A Comprehensive Parasitic Component Model for Spiral Air-core Coils in MHz Load-Independent Single-input Multiple-output Wireless Power Transfer System

This paper presents an enhanced parasitic component model for spiral air-core inductors in MHz load-independent single-input multiple-output (SIMO) wireless power transfer (WPT) systems. The model improves upon previous designs by incorporating inductance, parasitic capacitance, and both parallel and series parasitic resistances, accounting for dielectric and copper losses. A prototype system featuring a load-independent class-EF inverter and multiple class-D rectifiers is developed to validate the model, demonstrating strong agreement between theoretical predictions and experimental results. The model ensures Zero-Voltage-Switching (ZVS) at the transmitter and constant output voltages at all receivers, offering a reliable framework for high-precision, high-frequency load-independent SIMO WPT system design.