Research On Inductively Coupled Wireless Power Transfer With LCC/S Compensation Topology

Inductively Coupled Power Transfer(ICPT)is an active research direction in the fields of power electronics in recent years.It has the advantage of convenience,safety,low-maintenance cost,high reliability and strong adaptability to the environment,thus gaining more and more attention.Because the conventional model of fully coupled transformer is not applicable in the ICPT system,the paper firstly derives the T model and controlled-source model based on the law of electromagnetism and flux destribution,whose parameter measurement methods are also presented.Secondly,based on theorem of the maximum power transfer,a quantitative method is proposed to measure the energy transfer capacity of loosely coupled transformer.Finally,the mothod for optimization design of coils and cores are also introduced based on finite element simulation.An LCC/S high-order compensation topology is proposed based on the symmetric T-circuit and S compensation.Compared with the conventional compensation topologies,the proposed topology has wider output regulation range,lower sensitivity of the resonant components,and higher system efficiency.Firstly,the paper uses the fundamental impedance method to analysis the characteristics of LCC/S topology,such as input impedance and output gain.An asymmetric processing method is indroduced to achieve zero voltage soft switching,which can reduce the swiching loss and increase the efficiency of the system.And the influence of highorder harmonics produced by the inverter is discussed.The topology has strong inhibitory ability on harmonics,so it can reduce radio EMI problem in ICPT.Because the conventional Space State Averaging method is not applicable in modeling of resonant converter,the small signal modelling of ICPT system is based on the Generalized State-Space Averaging(GSSA)method.A preceding-satge Buck converter is established to adjust the output voltage on load accurately;a reasonable digital controller is designed,thus realizing the closed-loop control of the system.Finally,according to the theoretical calculation results,an ICPT prototype is built.In the case of 50 mm air gap,the 400 W wireless power transfer is achived,whose efficiency reaches 88.6%.