Parameter Optimization of Spread Spectrum Modulation to Minimize EMI Filter for Interleaved Totem-Pole PFC Converters

Recently, with SiC devices, switching frequency and electromagnetic interference (EMI) noise are increasing for power factor correction (PFC) converters, and EMI filter is used to reduce EMI noise. However, when EMI filter size is reduced from 2-stage and 1-stage for increasing power density, there is a problem that EMI noise is increasing and EMI standard is no longer satisfied with conventional fixed frequency modulation (FFM). To solve this problem, parameter optimization of spread spectrum modulation (SSM) is performed in this paper. Considering waveform shape, amplitude, and frequency of switching frequency, an optimal switching frequency for minimizing EMI noise is found. As a result, EMI noise is minimized when waveform shape is random and amplitude is 18 kHz, and EMI margin is 11.13 %. Therefore, it is possible to reduce EMI filter size with optimized SSM, and also there is no difference in terms of inductor and switch losses.