Dual Robust Controller Design for High Power AC Servo Drive

High power AC motors have a highly interacting multivariable control structure, and it is difficult to design high dynamic performance AC drive with traditional PID-like controller for high power AC servo motor. This paper presents analysis, design and simulation of velocity loop dual robust controller for 11 kw permanent magnetic synchronous motor (PMSM) in the AC servo system. By combining PDFF-MA and H^infin control algorithms with its own capability of achieving good performance criteria such as dynamic reference tracking and load torque disturbance rejection, the PDFF-MA controller is designed and analyzed in the forward loop to provide low frequency stiffness and overcome low-frequency disturbances like friction. To compensate the system response, moving average (MA) error filter is added. While in the feedback loop, H^infin controller is designed to meet system robust stability with the existence of external disturbance and model perturbations. The proposed PDFF-MA and H^infin controllers are designed based on the transfer function of the poly-phase synchronous machine in the synchronous reference frame at field orientation control (FOC). The parameter variations, load changes, and set-point variations of synchronous machine are taking into consideration to study the dynamic performance.