Novel Encoderless Detection of Motor-Bogie Suspension Failure in Railway Applications

Abstract

In electric rail transportation, traction motors are responsible for propulsion and transmit torque to the bogie wheelsets through a gear drive system. Typically, each traction motor is fixed to the bogie frame using a suspension system and thus motors might withstand a large amount of shock and vibration arising from wheel to track contact. With developing fatigue, the motor-bogie suspension might fail. To prevent destructive contact between motor and track, bogies are often equipped with an additional safety apparatus: a safety bar fixed to the bogie frame that is axially aligned with a motor-fixed safety catch when suspension is healthy. This is the last protective measure that prevents the motor from falling to the track and, thus, it is of tremendous importance to reliably and quickly determine suspension faults. While the motor-bogie suspension is broken, the motor can move up or down within the safety catch. This results in small but abrupt angular movements of the rotor after torque transients take place. Thus, detection of motor-bogie suspension fault can be detected by inspection of the shaft encoder signal or speed sensor signal under load changes. In this work, a novel detection method for motor-bogie suspension fault is presented, using spatial saliency information extraction thus only requiring current transducers and no traditional shaft encoder nor additional sensors. The transient spectra of the motor saliencies are used to define a trigger that serves to detect motor suspension failure during a test. The method is experimentally validated in a test bench equipped with a 1.6MW locomotive traction motor and a suspension-fault emulation system.