Active Thermal Control in Neutral-Point-Clamped Multilevel Converters based on Switching-Cell Arrays

Neutral-Point-Clamped multilevel converters are nowadays a suitable solution to implement low-medium voltage and power applications, thanks to their intrinsic superior voltage and current quality. The conventional configurations of these converters present uneven power loss distribution, causing thermal stress in some power semiconductors, which weakens the power converter reliability. For overcoming it, an implementation of the Neutral-Point-Clamped multilevel converter based on a Switching-Cell Array is introduced, adding redundant conduction paths on one side and more options to distribute the switching losses on the other side. An active thermal control is proposed here to balance the temperature distribution in the converter. A four-level converter has been implemented to evaluate the proposed solution. Experimental results show that the proposed implementation and active thermal control present enhanced temperature distribution in the converter and therefore reduced thermal stress and better reliability.