Multilevel-Clamped Multilevel Converters (MLC ²)

This letter introduces a new series of multilevel (ML) converters based on the ML clamping concept. By applying this technique, a ML clamping unit (MCU) conveys additional levels for synthesizing the output waveforms of a diode-clamped ML dc-ac power converter. The basic building block of the ML clamping scheme is the ML clamping cell, which is composed of a pair of dc sources associated with one single-pole/triple-throw type of switch arrangement. The number of series-connected ML-clamping cells will set the number of levels of the synthesized waveform. By depending on the MCU arrangements, different converter configurations can be derived, namely, the common clamping and the modular types. Both approaches can be accomplished by employing classical three-level neutral-point-clamped (NPC) technology. Thus, the overall structure of the resultant converter is kept simple, wherein the number of parts count can be reduced, when compared with conventional NPC counterparts. In this letter, emphasis is given on the common clamping converter configuration. The attractiveness of the proposed ML concept is evidenced by conducting a comparative cost analysis. Experimental results are presented as a practicality proof of the proposed ML power converter.