Inductor Size Evaluation of an Electromagnetic Interference Filter for a Two-Level Power Factor Correction Rectifier Using Different Modulation Techniques

Wide band-gap semiconductors exhibit superior performance compared to their silicon counterparts, which has enabled converters to work at higher switching frequencies. However, a higher switching frequency means larger harmonics in the electromagnetic interference (EMI) range which may lead to the need for a larger EMI filter. This paper has essentially two main purposes: to find the impact of switching frequency (swept from 40 kHz to 300 kHz) on the size of EMI filter (especially the inductor part of it) and to evaluate the size using different modulation techniques. This paper shows that the effect of increasing the switching frequency on the size of EMI filter is not linear. The differential mode filter part of EMI filter results differently against the common mode filter part of it when the switching frequency and modulation technique changes. Therefore, depending on the application a suitable modulation and frequency can be picked to result an optimum filter. To support the method of the filter design, a filter is designed and built for a 5kW two-level power factor correction rectifier and the design is supported with EMI measurement on the unit.