Wireless Power Transfer System Using Magnetic Coupled Resonant

Wireless power transmission transferred by magnetic and electric fields is a new kind of power transmission technology. It consists primarily of three ways: magnetically coupled resonance, electromagnetic induction coupling type, microwave type. Compared with the latter two, magnetically coupled resonant wireless energy transfer exhibit good characteristics in intermediate distances, medium power terms and it has important theoretical and practical value.In this thesis, magnetically coupled resonant wireless power transfer was modeled. Through the study of different transmission distances of two-coil efficiency indicator cannot evaluate the system fully. We put forward a comprehensive evaluation index: the product of efficiency and distance. Transmission distance of two-coil system is optimized based on the comprehensive evaluation index. With different transmission distance between the two coils, the index put forward can make the system to achieve a high level of transmission efficiency and distance.In this thesis, the influence of load changes on the system performance was discussed. Through analysis of the system model, the changes of the load will reduce system performance. In order to weaken the adverse effects of changes in load on the system, the DC / DC converter was introduced into E2 transmission structure. The duty cycle modulation enable different load resistors to match to the system’s optimal load resistance. With the modulation, output power and efficiency of the system can be maintained at a relatively high level of transmission.When the load changes in order to reduce system complexity and maintain the system work, the class E inverter is designed improvely. By the analysis of MOSFET voltage waveform, when choke and MOSFET shunt capacitor resonant at 1.5 times the system operating frequency, the waveform is less affected by load variations. So MOSFET continue to maintain soft switching and circuit can maintain work normally.The contents of this study were verified by the simulation results. Two-coil distance transmission characteristics test is designed, based on the comprehensive evaluation, the distance is 45 centimeters and the efficiency is 60%. Comparison between experiments with and without impedance matching network were designed, the performance of the former was significantly better than the later. The improved class E inverter compared to ordinary E class inverter can maintain normal operation during load changes were verified.