Reliability Improvement by Fault-Tolerant Operation of NPC Inverter for Motor Driving

The high-reliability operation of three-level inverters is crucial to prevent equipment damage, process downtime, and economic losses. This article investigates a three-level neutral-point-clamped inverter under all possible combinations of open-circuit and short-circuit faults and proposes a new postfault operation method without adding extra hardware. This method provides comprehensive solution for operations after single and multiple-device failures, increasing the inverter reliability by 24%. This article classified postfault modulations and uncovered previously unknown fault scenarios that can be addressed using the proposed control method. A new postfault modulation based on space vector modulation with virtual vectors is proposed. The feasibility of the proposed control method is verified by simulation and an experiment for one fault scenario in a three-level neutral-point-clamped inverter with a 3.73 kW motor load. This article contributes to improving the reliability of three-level inverters.

Automated summary

This article investigates the high-reliability operation of a three-level neutral-point-clamped inverter under various open-circuit and short-circuit fault combinations. It proposes a new postfault operation method that does not require additional hardware, providing a comprehensive solution for single and multiple-device failures and increasing the inverter reliability by 24%. The article classifies postfault modulations and uncovers previously unknown fault scenarios that can be addressed using the proposed control method. It also proposes a new postfault modulation based on space vector modulation with virtual vectors and verifies the feasibility of the control method through simulation and experimentation.