Operating characteristics of four-coil magnetic resonant coupling wireless power transfer under different resonant states

In wireless power transfer, the transfer efficiency decreases with the increase of the transfer distance. To improve the power transfer performance, the operating characteristics of a conformal coplanar four-coil magnetic resonant coupling wireless power transfer system are investigated and analyzed under four different resonant states. Based on the complete equivalent circuit model, the transmission coefficient and the input impendence are calculated. The performance of the systems operated under four resonant states is studied and compared. Also, the origin of the difference is specifically analyzed. The simulation results indicate that the wireless power transfer system operated under State 1, the state where the compensated serial capacitance makes the coils work at the frequency of the maximumQ-factor, shows the most excellent transfer characteristic among the four resonant states. The transmission coefficient can be well maintained above 0.8 within the transfer distance of 30 cm. Experiment has been carried out for validation, and the result indicates that more power can be delivered to the load for the system operated under State 1.

Automated summary

By investigating the operation characteristics of a conformal coplanar four-coil magnetic resonant coupling wireless power transfer system under four different resonant states, it is found that operating under State 1, where compensated serial capacitance allows coils to work at the frequency of maximum Q-factor, shows the best transfer characteristic. The transmission coefficient can be maintained above 0.8 within a 30 cm transfer distance, indicating better power delivery to the load compared to other states.