New unidirectional five-level VIENNA rectifier for high-current applications

In this paper a new AC/DC unidirectional PWM Vienna switching cell with five voltage levels is proposed. It is called 5L-Parallel-Unidirectional-Vienna (5L-PUV) cell and can be connected between an AC current source - on the input side, and a DC voltage source - on the output side. The novelty of 5L-PUV topology is based on two cascaded stages that work at different currents and different switching-frequency. The first stage contains two diodes that operate at high-current and low-frequency. The second stage works at low-current and high-frequency and contains two groups of stacked switching cells parallel connected by means of coupled-inductors (CIs). An interesting property of the 5L-PBV switching cell is the use of two CIs which work alternatively on a half-cycle. Thus, the currents in inductor windings of CIs are naturally set to zero on each cycle and any difference between these currents is cancelled periodically. Due to the parallel connection of high-frequency switching cells, the 5L-PUV concept appears as a useful solution for high-current applications. The operation principle of the 5L-PUV cell is verified by digital simulations both for single- and for three-phase unity power factor unidirectional PWM rectifiers.