Multilevel-clamped multilevel converters (MLC2) - an alternative approach for multilevel power conversion

In this paper a new multilevel power conversion concept is proposed, whereby an additional auxiliary circuit composed of multilevel clamping cells is applied to a main DC-AC converter. The resultant structure, the multilevel-clamped multilevel converter, or simply multilevel-clamped converter (MLC²), has the number of levels increased, while keeping circuitry simple, wherein the number of parts count can be reduced, when compared with classical NPC counterparts. Hence, the well established three-level neutral-point-clamped (NPC) technology can be applied, which has been the preferred choice in medium-voltage (MV) high power industry for several industrial products. A description of the proposed concept is provided, on which different topologies are derived. Moreover, a cost comparison analysis is shown to illustrate their attractiveness. Simulation and experimental results based on the space vector pulse width modulation (SVPWM) are shown, in order to illustrate the operation and effectiveness of the new multilevel method.