태양광 발전 시스템을 위한 새로운 Cascaded Modified Hybrid T-type Multilevel 인버터 및 고장 허용 운전 기법

Abstract

The growing demand for clean and sustainable energy has accelerated the development and integration of photovoltaic (PV) systems into power grids. In such systems, multilevel inverters play a crucial role in efficiently converting DC power from solar panels into AC power suitable for grid connection or local consumption. Among various topologies, the Cascaded H-Bridge (CHB) multilevel inverter has gained prominence due to its modular structure, scalability, and ability to generate high-quality output voltage with reduced harmonic distortion.

Despite these advantages, CHB inverters are inherently vulnerable to faults in power semiconductor devices such as IGBTs or silicon carbide (SiC) switches. Such faults can lead to partial or complete system shutdowns, compromising system reliability and introducing significant maintenance and operational challenges—particularly in large-scale solar farms.

To address these limitations, this paper proposes a novel Cascaded Modified Hybrid T-type (CMHT) multilevel inverter that enhances fault tolerance without compromising power output. The structure of the proposed inverter is introduced, and its fault-tolerant performance is evaluated under various open-circuit fault scenarios involving power semiconductor devices. A single CMHT module can generate five output voltage levels, thereby reducing total harmonic distortion (THD) more effectively when used in a cascaded configuration. Moreover, the proposed inverter maintains full power output during fault-tolerant operation, demonstrating superior performance compared to conventional CHB inverters. The fault-tolerant capability of the CMHT inverter is both theoretically analyzed and experimentally validated.

These advantages will make the CMHT inverter a promising solution for high-reliability, high-performance solar power applications.

Key words – Fault tolerant strategy, Multilevel inverter, Reliability, Solar power system, , Switching device failure