Electrical protection design for integrated motor drives with carbon fibre composite casings for aircraft

Replacing traditionally aluminum non-electrically active components of integrated motor drives (IMD) (e.g. casings) with lighter-weight carbon fibre reinforced polymer (CFRP) for offers a route to the key weight savings, desirable in future aircraft electric applications. However, CFRP casing designs must accommodate electrical interactions with encased equipment. Approaches to fault management and electrical protection must ensure that both electrical power system (EPS) and CFRP casing are protected against electrical faults. Knowledge of the electrical and thermal response of the CFRP casing underpins fault resilient casing design. The proposed CFRP casing is a wound filament (WF) CFRP tube for an integrated motor drive.
This paper presents the first experimentally validated methodology to capture macro-scale electrical and thermal response of a WF CFRP tube to low frequency current. This knowledge is subsequently combined with wider EPS design considerations, including electrical grounding and bonding, to control fault response, enabling implementation of appropriate protection solutions. The results indicate that tuning casing resistance is not a viable, immediate option to control fault response, and that wider electrical system design options (grounding topologies) must be considered. Hence incorporation of CFRP for non-electrically active components to improve power density, has significant impact on wider electrical power system design.