High adhesion locomotive performance under individual axle and bogie traction control strategies with the presence of wheel diameter difference

Two types of traction control systems for AC locomotives are commonly in use for heavy haul train operations. These traction control systems either act independently for each bogie, i.e. a locomotive is equipped with one inverter per bogie, or act independently for each axle, i.e. each axle is controlled by its own inverter. The locomotive manufacturers, who produce locomotives with individual axle traction control systems, state that it allows using greater wheel diameter variation between axles and eliminates this factor as an issue for achieving required tractive efforts. However, this statement needs to be verified, especially for diesel- electric locomotives equipped with three-axle bogies, where the dynamical behaviour is quite different in comparison with some previous studies performed for a two-axle design commonly used in electric locomotives. In addition, no comparison data were published for this topic in the public domain for high adhesion locomotives with both types of advanced AC traction technologies. In order to provide comprehensive analysis of both traction control systems, it is necessary to use a multidisciplinary approach which will include a combination of mechanical, electrical and systems engineering disciplines to ensure that all issues required for the investigation are covered at the appropriate level. This paper tries to analyse all these issues for heavy haul diesel-electric locomotives and presents results obtained from numerical experiments performed in the co-simulation mode between Gensys multibody software and Matlab/Simulink. The influence of the variation of wheel diameters on locomotive tractive efforts, motor torques, wheel loads and traction coefficients are performed through a comparison of simulation results and discussion is provided.