Control Research And Device Design Of Totem Pole Bridgeless PFC Converter

With the rapid development of data centers,electric vehicles,and consumer electronics,AC/DC converters are moving in the direction of high efficiency and miniaturization.Totem-pole bridgeless PFC has become a hot spot in current research due to its simple structure and high efficiency.In the continuous current conduction mode,the totem pole bridgeless PFC based on Si MOSFET cannot be practically applied due to the large reverse recovery loss.With the emergence of the thirdgeneration wide-bandgap semiconductor GaN HEMT/SiC MOSFET,due to its physical characteristics such as fast switching speed,low reverse recovery loss and high thermal conductivity,the totem pole bridgeless PFC has been applied.The converter in the continuous current conduction mode works in hard switching.This paper uses SiC MOSFET to develop a 1kW experimental prototype and test its performance.In the current critical conduction mode,the converter can realize soft switching,but the realization of soft switching has boundary conditions.This paper studies the principle and method of its soft switching realization.Based on the phase lock method in different coordinate systems,this paper studies the working principle and realization method of the totem pole bridgeless PFC converter in the static coordinate system and the dq rotating coordinate system.In the static coordinate system,the small signal model of the system under the average current control is studied,and the influence of the controller parameters on the stability of the system is analyzed.In the dq rotating coordinate system,the principle of single-phase phase-locked loop based on the second order generalized integrator and the double closed-loop control strategy of the system are studied.Finally,simulations verify the effectiveness of its control strategy in different modes.Based on the phase lock method in different coordinate systems,this paper studies the working principle and realization method of the totem pole bridgeless PFC converter in the static coordinate system and the dq rotating coordinate system.In the static coordinate system,the small signal model of the system under the average current control is studied,and the influence of the controller parameters on the stability of the system is analyzed.In the dq rotating coordinate system,the principle of single-phase phase-locked loop based on the second-order generalized integrator and the dual-loop control strategy of the system are studied.Finally,simulations verify the effectiveness of its control strategy in different modes.Finally,SiC devices are used to design the hardware circuit and software algorithm of the converter under the average current control,and a 1kW experimental platform is built.The converter can obtain good inductor current waveform and stable output voltage under different input voltage RMS,and its power factor is above 0.99.Its efficiency under different loads when the effective value of the input voltage is 110 V is tested,and the peak efficiency reaches 96.63%.The dynamic performance of the system is tested when the load and output voltage reference value changes.The experimental results show that the system has fast response capability and stability.