The optimal control of a constrained drive system with brushless DC motor

The optimal (according to the quadratic performance index) control method of a drive position system with an electronically commutated brushless DC motor is discussed. Initially developed for linear, unconstrained, and undistributed systems, this optimal control method is now applied to a system having constrained state and input variables (e.g. armature voltage, armature current, rotor speed) and unknown disturbances (e.g. load torque). The method uses an undisturbed and unconstrained model for a model-following adaptive control of the real system. The control method is verified through computer simulation using the data from a real drive position system. Results show that the controlled system operates effectively at the limiting state variables, which represent the real system. In addition, the final position is reached without overshoots.