Abstract
Among the research and development subjects of ENEA (Italian National Agency for New Technology, Energy and Environment) an important theme is the study of innovative vehicles with high energy efficiency and low emissions. ENEA has set up an infrastructure in order to execute research and development activity for electrical and hybrid vehicles and performed a number of laboratory tests that demonstrated the strong correlation between energy consumption and power management strategy.
For hybrid vehicles in particular the need of a controller, that could manage at the best the power flux between generator, storage and traction system, became soon apparent, so such a device was developed by ENEA and University of Pisa. The controller, monitoring the energy consumption during the mission and on the basis of steady state map values for motogenerator and battery, controls the power set-point and starts-up and shuts down the engine so that the generator can work at its best point and the energy stored in the battery remains within pre-defined limits Emin-Emax. The paper deals with features and working methods throughout the testing campaign on the ALTRA minibus drive-train, a 6m series hybrid developed by IVECO and ANSALDO, by using the roll bench of ENEA. The testing campaign was performed according to a number of European, American and Japanese urban driving cycles. Comparing the fuel consumption during the NEDC with the best case for the vehicle without controller, the results confirm the need for such a device on a hybrid vehicle, and demonstrate that it has to have a good knowledge of the operation of the various subsystems (internal combustion engine, battery, propulsion drive) to be able to optimize the overall vehicle performance. In particular it is very important to enough accurately know the battery state of charge.
The energy levels in the battery have to remain within a domain defined by the maximum battery derivable power and the need to avoid gassing during charge. In the next months, research center, university and industry will work in the same project in order to integrate different experiences and different approaches with the aim to further improve the control system performances.