Research On Key Issues Of Optimization Of Inductive Power Transfer System For Electric Vehicles

Recently,with the increasing attention on energy and environment issues,the electric vehicle has been developed rapidly.However,the traditional conductive charger restricts the promotion and application of electric vehicles.The wireless charging method eliminates the cable connection between the charger and the vehicle and helps promotion and application of the electric vehicle with its unique advantages.In this thesis,the wireless charger based on inductive power transfer technology for electric vehicles has been taken into research in order to optimize the performance of the system.The research mainly focuses on the compensation topology,the magnetic coupler and the power control method.Firstly,based on the review and summary of the research papers and the practical application of electric vehicles,the double-side LCC compensation topology,the magnetic coupler with DD pads and the secondary–side power control method are adopted as the scheme.The performance of the system and the optimization method are analyzed based on the chosen scheme.Secondly,the basic structure and principles of wireless power transfer are analyzed to find the key factors affecting the system performance.The double-side LCC compensation topology is analyzed to summarize its characteristics.According to the characteristics of the topology,the compact design of the magnetic coupler is proposed,and the characteristics of the compact design has also been studied.Thirdly,based on the characteristics of the compact design of the magnetic coupler,the theoretical analysis of the double-side LCC compensation topology is modified considering the influence of the extra couplings on the compensation topology.The optimal design minimizing extra coupling effects is analyzed and proposed for the compact magnetic coupler to ensure the performance of the whole system.Fourthly,the common power control method based the double-side LCC compensation topology is cascading a BUCK converter before the primary inverter.However,this power control method relies heavily on the wireless communication of the primary side and the secondary side to achieve closed-loop control,which has disadvantages of poor stability,bad reliability and low communication speed.Therefore,a secondary-side power control method is proposed and the characteristics of the circuit topology are also analyzed in this thesis to control the power in the secondary side independently and effectively.Finally,according to the theoretical analysis and simulation results,a prototype is built and tested aiming at the practical application of wireless charging for electric vehicle.The experimental results of the prototype validate the content and analysis of this thesis.When the power is 6 k W,the efficiency of the inductive power transfer system can achieve 95%and the total efficiency of whole prototype can also achieve 92%,which satisfies the design target and the requirement of the electric vehicles.