A Family of Fault-tolerant Single-phase 15-level Inverters for UPS Applications

This paper presents a family of fault-tolerant single-phase inverter topology for uninterruptible power supply (UPS) systems. The core structure is a 15-level inverter, consisting of two unidirectional switches, eight bidirectional switches, and six DC voltage sources. The proposed topology can facilitate realizing fault-tolerant multi-module inverters. If one of the power sources or semiconductor devices fails in one of the modules, the remaining modules can alternatively deliver all the expected voltage levels. Thus, this efficiently eliminates the possibility of UPS system failure for critical applications. The proposed topology is compared with the conventional 15-level inverters regarding the number of voltage sources, switches, and drivers to prove its advantages. The gate signals for the switches are produced employing the fundamental frequency switching technique. Further, the efficacy and performance of the proposed topology are supported with the simulation and experimental validations.