I. Introduction
Voltage source multilevel inverters are more and more used in many industrial applications such as AC power supplies, static VAR compensators, etc. One of the significant advantages of multilevel converters is the harmonic reduction in the output waveform without increasing the switching frequency and without decreasing the inverter output power [1], [2]. The output voltage waveform of a multilevel inverter is composed of intermediary voltage levels, which are typically obtained from capacitor voltage sources. From an economic point of view, it is interesting not to use external controlled voltage rectifier to feed capacitors but rather to use a minimal number of semiconductor components. The regulation of dc capacitor voltages remains the main barrier.