| In recent years,wireless power transfer technology has become a hotspot of scholars both here and abroad,It has been gradually popularized and applied in military,medical,smart home and automobile industries.Magnetic Coupled Wireless Power Transfer(MC-WPT)provides a new charging method for electric vehicles because of its long transmission distance,high efficiency and low radiation to the surrounding environment.The design of coupling mechanism is the key technology in MC-WPT,which has an important impact on the power,system efficiency,magnetic radiation and other parameters.When the vehicle is parked at the charging position,due to the uncertainty of the driver's manual operation,there are often offset between the pick-up coil and the underground transmit coil in the vehicle,which will affect the transmission performance of the system,reduce the output power and efficiency of the system,prolong the charging time and increase the loss,the serious situation will even cause the system can not work properly.Therefore,it is necessary to enhance the anti-offset capability of the coupling mechanism to ensure transmission performance of the system under the offset condition.To solve the above problems,this paper aims to find an anti-offset magnetic coupling mechanism based on MC-WPT system,to improve the anti-offset performance and system efficiency of the coupling mechanism.Based on the analysis of the original compensation capacitance of several common compensation topologies,the mutual inductance coupling model of the system is established based on the MC-WPT system with SS compensation topology.The influence of mutual inductance,coupling coefficient and quality factor on the power and efficiency of the system is analyzed.By comparing the common coupling coil structure,the circular-circular coil structure is determined,and the law between the coil radius,mutual inductance and coupling coefficient is explored.In order to improve the anti-offset performance,a multi-coil compensation structure is proposed based on circular coil.Based on the above rules,the coil parameter design method is given to improve the system efficiency.Then,the coupling between coils is increased by adding magnetic cores to reduce the amount of copper wire.Based on the simulation results of different core types with the same volume in the finite element simulation software COMSOL,concave-convex and L-shaped hybrid core structures with strong comprehensive properties such as mutual inductance value and migration resistance are added.Aiming at reducing weight and increasing coupling coefficient,the design method of core size is given.Finally,taking the 3.3KW electric vehicle wireless charging system as an example,according to the design method of coil and magnetic core,the parameters of coil and magnetic core are obtained.Based on COMSOL simulation software,the simulation model of multi-coil compensation coupling mechanism is established to verify the transmission and anti-offset performance of the system,and compared with the traditional coupling mechanism.Subsequently,the multi-coil compensation coupling mechanism is winded to test the transmission performance of the two coupling mechanisms.The experimental results show that the anti-misalignment distance of the multi-coil coupling mechanism is increased by 50 mm when the outer diameter of the coil is the same and the volume of the core is reduced by 48%,and the efficiency of the coupling mechanism is increased by 25.36% when the offset is 210 mm. |
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