Research on EMI reduction of interleaved Bridgeless Power Factor Corrector using frequency dithering

This paper proposes a cost-efficient method to reduce the electromagnetic interference (EMI) of interleaved Bridgeless PFC (IBPFC) system in a wide frequency range by carefully designing and utilizing frequency dithering. In this work, a valuable frequency dithering design is implemented for a 3.5kW universal line 2-stage IBPFC for class-D amplifiers. Detailed evaluations of impacts on EMI reduction from frequency dithering are carried out through both of the theoretical and experimental analysis. Furthermore, the impact on EMI filter's performances under frequency dithering condition is also researched through mathematical derivations. Experiments prove that with a proper design, it is possible to gain an useful EMI reduction in the IBPFC system by frequency dithering.