A generalized scalar pulse-width modulation for nine-switch inverters with maximum amplitude constant frequency operation mode

The nine-switch inverter has been proposed recently and, since then, a large number of applications has been investigated. The main advantage of the nine-switch inverter is its lesser number of switches (nine instead of twelve of the back-to-back converter), which has as a tradeoff some restrictions in the total attainable amplitude at its outputs, dependent on the phase shift between its two terminal sets. Thus, when migrating modulation techniques from the conventional three-phase inverter to the nine-switch inverter, more concerns have to be addressed. Based on this fact, the aim of this paper is to present the NSI focusing in the constant frequency operation mode in order to increase, as much as possible, the modulation indexes of top and bottom units of NSI. Experimental results demonstrate the feasibility of the generalization concept using CF mode.