Multi-Objective Heat Management Optimization For Fuel Cell/Battery Powertrain System

In fuel cell hybrids,low ambient temperature can result in lower total efficiency.The degradation rate of the battery can be increased by cold weather condition.To protect the components of the powertrain and avoid the replacement cost of the battery,a heating system for the fuel cell and the battery is necessary.Since the fuel cell's and the battery's output power is limited by the operating temperature,a strategy must be found defining how to split the component's power between the electric engine and the two heaters con-sidering the fuel consumption and the degradation.A MATLAB/SIMULINK model was built including the fuel cell's output voltage as a function of its operating temperature,the battery degradation caused by the output cur-rent and low temperature,and a heating/cooling system.Both components are heated up to a predefined temperature;a cooling system was implemented to limit the temperature rise.Ambient temperature was set to 0°C and-15°C.The fuel cell heating temperature,heating power for the battery and the fuel cell were varied in a fixed range.The system was evaluated by analyzing the total cost over 1-15 Chinese City Bus Cycle.The results show that the strategies are different for smaller and larger driving ranges.For short driving ranges,the battery's loss and hydrogen cost are increasing with P^Bat_Heat.Heating the fuel cell stack only improves total cost around 3%.For high driving ranges,the influence of increasing P^FC_Heat becomes negligible;total cost decreases with increas-ing P^Bat_Heat around 5.5%.By heating the fuel cell,total cost improves around 30%.The preheating process becomes increasingly necessary with decreasing ambient temperature and is not economic for 0°C.The maximum power given to the power train by the fuel cell is limited by two factors:the rule-based strategy and the power limitation by its op-erating temperature.