For many years, power electronics in the high-power area was performed with extremely
slow semiconductor switches. These switches, including the thyristor and the Gate Turn-Off
(GTO) thyristor, had the capacity to handle very high voltages and currents but lacked the abilityto perform high frequency switching. Low-power converters, such as computer power suppliesand low horsepower motor drives, have employed high-frequency switching for years and havebenefited from very nice output waveforms, good control dynamic performance, and manyotheradvantages compared to low frequency switching. Recent improvements in high-powersemiconductor technology has brought switching performance similar to that of the low-powerMOSFETs and IGBTs to the high-power area through the advancement of the IGBT’s ratings tocreate the High Voltage IGBT (HVIGBT) and the development of new GTO-derived devicesincluding the Integrated Gate Commutated Thyristor (IGCT) and the Emitter Turn-Off (ETO)thyristor. These new devices all feature high switching speed and the capability to turn off
without the requirement for a turn-off snubber. With these new device technologies the highpower
field of power electronics can realize dramatic improvements in the performance of
systems for utility applications and motor drives.