Suppressing Interference Peak in an Active Power Filter via Periodic Carrier Frequency Modulation Based on a Spectrum Analysis Approach

This paper aims at developing a spectrum analysis approach to suppress the electromagnetic interference (EMI) and the current harmonics in an active power filter (APF) via periodic carrier frequency modulation sinusoidal pulsewidth modulation (PCFMSPWM) control signals based on double Fourier series. The APF EMI concentrated at multiples of switching frequency results from the concentrative current harmonics. A novel spectrum analysis method based on PCFM and double Fourier series is developed to reduce the APF current harmonics. In this scheme, the optimal frequency deviations and waveforms of periodic signals are selected by calculating the spectrum of PCFMSPWM control signals. As a result, the modulation signal which has the best suppression effect on the interference peak is obtained and the quantitative design of PCFM is realized. Simulations and experiments of an APF driven by standard SPWM and triangular PCFMSPWM are implemented. On the basis of the simulations and experiments, effectiveness of triangular PCFM in alleviating APF current harmonics and EMI are validated.