Robust and Fault-Tolerant Grounding Scheme for Distributed Electrified Aircraft Propulsion

Distributed Electrified aircraft propulsion (DEAP) is one of the most important and critical modern electrified aircraft propulsion (EAP) architectures to maximize electrification benefits while incorporating other non-electrical and advanced technologies to overcome greenhouse gas and fossil-fuel depletion challenges in the aviation industry. There has been considerable progress made in DEAP. However, the conventional grounding scheme cannot support safe flight missions of DEAP, avoid excessive losses caused by the large common mode currents inherited with this scheme, and reduce the associated common mode EMI emissions. This paper proposes a new grounding scheme for DEAP, adopted and specialized from the utility smart grid system development. In the proposed system, the neutrals of AC electric machines are intentionally not connected to their enclosures that are solidly connected to the aircraft ground; the DC neutrals of all high voltage DC (HVDC) branches are grounded to the aircraft ground through high impedances. All the enclosures of power electronics are solidly connected to the aircraft ground. With this approach, the aircraft can continue its flight mission under a single ground fault, either at AC or DC side. This grounding scheme may be considered a preferred design practice for EAP including DEAP, MEA, etc.