Development of high frequency resistance test bench for high power fuel cell stack

The proton exchange membrane fuel cell (PEMFC) is considered to be the ultimate technical direction of vehicle power. Online water content diagnosis of PEMFC has become the basis for system control. With the commercial application of fuel cell, traditional electrochemical test instruments are incapable to meet the acquirements of power, voltage and current. As the fuel cell performance is mainly affected by the water content of membrane, HFR is more representative of the overall water content of the system. Meanwhile, high portability is an advantage in this test method. In this work, theory analysis and experiment are combined to realize effective online diagnosis of water content under the condition of small hardware modification. Through simulation and test, a high power fuel cell impedance monitor is designed and high frequency resistance (HFR) is selected as a diagnostic index of water content based on the characteristics of the PEMFC system. According to the experimental results, the boundary value of HFR as a fault diagnosis indicator for water state is determined and online monitoring of PEMFC water content is achieved by HFR.