Convergence and order reduction of controllers in PIM based digital redesign

A combination of the matched-pole-zero open-loop method and the so called plant-input-maping (PIM) closed-loop method is proposed as a new way to carry out digital redesign. The proposed method provides a digital controller whose internal signals converge individually to those of the analog controller as the sampling interval approaches zero, and whose order is the same as the analog controller, both of which have not been possible with the ordinary PIM method.