A novel PWM strategy of bidirectional AC/DC converters for micro grid system

In this paper, a novel simplified PWM strategy is proposed for the bidirectional ac/dc single-phase converter in the micro-grid system. Then, the operation mechanism of the novel simplified PWM is clearly explained. It is obvious that the switching numbers of the novel simplified PWM strategy are only one-fourth that of the conventional unipolar PWM and bipolar PWM. Based on the novel simplified PWM strategy, a feasible feed-forward control scheme is also developed to achieve better performance in both rectifier mode and inverter mode operation compared with the conventional dual control scheme. In addition, the proposed simplified PWM strategy with proposed feed-forward control scheme possesses lower total harmonic distortion than bipolar PWM, and higher efficiency than unipolar and bipolar PWM. Finally, a prototype system is constructed, and the control scheme is implemented using FPGA Spartan-3E XC3S250E. Both simulation and experimental results verify the validity of the proposed PWM strategy and the control scheme.