Increasing the Energy Efficiency of Rail Vehicles Equipped with a Multi-Motor Electrical Traction Drive

The main objective of this paper is to formulate proposals for improving the energy efficiency of rail vehicles equipped with a multi-motor electrical traction when operating with partial load. By processing the data of an on-board recorder, the dependence of the coefficient of performance (COP) to the traction power was obtained for electric locomotives (fed from AC and DC networks). An analytic interpolation of this dependency was derived. Then an algorithm regulating the number of traction motors which ensure the stabilization of the electric locomotive's COP across the whole range of loads, was elaborated. To validate this algorithm, a numeric model of a train consisting in an electrical locomotive and several carriages was built. In this model, the locomotive is represented as a controllable electromechanical system for which it is possible to regulate the locomotive power using each axis individually. Computer simulation results indicated the high efficiency of the proposed adaptive algorithm when the train is running on "standard" railway track profiles. The evaluation of the power consumption's reduction while in traction regime, obtained thanks to the presented algorithm, was also carried out. A direct measure of the reduced electricity consumption for a freight electric locomotive was also performed with a reduction of the energy consumption by 16,8 %. The proposed algorithm can also be used for shunting locomotives with hybrid traction drive. These results are of practical importance: indeed, the reduction of electrical power consumption for locomotive traction has great economic effects.