| Wireless Power Transfer(WPT)is a technology that realizes the wireless transmission of power through the coupling between two spatially separated coils.Because of its convenience,reliability and flexibility,it has been widely used in various occasions.The magnetic coupling coil is the key part of the power transmission in the WPT system,and mutual inductance is a key parameter in the WPT system as the power transmission medium between the magnetic coupling coils.However,the size of the magnetic coupling coils and the relative position change between the coils will lead to the change of mutual inductance between the coils,which will affect the transmission efficiency and output power of the WPT system,and then seriously affect the performance of the WPT system.Therefore,the research on mutual inductance between coils is one of the hot spots in this field.The main work and research contents of this thesis are as follows.Firstly,this thesis describes the background and significance of the topic,introduces the development of WPT technology and the research status of mutual inductance between coils,and briefly summarizes the common calculation method of mutual inductance between coils,which leads to the main research content of this thesis.Secondly,some basic theories of mutual inductance modeling between coils are introduced,and the calculation formula of mutual inductance between coaxial and non-coaxial rectangular coils in air is given in detail,and the correctness of the mutual inductance formula is proved by comparing the calculated results of mutual inductance and simulation results with the experimental results.At the same time,the influence of the relative position change between the coils on mutual inductance is studied.Then some common magnetic shielding materials are introduced,and their properties are simply analyzed through modeling.Aiming at the problem of adding magnetic shielding to the wireless power transmission system to reduce magnetic leakage and enhance coupling,through the mutual inductance modeling analysis of rectangular coils with magnetic shields,The calculation formula of mutual inductance between the coaxial rectangular coils with magnetic shielding is obtained based on the Fourier transform,Maxwell equations and boundary equations.And the correctness of the mutual inductance calculation formula is verified by simulation and experiment.Finally,aiming at the problem of relative position changes between two rectangular coils with magnetic shielding,a method for calculating the mutual inductance between two noncoaxial rectangular coils with magnetic shielding is proposed based on the coordinate transformation method.Firstly,the magnetic field intensity generated by primary coils at any position in space is obtained by modeling and analysis of rectangular coils with magnetic shielding,and then the mutual inductance calculation formula between rectangular coils with various misalignments is obtained by means of coordinate transformation method.Finally,the results of simulation and experiment are compared to verify the correctness of the mutual inductance calculation method.The theoretical model has important reference significance for the design and optimization of coil parameters in the practical application of WPT systems. |
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