Abstract:

A new method of improved Butterworth filter was proposed to denoise feedback vicecurrent of inverter effectively and make currentmode PWM controller work fast and steadily in the environment with strong interference, high voltage and large current. First, the signal was analyzed with fast fourier transformation to get the frequency spetrum of useful signal and noise. Then IIR Butterworth filter was designed after analysis of processing speed with FPGA realization. In order to improve the start and tracking speed, moving average median filter was proposed. The simulation and experiment results show the filter is characterized by small phase shift and fast dynamic response. All digital inverter can work accurately and reliably.

Key words: full digital inverter, IIR digital filter, Butterworth, moving average median filter, pulse noise