A Primary-Side Regulation Active-Clamp Weinberg Converter for Constant Current Control

Weinberg converter is a good candidate for server power supplies since it could realize electronic isolation, wide input range and high power density. However, hardswitching technique with significant switching losses is mostly utilized in traditional weinberg converters, resulting in low efficiency and large volume. And temperature drift, aging effect, and nonlinearity of optocoupler would cause decreased performance and reliability. To solve the problems, a primaryside regulation active-clamp weinberg converter with constant current control is presented in this paper. Soft-switching technique is implemented to reduce the switching loss with a simple active-clamp circuit. And based on charge balance principles, the average value of nonlinear output diode current could be predicted from primary-side variables and then constant output current could be realized. To verify the proposed topology and control method, an experimental prototype is built. The input voltage range is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$18 ~\mathrm{V}-48 ~\mathrm{V}$</tex> and the output voltage varies from 3 V to 5 V with a constant current of 10A. The converter achieves soft switching under various input and output conditions, and the current control accuracy is within 2.9 %.