Investigation Of Transmitter And Receiver In Wireless Power Transfer

With the development of the resonance wireless power transfer(WPT),transmitter and receiver have already become crucial parts of the system.Once transmitter and receiver are not working at the critical coupling point,the efficiency of the system will decrease.When transmitter is working too far from receiver,efficiency drops due to the weak coupling.On the contrary,if they are working too close,frequency splitting occurs which leads to low transfer efficiency.Meanwhile,more equipments need data transmission as well as power transmission.To meet these demands,this paper focuses on the themes of efficiency,operating frequency and frequency splitting.The main work can be summarized as follows in three parts:1.Efficiency-enhanced wireless power transfer based on multiple coupling paths.Firstly,theoretical analysis of a conventional WPT system is carried out.Based on the analysis,a novel scheme is proposed with dual resonators at both transmitting and receiving ends.In this case,multiple coupling paths are introduced,thereby improving the overall efficiency.The advantage of the proposed WPT system is verified by means of closed-form equations.For demonstration,a prototype WPT system is implemented on PCB.The simulated and measured results are presented and these attained results exhibits efficiency enhancement.2.Dual-band wireless power transfer.This paper presents two types of dual-band wireless power transfer with different operating principles.Based on equivalent scheme,frequency analyses are carried out.The first kind of system employs two resonant coil to extract dual band.Power of each band is transferred by its own resonator between transmitter and receiver.The other WPT introduces lump elements to extract dual band with one single resonant coil.For demonstration,two types of dual-band wireless power transfer are implemented on PCB.Good agreement between the simulation and measurement results validates the proposed methods.3.Distance-insensitive wireless power transfer using mixed electric and magnetic coupling for frequency splitting suppression.When the transmitter and receiver get close,both magnetic and electric couplings increase.However,the overall coupling strength can be kept nearly unchanged due to the electric and magnetic coupling cancellation.Thus,frequency splitting can be suppressed.Based on the analysis,the mixed electric and magnetic coupling scheme is introduced and characterized.After that,a WPT prototype is designed using copper wires and copper loops.In the design,the magnetic coupling and electric coupling coefficients are extracted by using a new method.It indicates that stable coupling strength can be realized at different separation distances.Finally,a high-efficiency WPT system with distance-insensitive characteristic is implemented and the results are presented.