MOTOR-DRIVEN POWER STEERING DEVICE

摘要

A motor-driven power steering device includes a band inhibit filter (15a) having a transmittance G1(s) suppressing resonance and a phase compensator (15b) having a transmittance G2(s). Moreover, the G1(s) is expressed by (s<2> + 2zeta11omega1 +omega1<2>)/ (s<2> + 2zeta12omega1 + omega1<2>), wherein s is a Laplace operator, zeta11 and zeta12 are attenuation coefficients, and omega1 is angular frequency. The G2(s) is expressed by (s<2> + 2zeta21omega2 +omega2<2>)/ (s<2> + 2zeta22omega2 + omega2<2>), wherein zeta21 and zeta22 are attenuation coefficients, and omega2 is angular frequency. Furthermore, the attenuation coefficients zeta21 and zeta22 satisfy zeta21 >= zeta22 >= 1. Thus, it is possible to suppress increase of the operation load and assure degree of freedom of filter design such as phase compensation. For example, it is possible to suppress resonance and obtain assist response in the normal steering speed region.