| Electric Vehicle Dynamic Wirelesss Power Transfer(EV-DWPT)technology is a major branch of Stationary and Dynamic Wireless Power Transfer of Electric Vehicle technology.This study is mainly about these several aspects,transmitter coils,index system and evaluation method of magnetic coupler,and multi-objective optimization of system parameters in the EV-DWPT system.Magnetic coupler is one of the key parts of the EV-DWPT system,which determines the system performance.However,magnetic couplers with different applications,different system working requirements,and different load characteristics perform different system performance and evaluation indices.And the final evaluation results can be given by more than one index.At present,there is no comprehensive evaluation index system of the magnetic coupler,and the rationality and superiority-inferiority cannot be given.Therefore,the comprehensive index system and evaluation method of the magnetic coupler are studied.The EV-DWPT system is a complex system with electric and magnetic field,because of the complexity of the nonlinear parts in the system,high independence among the system parameters,time-varying and uncertainty characteristics,and disturbance factors acting on the system,a multi-objective optimization should be considered in solving the system parameters optimization problem.To address these issues above,an entire system design method about system modelling,parameters selection,and optimization method is proposed in this paper.In this study,the work we have done and the methods we have used are as follows:(1)A study on the circuit framework in the EV-DWPT systemConsidering the EV-DWPT system’s special features and applications,it is important to research the inverters and compensation networks with for better performance.The entire system framework is proposed in this paper.First,the multi-level segment type of the transmitting rails based on the multi-leg inverter is proposed.Then,the multi-leg inverter is analyzed,including the driver signals and the circuit modelling.Also,the LCCLCC EV-DWPT circuit design is proposed and analyzed,including its steady-state behavior,system power loss and efficiency,and multiple soft-switching points.At last,simulation results show that the LCC-LCC type compensation network and the proposed multi-leg inverter go for the EV-DWPT application.(2)A study on the magnetic coupler in the EV-DWPT system.Based on the proposed multi-level segment coil type using the multi-leg inverter,the coil configuration of the transmitting rails and its excitation strategy is analyzed.In this paper,some improvements of the DD coil are achieved.The novel coil type is named crossed DD.And,using the Ansoft software,simulation results of the conventional D,DD and the proposed crossed DD are given.Then,the two-coil excitation strategy is proposed and compared to the single coil excitation strategy.Also,the length of the crossed DD coil is optimized considering the system output performance and electrical parameters.The mathematical model of the coil length and velocity is given.(3)A study on the index system and a comprehensive evaluation method of the magnetic coupler.The role of the magnetic coupler in the EV-DWPT system is fully analyzed in the aspects of the power transmission theory,performance,effects,and the research field requirement.Then,the index hierarchical model of the magnetic coupler is proposed using the AHP method,and the expressions of all the index were given.At last,multilevel evaluation model based on the FCE method is proposed,and the evaluation results of two different magnetic couplers are given and compared.(4)A study on the multi-objective optimization in the EV-DWPT system.Based on the research contents above,the NLP model of the multi-objective optimization in the EV-DWPT system is given,and the average efficiency and the charging equipment cost are set as the two optimization objectives.The system stability,electronics stress,rail turns and the road length are the constraints.Also,system parameters are optimized using NSGA-III,and some Pareto solutions are derived.These solutions can be applied to the entire system to get a good condition and high efficiency.The main creative contributions of this paper are as follows:(1)Focusing on the unqualified magnetic coupler evaluation,the index system including the power and efficiency characteristic,the compactness characteristic,and the spatial characteristic is offered.The index hierarchical model and the comprehensive evaluation method using the AHP and FCE method are proposed.(2)When EV moves to the switching points,the output power drops rapidly.To solve this problem,the crossed DD coil configuration with a two-coil excitation strategy is proposed to make the mutual inductance of the magnetic coupler fluctuates slightly to get a stable output power.(3)Considering the parameters modelling and optimization problem in the proposed EV-DWPT system,the average output performance and the charging equipment cost are considered as the optimization objective functions.The average output performance functions are derived based on the two-coil excitation strategy.The multi-objective optimization algorithm is analyzed.Finally,the system parameters are optimized. |
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