Investigation of optimal operating temperature for the PEMFC and its tracking control for energy saving in vehicle applications

The operating temperature, as one of the key factors influencing the system efficiency is very critical for the proton exchange membrane fuel cell (PEMFC). However, the specific relationship between the operating temperature of PEMFC and its efficiency remains unclear, which further challenge the high-efficiency operation of the PEMFC in the fuel cell vehicle (FCV). This paper aims to decouple the operating temperature from the complicated driving conditions of the FCV, and find the mapping relationship between the operating temperature and PEMFC output power, hence to improve the efficiency by the optimal control of PEMFC system. A temperature control model of the PEMFC cooling system is established and enhanced by a series of experiments under different power levels against different temperature. The mapping relationship between the optimal operating temperature and the PEMFC power is obtained by the experiments. Then, a predictive control with the function of tracking the optimal operating temperature is developed and verified under NEDC and CHTC-HT driving cycles. Simulation results show that compared with constant temperature control and the traditional rule-based temperature control, under the optimal temperature tracking control, the PEMFC efficiency is improved by 15% and 18.2%, 25.6% and 28.7% respectively in the two driving cycles.