CM noise reduction in interleaved multi-phase PFC
CPES has investigated the benefit of interleaved multi-phase PFC on EMI noise reduction. With proper interleaving phase angle, both differential mode (DM) and common mode (CM) EMI noise can be reduced. CM noise of interleaved multi-phase PFC converter can be further reduced with balance technique. By adding one turn on each boost inductor and adjusting the parasitic capacitance, CM noise of multi-phase PFC converter can be minimized. EMI filter for the converter can be reduced. This CM noise reduction technique can be applied to interleaved PFC with any phase number and any phase shift angle. One extra benefit of interleaved multi-phase PFC converter is its phase shedding ability. At light load condition, one or more phases can be shut down to achieve higher light load efficiency. However, the converter will lose the benefit of EMI noise reduction. With balance technique, CM noise of the converter remains low with phase shedding.