Study on Coupling Control Strategy of VFTs and Its Influence on Wheel Tread Wear

Objective With the gradual saturation of railway network capacity yet severely low passenger occupancy during off-peak hours, it is necessary to conduct a study on VFTs (virtual formation trains) capable of flexible formation to improve the utilization of existing lines, reduce station arrival/departure time, and improve train operational efficiency.

Method Based on multi-body dynamics theory, a virtual four-car train dynamic model is constructed. By investigating train communication methods, the safety distances and coupling conditions for VFTs are defined. A PID (proportional integral derivative) control strategy is adopted for dynamic simulations to validate the following performance during VFTs coupling operations. The running stability and safety of VFTs under PID control are evaluated by comparing with the simulation results of the physically coupled trains adopting two-motor-two-trailer configuration. Additionally, wheel tread wear during train coupling operations is simulated to study the wear evolution patterns.

Result & Conclusion The PID control strategy effectively meets the requirements for the coupling operations of a virtual four-car formation train and ensures its running stability and safety. However, a deceleration phenomenon is observed in the back-following train. Furthermore, coupling operations in VFTs lead to increased wheel tread wear, with the wear amount rising rapidly as the coupling distance increases.