A Multi-receiver Wireless Power Transfer System Using Self-oscillating Source Composed of ZVS Full-bridge Inverter

Nowadays, much effort focuses on research for the multi-receiver WPT system based on magnetic resonance. However, its output characteristics are significantly deteriorated by the variation of transfer spacing, loads, and cross-couplings, which exerts harmful effects on the performances of cascading bucks before loads if needed. Inspired by the work of a single-receiver WPT system based on the parity-time-symmetric model, in this paper, the self-oscillating source is first applied to the multi-receiver WPT system to tackle these drawbacks. Based on the coupled-mode theory, the proposed system's modeling is established and deduced to analyze its performance. The model analysis shows how the system can achieve zero-voltage switching simply via choosing the minimum dead time and leading time whose calculation method is provided. Meanwhile, a transmitting coil for a uniform magnetic field is designed to improve the free-positioning performance. The analysis is validated on a 36 W prototype, including the effects of the variation of transfer spacing, cross-couplings, and loads on the output characteristics, efficiency, and operating frequency. The proposed system is demonstrated to provide a much more robust power transfer than the conventional magnetic-resonant multi-receiver WPT system, which helps extend the transfer distance and improve the system efficiency.