A passive lossless
snubber cell for a switched-mode power converter comprises an
energy absorbing circuit and an energy resetting circuit coupled to said
energy absorbing circuit. The
energy absorbing circuit is arranged to release energy stored in a
snubber capacitor of the energy absorbing circuit to a storage
capacitor of the energy resetting circuit through a resonant pathway of the
snubber cell in response to a first switching action of a power converter
transistor switch. The energy resetting circuit is arranged to release the energy stored therein to a part of a circuit of the power converter in response to a second switching action of the power converter
transistor switch, the second switching action being a successive action to the first switching action. The passive lossless snubber
cell has several advantages over existing snubbering techniques. First, it provides zero-current-switching (ZCS) and zero-
voltage-switching (ZVS) conditions for turning on and off, respectively, the switch over a wide load range. Second, it does not introduce extra
voltage stress on the switch. Third, by taking the
ripple current through the switch into account, the peak switch current during the snubber
resonance period is designed to be less than the designed switch current without the snubber. Hence, the proposed snubber does not introduce extra current stress on the switch.