A new approach to measure the energy on-board train during braking

Measuring energy wasted during braking by trains is a non-trivial task because it is performed by power semiconductor devices that switch high current levels at a few hundred hertz. The chopped signals produced are difficult to analyze, not only for the high switching frequency but also for the high slew rate that produces even higher harmonic content. In this harsh scenario, it is challenging to guarantee an adequate level of accuracy and it could be very expensive for railway operators, who often completely renounce measuring these quantities of interest, estimating it from mechanical quantities. In a previous paper, the authors have already faced this issue by developing an accurate technique usable offline. Here, two simplified methods with suitable accuracy levels for train energy management, and easy to be implemented on train control unit are proposed. The paper describes the phenomena of interest and related measurement issues. A numerical solution together with a deep analysis on the input quantities needed are presented. The methods are applied to experimental data from a measurement campaign, conducted on-board train in the northern part of Italy. Furthermore, the metrological performances of the methods are assessed by adopting as reference the off-line technique.