Study of Passive Snubbers Applied to a Single-phase High Power Factor Rectifier

This paper presents a family of non-dissipative passive snubbers applied to a single-phase rectifier with unity input power factor. This single-phase rectifier presents reduced conduction losses because the current flows through two power semiconductors only, for any stage of operation. The family of lossless passive snubbers presented in this paper guarantees soft-commutation during the turn-on and the turn-off intervals of the switch within a large range of variation of the input current. The snubber circuit not only should slow the di/dt and dv/dt rates of the active switch, but also losslessly recover the energy stored in the zero-current inductor and in the zero-voltage capacitor, leading to reduced voltage stress across the switches and diodes. The association of the family of high performance snubber circuits here presented with the single-phase rectifier with reduced conduction losses results in a high efficiency rectifier, free from overvoltages across the power switches. To access the performance of the proposed family, simulation and experimental results for a single-phase rectifier 3000W laboratory prototype using one snubber of the family are also presented.