A Stator and Rotor Fault Detection Technique for Induction Machines in Traction Applications for Electric or Hybrid Electric Vehicles

Three phase induction machines for traction applications in electric and hybrid electric vehicles can be used with a fixed gear due to the wide speed range enabled by field weakening. Although the induction machine is know as an extremely reliable and robust device, machine faults may occur. Machine faults which do not become detected may cause complete failure of the vehicle. Therefore, early detection of machine faults must be seen as important contribution for reliability and predictive maintenance. Stator winding and rotor failures, however, are a serious problem of squirrel cage induction machines. In an electric or a hybrid electric vehicle the traction machine may undergo severe thermal stress. Stator faults may occur much faster due to insulation breakdown or overload and are therefore more critical with respect to time. Such failures have therefore to be detected immediately after occurring. This paper presents fault detection techniques for stator and rotor faults of squirrel cage induction machines. Both the presented methods are model based techniques, competent to handle variable speed and load operating conditions.