A Hybrid Wireless Power Transfer System with Constant and Enhanced Current Output Against Load Variation and Coupling Misalignment

Inductive power transfer (IPT) and capacitive power transfer (CPT) are two of the most commonly used near-field wireless power transfer (WPT) technologies, and these two systems share similarities and symmetries. This paper proposes a hybrid wireless power transfer (HWPT) system to achieve load-independent characteristic and anti-misalignment capability. The HWPT system utilizes the compensation inductors of the CPT system to create an additional inductive channel in which the capacitive and inductive channels are compensated for each other. Based on the modeling of the HWPT system, the load-independent and enhanced constant current (CC) output is derived. In HWPT system, the inductive coupler is employed with the capacitive coupler, which forms a compact hybrid coupler. As the coupler becomes misaligned, the loss of power transferred through the inductive channel can be compensated by the increase of power transferred through the capacitive channel. A 200 W experimental prototype is built to validate the performance of the HWPT system. Experimental results show that as the load resistance ranges from 20 to 40 \Omega and the coupling misalignment ranges from 0 to 100 mm, the output current remains nearly constant and the input current stays in phase with the input voltage. According to the experimental findings, the output current of the HWPT system is approximately twice as high as that of the CPT system when using the same capacitive coupler.