Characteristics Analysis of Resonant Topology in Three-Phase Wireless Power Transfer Systems Considering Star-Delta and Neutral Point Connections

Three-phase wireless power transfer (WPT) systems have the advantages of higher power density and low power fluctuations. However, increasing the number of phases complicates the resonant topology structure of the system. Existing research lacks analysis of the unique electrical characteristics of three-phase resonant topologies, particularly regarding the star-delta and different connections of inductor and capacitor neutral points. This article derives the expressions for the resonant capacitance of first-order and second-order topologies under star-delta connections. After contrasting the voltage stresses on resonant components and system transmission characteristics under different star-delta connections, the suitable application scenarios for each connection method are provided. Utilizing the symmetrical component method, expressions for the voltage of inductor and capacitor neutral points under star connection are derived, and then the optimal neutral point connection topology for both balanced current control and independent current control scenarios is proposed. Finally, an experimental prototype is constructed to validate the theoretical analysis presented in this article.