A Novel LCC-S Compensated Inductive Power Transfer System with Inherent Constant Current and Constant Voltage Charging

The inductive power transfer (IPT) system offers enhanced safety, convenience, and flexibility for battery charging compared to plug-in systems. The battery requires an initial charging mode of constant current (CC) followed by a subsequent charging mode of constant voltage (CV). To realize it, a novel LCC-S compensated IPT system is proposed in this paper. The proposed topology is equivalent to the conventional S-S topology in CC mode and to the novel LCC-S topology in CV mode as the equivalent resistance of the battery increases. The topology switching is automatic. Consequently, inherent CC and CV outputs can be achieved without the necessity for wireless communication, output sampling circuits, ac switches, additional components, or feedback control circuits, improving system reliability and reducing system cost. Besides, there is a simple two-coil structure to mitigate the issue of cross-coupling, and single capacitor compensation is achieved at the receiver side to facilitate the lightweight charging devices. The automatic switching of the proposed topology is analyzed, designed, and then validated through a laboratory prototype with an output of 48 V/2 A.