A new five-level rectifier based on parallel switching cells and stacked coupled inductors

In this paper a new AC/DC unidirectional switching cell with five voltage levels is proposed. It is called 5L-Stacked-Coupled-Inductors (5L-SCI) cell and can be connected between an AC current source and a DC voltage source. The novelty of 5L-SCI 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 stacked groups of basic switching cells parallel connected by means of coupled-inductors. An interesting property of the 5L-SCI switching cell is the use of stacked groups which work alternatively on a half-cycle. Thus, the active power devices that form the stacked groups switch only half of cycle. The operation principle of the 5L-SCI cell is verified by numerical simulations both for single- and for three-phase unity-power-factor PWM rectifiers.