A Single-Ended Hybrid Resonant Converter With High Misalignment Tolerance

This article proposes a single-ended hybrid resonant converter (SEHRC) for wireless charger to provide a cost-effective solution with high misalignment tolerance. A comprehensive characteristics analysis of the proposed converter is performed in both of time and frequency domain. The analysis discloses that the hybrid compensation performs impedance transformation which maintains the input impedance nearly constant. As a result, the optimum operation of SEHRC, including zero-voltage-switching, low voltage stress, high power transfer capability, and high efficiency can be maintained within a wide range of coupling coefficients. Also, it ensures a stable output current for both load and coupling variations. The design constraints and procedure are given. Furthermore, a zero-voltage-switching and zero-voltage-derivative-switching control scheme is proposed to achieve a higher efficiency and smaller output current fluctuation, as well as reduced peak switch voltage. Finally, a 1.3 kW prototype is built to verify the theoretical analysis. The test results demonstrate that the peak voltage of the proposed SEHRC is less than 2.7 times the input voltage. When the coupling coefficient varies 2.7 times, the output current changes by 1.16 times.