Experimental Validation of an Optimal Energy Management Strategy for a Hybrid Bus with Dual Storage System

Abstract

The operational efficiency in a hybrid electric bus(HEB) mainly relies on the suitable design of its energy management strategy (EMS) to operate, in a proper way, the onboard energy sources. This work addresses the experimental validation of an optimized EMS (at simulation level) proposed for an urban HEB. In this case, the EMS handled the proper power split behavior of the vehicle demand among the genset(internal combustion engine connected to an electric generator) and a dual energy storage system (combining Li-ion batteries with supercapacitors). To validate the EMS, a scaled test-bench including the energy sources connected to the electrical DC grid in an HEB was build. This test-bench aims to emulate the real behavior of the genset, battery, supercapacitor, traction demand and auxiliary loads while operating in an urban route profile. The experimental results showed how the real electrical phenomena(DC voltage variations, current balancing, system losses, current ripple, auxiliary and unknown consumptions, etc.) inherent of the power-train devices may affect the energetic performance of the optimal EMS obtained in ideal conditions. Thus, based on the operational dynamics and identified issues, the optimal EMS can be tunned to improve its performance in real operation scenarios.