| The Electric Vehicle Wireless Power Transfer(EV-WPT)system is a new type of charging system that enables electric vehicles to be connected to the grid in a wireless(non-contact)manner for charging.It provides a good solution for electric vehicles to achieve convenient,safe and flexible charging access.In the EV-WPT system,the most important and typical component and link is the electromagnetic mechanism whose function is to realize the wireless transmission of energy between the transmitting end and the picking end.The influence factors of the power and efficiency of the electromagnetic mechanism include its structural characteristics and parameters.variable.In practical applications,the pick-up end of the electromagnetic coupling mechanism is prone to lateral displacement due to inaccurate parking position;at the same time,different vehicles will have large deviations in the longitudinal transmission distance.These horizontal and vertical offset problems will inevitably lead to electric vehicles.Reduced efficiency of radio transmission systems and instability in pick-up output power.Therefore,in order to improve the stability of the system’s normal operation,designing a magnetic coupling mechanism for high-efficiency wireless transmission is an important issue that must be solved in the application and promotion of EV-WPT.This dissertation focuses on the lateral and longitudinal offset of the magnetic coupling mechanism of EV-WPT system.Taking a 3.3kW electric vehicle wireless power supply system as an example,first,using the COMSOL electromagnetic field simulation software,a finite element simulation model of the magnetic coupling mechanism was established,and the magnetic field distribution and offset characteristics of the common coil structure were analyzed.A method of group winding coil winding and its parameter optimization design method are proposed.At the same time,the magnetic induction intensity and lateral anti-offset ability of the packet winding coil and the common tight winding coil are compared and analyzed.Secondly,in order to further improve the longitudinal anti-offset capability of the system,a concavo-convex core structure was proposed.For the coil at both ends of the raised core height,the coil at both ends of the raised core length ratio,the length of the core,the core length and width constraints and the core thickness of the main structural parameters,from the mutual inductance and coupling coefficient The angles were analyzed and optimized respectively,and the magnetic saturation characteristics of the magnetic core after optimized thinning were studied to ensure the optimization of the structure of the magnetic core when it is far from the magnetic saturation and the magnetic loss is small.The optimized concave-convex magnetic core structure increases the longitudinal anti-offset capability while reducing the magnetic core volume,achieves better coupling characteristics,and improves system power transmission capability.Finally,on the basis of a comprehensive analysis of coil winding method and core structure design,a hybrid coupling mechanism of “group-sequential coil + concavo-convex core” is proposed,and its magnetic field distribution characteristics,horizontal and vertical resistances are proposed.Parameters such as offset characteristics,mutual inductance,system power,and efficiency were simulated and analyzed.Under the experimental platform,the composite coupling mechanism was made and tested experimentally.The feasibility of the designed coupling mechanism and its advantages in magnetic field distribution and coupling characteristics were verified through simulation and experimental tests,and the coupling mechanism was compared in both horizontal and vertical directions.The anti-drift ability of the system is greatly improved,and it has a good practical application value. |
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