Comparison of EMI performance of PWM and resonant power converters

When utilized in a power supply, hard switching and soft switching converters have different noise performances. Depending on their power, frequency range, and application, zero-current switching (ZCS) and zero-voltage switching (ZVS) techniques can significantly lower the noise. This work characterizes and compares the conducted and radiated electromagnetic interference (EMI) performance of hard and soft switching, including both ZVS and ZCS converters. An experimentally tested topology selection procedure for EMI minimization in power supplies is presented. The effects of increasing the switching and resonant frequencies and of utilization of snubbers and integrated control circuits for the purpose of EMI reduction are studied and demonstrated