Robust design of the self-tuning resonant controller for AC current control systems

The multiple-frequency resonant controller is usually used to track the non-sinusoidal command and/or reject some kind of higher-order harmonic disturbances in AC current control systems. By adjusting its coefficients in real-time, the self-tuning resonant controller is capable of regulating ac current with time-varying frequency. In this paper, we first present how to design the self-tuning resonant controller using pole assignment technique. After analyzing the influence of time delays on system stability, a simple criterion is proposed to design robust self-tuning resonant controller for the real-time control system with unit time-delay. The controller designed by the proposed method has been implemented in a FPGA based DSP development board to control ac current with time-varying frequency in a single-phase system. Satisfying excremental results validate the proposed method.