The Design Of High Frequency Converter With PFC In Fixed-point Wireless Power Transfer System

The converter in magnetically coupled resonance wireless power transfer(MCR-WPT)system generally adopts traditional rectification and inverter method with diode,which can cause harmonic currents and affect the transmission characteristics of the system.The loss of the switching device will increase to result in the inormal operation.Power factor correction(PFC)can keep the voltage and the current of the system in the same phase to increase the power factor and reduce the impact of harmonics on the system.Therefore,this paper designs a high frequency converter with PFC used in 3k W MCR-WPT system,which aims to improve the transmission characteristics by reducing the harmonic current of the system.The main work of this paper is as follows:Firstly,the research background and significance of this paper were explained.The research status on wireless energy transmission,PFC technology and DC-AC converter were introduced.The research contents of this paper was presented,mainly including system harmonic analysis,high frequency converter design with PFC,and system simulation and experimental design and verification.Secondly,in order to analyze the harmonics influence on the current and the transmission characteristics of the system,the equivalent circuit model of the system was established with the mutual inductance theory.The formular of the input current,the output current and the transmission characteristics of the system with harmonic wave were derived.When quality factor,load or frequency of the coil change,the influence of harmonic wave on the system performance was analyzed,which provides a theoretical basis for the research and design of high frequency converter with PFC.Then,the high frequency converter with PFC in the wireless power transfer system was studied and designed,including the AC-DC converter with PFC and the high frequency DC-AC converter.According to the parameters and performance requirements of the system,an interleaved Boost PFC structure was designed in AC-DC converter,including the main circuit,control circuit and drive circuit.The high-frequency full-bridge inverter structure was designed in DC-AC converter,including the main circuit,drive circuit,protection circuit and soft switching technology with digital phase-locked loop.In addition,the coil structure,communication device and current sampling system in the wireless energy transmission system were also designed.Finally,a simulation platform and an experimental platform for the wireless energy transmission system were built.The system performance was analyzed by Simulink module in Matlab.The load experiment,the frequency experiment and the waveform test were carried out on the experimental platform.The experimental results show that when the load RL is 50 ? and the system frequency is 85 k Hz,compared to the traditional AC-AC converter,the high frequency converter with PFC increases the output power and transmission efficiency of the system and reduces the input harmonic current of the system.,which satisfies the design requirements of this paper.