Analysis and Design of Optimal Power Transfer Mode in Domino Wireless Power Transfer Systems Utilizing Cross Coupling

Domino wireless power transfer (WPT) systems can achieve insulated power transfer in the high-voltage environment. However, due to the increase of coil number, the complex cross-couplings among coils make it difficult to design a fine-tuned and high-efficiency system with constant voltage (CV) output and zero-phase angle (ZPA) input characteristics. Therefore, this article proposes a design method for domino WPT systems with an arbitrary number of coils to achieve CV, ZPA, and optimal efficiency simultaneously. The frequency of the domino WPT system and the compensation capacitors are adjusted to satisfy the CV and ZPA conditions, which allows the system to operate in three different modes. The circuit characteristics and power transfer efficiency of the three modes are analyzed and compared. Based on the analysis of the three operation modes, this article further proposes an efficiency improvement design method for domino WPT systems. To validate the theoretical analysis, two prototypes of 13-coil and 8-coil domino WPT systems were designed and built. The experimental results indicate that both prototypes achieve CV output and ZPA input, with maximum dc–dc efficiency of 81.52% at 1.2 m and 85.27% at 0.7 m transfer distances.