Spectral synthesis of switching distortion in multilevel converters

Abstract

We present a novel modulation method for selective reduction of peaks and practically free control of the output spectrum. In contrast to conventional pulse-width modulation (PWM), the model-predictive approach controls the output spectrum directly in the frequency domain to obtain the desired shape. Specified frequency bands can be kept free from spectral distortion to minimize electromagnetic interference (EMI). For equal switching frequencies, our method shows reduction of the peak switching distortion power density by >24 dB, while even narrow-band spectral gaps with −74.8 dB were achieved. In addition, the demonstrated method takes into account switching to trade-off switching loss with the spectral control to reduce loss by 37% with moderate impact on the spectrum.