High-Performance DC-Link Voltage Regulation in Fuel-Cell Hybrid Systems Using Adaptive Observer-Based Control

This paper presents a robust converter-level control strategy for a fuel-cell hybrid electric vehicle (FCEV) integrating a fuel cell, battery, and ultracapacitor through a common DC-link. An Adaptive Disturbance–Observer–Based Sliding Mode Controller (ADOB–SMC) is proposed to achieve precise DC-bus voltage regulation and fuel-cell current tracking under multiple source-side uncertainties. The controller combines real-time disturbance estimation with a continuous super-twisting sliding-mode law, effectively suppressing chattering while ensuring fast and stable convergence. A comprehensive nonlinear model of the hybrid powertrain was developed, and the control law was designed based on Lyapunov stability theory to guarantee global bounded-ness and robustness. Simulation studies were performed in MATLAB/Simulink under varying voltage disturbances of the battery, ultracapacitor, and fuel cell. The results confirm that the proposed controller maintains the DC-link voltage at 400 V with negligible steady-state error and rapid error convergence, even under combined source-voltage variations. The fuel-cell current adapts smoothly to load dynamics, ensuring coordinated energy sharing among all sources. Overall, the ADOB–SMC provides a highly effective and computationally feasible solution for stable and efficient operation of next-generation hybrid fuel-cell powertrains.