Introduction of feedforward control for an improved optimal regulator system and its application

An improvement to a control system with only feedback control loops proposed in a previous paper by means of the introduction of feedforward control loops is proposed. This method consists of two steps ; the determination of the feedback gains by means of an original optimal regulator technique, which results in the determination of the minimum value of the defined quadratic performance index as in the usual optimal regulator problem, and the determination of the feedforward gains by minimizing the minimum value of the performance index obtained in the first step, which is carried out by choosing the optimal feedforward gains so that the system deviations from the steady state values caused by the changes in the desired signals and/or the disturbance signals will be minimum. The structure of the designed control system with the feedback and feedforward control loops is clarified and the method is applied to an induction motor speed control system with an input delay time due to the processing time required to execute the employed control algorithm in a microprocessor.