Digital repetitive learning controller for three-phase CVCF PWM inverter

In this paper, a plug-in digital repetitive learning control scheme is proposed for three-phase constant-voltage constant-frequency (CVCF) pulsewidth modulation inverters to achieve high-quality sinusoidal output voltages. In the proposed control scheme, the repetitive controller (RC) is plugged into the stable one-sampling-ahead-preview-controlled three-phase CVCF inverter system using only two voltage sensors. The RC is designed to eliminate periodic disturbance and/or track periodic reference signal with zero tracking error. The design theory of plug-in repetitive learning controller is described systematically and the stability analysis of overall system is discussed. The merits of the controlled systems include features of minimized total harmonics distortion, robustness to parameter uncertainties, fast response, and fewer sensors. Simulation and experimental results are provided to illustrate the effectiveness of the proposed scheme.