Low Side Switch Based Regenerative Snubber Circuit for Flyback Converter

This paper presents a regenerative snubber circuit for gallium nitride (GaN) high electron mobility transistor (HEMT) based low power flyback converter. The proposed snubber recycles the energy stored in the primary leakage as well as PCB stray inductances to avoid overshoot in the voltage across the GaN HEMT during its turn OFF. The snubber circuit also helps to achieve zero voltage turn ON for the main flyback switch as well as zero current turn OFF for the auxiliary switch, leading to reduced switching losses. Two diodes, one capacitor, one auxiliary winding of the flyback transformer and one low side N-channel switch are used in the snubber circuit. Detailed operation principle and design considerations of the proposed snubber circuit are presented. Operation of the proposed circuit is validated by simulation and experimentation. A reduction of 18.8% is observed in the peak voltage across the main switch in the experimental setup compared to conventional resistor-capacitor-diode snubber circuit.