An experimental investigation into natural balancing of three level neutral point clamped multi-level inverters

This paper presents an experimental study of the natural balancing theory for three level neutral point clamped multi-level inverters. An equation describing the natural balancing mechanisms is given and discussed, and a passive circuit to improve balancing is presented and discussed. Three different switching patterns for space vector modulation and the effects thereof are discussed with regards to experimental results. Finally, the results of balancing experiments with and without the balance booster are given and discussed. It is seen from these results that the balance booster circuit can drastically improve balancing for this topology.