Passive lossless snubber cell for nonisolated PWM DC/DC converters

A passive lossless snubber cell is proposed to improve the turn-on and turnoff transients of the MOSFET's in nonisolated pulsewidth modulated (PWM) dc/dc converters. Switching losses and EMI noise are reduced by restricting di/dt of the reverse-recovery current and dv/dt of the drain-source voltage. The MOSFET operates at zero-voltage-switching (ZVS) turnoff and near zero-current-switching (ZCS) turn-on. The freewheeling diode is also commutated under ZVS. As an example, operation principles, theoretical analysis, relevant equations, and experimental results of a boost converter equipped with the proposed snubber cell are presented in detail. Efficiency of 96% has also been measured in the experimental results reported for a 1-kW 100-kHz prototype in the laboratory. Six basic nonisolated PWM dc/dc converters (buck, boost, buck-boost, Cuk, Sepic, and Zeta) equipped with the proposed general snubber cells are also shown in this paper.