Energy management control strategy to improve the FC/SC dynamic behavior on hybrid electric vehicles: A frequency based distribution

This paper presents a breakthrough energy management strategy developed to coordinate a hybrid power supply system for typical solicitations of electric vehicles, but the whole system is scaled to a maximum power of 1.2 kW. The system is composed of a polymer electrolyte membrane fuel cell (PEMFC), a supercapacitor (SC) bank and their respective power conditioning units. The proposed strategy is organized in three hierarchical levels for treating the problems of: (i) global control, (ii) power demand split and supercapacitor state of charge (SOC) preservation, and (iii) interaction between power conditioning units and the sources. The power split is determined in real time with a basis on a frequency distribution, for which a cutoff frequency is defined in agreement with the dynamical capabilities of the sources. The focus is then, to use basic dynamic measurements of an experimental PEMFC module in order to integrate a simulation environment that allows analyzing the interactions and performances of the power train components and the regulation architecture under different scenarios. Results demonstrate that the strategy allows regulating the DC bus voltage under different load profiles; preserving the SC SOC within the recommended range; operating the PEMFC all over the safe region; and diminishing the FC start-ups and shutdowns.