Multi-phase coupled and integrated inductors for critical conduction mode totem-pole PFC converter

Coupled inductor has been widely used in voltage regulator (VR) applications for many years because it can help reducing current ripple and improving transient performance. In this paper, the coupled inductor concept is applied to interleaved totem-pole critical conduction mode (CRM) PFC converter for 6.6kW on board battery charger. The difference between negative coupling and positive coupling will be discussed. The benefit of positive coupling for battery charger will be presented, such as reducing switching frequency range and reducing input differential mode (DM) noise. In addition, balance technique is applied to help minimize common mode (CM) noise. Last but not least, the inductor will be integrated into PCB winding with a little sacrifice on loss. With the inductor integration, the converter can avoid labor intensive production and achieve fully automated manufacture. The analysis is verified by both simulation and experiment.