Prototyping and Evaluation of a Fault-Tolerant Three-Level TNPC Inverter for Aircraft Propulsion

Abstract:
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.