Buck Based Active-Clamp Circuit for Current-Fed Isolated DC-DC Converters

In this paper, a buck based active-clamp circuit for current-fed isolated DC-DC converters is proposed. The proposed active-clamp circuit can not only suppress the voltage spikes caused by the current difference between the current-fed inductor and leakage inductor of the transformer, but also transfer the energy of the above process to the input voltage source. Different from the traditional active-clamp circuit, the proposed active-clamp circuit needs only one switch regardless of the number of input phases in the main circuit. Moreover, the control of the proposed active-clamp circuit is decoupled with the main circuit, which makes the design and implementation of the system controller easier. A 400W experimental prototype has been built to verify the effectiveness of the proposed circuit.