Single phase three-level power factor correction circuit with passive lossless snubber

Multilevel conversion techniques, power factor correction (PFC) techniques and soft switching techniques are the three research hot points of power electronics. The paper proposes a single phase three-level PFC circuit with passive lossless snubbers which embodies these trends. Firstly, the three-level buck and boost topologies are derived from one bridge leg of the traditional diode clamped three-level inverters. Then, a single phase three-level PFC circuit is presented based on the three-level boost topology, and the principle and implementation approaches of the three-level PFC circuit are described. To realize the soft switching of the main switches and freewheeling diodes, two passive lossless snubber cells are added to the circuit. The operating principle and design considerations of the new circuit are discussed in detail. Finally, a 2 kW prototype of the single phase three-level PFC with the passive lossless snubber is built and tested. The simulated and experimental results indicate that the proposed circuit can realize the function of three-level PFC, increase system efficiency and have no over-voltage stresses on main power switches. Moreover, the power factor of the proposed circuit with the passive lossless snubber is higher than that of the circuit without the snubber.