3D Analytical Model Of WPT System Coupling Mechanism And Electromagnetic Environment Assessment

Wireless Power Transfer(WPT),as a new type of power supply,has a broad market prospect as it is free from the traditional power supply methods and has more convenient applications.Due to magnetic flux leakage,the WPT system will produce electromagnetic radiation to the surrounding space and cause environmental electromagnetic pollution.Therefore,it is necessary to enhance the safety of the electromagnetic environment of the WPT system through effective electromagnetic environment assessment methods and reasonable electromagnetic shielding measures.From the transmission principle of the WPT system,the equivalence circuit model of the S-S type WPT system is used to derive the function relationship between the magnetic flux density and the system operating parameters.Based on the electromagnetic shielding mechanism,the influence of passive shielding medium and active shielding coil on the electromagnetic environment of the system is analyzed.In addition,according to the actual working conditions of the system,this paper expounds on the electromagnetic environment assessment standards and measurement methods.To enhance the flexibility of electromagnetic environment assessment,a twodimensional sub-domain model considering electromagnetic shielding medium is established based on the sub-domain analysis technique under the Cartesian coordinate system.Secondly,the unknown coefficients existing in the magnetic vector potential equation are solved by combining the boundary conditions of each subdomain.On this basis,the compensation function is introduced into the two-dimensional subdomain analytical model,and then the three-dimensional(3D)analytical model of the coupling mechanism with electromagnetic shielding medium is obtained.In order to increase the calculation cost of the model,the model of the active shielding coil is optimized based on Biot Savart law,and the calculation time of the optimized model is reduced by 17.8%.Finally,the accuracy of the model is verified by simulation based on the finite element analysis method.The results show that the relative error between the model calculation value and the simulation value under different working conditions of the coil is less than 3%,which verifies the effectiveness of the model deduced in this paper.Based on the 3D analytical model of the coupling mechanism with shielding medium,the effects of passive shielding medium and active shielding coil on the electromagnetic environment of the WPT system are studied,and the effects of different electromagnetic shielding media on the spatial magnetic field distribution are analyzed by finite element method.On this basis,the WPT system experimental platform for electromagnetic environment assessment is built,and the influence laws of different working conditions such as coil misalignment and transmission distance on magnetic flux density are revealed,which provides a theoretical basis for further electromagnetic environment assessment and optimization of WPT system.