3kW Four-Level Flying Capacitor Totem-Pole Bridgeless PFC Rectifier with 200V GaN Devices

This paper introduces a flying capacitor multilevel (FCML) totem-pole hridgeless power-factor-correction (PFC) rectifier for the high-efficiency and high-density switching power supplies of data centers. A 3kW four-level FCML totem-pole PFC with 200V GaN devices is discussed and designed in this paper. Compared with the conventional two-level GaN totem-pole PFC, this four-level FCML GaN totem-pole PFC utilizes the low voltage GaN devices, reduces the switching voltage, reduces the voltage stress on the inductor and increases the equivalent ripple frequency of the inductor. Since the reduced switching voltage also reduces the dv/dt, the EMI noises are also reduced. Based on the commercial cubic composite inductors, a modular compact and low-profile inductor design method is introduced for this four-level totem-pole PFC. A high density 3kW four-level-FCML GaN totem-pole PFC prototype is developed and tested. The working principles, control stratea and performance of this PFC rectifier are verified by the experimental results. The estimated peak efficiency of the prototype is 99%, and the power density is about 125W/m(3).