Comparison of Performance Fault-Tolerant Five Level Inverter with and without PWM Technique Multilevel Inverter

Five-level Neutral Point Clamped (NPC) inverters are widely utilized in high-power and industrial systems due to their ability to generate high-quality output waveforms, minimize Total Harmonic Distortion (THD), and evenly distribute voltage stress across semiconductor switches. Despite these advantages, their intricate topology makes them vulnerable to faults such as open-circuit switches, diode failures, and imbalanced capacitor voltages. Such faults can severely impact output performance, cause waveform distortion, and potentially lead to complete system failure, particularly in precision-demanding environments like motor drives and industrial controls. This paper investigates the fault behaviour of conventional five-level NPC inverters and contrasts their performance with a Pulse Width Modulation (PWM)-based fault-tolerant inverter design. Traditional fault mitigation approaches often rely on additional hardware or redundancy, increasing both complexity and cost. In contrast, the proposed method employs a control-centric strategy using PWM to dynamically adapt switching states in the presence of faults, ensuring balanced voltage output and reduced harmonic distortion without requiring extra components. Comprehensive simulations were carried out under several fault scenarios, including single-switch failures, clamping diode defects, and imbalanced DC-link conditions. The analysis focuses on key performance indicators such as output voltage quality, THD levels, and system recovery response. The results reveal that the PWM-controlled fault-tolerant inverter consistently outperforms its conventional counterpart in maintaining waveform stability and overall reliability under fault conditions. This study emphasizes the effectiveness of PWM-based control strategies in enhancing the fault resilience and operational efficiency of five-level NPC inverter systems.