Compound wireless power transfer topology for two stage charging of batteries

Wireless power transfer (WPT) for battery charging application is gaining popularity due to its advantages compared to conductive charging. Batteries have to be charged in two modes i.e. Constant Current (CC) and Constant Voltage (CV) modes which replicates variable load. Proper design of WPT for variable load is important task due to its dependency on coil coupling characteristics, frequency and loading profile. This paper proposes a compound topology which ensures CC and CV as per the battery charging profile. LCL-S topology with switched capacitor is used to realize CC and CV outputs. Analytical study of LCL-S for CC and CV output is carried out and strategy to switch between two modes is presented. At the end, the proposed topology and the mode switching are validated through simulations.