A Novel Clamp Coil Assisted IPT Battery Charger With Inherent CC-to-CV Transition Capability

Abstract

A constant current (CC) output followed by a constant voltage (CV) threshold is usually needed for an inductive power transfer (IPT) charger to comply with the battery charging profile. This letter proposes a novel clamp coil assisted IPT battery charger that features inherent, passive, automatic, and smooth CC-to-CV transition. Since the CC-to-CV transition eliminates the necessity of state-of-charge detection, wireless feedback communication, and active control, the proposed IPT charger is rugged and reliable. The inherent CC-to-CV transition capability also tackles the open-circuit risk during a CC charging process. As minimalist design is achieved in the secondary, the proposed IPT charger is suitable for wireless onboard charging applications. Near-unity power factor design is also considered to minimize the voltage-ampere rating and permits soft switching. Experiment results validate the inherent CC-to-CV transition capability.