Adaptive speed control of a converter-driven DC motor

Numerous studies have appeared in the control literature regarding the regulation of the angular speed of DC motors driven by DC-DC converters. In this work, we considered a buck converter-driven DC motor system. The implementation of the proposed adaptive controller requires only one sensor to measure the motor angular speed. An estimator was developed to estimate the inductor current and the output voltage of the converter, the armature current of the DC motor, and to generate a simple adaptation law for the estimate of the external load torque. A linear sliding surface was used to derive an adaptive controller that is simple in its design and guarantees closed-loop system stability and precise speed regulation in the presence of the inductor parasitic and parameter uncertainties of the converter/motor system. Furthermore, the controller was shown to be robust against external disturbances. A simple systematic procedure was outlined to select the three gains of the proposed adaptive controller. The robustness and effectiveness of the controller were validated by computer simulations and compared to the proportional integral derivative (PID) control.