Research On Inductively Coupled Power Transfer System

The inductively coupled power transfer (ICPT) system technology has become an importanthot research object because of the prominent advantages in the low power applications. This paperintroduces the main modules and the operation principle of the ICPT system in detail, andresearches the selections of the topology and chips for the power conversion circuit with providingthe corresponding bases. After building the equivalent model of the inductive coupling transformer,the measurement method of the transformer induction coupling coefficient is discussed. Andthrough the analysis of four compensation topologies of the system harmonic compensation circuit,the conclusion that the voltage ICPT system is superior to the current in the aspect of the loadadaptability is obtained.The stability of the voltage ICPT system is researched, and the boundary condition of avoidingthe frequency bifurcation is provided. The calculation formulas of the ICPT system output powerand efficiency are deduced, which proves the system output power and efficiency are affected bythe mutual inductance coupling parameters, and a new type of comprehensive evaluation indexsystem is proposed. Based on the index, the optimized system mutual inductance couplingparameters could increase the transmission performance of the voltage ICPT system efficiently. Andwith the simulations, the above results are proved to be correct.The paper presents the detailed discussion about the constant voltage output control strategyfor ICPT system in the time of dynamic load. Based on the analysis of the merit and demerit of thetraditional control strategies, and in order to avoid the complicated deduction of the transferfunction for the non-linear system, a new type control strategy based on the energy control, that ispower supply and self-circulation, is proposed. After analyzed the operating principle of this controlstrategy, the equivalent mathematic model is built. And through the control of the operation timeratio of the power supply mode and the self-circulation mode, the constant voltage output of thesystem is achieved. Using the Matlab/Simulink to build the system models, the effectiveness of theproposed method is verified with the simulations.Last, taking the design principle of the inductive coupling system applied on the cell-phonecharger as an example, the model of the power switch in the system high frequency inverter circuitis selected and the drive circuits are designed. For the system harmonic compensation unit, thepaper shows the topology selection and the parameter calculation. And With the DSP （TMS320F2812）as the main controller, the hardware design and the production debugging of thesmall power induction coupling power transmission system is completed and the control software isprogrammed. Meanwhile, some physical circuits and test results are provided.