Discrete-time least-squares Padé order reduction: A stability preserving method

Abstract

A new stability preservation property is proved for the least-squares Padé order reduction method when applied to discrete-time systems. It is shown that the property depends on which free reduced model parameter is chosen to be unity. Clarification is also given on how the system is actually approximated using this method. An example illustrates the enhanced appeal of the method as a result of the stability preservation property.