Eliminating DC/DC Converter in LCC-S Compensated WPT Systems with a Switch-Controlled Capacitor for CC-CV Charging

In this paper, a wireless power transfer (WPT) system employing an LCC-S compensation network is investigated for battery charging applications. Instead of using a conventional DC/DC converter for output regulation, we propose replacing the secondary-side compensation capacitor with a switch-controlled capacitor (SCC) to achieve constant current-constant voltage (CC-CV) charging. This novel approach leverages the SCC's variable capacitance to adaptively regulate the system output, thereby eliminating the need for additional bulky regulation components while incurring only slight efficiency degradation. We analyzed the detuning characteristics of the LCC-S compensated WPT system and proposed an effective SCC-based output control scheme. The simulation results demonstrate that the use of the SCC enables the desired CC-CV charging profile, with the average charging efficiency being only 0.41% lower than that of the Buck converter-based approach, demonstrating its potential for efficient and compact WPT systems.