Discrete mapping modeling and nonlinear characteristics analysis of fuel cell-battery hybrid energy storage parallel system

Fuel cell-battery hybrid energy storage systems are critical components in distributed power systems due to their high efficiency and reliability. This paper aims to focus on modeling and analyzing the nonlinear dynamics of a dual-input, single-output parallel hybrid energy storage parallel system. A fifth-order state-space model is developed by integrating the constant-pressure fuel cell model, the Rint battery model and a constant power load equivalent circuit, based on a simplified discrete-time mapping method. Using the load power and the reference current as the bifurcation parameters, the system’s fast-scale nonlinear behavior is investigated. Simulation and experimental results validate the model’s accuracy in capturing phenomena such as period-doubling bifurcation and chaos, specifically identifying critical stability boundaries. The study demonstrates that the simplified discrete-time model effectively identifies fast-scale bifurcation behavior, providing a theoretical foundation for optimizing parameters and ensuring stable operation of parallel hybrid energy storage systems. Future work can extend this modeling method to the nonlinear analysis of cascaded operating modes and other topological structures.