A 45-W Two-Stage Wireless Fast Charger Using Unregulated Inductive Power Transfer

• Published in: IEEE journal of emerging and selected topics in industrial electronics (Print) Vol. 2; no. 3; pp. 287 - 296
• Main Authors: Zhao, Peng, Zheng, Guangce, He, Rong, Liu, Yu, Fu, Minfan
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Batteries; Buck converters; Charging; Efficiency; Electronic devices; Energy conversion; Evaluation; Fast charger; high step-down voltage ratio; high-order resonance; Power transfer; Redundancy; Regulation; Stress; unregulated inductive power transfer; Voltage control; Voltage gain; Wireless communication; Zero voltage switching; zero-voltage-switching (ZVS) model
• ISSN: 2687-9735; 2687-9743
• DOI: 10.1109/JESTIE.2021.3061959

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.