Research On ABLT Magnetic Coupling Mechanism And Its Design Method For Dynamic Wireless Charging Of Electric Vehicle

There are some problems in electric vehicles,such as high battery cost,limited capacity,short driving range and so on.The dynamic wireless charging technology provides a good solution for the electric vehicle to supplement power in real time.Magnetic coupling mechanism is the key component of wireless power transmission,which directly affects the construction cost,power level,efficiency,output stability and other system characteristics.The magnetic coupling mechanism of alternating bipolar long track(ABLT)has the advantages of narrow power supply rail at the transmitter,small influence on the road surface,large lateral tolerance and small magnetic leakage field,which has a good application prospect.ABLT structure is chosen as the main research object and this thesis studies the calculation model,structural form,parameter design method and comprehensive optimization method of magnetic coupling mechanism.In order to quickly calculate the performance characteristics and scheme when analyzing the magnetic coupling mechanism and selecting the material and structure parameters,three modeling methods of ABLT magnetic coupling mechanism are studied in this paper.Based on the establishment of finite element simulation model,the equivalent model of fast finite element simulation is established and the principle of equivalent simplification is given.Compared with conventional finite element simulation,the error of inductance calculation result is less than 1.5%,and the calculation time is reduced to one third.Aiming at the problem that there is no magnetic circuit model of ABLT magnetic coupling mechanism,according to the distribution of space magnetic induction line obtained by finite element simulation,the magnetic circuit model is established on the basis of analyzing the relationship between space magnetic conductances and coupling performance of each part.The model provides a theoretical basis for clearly and intuitively analyzing the influence of structural parameters on the performance.Furthermore,a more accurate analytical calculation model of mutual inductance is established,and an analytical calculation method based on magnetic circuit fitting is proposed.The example calculation shows that the maximum error of mutual inductance is 6% compared with the simulation calculation,and the calculation time is reduced to a few milliseconds.The calculation speed of optimization design is improved and a lot of simulation calculation in the design process is avoided.Aiming at the problems of output fluctuation and high cost of ABLT magnetic coupling mechanism,this paper studies the influence of structure on performance,and proposes a novel structure based on n-type magnetic pole transmitter and multiphase receiver.Compared with the conventional I-type pole,the number of magnetic cores of n-type magnetic pole with multi-turn winding in single pole is reduced by 26.7% and the cost is reduced by 21.4%.The multi-phase receiver composed of multiple groups of coils effectively reduces the output fluctuation,and the four-phase structure reduces the fluctuation factor from 1.0 to 0.08.Based on the above research,the cost,loss and size of multiphase receiver with different phase numbers and connection modes under the same output capacity are compared and analyzed,and the applicable conditions of different structures are clarifi ed.In order to reduce the size of the receiver and realize decoupling between phases,three kinds of variable structure multiphase receiver unit structures,including DD-Q,DD-Q'QQ' and D-Q are constructed.The influence of output characteristics and structural parameters on coupling performance is analyzed,and the application selection of multiphase receiver is expanded.There are many performance and parameters to be designed for ABLT magnetic coupling mechanism,and there is coupling between them.Ther efore,it is necessary to study the design method that can improve the design speed and comprehensiveness.Firstly,the mapping relationship between the design parameters and seven system characteristics,such as average efficiency,cost and frequency lateral tolerance,is studied.The calculation model of system characteristics reflecting the relationship between them is established and the analytical formula is derived.The influence law of design parameters on system characteristics is analyzed and the theoretical basis for the realization of rapid design is established.Secondly,the rapid design method is proposed and the flow is given;during the design process,the design results that meet the system requirements are obtained after the calculation model is iterated for many times to realize the rapid design.Furthermore,the field-circuit coupling design method is proposed,and the simulation analysis of electromagnetic characteristics is added to improve the accuracy and safety of the design results,which makes the design results more valuable for engineering application.For multiple design results,a decision method combining subjective weight and objective information entropy weight is studied to avoid the blindness of subjective weight selection.Aiming at the comprehensive optimization problem in the complete design space,the multi-objective optimization method of ABLT magnetic coupling mechanism considering multiple system characteristics is studied,and the optimization process is given.The optimization method based on enumeration method is proposed,and the fast optimization and rule analysis are realized when different characteristics are taken as objectives or constraints.Taking the optimization problem of cost and efficiency as an example,the effects of different objective analysis methods and different characteristics as constraints are compared and analyzed.In order to improve the accuracy and speed of optimization,an optimization method based on improved multi-objective particle swarm optimization algorithm is proposed.The external files with crowding degree sorting and mutation operation are added to enhance the ability of local convergence and global optimization.By improving the basic particle swarm optimization algorithm,Pareto front with better cost-efficiency and more non-dominated solutions with uniform distribution are obtained.A novel ABLT magnetic coupling mechanism experimental device based on n-type pole transmitter,multiphase receiver and variable structure dual-phase receiver is designed and manufactured,and the experimental platform of dynamic wireless power charging system is built.The feasibility of the structure and the correctness of the design method are verified by coupling performance test and dynamic experimental application.