Tracking performance of an H∞ position controller for current-fed induction motors under mechanical load variations

This paper describes a systematic procedure to design a position tracking H_∞ controller for current-fed induction motors actuating mechanical loads which ensures robustness with respect to load torque disturbances. This feature is very important in many industrial applications; in fact during normal operating conditions if variations of the mechanical load driven by the induction motor appear the tracking performance achievable by the controller can degrade. These variations are seen by the H_∞ controller as if they were load torque disturbances. Due to the good disturbance rejection capability exhibited by the robust controller, a satisfactory dynamic performance is achieved. A numerical simulation study, in which an induction motor drives a one-link robot manipulator, shows the tracking performance of the designed H_∞ position controller in presence of mechanical load variations