Hydrothermal state management is of great significance for improving the output performance of fuel cell stack. Based on the principle of electrochemical impedance spectroscopy

this paper combines the equivalent circuit model and obtains the response of two impedance spectrum characteristic frequency points to calculate the angle between the frequency response point connection line and the real axis (frequency secant angle) and proposes a frequency secant angle calculation method. The angle has a unique correspondence with the resistance change of the stack proved by theory. The simulation and experimental results show that the results of the frequency secant angle can describe the changes of the hydrothermal management state in the reactor and the effects of the operating conditions on the output performance of the reactor. This method avoids the deficiencies of complicated AC impedance test procedures

long time period

difficulty of parameter fitting

etc.. It provides an obvious

direct

and simple diagnostic method

which lays a foundation for the optimization of the operating conditions of the stack and the early warning of output performance failure. It has a good application prospect.