Research on distributed braking control for high-temperature superconducting pinning levitation trains

Abstract During high-speed operation, a high-temperature superconducting pinning levitation (HTSPL) train must rely on independent eddy current brakes on its maglev bogies for distributed braking in the event of linear motor failure. To investigate the braking process and enhance its performance, the train is modeled as an interconnected system, with the modularly designed maglev bogies treated as subsystems. A comprehensive longitudinal dynamic model of the train is developed. Based on the desired braking acceleration corresponding to the current speed, combined with displacement and velocity feedback, control currents are applied to the brakes to achieve eddy current braking. However, this simple control strategy does not account for relative errors between maglev bogies or the transmission of longitudinal vibrations between carriages, posing safety risks. To address these issues, a ‘Look-Forward’ sliding mode control strategy is implemented under the same feedback conditions. A braking current control law is designed, and the range of control parameters is determined through Lyapunov stability analysis. Numerical simulations compare the braking performance of the two strategies. Results show that both strategies achieve a complete stop within acceptable time (135 s) and distance (9 km), although the time and distance under sliding mode control are slightly longer. With simple control, longitudinal acceleration and force exhibit superimposed vibrations at approximately 5 Hz and 30 Hz, adversely impacting train reliability and passenger comfort. In contrast, the ‘Look-Forward’ sliding mode control significantly reduces vibrations, achieving the desired synchronized braking effect among maglev bogies. However, there is room for parameter optimization, and other advanced control methods could be explored to address more complex operating conditions.