A novel modeling and analysis of capacitor-clamped multilevel converters

Multilevel converters have recently emerged as significant alternative energy conversion voltage source converter technologies. Modeling, analysis and control of these modern power converters have recently become important research issues. This paper presents novel modeling approaches to capacitor-clamped multilevel converters. First, by examining all possible switching states, switching function models for the capacitor-clamped multilevel converters are derived. Then average models in abc and in dqo coordinates are developed. Furthermore, a small-signal linearization of the model in dqo rotating frame is presented, and a feedback control system is designed. With the help of these models, a novel capacitor voltage balancing method to control the voltage of the flying capacitors is proposed. Eventually, simulation results are provided to validate the proposed models and control system.