Prototype of multiphase modular-multilevel-converter with 2 MW power rating and 17-level-output-voltage

A versatile prototype converter system of the new modular-multilevel converter (M²LC) family is introduced. The new concept stands out due to its stringent modular construction as well as its extremely good control characteristics. This new M²LC concept is well suitable for a wide range of high voltage applications. The basic working principle as well as the static and dynamic behaviour is explained in detail on a single-phase AC/AC-converter enabling four-quadrant operation. The M²LC-family has already been introduced and examined for applications like traction converters, operating directly on the power line, and network interties [Marquardt, R et al., 2003 and Lesnicar, A et al., 2002]. With this prototype converter system, the characteristics of various different M²LC-topologies can be investigated, including single or three phase DC/AC converters as well as multiphase AC/AC converters. The prototype converter has been designed in such a way that its configuration can be quickly changed between wide ranges of topologies. A flexible control system has been implemented, which is capable of controlling up to 32 IGBTs per converter arm, independently. Next to the presentation of the converter and its control system, measurement results are presented including converter operation.