Research on train braking model by improved Polach model considering wheel‐rail adhesion characteristics

To study the braking process of the train under different adhesion conditions, this paper takes the braking system of a single rail vehicle as the research object. The author establishes a corresponding co‐simulation platform based on MATLAB/Simulink and AMESim, including the sub‐models of braking control, vehicle brake longitudinal dynamics and air brake unit. Considering the cleaning effect caused by large sliding, the author builds a suitable adhesion model for different adhesion conditions based on the improved Polach model, which is the input of the vehicle braking longitudinal dynamics sub‐model. Based on the finite state machine, the anti‐skid control algorithm of the train is constructed as the core of the brake control sub‐model, which can judge the motion state of the wheelset, and control the stage release and hold of the brake cylinder pressure. According to the International Standard EN15595 and the actual operating parameters of a certain type of train, the braking process of the train under dry and wet rail conditions is simulated on the platform. The validity of the model is verified, which provides a reliable method for future research on the braking process. This paper focuses on the wheel‐rail adhesion characteristics under degraded adhesion conditions, so the improved Polach model is used as the input of the braking force. Based on the working principle of the braking system, the corresponding sub‐models are established to build a co‐simulation platform. Based on the standard EN15595, the corresponding indicators are calculated to verify the validity of the simulation platform.