Compact Wireless Power Transfer With Enhanced Misalignment Tolerance via Independent Secondary PWM Control

Improving power density and system integration is a pivotal focus for wireless power transfer (WPT) in portable devices. However, challenges, such as misalignment tolerance and power fluctuation persist. This letter introduces a robust solution utilizing secondary independent PWM control. A coil structure combining solenoids and reverse windings ensures passive misalignment tolerance, while a grooved magnetic core integrates the converter, optimizing compactness. In addition, the secondary PWM control achieves precise output voltage regulation without communication. A high-power-density WPT prototype validates the proposed coupler and control method, demonstrating less than 1% output voltage fluctuation under a 50% misalignment and maintaining over 89% efficiency at 100 W. The secondary device is highly compact, measuring only 60 mm × 30 mm × 7.5 mm and achieving power density of 7.41 W/cm³.