Shifting Maximum Efficiency Point Tracking and Battery Model to the Primary-Side Control of SS-Compensated Wireless Charging Systems

Shifting optimal performance control to the primary side of wireless power transfer (WPT) systems represents a significant paradigm shift in next-generation WPT technologies. This paper focuses on enhancing energy efficiency throughout the entire battery charging process by employing primary-side control. Frequency modulation and load-matching control are managed on the primary side. Particularly, the battery load is accurately monitored and modeled on the primary side with special attention to critical low-equivalent load resistance starting at 1 Ω to represent fast charging. The proposed scheme is particularly well-suited for fast-charging applications that demand simple and lightweight receiver circuits, such as medical implants, mobile phones, and drones. Its effectiveness has been practically validated in three Series-Series (SS) compensated WPT systems, delivering 5 W, 15 W, and 130 W, respectively. Sensitivity analysis demonstrates that the method provides rapid tracking speed and strong resilience to parameter variations. Both sensitivity analysis and practical evaluations confirm the scheme’s capability to achieve accurate output tracking and high energy efficiency across the entire charging process. The maximum dc–dc efficiency reaches 94.3%.