Influence of powertrain parameters on vehicle performance of a fuel cell / battery city bus

Proton Exchange Membrane (PEM) fuel cell is favored in automotive applications because it is clean, efficiency and quiet. Performance of a fuel cell-powered vehicle depends on two aspects, the component sizing and the control strategy. The former determines how good a vehicle can be, and the latter decides the degree of exploiting system potential. This paper presents the influence of primary parameters of the hybrid powertrain on vehicle performance. Generally speaking, the performance of a vehicle can be evaluated using following indicators: the maximal speed that can be reached, the accelerating time from zero to a certain speed, the maximal climbing angle, the mileage in a certain condition and the hydrogen consumption in a specific cycle. When the vehicle moves, the fuel cell system fulfills the stationary power requirement, and the battery supplies the accelerating power and recycles brake energy. The vehicle performance is affected by parameters of the hybrid powertrain, e.g. the maximal power of PEM fuel cell system, the PEM fuel cell average efficiency, the battery charging/discharging resistances, the battery open circuit voltage and the vehicle auxiliary power. A theoretical model describing the relationship between these parameters and vehicle performance is firstly proposed. The model is verified by several prototypes of fuel cell city buses developed in past years. Influence of system parameters on vehicle performance is explained in detail. Several suggestions for improving the entire system performance are proposed.