The Compensation Technology And Optimum Design Of Loosely Coupled Transformer For Electric Vehicles Wireless Charging System

With the rapid development of electric vehicle industry,charging infrastructure construction has become an important prerequisite for the popularization and promotion of electric vehicles.Wireless charging is a hot topic in the field of the electric vehicle charging technology,it has the advantages of safety,convenience and so on.While loose coupling transformer is a key part of the wireless charging system,Acts as the non-contact energy transmission link of the in-vehicle and the outside-vehicle.Therefore,it is of great significance and has wide application prospect to carry out the optimal design of the loose coupling transformer and to study the compensation technology for the purpose of improving the transmission efficiency.For the problem of the low coupling coefficient of primary and secondary coupling of electromechanical loosely coupled transformer,the transformer magnetic circuit model is established,and the transformer transmission efficiency is improved by the compensation scheme,and the system design is designed for the loose transformer(DCT).In this dissertation,The main work is as follows:Firstly,the working principle of the transformer is studied,and the magnetic circuit model of the transformer is established.The distribution of magnetic induction line is obtained by using ANSOFT to simulate the winding model,air gap and horizontal lateral displacement.Combining the distribution law of the magnetic lines,the model of magnetic is obtained by dividing the magnetic Then the relationship between the coupling coefficient and magnetic resistance is derived.Using the three parameter measurement method,the relationship among the coupling coefficient the air gap and the horizontal lateral displacement is obtained by measuring the loosely coupled transformer parameters.Then,the compensation technology of the original secondary side of loose coupling transformer is studied.The primary side of the high-frequency inverter circuit and loose coupling transformer are considered as a whole,which compose loose coupling DCT.The relationship among efficiency,switching angular frequency and the compensation parameters is obtained by the quantitative analysis of the compensation of loose coupling transformer.Based on the above analysis,an optimized compensation scheme is proposed,.The compensated DCT can be equivalent to the LLC-DCT,then can achieve the soft switching,further improve the efficiency of the transformer.Finally,the DCT system is designed.The design of DCT is designed from four aspects: compensation parameters,winding ratio,transformer parameters and hardware of open loop control module.The simulation model and experimental principle prototype of DCT are verified.Simulation and experimental results show that the designed DCT and DCT can improve the transmission efficiency and reduce the voltage stress of the power device.The optimized DCT transmission efficiency is 2.248%.