Analysis of PEM fuel cell – Supercapacitor – Battery pack system during standard cycle

Today the application of PEM (Polymer Electrolyte Membrane) fuel cell stack in the automotive field is a topic on central interest. Unfortunately, a PEM fuel cell stack cannot directly supply variable speed drives because of their non-linear behaviour in dynamic conditions. This paper is mostly concerned with the sizing of the supply system, PEM fuel cell-supercapacitor-battery pack, of an electric vehicle, based on the urban/suburban drive cycle NEDC (New European Driving Cycle). The average required power is used to design the fuel cell stack by imposing a preset operating point; the battery capacity is chosen in order to satisfy the constrain on the minimum value of the state of charge during the cycle; finally, the supercapacitor is determined by imposing the current sharing between battery and supercapacitor in transient condition.