Multi-Level Power Output for Wireless Power Transfer System Based on Hardware Reuse and Inverter Mode Selection at Primary Side

To satisfy the requirements of multi-level power output in wireless power transfer (WPT) systems, this paper proposes a multi-level power regulation strategy based on primary-side hardware reuse and inverter mode selection. The proposed approach reduces hardware complexity and control difficulty under diverse power demands, while eliminating the performance degradation of inverters induced by wide-range duty-cycle modulation. In this study, the configuration of the established system is first presented. Maintaining the inherent output connection of the full-bridge inverter, two operational modes realized via power device gating control are analyzed and deduced. On this basis, an analytical circuit model is constructed for the multi-level power output system incorporating primary-side hardware reuse, and the corresponding static characteristics of the system are investigated. Combined with the application of receiving coils with different specifications, a refined multi-level power output scheme relying on inverter mode selection is further formulated. Finally, experimental validation demonstrates that the prototype system achieves four discrete power levels simply through primary-side hardware reuse and mode switching, without modifying circuit connections or adjusting duty ratios. The maximum received power under each level reaches 405 W, 212 W, 101 W and 51 W, respectively; meanwhile, the corresponding DC–DC efficiency is maintained at 92.6%, 91.5%, 92.3% and 90.92%.