Research Of Single-stage Isolated AC/DC Converter

The energy and environment problem is a great challenge for the whole world in the 21st century,especially for the automobile industry.In order to alleviate China's increasingly severe environmental pressure and ensure China's energy security,transportation energy transformation must take the responsibility.At this stage,all countries in the world are focusing on promoting electric vehicles as an important way to solve the environmental pressure and energy crisis.Urnder the background of the rapid development of electric vehicle industry,the research of on-board charger of electric vehicle has attracted wide attention.How to improve the efficiency of on-board charger,reduce input harmonic distortion,reduce size and improve power density has become the key issue of the research.In this paper,a digital controlled 1.1 kW single-phase single-stage isolated AC/DC converter is studied.Firstly,the power factor correction and AC/DC converter topology are investigated.The advantages and disadvantages of two-stage AC/DC converter are analyzed,and the single-phase single-stage isolated AC/DC converter scheme by multiplexing bridge arm is proposed.Then the circuit structure,working principle and steady-state gain of the converter are introduced and analyzed.At the same time,the technical problems of FBSS topology are introduced.The PFC control mode is investigated.Through small signal modeling of Boost circuit,the shortcomings of control are found,and repetitive control is introduced for compound control.Next,on the basis of circuit working principle and steady-state gain,the main circuit parameter design and device selection are given.The design method and steps of magnetic elements(inductors and transformers)are emphasized.The system model is built by MATLAB,and the main circuit working principle analysis and design parameters are verified.Finally,the digital control system,hardware design of control circuit and software implementation are introduced.Based on the analysis of working principle and topology,parameter design and simulation results of single-phase single-stage power factor correction converter,a 1.1kW test prototype is made to observe the key waveforms in the circuit.The feasibility of the circuit and the rationality of the design are verified by the prototype.