A New PFC Design With Interleaved MHz-Frequency GaN Auxiliary Active Filter Phase and Low-Frequency Base Power Si Phase

Wide bandgap (WBG) power semiconductors offer lower switching loss and higher power density than silicon but suffer from significantly higher cost. In this article, we introduce a design methodology which uses a low-frequency silicon base power processor to achieve high efficiency and low cost, and a high-frequency WBG fractional power active filter to reduce harmonics and achieve high power quality. The mixed use of WBG and Si delivers the same WBG benefits but at a reduced component cost. A boost PFC converter based on this design principle is reported that comprises two interleaved Si and GaN phases. We develop a new unified control strategy to allow the base power processed efficiently by the Si phase switching at a low frequency of 10 kHz and the harmonics to be minimized by the MHz-frequency GaN phase as an active filter. A 2.1-kW Si/GaN interleaved PFC prototype exhibits a peak efficiency of 98.04% and a power factor of 0.998, even with a frontend diode bridge. The new interleaved PFC is validated by simulation and experimentally to achieve excellent efficiency, power density, and harmonics mitigation at a cost much lower than a full-scale WBG design.