Constant vs. Variable Efficiency of Electric Drive in Train Run Simulations

Train run simulations, which focus on various power- and energy-oriented aspects, should reflect the losses in the electric powertrain. In general, the powertrain efficiency varies with respect to load and speed. Including this relation in simulation requires knowledge about detailed drivetrain parameters, which are often unavailable. This paper verifies the possibility to approximate the drivetrain efficiency in train run simulations by an equivalent constant that provides the same results of total energy usage. A case study of a suburban electric traction unit was selected to compare results of simulations carried out for different operating conditions including: route length, cruising speed and route inclination. The impact of replacing the variable efficiency with the equivalent constant on various outcomes of train run simulations was discussed and the limitations were formulated.