Design And Research On Capacitive Auxiliary Power Transfer System Applied To Maglev Train

Traditional high-speed maglev trains need to obtain auxiliary power through the third rail.There are frictional wear and sparking problems in this kind of contact power supply device,which causes a higher maintenance cost and lower security.Wireless power transfer can avoid those problems.Capacitive power transfer(CPT)delivers electric energy through lightweight metal plates.It has some advantages of being low-cost and lightweight.Besides,CPT has good prospects in short-range energy transmission applications such as maglev trains.However,the traditional idea is that the capacitive power transfer has a low transmission power and is not suitable for rail transit.This paper aims to design a capacitive power transfer system suitable for the auxiliary power supply of maglev trains,and study its feasibility.This paper first analyzes the basic working principle and structure of the electric field coupled power supply system and finds that the transmission capacity of the capacitive power transfer system relates to the value of its coupling capacitor(C_s).Therefore,this paper presents a side-vertical coupling mechanism for the maglev train.Using Maxwell simulation software,this paper compares the side-vertical coupling mechanism with the traditional horizontal coupling mechanism and superposed coupling mechanism.And it turns out that the side-vertical coupling mechanism has the largest coupling capacitance extreme value under the same installation area.Moreover,the simulation results indicate that the coupling capacitance of the side-vertical coupling mechanism varies little in the dynamic power supply process.Next,this paper presents a neat CLLC-CL compensation topology compared to S-S,double-sided LCL,and double-sided LCLC compensation topologies.This paper optimizes the parameters of the above topologies by using the voltage value of the compensated capacitor as a limiting condition.The result shows that compared with other compensation topologies,the CLLC-CL compensation topology requires the least material cost when transmitting energy with the same power.This paper studies the output characteristic of CLLC-CL compensated topology and output voltage/current sensitivity to parameter perturbation,and presents a multi-system series scheme.Finally,this paper uses Matlab/Simulink simulation software to simulate the capacitive power transfer system based on the compensated topologies above and the series system.The simulation results verify the rationality of choosing the CLLC-CL capacitive power transfer system and the feasibility of four sets of CPT systems running in series.And the simulation results confirm the influence of parameter perturbation to system output voltage and power balance.Moreover,this paper builds a scaled-down experimental model that achieves an energy output of 1.41k W power,at a working frequency of 1MHz,through 250mm×250mm receiving plates and 35mm transmission distance,with DC-DC transmission efficiency reaching 91.67%.The experimental results verify the feasibility of the capacitive power transfer system for the maglev train presented in this paper.