An Efficient Hybrid Wireless Power Transfer System with Less Gain Fluctuation

This paper proposed a hybrid wireless power transfer (HWPT) system that combines inductive power transfer (IPT) and capacitive power transfer (CPT). The HWPT system is advantageous in that it is not sensitive to pressure change compared with conventional CPT system. Compared with IPT system, the HWPT is superior with higher efficiency. The advantages of both IPT and CPT are utilized and the shortcomings of them are tactfully avoided. For the applications like the wireless charging of laptop, pad or drone where both IPT and CPT is realizable, it is desired to charge with HWPT system since it offers better charging robustness and system efficiency. In this paper, the gain characters of CPT, IPT and HWPT are analyzed firstly, the design guideline is presented next, then the simulation and experimental study is given to evaluate the proposed solution. A 40W, 6.78MHz prototype using GaN device is designed and implemented to evaluate the feasibility as well as the advantages of the proposed system. The experiment results show that the open-loop output voltage of HWPT fluctuates from 20V to 28V while conventional CPT fluctuates from 4V to 22V refers to the same level of change in pressure, thus the system is much less sensitive to pressure change and at the same time a relatively higher system efficiency is achieved.