Unified passive circuit for snubber energy recovery in UPS inverters

This paper presents a complete passive lossless snubber suitable for high frequency UPS inverters, where bridge leg modules and miscellaneous PWM mode can be adopted. The proposed configuration recovers snubber energy into the DC rail and/or load automatically at main switches turn-on and turn-off via resonance in a simple network without any transformer or coupled inductors, which minimizes the additional parts' number. For a single-phase UPS application, snubber operation analysis, parameter designs are presented along with simulated and experimental confirmation.