Cascaded multilevel inverter modulation strategies: a novel solution based on duty-cycle space vector approach

In this paper the problem of the modulation strategy of a cascaded multilevel inverter is solved using the duty-cycle space vector (DCSV) approach, which is based on the space vector representation of the switch state. This approach simplifies the study of the modulation strategies and leads to a general solution of the problem, providing an intuitive graphical representation of the modulation properties. Starting from the general solution, a great number of particular modulation strategies, having different characteristics, can be immediately derived. An example of application to a 5-level inverter is presented. The effectiveness of the proposed approach is tested by numerical simulations.