PRACTICAL IDENTIFICATION AND PI-OPTIMAL CONTROLLER OF A LABORATORY DRIVE SYSTEM

The design and practical application of digital control techniques to a solid-state DC drive system are described. The aim is to design a pr oportional-plus-integral optimal controller on the basis of an accurat e linear model of the thyristorized drive system. This controller over comes the steady-state error problem and provides perfect tracking of the input disturbances. The drive system consists of a converter bridg e feeding a separately excited DC motor. A linear model of the drive s ystem is identified using the unbiased recursive least squares identif ication approach. This model overcomes the inaccuracy of the analytica l linear model for both the converter bridge and DC motor. Approaches to practical identification and digital control of the drive system ar e described. Experimental results are presented to illustrate the effe ctiveness of the identified model and the improved controlled system p erformance. In addition, a programmable starting technique of the driv e system is tested.