Chaisakdanugull, Chanuch

This paper presents the prototyping of a fault-tolerant three-level T-type Neutral Point Clamped (TNPC) inverter for electric aircraft propulsion systems. To enhance robustness against various semiconductor failures, disconnecting devices are integrated in series with both the high-side and low-side switches. However, this implementation also increases parasitic inductance in the commutation loop. To mitigate the challenges associated with a highly inductive commutation path, a DC snubber circuit is designed to suppress overvoltage and damp switching oscillations. The switching behavior is analyzed through double-pulse testing (DPT). Additionally, a three-phase, three-level inverter employing space vector pulse-width modulation (SVPWM) is implemented, and its performance under normal operating conditions is evaluated. Furthermore, post-fault operation is investigated when one phase is connected to the neutral point.

This paper presents an analysis of a five-phase three-level TNPC inverter focusing on its fault-tolerant capabilities and mitigation techniques for electric aircraft propulsion systems. The space vector pulse-width-modulation (SVPWM) schemes in both normal and post-fault operations accounting for short-circuit and open-circuit occurrences in individual power electronic switches in a single phase are discussed. In fault cases, the remaining switching vectors and their sequences are selected to produce the necessary voltage in the αβ-coordinate system. This selection aims to efficiently suppress undesired voltage components and complying with the rules focusing on minimizing switching losses. These methods are implemented and assessed through simulation, showing the ability and performance limitations of the inverter under various fault conditions.