Adaptive Fractional-Order Resonant Control With Fixed-Time Augmented Extended State Observer for Current Disturbance Attenuation in Electric Propulsion System

Classical current control strategies in electric propulsion systems often suffer from degraded performance under periodic and aperiodic disturbances. To overcome these limitations, this paper proposes a novel current control framework that combines an adaptive fractional-order resonant controller (AFRC) with a fixed-time augmented extended state observer (FxTAESO), aiming to enhance disturbance rejection and dynamic robustness. Firstly, the proposed AFRC introduces a self-tuning fractional-order operator, which adaptively adjusts in real-time according to load current, harmonic rejection strength, and desired phase margin. This adaptive mechanism enables precise harmonic compensation while ensuring stability and robustness across the varying operating conditions. Subsequently, the FxTAESO incorporates a current integral term as system augmented variable to decouple the coupling effect between current measurement noise and high observer gains. Additionally, by embedding an improved nonlinear fixed-time convergence law, the observer ensures that the estimation error converges to a bounded neighborhood of the equilibrium point within a predetermined time, independent of initial conditions. Finally, experimental validation on a PMSM drive platform demonstrates that the proposed FxTAESO-AFRC scheme achieves superior steady-state accuracy, faster transient response, and stronger disturbance suppression compared to conventional methods.