Research On Totem-pole Bridgeless PFC Converter Based On GaN

Vigorously improving energy efficiency is a challenge to achieve the "carbon peak" and "carbon neutral" goals for our country.Power electronics technology can greatly improve the utilization efficiency of electric energy and is a crucial technology to realize high-efficiency electric energy conversion.Power factor correction(PFC)technology is introduced to reduce the pollution of harmonic currents to the power grid,thereby improving the power supply quality of the power grid.In the current research on power factor correction,how to realize the high efficiency,high power factor and high power density of the converter is the key to the current research.In this thesis,the advantages and disadvantages of current PFC technology are analyzed and compared,considering three aspects: circuit structure,new materials and novel control methods.At the same time,combining the advantages of the Wide-BandGap(WBG)semiconductor device gallium nitride(Ga N),a Ga N-based Totem-pole bridgeless PFC converter is designed,and the performance characteristics of the Totempole PFC in different working modes are compared,simulation and experimental verification are carried out.The research content of this thesis mainly includes the following points:1)The research background and current research status of this thesis are analyzed,compares the advantages and disadvantages of bridged PFC circuits and bridgeless PFC circuits,and the development and application of new Ga N devices are reviewed.Finally,the main research content of this thesis is summarized.2)The circuit working mode of the Totem pole PFC under the current continuous mode(CCM)condition is analyzed.The main circuit parameters are designed in CCM mode.According to the state space model of the converter,a voltage and current double closed-loop control system is designed to control the stable operation of the converter.The current distortion near the zero-crossing of the AC voltage is analyzed,a strategy to improve the current distortion suppression improved strategy is proposed,and a simulation platform is built to verify the effectiveness of the proposed control strategy.3)The working principle of the totem pole PFC converter in Discontinuous Current Mode(DCM)is analyzed,and the three different control strategies are analyzed and compared respectively through formula derivation.Finally,a current predictive control method based on digital control is adopted,which can achieve unit power factor correction of the input current under a wide input voltage range..And the main circuit parameters are designed in DCM mode,and the simulation platform is built to verify the effectiveness of the proposed control scheme.4)The experimental prototype is built,and the experiment verification work is carried out.The experimental results are analyzed and compared to verify the correctness of the theoretical analysis and the validity of the research methods.5)Finally,the work of this thesis is summarized and the future research work is prospectively looked forward to.