| In recent years,the development of wireless power transmission technology has made the development of public mobile charging equipment possible,and to a certain extent has led to the development of infrastructure.However,when the transmitter side of the coupling coil mechanism is offset from the receiver side,it caused the transmission efficiency and output power of the system to drop so rapidly that the whole system is weak to anti-offset.In order to solve the above problems,this paper adopted the method of theoretical analysis and experimental verification to investigate the offset characteristics of the magnetically coupled mechanism of the wireless power transmission system,which is reflected in the following four aspects:Firstly,on the basis of previous research work,this paper proceed to the resonant network and equivalent circuit model of the system,studied the working principle of magnetic field resonant coupling in depth,and basis on the system transmission efficiency and output power,analyzed the effects of frequency,mutual inductance and load on system transmission performance,as well as the effects of coupling coil offset on mutual inductance,it is clear that coupling coil mutual inductance is the key factor to affect the system’s ability to anti-offset.Secondly,combined with the method of finite element,a composite resonant coil structure is proposed based on the analysis of the magnetic field distribution of conventional coils.Build a joint simulation platform,when the axial shift of the coupling coil occurs under the change of input voltage,the changes of system output power and transmission efficiency are analyzed and compared with the trends of corresponding mutual inductance and system transmission performance to verify that the system input voltage level and axis spacing have little effect on the study of mutual inductance in this paper.Analyzed the trend of the change of system output power and transmission efficiency when the coupling coil offset,compared with the trend of the mutual inductance,which not only verified the excellence of the composite coil,but also showed the importance of the mutual inductance of the composite coil for the optimization of the composite coil structure.Thirdly,based on the conventional coil mutual inductance solution formula for conventional coils,combined the principle of mutual inductance and Biot-Savart law,a mutual inductance solution method for composite coil structure in coaxial and noncoaxial cases is given.Through theoretical calculation and finite element simulation,the relative error between the calculated value of the mutual inductance solution formula for composite coils and the finite element simulation value was within 2.5%,which indicated that the derived mutual inductance solution method for composite coils is effective.Fourth,according to the parameters to wind the coupling coil,used a HIOKI LCR meter,used its transformer mode,the mutual inductance between the actual wound coils is measured for different turn ratios of composite coils of 0.84 mm wire diameter and1.22 mm wire diameter under different offset angles occurring in the coaxial and noncoaxial cases.Measured the mutual inductance of different wire diameter,different turns ratio when the composite coil at different offset angle.This paper compared solution mutual inductance with formula calculated value,the measured value and the calculated value of the relative error within 1%,further proof of the accuracy of the composite coil mutual inductance solution formula. |
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