Common mode EMI study and reduction technique in interleaved Multi-channel PFC

Interleaved Multi-channel Power factor correction (PFC) converter is very popular nowadays with its ability to reduce the input and output current ripples. In this paper, common mode (CM) EMI noise emission model of multi-channel PFC is studied. Topology modification to implement balance technique is made to reduce its CM noise emission. To improve the high frequency balance, a novel topology with coupled inductor structure is proposed. Design guideline is provided to achieve balance in practice. This topology can greatly reduce CM noise with only little changes to the original multi-channel PFC topology. Effects of phase shift and channel shedding on this solution are also studied. The proposed topology has effectively reduced CM noise under any phase shift and channel shedding condition. A two-channel PFC is built to verify the proposed balance technique. Experimental results show that CM noise is reduced up to 20dBuV between 150 kHz and 7 MHz.