Fault Detection in Surface PMSM with Applications to Heavy Hybrid Vehicles

This report explores detecting inter-turn short circuit (ITSC) faults in surface permanent magnet synchronous machines (SPMSM). ITSC faults are caused by electrical insulation failures in the stator windings and can lead to shorts to ground and even fires. This report proposes methods for detecting these faults using a moving horizon observer (MHO) to reduce the chance of electrical shocks and fires. Specifically, this report constructs a MHO for ITSC fault detection in SPMSM. ITSC fault tolerant control is investigated for a 2004 Toyota Prius hybrid vehicle having a traction SPMSM. Once the supervisory-level powertrain power flow control becomes aware of the presence of a fault and its degree from the MHO, the control (i) reduces the maximum possible vehicle speed to ensure SPMSM thermal constraints are not violated and (ii) switches to a traction motor input-output power efficiency appropriate for the degree of fault. These steps are taken during a fault rather than shutting down the traction motor to provide a “limp home” capability. The traction motor cannot simply be turned off because its rotation is not independent of drive wheel rotation. The control is demonstrated by simulating the Prius over a 40 s drive velocity profile with faults levels of 0.5%, 1%, 2%, and 5% detected at the midpoint of the profile. For comparison, the Prius is also simulated without a traction motor fault. Results show that the control reduced vehicle velocity upon detection of a fault to appropriate safe values. Further, the challenges of ITSC fault tolerant control for heavy hybrid vehicles are examined. This work is partially supported by the Department of Energy, Award No. DE-EE0005568. The authors would like to acknowledge the support of Greg Shaver and the Hoosier Heavy Hybrid Center of Excellence. S. Johnson, R. DeCarlo, and S. Pekarek are with the Department of Electrical and Computer Engineering at Purdue University, 610 Purdue Mall, West Lafayette, IN 47907 (email: [email protected], [email protected], [email protected]). R. Meyer is with the Department of Mechanical and Aerospace Engineering at Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008 (email: [email protected]).