Experimental evaluation of advanced delay-compensated speed control of a four-quadrant chopper-fed DC motor for microgrid prime mover applications

This is the authors' abstract. We don't add key points for this paper.

This paper presents the design, implementation, and experimental evaluation of advanced delay-compensated speed-control strategies for a four-quadrant chopper-fed DC motor (DCM) employed as a prime mover for a synchronous generator in islanded microgrid applications. The study investigates and comparatively evaluates four control approaches: Lead-Lag control, observer-based State-Feedback control, Smith Predictor (SP) control, and RST predictive control. The observer-based State-Feedback controller is developed using a state-space representation of the DCM, where rotor speed is directly measured while armature current is estimated using a Luenberger observer designed through pole-placement techniques. To address sensor-induced measurement delays, a Smith Predictor-based controller is implemented for delay compensation and improved closed-loop stability. In addition, an RST predictive controller is designed to enhance reference-tracking capability and disturbance rejection under delayed-feedback conditions. All controllers are integrated with PWM generation for real-time four-quadrant chopper operation. The proposed control strategies are validated through MATLAB/Simulink simulations and FPGA-based experimental implementation under varying load torque disturbances and speed-reference transitions. Furthermore, the DCM-driven synchronous generator is experimentally evaluated in an islanded microgrid supplying RL and induction motor loads. Comparative results demonstrate that the RST and State-Feedback with Observer controllers provide superior dynamic response, reduced settling time, improved disturbance rejection, and enhanced robustness against measurement delays compared with conventional Lead-Lag control. The findings confirm the suitability of advanced delay-compensated control strategies for reliable DC motor drive operation in microgrid prime-mover applications.