Comparative Study of Different Air Supply Systems for Automotive Fuel Cell Applications

The dynamic and efficiency of automotive fuel cell drives is significantly influenced by air supply system. Different air compression architectures use electric compressor (EC), electric turbocharger (ETC), or a serial booster (SB) consisting of turbocharger and electric compressor. These three variants of air compression systems were modeled using a map approach and added to a 0D fuel cell air supply model. The characteristic maps of the turbomachinery were measured on the test bench under fuel cell conditions. Subsequently, the calculated isentropic efficiencies were corrected with respect to heat transfer phenomena occurring during the measurement. Moreover, a scaling method for the maps of the turbomachinery is explained. The initial simulation of the air compression systems with equal diameters for the turbomachinery showed no difference in the mechanical power demand. Therefore, the particle swarm algorithm (PSA) was applied to optimize the turbomachinery maps of EC, ETC, and SB with the scaling method. The PSA reduces the mechanical power demand of EC by 17%, of ETC by 18%, and of SB by 27%. This leads to the lowest power consumption of SB followed by ETC and last EC. The best performance of SB is caused by the higher recuperated mechanical power of the turbine.