Single-Rating Multilevel Current Source Inverter with Fault Tolerance

The paralleled H-bridge multilevel current source inverter (PHB-MLCSI) provides a practical means to enhance both the system’s current rating and power quality simultaneously. Even so, challenges such as separate dc sources and the need for bulky input dc inductors present notable obstacles in the PHB-MLCSI with an independent dc-link configuration, potentially increasing the system’s cost and size. The PHB-MLCSI with a shared dc-link, also known as the single-rating MLCSI (SR-MLCSI), can overcome these limitations. However, the SR-MLCSI faces the issue of open-circuit fault (OCF), similar to other traditional CSIs. Recently, a topology known as paralleled H-bridge multilevel switching-cell current source inverter (PHB-MLSC
²
SI) has been proposed in the literature to address the OCF issue in conventional PHB-MLCSI. However, this topology retains the same limitations as those mentioned for PHB-MLCSI. This paper proposes a modified version of SR-MLCSI, termed SR-MLCSI with fault tolerance (SR-MLCSIFT), to address the OCF issue in SR-MLCSI and mitigate the size, weight, cost, and complexity drawbacks of PHB-MLCSI and PHB-MLSC
²
SI. Additionally, the article investigates several extremely severe faulty scenarios for the first time within the proposed topology. A detailed operational principle of the suggested inverter under OCF conditions is provided, accompanied by a comprehensive comparison with several MLCSI counterparts. Extensive experimental tests are conducted to validate the effectiveness of the proposed solution.