A gain scheduled controller for sinusoidal ripple elimination of AC PM motor systems

An adaptive control algorithm for the elimination of torque and velocity ripples in the alternating current (AC) permanent magnet (PM) motor control systems is presented in this paper. A model of AC PM motor system includes n sinusoidal disturbances is first developed. The internal model principle (IMP) is then applied to design a controller to eliminate the torque and velocity ripples without estimating the amplitude and the phase values of the sinusoidal disturbances. Based on the IMP and the pole-zero placement technique, a gain scheduled (GS) robust two-degree-of-freedom (2DOF) speed regulator is developed to eliminate the torque and velocity ripples and to achieve a desirable tracking response. Using the small gain theorem, the system stability radius is obtained for n sinusoidal disturbances with slowly time-varying frequencies. The effectiveness of the proposed GS robust 2DOF speed regulator can be shown by the simulation results of an example with two sinusoidal disturbances.