: In a system to add assist torque to steering torque by driving an assist motor 40 by a motor drive command value as a base assist current command value T1 decided by output of a torque sensor 20 to detect steering torque and output of a car speed sensor 30 to which a steering torque differentiation command value T2 decided by a first differentiator 24 is added, it is provided with a cogging frequency determination means 52 to determine a cogging frequency by detecting rotation speed of the assist motor 40, a center frequency changeable band pass filter 53 to let a required frequency coincide with a center frequency, and detect pulsation torque at the center frequency, and a second differentiator 54 to differentiate its output to advance a phase, and a compensation current command value corresponding to output of the second differentiator 54 is added to the motor drive command value.</p> |
