Optimization of Propulsion Systems for Series-Hybrid City Busses through Experimental Analysis

This article describes a methodology for the optimization of hybrid propulsion systems combining an on-road measurement campaign with the development of a simulation tool. This methodology has been applied in particular on a series-hybrid city bus using super capacitors. The experimental set-up and the software tool are presented. The measurement setup is based on a National Instruments-cDAQ data acquisition system, containing a real- time programmable embedded processor. The software model is mainly based on the 'backwards-looking' or 'effect-cause' method which calculates the energy consumed by a vehicle following a predefined driving cycle by going upstream the vehicle components. Experimental as well as simulated results are presented and compared. The developed simulation tool is assessed and refined by means of the experimental data obtained during the thorough on-road measurement campaign. Suggestions for an improved and more efficient power flow control strategy for series-hybrid city busses are given. The dimensioning of the supercaps is optimized.