Aspects of Fault-Tolerant Electrical Aircraft Propulsion

Abstract:
This paper describes aspects of the design strategy and the testing of fault-tolerant propulsion systems for aircraft applications, and the specific challenges involved in the use of permanent magnet synchronous machines (PMSM) in such systems. Different electrical machine faults and detection methods as well as possible system reactions are addressed. PMSMs are a specifically challenging machine type since the permanent magnetic excitation may prevail after a fault event potentially feeding excessive power into the fault location. Minimizing fault progression and enabling fault-tolerant operation requires quick reactions based on unambiguous fault identification. Post-fault operation may introduce addi-tional design challenges. The importance of model validation and experimental verification is underpinned with examples. Methods are described to emulate faults. Obtained measurement results are utilized for electrical and mechanical drivetrain characterization. Requiring thorough preparation, the concomitant safety aspects of such drive system testing are highlighted demonstrating the feasibility and the challenges involved in experimental assessments of transient terminal short circuits and turn-to-turn short circuits. Terminal short circuit test results are compared with complementing finite element simulations. Numerical predictions also yield requirements for inter-turn short circuit testing. The paper concludes with an outlook into current research topics and future demand.