Adaptive Passivity-Based Control for DC Motor Speed Regulation in DC-DC Converter-Fed Systems

This paper presents a unified adaptive passivity-based control strategy using incremental modeling to regulate the angular speed of a DC series motor driven by DC-DC converters operating in both buck and boost configurations. The proposed approach leverages an incremental port-Hamiltonian framework to design control laws that ensure global asymptotic stability of the closed-loop system. To address the challenge of unknown load torque, a nonlinear disturbance observer is incorporated, enabling real-time estimation required for accurate computation of equilibrium points and reference tracking. Theoretical developments are validated through experimental implementation and compared against an inverse optimal control (IOC) strategy. Results show that the proposed IDA-PBC controller significantly outperforms the IOC method in terms of transient response, tracking accuracy, and disturbance rejection. In the buck configuration, the IDA-PBC reduced the rise time by up to 50.24% and completely eliminated overshoot. Similarly, in the boost configuration, rise time was improved by 20.63%, with enhanced stability and lower phase lag under sinusoidal tracking. These findings confirm the robustness and effectiveness of the proposed control strategy for real-time applications in electromechanical systems.