Thermal and efficiency analysis of five-level multi-level clamped multilevel converter considering grid codes

In this paper a five-level Multi-Clamped Multilevel Converter (5L-MLC2) topology is analyzed based on a typical grid integration application for renewable energy generation system. The loss and thermal distribution of the power devices in different switching legs are investigated and illustrated under rated operation. Afterwards, a loss and efficiency evaluation method is proposed and applied which takes into account various reactive power operation boundaries regulated by the grid codes. It is concluded that the 5L-MLC2 multilevel topology shows a good and consistent efficiency characteristic under different output active powers when complying with the active/reactive power operation range regulated by e.g. the German grid codes.