System-Level Reliability Assessment of Short Duty Electric Drives for Aerospace

The reliability performance of electrical machines (EMs) and power electronics converters (PECs) is generally verified separately even if the two components are meant to be part of the same electric drive. Depending on the application, however, it might be necessary that the whole drive fulfills a certain reliability target, which is predefined by the application itself. An appropriate design approach should involve joint efforts between machine and converter designers so that the final product is as optimized as possible while still satisfying reliability constraints. In this work, a system-level reliability study for short duty electric drives is proposed and implemented using an aerospace electromechanical actuator as a case study. Concepts of statistical postprocessing for the lifetime prediction of power modules are discussed throughout. In addition, accelerated lifetime tests on EM windings are performed for predicting the motor insulation's time to failure. For the short duty aerospace drive under investigation, i.e., case study, it is finally verified that the PEC represents the reliability bottleneck.