Introduction

The control of energy in its various forms was always a necessity that became more relevant with the increasing performance requirements of the twentieth century. The control of energy conversion contributes to the optimization in performance and energy efficiency for all processes, machines, and devices.

Technology developments from 1960 to 2000 in the areas of microelectronics and power electronics made possible the development of more complex, efficient and reliable energy controls. In this century there were significant technology mutations, with controls going from mechanical to electromechanical devices, evolving gradually to full electronic controls without moving parts. Since the 1970s electronic controls have been implemented more and more with programmable systems through the use of microcomputers.

The complexity and reduced time constants of modern processes imply the adoption of high performance programmable controllers. This requires not only higher processing speed but also more advanced...