Adaptive Integral SMC for Power Conversion of PEM Fuel Cell with Practical Fixed Time Stability

This paper addresses the challenge of output voltage regulation in DC-DC boost converters used in Proton exchange membrane (PEM) fuel cell, where parametric uncertainties in load resistance and input voltage can hinder the performance. To address this, a novel adaptive fixed time (FxT) integral sliding mode control (ISMC) strategy is proposed. The key advantage of the FxT ISMC lies in its adaptive gains, which eliminate the need for a priori knowledge of disturbance bounds. This feature, combined with the ISMC, guarantees robustness and practical fixed-time convergence for all the closed-loop system states. As a result, the sliding surface and relative states will reach the vicinity of zero within a fixed time, which is independent of the initial conditions. A comprehensive Lyapunov analysis proves the practical fixed-time stability of the system. Moreover, comparative simulation results demonstrate the superior performance of the proposed controller in terms of faster convergence, low overshoot, chattering alleviation, exceptional resilience to voltage and load fluctuations, and improved error indices.