Introduction

This chapter discusses the history of power devices on the necessity of expanding usage of power electronics to support energy conscious social environment and on some of the key roles that power devices play in this respect for efficient power conversion. Active electrical devices have a history dating back to 1906, starting with the invention of the triode. History says that these triodes could be replaced by a much smarter active device solution, named "transistor," after its invention in 1947. The germanium grown transistor type was commercialized in 1953. Power electronics, which was newly defined by Dr. W. E. Newell in the early 1970s, meant a new frontier of electronics application involving power and energy whereby all kinds of electronics related to the control various electricmachines and other power systems based on computer control and relays were meant to be covered.