Design issues of interleaved critical conduction mode Boost PFC converter with coupled inductor

The operation of the two-phase interleaved CRM Boost power factor correction (PFC) converter with coupled inductors is analyzed in this paper. Since the equivalent inductance varies with the switching mode and duty cycle, the current mode control method should be adopted to achieve PFC rather than the voltage mode control. The switching frequency is derived, and the self inductance is discussed in term of the minimum switching frequency, which should be higher than 20 kHz to avoid acoustic noise. The design methodology of the coupled inductors is presented as well. Compared to the discrete inductors, the coupled inductor has small size and low copper usage, so the power density of the PFC converter can be increased.