A Novel Pull-Up Active-Clamping Wireless Charging Circuit with Low Cost and Voltage Stress

Abstract

The traditional single-switch circuit has the advantages of fewer components, no shoot-through problems, and suitability for high-frequency wireless charging applications. However, because of the high voltage stress of the switch, the bulky inductor, and the narrow soft-switching range, its power and applications have some limitations. To relieve this problem, this paper proposes a pull-up active-clamping circuit, which not only offers a low component count with no bulky inductors, but also greatly reduces the switch voltage stress. In addition, a wide range of soft switching can be achieved by designing a primary-side compensation capacitor. A detailed parametric design method is given and compared with existing circuits from the aspects of switch voltage stress, component count, efficiency, cost, and so on. Finally, a 1 MHz, 180 W active-clamping wireless charging system is built to verify the proposed circuit and design method.