A Generalized Multilevel Converter System and its State Observation

Multilevel converters (MCs) are an integral part of many medium/high voltage and power applications. Most of the existing multilevel converter topologies share similar mathematical structures. Encapsulating numerous converter topologies, a generalized multilevel converter system (GMCS) model is proposed considering the behaviour and operating principle of MCs. For the operation of MCs, voltage sensors across the capacitors are required, which increases the complexity, and degree of maintenance. An observer design for the GMCS helps in reducing the number of sensors and provides a framework for voltage estimation for numerous MCs. It is worth mentioning that a classical Luenberger observer cannot be designed for the GMCS model due to its structural properties. Therefore, a sliding mode observer (SMO) is designed for the proposed GMCS for state observation. A modular multilevel converter (MMC) is taken as a test case of the proposed GMCS and its state observation problem is solved using the proposed SMO.