A new nine-switch non-regenerative four-level rectifier

This paper has proposed a new non-regenerative three-phase four-level rectifier topology with only half of the active devices of the conventional four-level rectifier. Each phase leg has only three active devices. The operation of the rectifier with regards to current path and output voltage levels are analysed. The available voltage vectors in this type of rectifier are constrained by the current flow direction. The maximum active power and reactive power capacity of the rectifier have been derived. A simple carrier-based modulation scheme is presented to modulate the rectifier as well as balance the dc-link capacitors´ voltages. Simulation results have validated the topology and control scheme.