| In the high-power applications of dynamic wireless power transfer system,the coupler will inevitably be affected by electromagnetic force over the power transferring,as well as the track and other materials,due to the coupling of high-frequency electromagnetic field.The long-term effect of high-frequency electromagnetic force on coupler will lead to its deformation,loosening,fracture and even falls off,which will affect the service life and bring security threat.In this thesis,the mechanism and characteristics of the high-frequency electromagnetic force acting on the coupler of dynamic wireless power transfer system are studied.(1)Based on the dynamic wireless power transfer system with coil array structure,the reasonable simplified model is built and analysed according to the special theory of relativity and electromagnetic wave theory.By using the theories of Lorenz force and Maxwell stress tenser,the principle and characteristics of high-frequency electromagnetic force on coupler,ferrite and metal materials in the resonant magnetic field are obtained.(2)The finite element model in Galerkin weak-forms for high-frequency electromagnetic force on coupler,ferrite and metal materials are built to obtain the characteristics of periodic force and static attraction/repulsion force.Inputting the pulse current on transmitting coil,its influences on high-frequency electromagnetic force and the characteristics of transient pulse force are obtained.Besides,based on the parameters of Aluminum plate,the force and the effects of material permeability and conductivity are analysed by varying material permeability and conductivity setting(3)An equivalent prototype for high-frequency electromagnetic force investigations is established according to simulation model in equal proportion.The characteristics of high-frequency electromagnetic force and its differences between coupler,ferrite and metal materials are investigated and compared with simulation results,which prove the correctness of theoretical analysis and simulation.(4)An electromagnetic force smoothing method is proposed by characteristic differences between ferrite and metal materials,which is verified by the simulation.The results show that the high-frequency electromagnetic force on the transmitter is larger than that on the receiver.The directions of static force caused by eddy current effect and magnetization effect are opposite,and the Lorenz force induced by eddy current plays the major role.The existence of transient pulse current will change the amplitude of high-frequency electromagnetic force.Besides,the magnetic shielding structure can reduce the high-frequency electromagnetic force of the coupler.And the different combinations of ferrite and metal materials can be used to smooth the high-frequency electromagnetic force. |
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