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Switching sequences of multilevel inverters have to be properly chosen based on the desired control criteria such as dc-link voltage regulation, common mode voltage reduction, and other application dependent criteria. Control of a converter to satisfy a desired criterion is challenging, especially in high voltage level converters. This paper proposes a simple control method for multilevel inverters with high modularity such as flying capacitor multilevel inverters, H-bridge multilevel inverters, and modular multilevel inverters. It is shown that the method considerably simplifies generation of the switching sequences and fulfills the desired criteria with a reasonable computational cost. The proposed method is computationally efficient in the sense that its implementation for high voltage level inverters requires the same effort as required for a multilevel inverter with a low number of cells. Other prominent advantages of the proposed control method, compared to earlier methods, include its applicability for multiphase multilevel converters and converters with asymmetrical structure and/or unevenly distributed dc voltages, independence from the level number and structure of the converter, and not requiring a lookup table. These advantages make the proposed scheme well suited for high cell-number converters, mainly utilized in FACTS, HVDC, and power quality applications. Simulation and experimental results are presented which verify the performance of the proposed method. [ABSTRACT FROM AUTHOR]

The flying capacitor multilevel inverter (FCMLI) is one of the well-known structures of multilevel inverters having attracted considerable attention because of its merits. In spite of its many advantages, it has some limitations such as high volume and complicated control method because of its bulky capacitors and their voltage balancing requirement. Moreover, the high number of power semiconductors required makes this structure susceptible to failure. To increase the ratio of the number of levels to the number of components, an uneven distribution of capacitor voltages has been suggested in previous reports; however, this approach complicates the control method. Up to now, almost all presented methods suffer from high computational load and/or structure-dependent algorithm. In this paper, a simple state-based and structure-independent method is proposed for capacitor voltage regulation. The proposed method is straightforward and can perform online computation of switching sequences in a computationally efficient manner without any need for stored information or look-up tables. The method is conveniently extendible to any number of cells and levels in an FCMLI structure with arbitrary dc link voltage distribution schemes. Simulation and experimental results show the effectiveness and simplicity of this method. [ABSTRACT FROM PUBLISHER]