A 45-W Two-Stage Wireless Fast Charger Using Unregulated Inductive Power Transfer
Peng Zhao, Guangce Zheng, Rong He, Yu Liu, Minfan Fu
Abstract
Most of the existing wireless offline chargers would employ redundant power conversion and isolation stages to charge a low-voltage battery, which leads to limited overall efficiency. In order to address the redundancy issue, this article proposes a wireless fast charger by using a two-stage configuration. An unregulated inductive power transfer (IPT) stage can not only offer galvanic isolation, but also provide high step-down voltage ratio, and then, only a simple buck converter is needed for voltage regulation. This article evaluates the influence of voltage gain on efficiency and voltage stress of an LCC-C compensated IPT stage. The zero-voltage-switching (ZVS) lost mechanism is also studied and evaluated by a proposed ZVS model. Finally, a 45-W fast charger prototype is designed for 264-V/12-V conversion. The measured peak efficiency is 78%, which is much higher than the Qi-based charger.