Magnetic Coupler Structure For Improving Misalignment Tolerance Ability In Electric Vehicle Wireless Charging Application

Wireless power transform(WPT)technology has become an important development trend in the field of electric vehicle charging technology in the future due to its high reliability and safety,high space utilization and convenient maintenance.However,in the actual operation and use of electric vehicles,the misalignment between the vehicle receiving device and the transmitting end of electric vehicles leads to the position deviation between the energy transmission coils,which will cause the instability of the efficiency and power of the wireless charging system.To sum up,this thesis focuses on the magnetic coupler part of WPT system,through the optimization design to improve the misalignment tolerance ability of WPT system.The main work is as follows:1)This thesis compares the performance of square two coil and three coil loosly coupled transformerin the case of offset,selects the appropriate three coil square coil loosly coupled transformerstructure,analyzes the operation characteristics of the loosly coupled transformerin the non complete resonance state,and determines the three coil loosly coupled transformerused to improve the misalignment tolerance ability of WPT.2)In order to improve the power stability of WPT system in the case of offset,a compensation capacitor parameter selection method based on quality factor is proposed for the selection of capacitor compensation parameters.In different offset cases,the misalignment tolerance ability is improved by switching the compensation capacitor.In order to simplify the actual operation difficulty,the control strategy of compensation capacitor is further optimized by changing the compensation capacitor only in some positions Primary side(transmitter)compensation capacitor.3)In this thesis,a prototype platform of 3 kW WPT is designed and manufactured.the self-inductance and mutual inductance of different coils of magnetic coupler are measured by experiments.It is found that the errors of self-inductance and mutual inductance of coils are less than 10%,which verifies the rationality of simulation.Comparing the efficiency of two coils and three coils under offset,it is concluded that the three-coil magnetic coupler has better efficiency and anti-offset ability.In addition,through the comparison of three-coil resonant and non-resonant experiments,it is concluded that the non-resonant three-coil magnetic coupler is reasonable.Furthermore,the efficiency and power of the three-coil magnetic coupler with optimized control strategy are measured by experiments,which proves that the three-coil magnetic coupler designed in this paper has high misalignment tolerance ability.