Non-full compensation optimized efficiency method for three-coil WPT system with S/S/S topology

TIAN Zihan; WU Xiaokang; ZHANG Xueying; QIU Yue; LIU Dengrui; WEI Bin

doi:10.11860/j.issn.1673-0291.20230109

Abstract：The three-coil structure has proven effective in enhancing the transmission distance of Wire-less Power Transfer (WPT) systems. The S/S/S topology is widely adopted in three-coil WPT sys-tems due to its simplicity and practicality. However,traditional full compensation methods lead to sub-optimal efficiency due to reverse coupling between coils and a single power transmission path. To ad-dress this issue,a non-full compensation method is proposed for parameter configuration in S/S/S to-pology. Firstly,based on the analysis of the traditional compensation method,the reason for the ineffi-ciency under full compensation is clarified. Subsequently,aiming to minimize coil conduction losses,compensation parameters of relay and receiving coils are optimized using nonlinear programming. The optimal compensation parameter for the transmitting coil is determined to reduce power device switch-ing losses. Finally,simulation analysis reveals the characteristics of the system under the proposed non-full compensation method,elucidating the intrinsic mechanisms behind efficiency improvement. Experimental validation is conducted on a three-coil WPT system with 1 kW output power. Experi-mental results indicate that compared to full compensation,the proposed method enhances AC-AC ef-ficiency by 5.813％ and reduces input voltage by 85.3％. Furthermore,compared to relay coil switch-ing,it improves AC-AC efficiency by 4.214％. The proposed method facilitates zero voltage switch-ing of power devices in the inverter,optimizing system efficiency and enhancing the practicality of three-coil WPT systems.