Novel Passive Snubber Suitable for Three-Phase Single-Stage PFC Based on an Isolated Full-Bridge Boost Topology

Abstract

In this paper a novel passive snubber is proposed, which can suppress the voltage spike across the bridge leg of the isolated full-bridge boost topology. The snubber is composed of capacitors, inductors and diodes. Two capacitors connected in series are used to absorb the voltage spike and the energy of each capacitor can be transferred to the load during one switching cycle by the resonance of the inductors and capacitors. The operational principle of the passive snubber is analyzed in detail based on a three-phase power factor correction (PFC) converter, and the design considerations of both the converter and the snubber are given. Finally, a 3kW laboratory-made prototype is built. The experimental results verify the theoretical analysis and evaluations. They also prove the validity and feasibility of the proposed methods.

Investigation and Implementation of a Passive Snubber with a Coupled-Inductor in a Single-Stage Full-Bridge Boost PFC Converter

“…L lk and n are the equivalent leakage inductance and the voltage ratio of transformer T, respectively. The switching mode of S 1~S4 is the same as that in [23]. The converter in Fig.1 operates in the continuous current mode (CCM).…”

“…Theoretical analysis and experimental results show that the voltage spike can be suppressed efficiently after adoption of the improved snubber. It can also overcome the drawback of the passive snubber in [23].…”

“…In this paper, based on the passive snubber in [23], an improved passive snubber is investigated in a single-phase single-stage full-bridge boost PFC converter. In the improved snubber, the two single-inductors are replaced by a coupled-inductor.…”

“…However, after the adoption the passive snubber, a diode is connected in series with the bridge leg switches, which will reduce the efficiency of the converter. In [23], another passive snubber is investigated in three-phase single-stage PFC which overcomes the disadvantage of the snubber in [22]. However, an unbalance of the voltage and current appears between the two resonant circuits.…”

“…The reasons why this type of PFC has not been widely used can be attributed to: 1) an additional starting-up circuit is required to establish an initial output voltage, and 2) there is a voltage spike across the bridge leg caused by the transformer leakage inductor [4], [5]. For normal single-stage full-bridge boost PFC, starting-up has been realized through many efficient methods.…”