Maintaining soft switching in a phase-shifted bipolar DC-to-DC converter

In a bipolar DC-to-DC power converter, a phase-shift scheme cannot maintain soft switching when the load current is negative. A simple and elegant solution is proposed for the first time. The end result is an operation symmetrical to that of the case with positive current, hence retaining all the benefits. The measured results support fully the analytical predictions. An efficiency of 94.5% was observed on a 1.5 kW power converter breadboard for operations with positive and negative load currents, respectively.