An improved auxiliary circuit for IPT systems to achieve inherent CC‐to‐CV transition and load fault‐tolerant operation

• Published in: IET power electronics Vol. 17; no. 10; pp. 1324 - 1335
• Main Authors: Ren, Sheng, Yang, Ping, Wang, Xiaoqiang, Xu, Jianping
• Format: Journal Article
• Language: English
• Published: Wiley 01.08.2024
• Subjects: DC‐DC power convertors; power conversion
• ISSN: 1755-4535; 1755-4543
• DOI: 10.1049/pel2.12531

Three‐coil inductive power transfer (IPT) charging system can not only achieve inherent constant current (CC) to constant voltage (CV) transition but also tolerate load open‐circuit. However, due to the cross‐coupling between the auxiliary coil and the receiver coil, the output voltage in CV mode may deviate from the CV voltage significantly, which makes the design freedom of the three‐coil coupler low. By replacing the auxiliary coil with a transformer, an improved auxiliary circuit is proposed in this paper to address the cross‐coupling issue and to increase the design freedom of the loosely coupled transformer (LCT). The improved auxiliary circuit can achieve load short‐circuit and open‐circuit protection. Besides, the optimization design of LCT is easy to achieve by load impedance matching. The operating principle and parameters design of the improved auxiliary circuit are discussed. A 1 kW experimental prototype is built to verify the feasibility of the proposed method. By replacing the auxiliary coil with a transformer, an improved auxiliary circuit is proposed here to address the cross‐coupling issue and to increase the design freedom of the loosely coupled transformer (LCT). The improved auxiliary circuit can achieve load short‐circuit and open‐circuit protection.