1 Power semiconductors
Power semiconductors, in their many and various designs, have become an essential
part of every aspect of our daily lives. Amongst other things, they enable variable speed
drives in consumer goods (e.g. washingmachines), industry (e.g. pumps) and transport
technology (e.g. electric locomotives).
Power semiconductors can be divided into two main groups: Controllable and non-
controllable power semiconductors. The first group comprises mainly thyristors, bipolar
transistors, power MOSFETs and, last but not least, IGBTs. The second group
comprises power diodes
shows an overview of common power semiconductors
with their typical power ranges, blocking voltages and switching frequencies.
While thyristors dominated for decades amongst controllable semiconductors, especially
in the higher power ranges, IGBTs, which have been gaining in profile since the mid-
1980s, nowdominate at power ranges of several MW.
A series of structures based on other power semiconductors or basic mechanisms is
evident in an IGBT. These include:
Three pn-junctions J
One pnp-transistor structureT
One npn-transistor structureT