Research And Design Of Digital Control Totem Pole Bridgeless PFC Converter Based On GaN HEMT

The switching power supply is usually composed of a two-stage AC-DC converter including a front-stage PFC circuit and a back-stage DC-DC circuit.In the front-end PFC circuit,the PFC circuit of the Boost topology has become the most mature PFC design scheme due to its simplified structure and easy access to high efficiency.However,due to the existence of the rectifier bridge in the Boost circuit,its performance tends to be limited due to hardware limitations.The rapid development of the communication industry has put forward higher requirements for the performance of communication power supplies.The bridgeless PFC technology has further improved the overall efficiency of the circuit due to the reduction of the number of power devices in the circuit,and has gradually replaced the traditional bridged PFC.Among them,the power device required in the totem pole bridgeless PFC is reduced to only one inductor,two MOSFET tubes and two slow recovery diodes,and the circuit has extremely small conduction loss during normal operation.The birth of the new wide bandgap GaN device provides a reliable hardware foundation for the safe operation of the totem pole PFC in the high current CCM mode.This makes it possible to apply totem pole bridgeless PFC to actual industrial production.Totem pole PFC has also changed from a marginalized topology to a new research focus.The main research content of this article includes analyzing the working principle and design difficulties of totem pole bridgeless PFC;calculating the parameters of the main power devices in the circuit and selecting the device types;loop analysis of the dual-loop control system in CCM mode,through Z transformation The discrete domain model is obtained from the loop complex frequency domain model,and the double loop transfer function and differential equation in the discrete domain are calculated from this,and the full digital control of the current loop and the voltage loop is realized.Finally,a totem pole bridgeless PFC experimental prototype was designed according to the conclusions drawn from the calculation and analysis,and the feasibility of the design scheme was verified through the experimental results.