Design of lossless snubber circuit for phase-shifted full-bridge converter

Abstract

In the phase-shifted full-bridge circuit, the voltage spike caused by the hard turn-off of the switch tube increases the voltage stress of the switching device. Due to the existence of energy-consuming components such as resistance in the traditional absorption circuit, the efficiency is not always high. Based on the RCD snubber circuit, a low-loss absorption circuit is designed in this paper. This circuit absorbs voltage spikes through an absorption capacitor, and then slowly releases energy through an oscillating circuit consisting of current-limiting inductance, stray inductance, and absorption capacitance. The current-limiting inductance reduces the current stress of the blocking diode effectively, which can be achieved with the absorption not being affected and the power loss being reduced. Finally, the absorption effect and energy loss of the new low-loss absorption circuit and the commonly used RCD circuit were simulated and compared in PSpice software, and verified its feasibility.