A Dynamic Series/Series-Parallel (S/SP) Compensated Wireless Battery Charger with Constant-Current and Constant-Voltage Outputs under Varying Coupling Condition

In this paper, a dynamic series/series-parallel (S/SP) compensation network is proposed to achieve constant-current (CC) and constant-voltage (CV) outputs for battery charging applications. By modulating the switching frequency and the effective value of the compensation capacitance by switch-controlled capacitor, load-independent output voltage and current and zero-voltage-switching operation of the primary bridge can be maintained over varying load and coupling conditions. Due to the extra controllability of the parallel compensation capacitance, the efficiencies in CC and CV stages are analyzed. An experimental prototype with air gap ranging from 10 – 16 cm is built to verify the idea.