Research On The Magnetic Coupler For Electric Vehicle Dynamic Wireless Charging

Based on the inductive dynamic wireless power transmission technology(DWPT),the electric vehicle(EV)can be charged in the road section,which can greatly save the charging time of the EV.The bottleneck of DWPT technology is the design of the magnetic coupler,which determines the core parameters of wireless power supply such as system power level,anti-offset capability and transmission distance.The existing DWPT is mostly a small power experimental prototype,and its structure is transformed into a high power prototype,which has problems such as insufficient power density and magnetic saturation.Magnetic couplers that are dominant in power density and transmission distance are currently staggered pole-type structures.In the staggered magnetic pole type magnetic coupler,the bipolar magnetic coupler has the advantages of simple structure and stable control.In the DWPT system,especially in the small-size platform of the car,the main problem of the staggered magnetic pole type magnetic coupler is that the power fluctuation is large,and the system stability and safety are also greatly affected.In view of the above problems,this paper aims to propose a design method suitable for DWPT system and magnetic coupler of EVs.Based on this,a set of high-power wireless power supply system for cars and a magnetic coupler for volatility problems are designed.Design and optimize.The specific work is as follows:Firstly,this paper analyzes and calculates the multi-coil structure,and quantitatively compares the performance parameters such as voltage fluctuation and power fluctuation of single coil and double coil.Based on this basis,the derivation of the general term of the fluctuation coefficient based on the parallel multi-coil structure is performed.And comprehensively compare the requirements and constraints of the magnetic coupler topology from the aspects of fluctuation coefficient,line quantity,loss,size and so on.The selection result has guiding significance for the selection of the receiving end of the magnetic coupler.Accordingly,the actual demand from the receiving end of the DWPT system is designed from the perspective of the magnetic coupler.By designing and optimizing the coil,core structure and topology of the magnetic coupler,power fluctuations are effectively suppressed.Improve system security and stability and reduce system cost.Secondly,aiming at the characteristics of DWPT system,this paper proposes a system structure and magnetic coupler design method with general applicability.The existing design method is solved,the design flow in the sink is not clear,the integrated circuit and magnetic circuit simulation is difficult,the number of simulation and calculation iteration steps is large,and the evaluation parameters of the magnetic coupler design are not clear.Covers the discussion of initial selection of parameters from system design,tradeoffs of core target parameters in optimization,and evaluation parameters.It can effectively improve the design efficiency of the magnetic coupler and has reference significance for the design of medium and small power and static radio energy transmission systems.Subsequently,a design example is given around the DWPT system platform of the electric car platform.According to the requirements of high ground clearance,high power density,low traveling fluctuation,etc.,the system design and magnetic coupler design are carried out according to the above proposed design method..The system design is carried out around the voltage stress and loss under high power application,which improves the practicability of the system.In the end,a DWPT system for electric cars was built.In the power test,a DWPT of 20 kW at 30 kHz was realized,and the magnetic coupler efficiency was 91%,which verified the scientific design of the design.The power fluctuation coefficient was reduced to 0.14,and the three-coil parallel structure was verified to effectively suppress power fluctuations.