Research On Class E Amplifier For Wireless Power Transfer System

As new power supply technology,Wireless Power Transfer?WPT?technology has been widely researched in recent years.Compared with traditional power transfer mode,WPT has the advantages of high flexibility and safety.It is suitable for power supply in transportation,medical equipment,mobile communication and special occasions.Firstly,this paper introduces the research background of WPT.Several kinds of commonly used high frequency inverters circuit are studied and analyzed about their advantages and disadvantages in this paper.Class E amplifier adopts single switch,which has simple structure and can realize soft switching.Under the condition of high frequency operation,its efficiency is much higher than other inverters.In this paper,class E amplifier and its improved form are used as high frequency inverters of WPT system.The working principle of class E amplifier is analyzed.The operation process of class E amplifier is deduced in detail through theoretical calculation.The relationship between the switching stress and power output capability of class E amplifier and duty cycle is obtained.The parameters designing of class E amplifier is given under the condition of duty cycle of0.5.Several common impedance matching networks of load are analyzed for the load variation of class E amplifier.The DC inductor and series resonant inductor of class E amplifier are coupled by a separable transformer.A transformer class E amplifier is proposed,which reduces the number of independent inductive components.The operation process of transformer class E amplifier is analyzed in detail,and the relationship between working performance and main parameters is obtained.To solve the problem of high voltage stress of switch in class E amplifier,class EF₂amplifier is analyzed.The working process is deduced,and the relationship between working performance and duty cycle is obtained.The parameters designing process is given under the condition of maximum power output capability.The class E amplifier,transformer class E amplifier,class EF₂ amplifier are simulated and analyzed using LTspice IV simulation platform,and then the experimental verification is carried out.Finally,the experimental study of WPT system is carried out.Planar coils used as coupling mechanism are made by litz line.Two calculation methods of the coupling coefficient are given when the coupling coefficient is low.The series compensation WPT systems based on class E amplifier,transformer class E amplifier and class EF₂ amplifier are analyzed.The experimental platform of the WPT system is built.The experimental verification is carried out.