Research On Application Of Bridgless PFC In Electric Vehicle Charger Based On GaN Device

The vigorous promotion and popularization of new energy vehicles have made the development of high-efficiency chargers very necessary.Increasing the conversion efficiency has become one of the current research hotspots.Electric vehicle chargers generally adopt two-level topology,which is composed of AC/DC converters and DC/DC converters.This paper takes the AC/DC converter in the off-board charger of electric vehicle as the research object,and solves the problems that the traditional bridged PFC topology has large loss of rectifier bridge and low efficiency of the whole machine.This paper adopts a totem-pole bridgeless PFC topology composed of gallium nitride devices to replace the bridged PFC topology formed by traditional silicon devices,and studies the application characteristics of the new device in a totem pole bridgeless PFC topology to improve system conversion efficiency and power level,and improve system performance.The purpose of the stability of the work.In this paper,some basic theories and applied technologies are studied in the field of PFC in off-board chargers for electric vehicles,and some achievements have been achieved.This paper analyzes the differences in the characteristics of silicon materials and gallium nitride materials,introduces the advantages of gallium nitride materials in high-frequency and high-temperature applications,analyzes the turn-on and turn-off principles of Cascode-structured reinforced GaN HEMTs,and analyzes nitrogen.The application characteristics of the germanium devices prove that applying the gallium nitride device to a totem pole bridgeless PFC topology can improve the efficiency of the topology.This paper analyzes the working mode of the totem pole bridgeless PFC topology and establishes the small signal model of the current loop and voltage loop.In order to achieve maximum power charging in different power environments,this paper proposes an adaptive charging power control algorithm.The nonlinearity of the inductor changes the characteristics of the system and increases the total harmonic distortion.In this paper,a dynamic PI compensator is used to reduce the influence of the nonlinearity of the inductor.The PFC inductor causes a phase difference between the input voltage and the switching voltage.It causes distortion of the input current zero-crossing and increases the total harmonic distortion rate.This paper introduces the duty-ratio feedforward control to solve the zero-crossing distortion problem.In order to further reduce the input current total harmonic distortion,this paper qualitatively analyzes the current loop.The effect of bandwidth on harmonics.In this paper,according to the design requirements,the circuit parameters are calculated and the hardware circuits of each part are designed.Because GaN HEMTs have fast switching speeds,which are sensitive to parasitic parameters and reduce the reliability of the system,this paper quantitatively analyzes the influence of parasitic parameters on the switching characteristics of GaN HEMTs,introduces the optimization methods for PCB design,analyzes the prototype losses,and improves the prototypes.The efficiency provided the basis for optimization,and a totem pole bridgeless PFC prototype with a peak efficiency of 98.4% of 1.5 kW applied to off-board chargers for electric vehicles was designed and manufactured.In this paper,MATLAB/SIMULINK platform is used to verify the totem-pole bridgeless PFC topology,which verifies the correctness of the parameter design and the effectiveness of the harmonic suppression optimization strategy.It also verifies the feasibility and correctness of the proposed scheme,and the effectiveness of the harmonic suppression optimization strategy.