Conducted electromagnetic interference analysis and mitigation using zero-current transition soft switching and spread spectrum techniques

Switching power converters cause electromagnetic interference (EMI), which can disturb the normal operation of the converter itself and other adjacent systems. Power converters must comply with electromagnetic compatibility (EMC) standards to guarantee proper operation of converters and nearby systems. Soft switching methods can be employed as EMI mitigation techniques in power converters. Although, soft switching converters are commonly addressed to have lower EMI than hard switching counterparts, they may not satisfy EMC regulations. In this study, spread spectrum by the means of pseudorandom modulation is applied to a zero-current transition (ZCT) flyback converter. By extracting the converter EMI model, the effect of using ZCT soft switching method is simulated and compared to its hard switching counterpart. The reduced amount of conducted electromagnetic emission is demonstrated via the proposed simulation method. To justify the theoretical analysis, the experimental results are presented.