Research On LCL-type Inductively Coupled Power Transfer System

Inductively Coupled Power Transfer (ICPT) technology realizes the power transfer based on the electromagnetic induction principle.Because there is no physical contact between the power sender and the power receiver, ICPT technology has a great advantage in rail transit, underwater, mine shaft, biomedical and other special power-supplying fields.The study on ICPT technology in this paper included the following aspects:Firstly, the basic principle and system structure, the commonly used voltage source inverter and current source inverter of the conventional ICPT system are studied.In addition, the mutual inductance model and the leakage inductance model of the loosely coupled transformer are analyzed.Besides, the four kinds of bilateral compensation topologies based on LC resonance are introduced,and the parameter setting methods,compensation characteristics and the frequency bifurcation phenomenon of the four kinds of topologies are analyzed. Analysis results show that the traditional LC type compensation topologies have some defects when supplying power for load which changes frequently and multiple loads.Secondly,the constant current output characteristic,resonance frequency load independence,unity power factor input characteristic and low pass filtering properties of LCL resonant converter are analyzed.Futhermore, the topology and equivalent model of ICPT system based on LCL resonance compensation are studied.In addition, the parameter setting method and performance characteristics of LCL-type ICPT system are analyzed.Besides,the correctness of the theoretical analysis is verified by simulation.Analysis results show that LCL-type ICPT system has a great advantage when supplying power for load which changes frequently and multiple loads due to these characteristics of itself.Thirdly,the topology structure and mathematical model of ICPT system based on LCL parallel resonant compensation are studied.Meanwhile,the distribution of inverter bridge output current,active power and reactive power among modules and the change of primary winding current are analyzed when the system working at parameter balance,inverter bridge output voltage amplitude imbalance,inverter bridge output voltage phase imbalance and resonant inductance imbalance.Analysis results show that the parallel system has a strong inhibitory effect on uneven distribution of inverter bridge output current,active power and reactive power among modules caused by parameter imbalance.Besides,the phase shift control method for the parallel system is studied in order to control the primary winding current.Finally,a experimental circuit of LCL-parallel-type ICPT system consists of two modules is designed and built.Meanwhile, the working characteristics of system are verified by experimental results when the system working at parameter balance,inverter bridge output voltage amplitude imbalance and inverter bridge output voltage phase imbalance.