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.