A simple and low cost generalised modulation technique for neutral point clamped multilevel inverters

Multilevel inverters are widely used for medium voltage, high power applications. Although numerous modulation schemes have been proposed for multilevel inverters, space vector modulation (SVM) technique is the modulation scheme which has the ability to utilize all the degrees of freedom possible in multilevel inverters. SVM with two-dimensional and three-dimensional control regions has been developed in the past. Another modulation scheme, which is functionally equivalent to space vector modulation is the nearest level modulation (NLM). In this paper, a nearest level modulation technique with a one dimensional control region is implemented and a switch matrix is introduced for the selection of switching sequence of the inverter. The switch matrix is specific to the inverter topology and here a neutral point clamped inverter (NPC) is used to demonstrate and validate the modulation technique.