The Influence of the Number of Frequencies and the Frequency Repetitions Rates in Spread Spectrum Sigma-Delta Modulated DC-DC Converters

This paper explores the impact of using a Spread Spectrum modulation technique based on a Sigma-Delta modulator for a DC-DC SiC-based power converter. A simple block is proposed for the PWM to generate square pulses close to 20 kHz with a controlled ramp profile. Then, different frequencies and repetition rates are used to systematically evaluate their influence of carrier related emissions. The comparison of results is carried out by measuring the peak of the switching harmonic and the average value over CISPR band A (9–150 kHz). The measurements are taken at the input voltage of the converter.