Single-Phase 15-Level Inverters for Uninterruptible Power Supply Applications: Fault-Tolerant Strategies

An uninterruptible power supply (UPS) is commended unit or even necessary for consumers' electronic devices in the individual, industry, and critical categories to protect them against power shortage for loads. This article proposes a family of single-phase inverters for UPS applications requiring significant fault tolerance. The main inverter comprises two unidirectional switches, eight bidirectional switches, and six DC voltage sources to produce a fifteen-level voltage waveform across the load terminals. The proposed topology can tolerate failures of various semiconductor switches and voltage sources, preserving voltage levels at the output. The core structure of the proposed inverter is first explained, followed by a comparison with the existing fifteen-level inverters in terms of several parameters to demonstrate its superiorities. This article presents several fault-tolerant strategies that can be implemented using the proposed topology to facilitate the realization of reliable UPS systems for critical applications. The effectiveness of the suggested schemes is verified through experimental evaluations under various conditions.