Page 10 - Power Electronics Handbook

Chapter 1

Power semiconductor devices

1.1 Introduction
1.1.1 Historical development
The field of power electronics is not new. The post- and pre-war periods,
from about 1930 to 1950, saw extensive application of power electronics,
based primarily on the mercury arc rectifier and the gas-filled tube.
It was in December 1939 that William Shockley first noted the principle
of a semiconductor which could be used for controlling electrical power.
However, it was not until 23 December 1947, the official date for the
invention of the transistor, that a simple point contact transistor was
demonstrated by William Shockley , John Bardeen and Walter Brattain, to
the executives of Bell Laboratories. It was at this point that semiconductor
electronic technology was born.
Two other dates are important when tracking the development of power
semiconductors. The integrated circuit was invented by Jack Kelby of
Texas Instruments in 1958. Integrated circuits, especially microprocessors,
are now used extensively to control power semiconductor devices. Finally,
the thyristor, the workhorse of the power semiconductor field, was
announced by General Electric in 1957. It was originally called the
silicon-controlled rectifier (SCR), to differentiate it from the common
silicon rectifier, and it was some time later that the name was changed to
thyristor.
1.1.2 Applkations
Power semiconductors are used in wide-ranging applications. The
following gives only a representative sample.
(i) Industrial applications consist primarily of two areas, motor control
and power supplies. The motors which are controlled vary from the
very large, as used in steel mills, to the relatively smaller ones, such
as in machine tools. Power supplies too come in many shapes and
sizes, such as for battery charging, induction heating, electroplating
and welding.
(ii) Consumer applications cover many different areas in the home, such
as audio amplifiers; heat controls; light dimmers; motor control for
food mixers and hand power tools; and security systems.

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