Modeling, simulation and re-adhesion control of an induction motor–based railway electric traction system

Increasing the traction force is a complex problem in the design of railway vehicles; therefore, effective traction systems and algorithms have to be developed. During the traction process, the verification of traction algorithms and control strategies are based on simulations covering all locomotive dynamics. In this article, traction model of a railway vehicle and re-adhesion control method based on simulation approach are investigated to obtain more effective results. The longitudinal dynamic of a railway vehicle having traction system, which comprises two parallel motor groups, each of which has two field-oriented induction motor connected in series, is simulated to examine time-dependent changes in motor stator currents, traction torque, adhesion and resistance forces according to a given speed reference. The interaction between the adhesion force and the slip ratio is established according to the Burckhardt adhesion model, and a modified super-twisting sliding mode slip control is implemented in a computer simulation under various contact conditions so that simulation results approve the presented control method works under the maximum adhesion force. The comparison between the classical and modified version of the proposed control strategy was made to better evaluate the performance of the control system and to better optimize the traction system.