Research On The Characteristics Of Magnetically Resonant Coupled Wireless Power Transfer

As a new technology of wireless power transfer, wireless power transfer using strongly coupled magnetic resonance(WPT/SCMR)has lots of advantages compared to traditional wireless power transfer, which includes mid-range transfer distance, higher transfer efficiency, transferring through obstacles and so on, it provides a convenient and efficient way for electronic devices and implants. WPT/SCMR is of great importance in theoretical research and application.The hotspot of WPT/SCMR system were transfer efficiency and transfer distance. In the thesis, circuit models were built for two/four coils systems, and theoretical analysis,simulation and experiments were performed to get the conclusion for designing the WPT/SCMR system.First, the series and parallel circuit models of two coils WPT/SCMR system were built, and the conditions of impedance matching were proposed. The effects of the loaded quality factor to the transfer efficiency were also analyzed, and the reasons about the low transfer efficiency of two coils WPT/SCMR system were explained. Then, the circuit models of four coils WPT/SCMR system were also built for high efficiency. What's more,the differences of the maximum transfer efficiency and transfer distance among series resonant system, parallel resonant system and drive coil and load coil detuning system were discussed. The results showed that the transfer efficiency was the highest when the model was series resonant, and the transfer distance was the longest when the driver/load coil was detuned. Next, the influences of the driving frequency and coupling coefficient on series model system's transfer efficiency based on four coils were analyzed. It indicated that the impedance could get rematched by adjust the driver frequency andcoupling coefficient. The influences of the inductance of the driving coil and load coil on transfer efficiency were also discussed.Finally, to verify the correctness of the analyses of the system, WPT/SCMR based on four coils were designed, and the experimental results were coincided well with the theoretical analysis, the conclusions were of great importance for improving the performance of the WPT/SCMR system.