Dynamic response of a locomotive with AC electric drives to changes in friction conditions

Abstract

Locomotive traction control behaviour and its dynamic impacts on rails and vehicles have not been comprehensively investigated in respect to transient conditions. Such transient traction behaviour could be more significant than steady state behaviour in determining dynamic traction performance and track degradation (i.e. squat/corrugation formation, etc.). In order to study this effect, detailed numerical simulations are performed to investigate a locomotive's dynamic response to a change in contact conditions. In particular, creep response, vibration of the locomotive, and dynamic normal and traction forces are determined using a developed full-scale dynamics model of a locomotive. The model includes a detailed representation of the AC motor dynamics, which has not been considered in previous works. The results show that the detailed model is capable of simulating the dynamic fluctuations in creep and traction forces that are not considered in simpler models. Such transient responses may cause damage to the track and vehicle components.

Modelling of track wear damage due to changes in friction conditions: A comparison between AC and DC electric drive locomotives

“…These high frequency oscillations are most likely associated with high frequency electric dynamics of the detailed AC model. Detailed discussion of the AC drive creep response is available in [12]. Furthermore, it takes a longer time (30s) after the transient for the AC model to stabilize than that with the DC model (10s).…”

“…Combining with contact mechanics model [11], and complex electric dynamics model [8] to investigate the effect of wheel-rail contact surface [6], and electric dynamics, the model is capable to simulate many features such as wear behaviour of a locomotive in real operation conditions. It has been concluded that the transient dynamics can induce excessive traction and normal force oscillation, therefore cause extra wear for a short period of time after a change in friction conditions [12]. However the quantitative analysis of such wear is missing.…”

Problems, assumptions and solutions in locomotive design, traction and operational studies

“…In the process of formulating a locomotive dynamic model to be used in traction studies, several disciplines including electrical engineering, mechanical engineering and civil engineering are involved. In general, there are four common modelling approaches [13]: implementing a locomotive model using a general-purpose scientific commercial software like MATLAB/Simulink [34][35][36]; implementing a locomotive model using in-house software [37]; implementing the locomotive model in commercial multibody software packages [13,38,39]; or co-simulation approaches where the multibody locomotive model and the traction mechatronic system are modelled independently in two different software packages that interchange data Fig. 2 Proposed V-model with several system integration stages for the design of a locomotive product during the simulations [19][20][21][22].…”