Mutual Inductance Model And Mechanism Analysis Of Wireless Power Transfer System Based On Hexagonal Coil

Wireless power transfer(WPT)technology enables non-contact power transfer through electromagnetic coupling,and have been investigated by researchers due to its flexible and convenient feature.The magnetic coupler is one of the critical part of power transmission,and researchers have had an abundant researches on magnetic coupler in WPT,including analysis of mutual inductance model,coil optimization design and its electromagnetic characteristics analysis,etc.In a WPT system,power is transferred by mutual inductance between coils,thus the transmission efficiency and output power are related to mutual inductance.Generally,the mutual inductance is subject to coil parameters and the relative position between two coils,thus giving an analytical mutual inductance and coupling characteristics analysis for magnetic coupler in WPT system is of significance to achieve a better transfer performance.And the researches of mutual inductance and coupling characteristics of magnetic coupler in this paper are summarized as follows:(1)To build the analytical model of mutual inductance between two hexagonal coils with horizontal misalignment,the Biot-Savart law and coordinate axis rotation method is introduced to obtain the magnetic flux density of primary hexagonal coil.Then the integral area in secondary hexagonal coil is divided reasonably for simplifying the calculation.The mutual inductance data taken from the simulation and experimental prototypes are compared with the mutual inductance model.Both the experimental and simulation results demonstrate the validity of the mutual inductance model.(2)The overall dimension of transmitting hexagonal coil of magnetic coupler is determined by electromagnetic theory.The hexagonal coil parameters and its coupling characteristics with horizontal misalignment are analyzed by using the mutual inductance model presented in this paper.Furthermore,the magnetic core layout of magnetic coupler are analyzed by electromagnetic simulation software.(3)And the WPT system experimental prototype is built based on the hexagonal coil.The effectiveness of the theory analysis is validated by this experimental prototype.The analytical mutual inductance model between hexagonal coils with horizontal misalignment and its coupling characteristics under different circumstances are analyzed.And the researches presented in this paper provides a theoretical basis for the subsequent analysis and design of hexagonal magnetic coupling coils in WPT system.