Design And Development Of The Inductively Coupled Power Transfer System For Electric Vehicle

With the shortage of fossil fuels and the deterioration of the earth ’s natural environment,this phenomenon has been worsened by the large-scale fuel vehicles and the exhaust gas they produce.Electrical energy gradually replaces the status of fossil fuels as the main driving energy of automobiles.Driven representative green transportation has great potential for development.At present,the transmission of electric energy in electric vehicles is mainly based on wire transmission,but wired transmission has great disadvantages: charging equipment occupies a lot of space for use;inconvenient to use when connecting and bulky structure;after long-term use of the plug-in wear,it may induce leakage of electricity;when the cable is aged and exposed to harsh environments such as rain and snow,it is also likely to cause hidden safety hazards.Wireless power transfer(WPT)technology,as a frontier research field of pure electric vehicles,can make up for the disadvantages of wire transmission to a certain extent.It has the advantages of convenience,safety,no sparks and risk of electric shock.The influence of the conditions is small,and the use is flexible and convenient to facilitate the transmission of electric energy,which is beneficial to the use and popularization of electric vehicles.To this end,this thesis,funded by the National Natural Science Foundation of China(No.51675258)and the Jiangxi Science and Technology Support Project(No.20141BBE50021),has focused on the LCC compensation-based electric vehicle inductively coupled wireless transmission system.First,it introduces the different implementation methods of WPT technology and the current research status at home and abroad,and discusses the inductive wireless energy transmission system most suitable for electric vehicles.Through the establishment of the equivalent circuit model of the loosely coupled transformer,the difference between it and the traditional tightly coupled structure is obtained.Then,the four basic resonance topologies of the magnetic induction coupling type are analyzed.Based on the conclusion of the typical structure,the double LCC compensation system characteristics of the resonant network are analyzed,and the effects of various parameters of the wireless transmission system on the system power and transmission efficiency under the compensation state are discussed.Secondly,the finite element electromagnetic simulation software is used to design the loosely coupled structure in the inductively coupled charging system.Because the layout of different loosely coupled structures will have different effects on the entire system,in order to ensure the efficient operation of the system’s transmission capacity,this thesis adopts The process optimization of the simplest circular loose-coupling structure in the loose-coupling structure is carried out.The three-dimensional finite element electromagnetic simulation software Ansoft is used to establish a structural simulation model.According to the optimization process,the coupling coefficient of the loose-coupling structure is used as the reference standard.From the coil diameter and coil The number of turns and the arrangement of the magnetic core are loosely coupled structural parameters,which are simulated as optimization goals.After the optimization is completed,a circular electromagnetic coupling structure with a diameter of 500 mm is designed.By comparing the simulation data,it has the characteristics of high coupling coefficient and strong anti-offset ability.Then,the circuit components of the wireless power system are analyzed,and the circuits composed of different structures are listed.The advantages and disadvantages of different highfrequency inverter circuits are compared from the aspects of circuit device performance,transmission power level and economy.Establish the high-frequency inverter circuit at the transmitting end,select the appropriate rectifying and filtering circuit at the receiving end in the context of electric vehicle use,and finally complete the main circuit structure of the entire system.Finally,combined with the analysis of the mutual inductance model,complete the circuit topology design and equipment selection of the system topology,and then complete the fieldcircuit coupling joint simulation of the entire wireless charging system based on Simploler and Maxwell to obtain the transmission power and transmission efficiency of the system.On the basis of simulation,a bilateral LCC wireless charging prototype with an output power of 500 W was scaled down to complete the load and coupling coefficient characteristic experiment to verify the feasibility of the system design scheme.The prototype works steadily.The transmission efficiency of the system is about 80% after the load battery pack is connected.It is similar to the trend of the simulation results.It verifies the rationality of the circuit parameter optimization design and the feasibility of the loose coupling transformer optimization scheme.