Analytical Study on the Performance of a Hybrid Inductive-Capacitive Wireless Power Transfer System

Inductive wireless power charging applies the magnetic field to transfer power from one coil to another. In contrast, capacitive wireless power transfer uses the electric field as medium. Both technologies offer distinct advantages and challenges, but a common requirement is the need for resonance to achieve high efficiency, necessitating the use of inductors and capacitors. By combining both electric and magnetic fields, hybrid wireless power transfer systems can use the benefits of both technologies, resulting in improved power density. Despite this potential, research on hybrid systems remains limited. To evaluate this technology, analytical expressions for the transferred power and efficiency are crucial. This work derives expressions for the three gains (operational power gain, available gain and transducer gain) of a general series-connected hybrid system, based on a two-port network approach. Optimal terminations for the system are determined to maximize efficiency or power transfer. The analytical results are validated by electrical circuit simulations.