Health assessment for low-voltage electromagnetic coils based on fusion of creep degradation mechanism and transformed MD

Abstract Low-voltage electromagnetic coils play ever-increasing roles in safety-critical systems, like electromechanical actuators in more electric aircraft and tractors in zero emission vehicles. Identifying insulation degradation prior to the formation of turn-to-turn short can effectively avoid accidental shutdown and enable predictive maintenance for these systems. High-frequency electrical response analysis is currently a promising technique for electromagnetic coil insulation health assessment. However, the correlation between high-frequency electrical response parameters (HFERP) and actual insulation degradation status (AIDS) is still not clear, which brings challenges in insulation health assessment and remaining useful life prediction. Therefore, in this paper, a fusion method based on creep degradation mechanism and transformed mahalanobis distance (MD) for insulation health assessment is proposed. First, correlation analysis between the coil HFERP and the AIDS is performed from coil insulation coating creep degradation point of view. Second, a coil on-line monitoring parameter (OLMP) for monitoring insulation degradation status on-site is constructed based on transformed MD. A correlation model between OLMP and AIDS is consequently built to assist in determining OLMP failure threshold for coil insulation health assessment. Coil accelerated testing shows that the fusion method can be used to assess insulation status prior to the formation of harmful shorts, enabling condition-based maintenance for components or systems that incorporate electromagnetic coils.