Simulation-Based Optimal Speed Control of PMSM Drives Using Discrete LQR with Integral Action: Design, Analysis, and Robustness Validation
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Author list: Paponpen, K.; Kumpao, T.; Mujjalinvimut, E.; Sapaklom, T.; Konghirun, M.
Publication year: 2025
Volume number: 23
Issue number: 3
Languages: English-Great Britain (EN-GB)
Abstract
This paper presents a discrete-time linear quadratic regulator (LQR) augmented with integral action for high-performance speed control of permanent-magnet synchronous motor (PMSM) drives. Integral augmentation is embedded directly into the discrete-time LQR framework to eliminate steady-state error in both reference-speed tracking and load disturbance rejection. A discrete-time Lyapunov function is derived, with real-time evaluation under parametric uncertainty, to guarantee asymptotic stability of the closed-loop system. A MATLAB m-file implementation enables fine-grained tuning of sampling rates and seamless translation to embedded architectures. Robustness is assessed via a comprehensive simulation suite comprising step changes in speed reference, load-torque disturbances, ±10% variations in stator resistance and inductance, and ±15% variations in rotor inertia and viscous friction. Head-to-head benchmarking against a cascaded PI controller and a standard discrete-time LQR (without integral action) under identical scenarios quantifies improvements in convergence rate, overshoot, and disturbance-rejection performance. Simulation results demonstrate rapid convergence, minimal overshoot, and zero steady-state error, confirming the proposed method as a reliable, implementation-ready alternative for robust PMSM speed control. © 2025 Author(s).
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