Slip misdetection phenomena caused by bogie vibration during re-adhesion control of railway vehicle

Abstract

Wheel slips in railway vehicles cause poor acceleration and damage to wheels and rails. Re-adhesion control is widely used to resolve wheel slips in electric motor cars. In re-adhesion control, it has been an important problem to consider appropriately the vehicle dynamic motion, which affects the control performance greatly. In this study, we investigate the mechanism and characteristics of slip misdetection phenomena which occur due to bogie vibration excited during re-adhesion control. We construct a three-dimensional vehicle model including roll motion with parallel Cardan drives. The tangential force coefficient model between wheels and rails includes the influence of translational velocity, slip velocity and wheel loads. The simulation model is validated by comparison with measurements in a test run of a real vehicle conducted in previous research. Simulation results illustrate the behavior of the bogie under traction such as the difference of wheel loads of four wheels and the attitude of the bogie frame. It is shown that continual slip misdetection can occur because of pitch and roll vibration of the bogie frame which is excited during re-adhesion control when the primary vertical damping coefficient is small. The misdetection is prevented by changing the amount of motor torque reduction in re-adhesion control. The appropriate range of the amount of reduction to avoid the misdetection gets narrower as the primary vertical damping coefficient decreases. The primary vertical suspension stiffness and characteristic of tangential force coefficient also affect the occurrence of the misdetection.