Multilevel converters for UPS applications: comparison and implementation

In this paper the possibility to use multilevel converters in UPS applications is discussed. Three different converter topologies, i.e. the three-level diode-clamped, the four-level diode-clamped and the four-level Multi Point Clamped (MPC) have been firstly compared by simulation simulations to find out their efficiency. The Simulink environment has been used, together with Plecs toolbox, to obtain a fast simulation including conduction and switching losses in the components. The MPC turned out to be the converter with the highest efficiency among the three considered and it was implemented to prove the simulation result with some experimental tests. Furthermore, two switching tables for the MPC converter have been implemented and compared in order to minimize the voltage spikes across the switches during the commutations.