Robust PID Controller in Brushless DC Motor Application

The PID controller is most commonly used for industrial applications. After studying the standard nested two loop controller structure in a permanent magnet brushless DC motor speed servo system applications, this paper proposes a state space parametrization model which allows to convert robust PID controller design into an linear matrix inequality(LMI) optimization problem. An analysis of experiment results demonstrates that the proposed robust controller with LMI optimization, offers noticeable improvements in performance especially in cases of(relatively large) model uncertainties. And the proposed technique guarantees uniform exponential stability of the closed loop system, a desired rate of convergence, and Hinfin norm bound.