State-Plane Analysis of Regenerative Snubber for Flyback Converters

The flyback converter is a popular topology for implementing low power and multiple output power supplies. However, the high leakage inductance of the flyback transformer causes high voltage spikes that can damage the main transistor when the switch is turned OFF. Therefore, a turn-off snubber is needed to limit the peak voltage stress. This paper presents the analysis of an energy regenerative snubber using the graphical state-plane technique. The undertaken approach yields a clear-cut design procedure for minimum switch voltage stress. Experimental evaluation of the energy regenerative snubber in comparison with other common snubbers shows that under the same voltage stress the efficiency of energy regenerative snubber has 8% improvement on average over an RCD snubber and 2% improvement over the nondissipative LC snubber.