Comparison of the re-adhesion control strategies in high-speed train

Abstract

Excessive driving force applied to the trains leads to an inadequate utilization of the adhesion phenomenon occurred at the wheel-rail contact, and an unnecessary power consumption, while inadequate driving force causes the train to run inefficiently. For this reason, the necessity of re-adhesion control in the safe and reliable operation, in the balance of energy consumption, is indisputable. A comparison of the two re-adhesion control strategies, one of which is robust adaptive and the other of which is the modified super-twisting sliding mode, has been presented in this article. These control algorithms developed suppress the wheel slip on time and maintain optimal traction performance after readhesion under the nonlinear properties of the traction system and the uncertainties of the adhesion level at the wheelrail interface. Due to the complex nonlinear relationship between the adhesion force and the slip angular velocity, such a problem becomes a hard problem to overcome as long as the optimal slip ratio is not known. An optimal search strategy has also been developed to estimate and to track the desired slip angular velocity. By means of the proposed strategies, the traction motor control torque is automatically adjusted so as to ensure that the train operates away from the unstable slip zone but adjacent to the optimal adhesion region, and the desired traction capability is attainable once adhesion is regained. Mathematical analyzes are also provided to ensure the ultimate boundedness of the algorithms developed. The effectiveness of the proposed re-adhesion strategies is validated through the theoretical analysis and numerical simulations conducted in MATLAB and Simulink. As a result of consecutive simulations, modified supertwisting algorithm has shown better performance as compared to the robust adaptive one in tracking the optimal slip velocity as wheel-rail contact conditions switch suddenly.

Prescribed Performance Active Braking Control with Reference Adaptation for High-Speed Trains

“…The actual gear rotational velocity corresponds to the updated wheel angular speed ω. Moreover, a Burckhardt and Reimpell friction model [26] is utilized by the simulator to emulate the train adhesion µ, and its function is µ = (−1) α 0 1−e −α 1 λ − α 2 λ for the train braking process, where constant parameters α 0 , α 1 , α 2 vary with different rail conditions. Therefore, the changes of wheel-rail contact condition can be simulated through altering these friction parameters.…”

“…(a) Different wheel-rail contact conditions [26]. Following the above discussion, there are three main difficulties in active brake control design: (i) The uncertainties and nonlinearities of the train dynamics, (ii) the time-varying and unknown optimal slip ratio for use as the reference, and (iii) the high requirements of tracking performance.…”

“…Different from general control techniques, an appropriate active braking controller requires an optimal slip ratio as the reference under the time-varying wheel-rail contact conditions. Existing optimal slip ratio generation methods are mostly carried out by using various gradient methods based on adhesion curve characteristics [14,26]. However, sensor measurement noises inevitably lead to estimation fluctuations, which means the ideal optimal slip ratio is hardly achieved using sampling results of one control cycle.…”

Torsional Vibration Suppression in Railway Traction Drives

“…Excessive slip or skid will result in an increase in wheel wear and a reduction of the overall traction performance. Therefore, many efforts have been devoted to limiting the slip/skid between the wheel and the rail [8]- [10]. Both direct and indirect re-adhesion control methods have been proposed to limit the slip within a predefined threshold [11]- [14].…”

Adhesion Control of Heavy-Duty Locomotive Based on Axle Traction Control System

“…Thus, the locomotive must be able to steadily provide the traction force to satisfy the actual traction demand with the increasing load [2]. Adhesion utilization of wheel-rail plays an important part to ensure the stabilization of traction force [3]. Therefore, it is crucial to research effective adhesion control methods to improve adhesion utilization and ensure the stable traction force to fulfill the actual demand [4].…”