Research On Performance Optimization Of GaN Totem Pole Bridgeless PFC Converter Based On VSFPWM

Totem pole bridgeless PFC(Power Factor Correction)converter is developed on the basis of traditional bridgeless PFC converter,which improves the common-mode EMI(Electromagnetic Interference)problem of traditional bridgeless PFC converter.Among many topologies,totem-pole bridgeless PFC converter has the least number of semiconductor power devices and the least conduction loss,and is the most efficient power factor correction converter.The advent of gallium nitride(Ga N)device has solved the problem of reverse recovery of MOSFET body diode,and enabled totem pole bridgeless PFC converter to work in continuous conduction mode,and the switching frequency has been significantly improved.However,the EMI problem aggravated by the increase of switching frequency and the current spike near the zero-crossing point of AC input voltage all hinders the popularization and use of totem pole bridgeless PFC converter.Therefore,it is of great significance to solve the EMI problem of totem pole bridgeless PFC converter and the current spike problem near the zero-crossing point of AC input voltage.Ga N totem pole bridgeless PFC converter is taken as the research object in this thesis,and a new control method is designed to solve the problems of EMI and current spike combined with VSFPWM(Variable-Switching-Frequency PWM)technology.The main work is summarized as follows: Firstly,the control principle and working state of Ga N totem pole bridgeless PFC converter working in continuous conduction mode are introduced in detail,and the generation principles of conducting EMI and AC input voltage zero-crossing current spike are analyzed in depth respectively.Then,a model predictive VSFPWM control method based on the soft start algorithm of high-frequency switching tube is designed to solve the problems of conducted EMI caused by fast onoff of high-frequency switching tube and current spike caused by duty cycle limitation of high-frequency switching tube.Finally,Matlab/Simulink is used to build a simulation model and complete the hardware and software design of a 400 W Ga N totem pole bridgeless PFC converter.Based on the prototype,the control method of the above theoretical analysis and design is verified by experiments through the test platform.The experimental results show that the initial switching frequency is 100 k Hz,which ensures the efficiency of the converter to meet the design requirements.The application of new control strategy in Ga N totem pole bridgeless PFC converter can effectively improve the EMI and current spike problems of the converter,which proves the feasibility of the technical scheme.