Control strategy optimization of a fuel-cell electric vehicle

In the last decades, due to emission reduction policies, research focused on alternative powertrains among which electric vehicles powered by fuel cells are becoming an attractive solution. The main issues of these vehicles are the energy management system and the overall fuel economy. An overview of the existing solutions with respect to their overall efficiency is reported in the paper. On the bases of the literature results, the more efficient powertrain scheme has been selected. The present investigation aims at identifying the best control strategy to power a vehicle with both fuel cell and battery to reduce fuel consumption. The optimization of the control strategy is achieved by using a genetic algorithm. To model the powertrain behavior, an on purpose made simulation program has been developed and implemented in MATLAB/SIMULINK. In particular, the fuel cell model is based on the theory of Amphlett (1995, "Performance Modeling of the Ballard Mark IV Solid Polymer Electrolyte Fuel Cell. II. Empirical Model Development," J. Electrochem. Soc., 142(1)) whereas the battery model also accounts for the charge/discharge efficiency. The analyzed powertrain is equipped with an energy recovery system. During acceleration, power is demanded to the storage system, while during deceleration the battery is recharged. All the tested control strategies assume charge sustaining operation for the battery and that the fuel cell system has to work around its maximum efficiency. All the tested strategies have been validated on four driving cycles.