Comparative Study of Three Snubber Circuits for a Phase-Shift Converter

摘要

The phase-shift full-bridge converter (PSFB) is one of the most popular topologies for high power and high output voltage converters. A high number of turns are usually needed to design the main transformer used in this converter for galvanic isolation, resulting in large leakage inductances and stray capacitances of this transformer. The parasitic inductances in combination with the parasitic capacitances of the power semiconductor devices used can cause ringing oscillations leading to: electromagnetic compatibility problems and large voltage overshoot that can damage the power semiconductors. To reduce the high amplitude voltage oscillation produced by ringing, different snubber circuits are used. In the present paper, three snubbers will be compared: a passive resistor-diode-capacitor (RDC) snubber, a clamp diodes snubber and a regenerative active clamping snubber. Advantages and disadvantages as well as differences between them will be highlighted. The work will also propose a novel control method for the regenerative active clamping snubber that uses an extra winding on the output coil. Simulations and experimental results are used to validate the efficiency of the control method.