Deviation Detection For EV-DWPT Based On A Three-Coil Synthesis Algorithm

One of the biggest bottlenecks in the promotion and application of electric vehicles is the fast,convenient and reliable charging mode of electric vehicles.Wireless Power Transfer(WPT)technology provides a good solution for the power of electric vehicles.WPT for electric vehicles is flexible,convenient,safe and reliable.It is divided into Static(parking)Wireless Power Transfer for electric vehicles(EV-SWPT),and Dynamic(no stop)Wireless Power Transfer for electric vehicles(EV-DWPT).This paper focuses on the research of EV-DWPT system.As the EV-DWPT system,the energy launch rails are usually placed under the ground.When electric vehicles operate on the electrified rails,the electric vehicles often deviate from the rails so that resulting in instability of dynamic power supply and shortage or loss of power supply in the vehicle.So,designing a reasonable deviation detection device for vehicles can provide the driver with the deviation state information of the electric vehicle and rails.So that the electric vehicles can run better on the magnetic field launching rails and pick up the electric energy steadily.The traditional method of electromagnetic guided technology is designed for path tracking with a single conductor or magnetic nails.For the EV-DWPT system based on the energy launching rails,this method cannot realize well the deviation state detection.At present,there are few research literatures on the deviation detection of Wireless Power Transfer for electric vehicles.In order to satisfy the requirements of the system,it is necessary to get the deviation state information of vehicles and rails in real time.The deviation state information include the direction and degree of deviation.To solve these problems,a novel deviation state detection method for the EV-DWPT based on a three-coil synthesis algorithm was proposed.The main contents are as follows:(1)Based on the analysis of various location sensing methods and the analysis of the special requirements of EV-DWPT,the wireless powered deviation state detection technology based on electromagnetic induction is selected and used in this paper.(2)Studying and putting forward three circular detection coils with the same parameters are placed horizontally under the electric vehicles' chassis.They form a kind of "alpha-isosceles right angled triangle" deviation detection mechanism model,and all kinds of parameters which belong to detection coils and detection mechanism are designed.Combined with the engineering application and theoretical analysis,the right angle length of the "isosceles right angled triangle" detection mechanism can be equal to the width of the rails.The size of the alpha angle is only related to the placement height of the detection mechanism and the width of the rails.(3)Considering the practical application,in order to make the deviation detection method and the principle more universal,this paper uses the voltages induced in three small pick-up coils as the foundation of deviation detection.Combined with theoretical research and experimental analysis,the variation trend of the voltages,which are induced in three small pick-up coils in the driving process of the electric vehicle,can be obtained.By analyzing the variation trend of the voltages,the deviation information of the electric vehicles can be determined.(4)Fuzzy algorithm is used as deviation detection algorithm in this paper.Based on the detection principle,and synthesized and analyzed the pick-up voltage of the three small coils,direction and degree of deviation between electric vehicles and rails can be determined in real time.(5)Experimental results are well consistent with the theoretical analysis,which shows the right and effectiveness of the proposed method.Thus provides an effective way to realize that electric vehicles can run better on the predetermined rails and pick up electric energy steadily.It has strong academic and practical significance for the efficient wireless power acquisition and the full use of energy for the wireless power transfer technology.