Science Fair Project Encyclopedia
The Insulated (or sometimes called Isolated) Gate Bipolar Transistor combines the simple gate drive characteristics of the MOSFET with the high current and low saturation voltage capability of bipolar transistors by combining an isolated gate FET for the control input, and a bipolar power transistor as a switch, in a single device.
The IGBT is a recent invention. The "first-generation" devices of the 1980s and early '90s were relatively slow in switching, and prone to failure through such modes as latchup and secondary breakdown. Second-generation devices were much improved, and the current third-generation ones are even better, with speed rivalling MOSFETs, and excellent ruggedness and tolerance of overloads.
The IGBT is mainly used in switching power supplies and motor control applications.
The extremely high pulse ratings of second- and third- generation devices also make them useful for generating large power pulses in areas like particle and plasma physics, where they are starting to supersede older devices like thyratrons and triggered spark gapss.
These high pulse ratings, and low prices on the surplus market, also make them great fun for the hobbyist, who can now generate colossal amounts of high-frequency power to drive experiments like Tesla coils.
Availability of affordable, reliable IGBTs is a key enabler for hybrid cars. Toyota's second generation Prius has a 50 kW IGBT inverter controlling two AC motor/generators connected to the DC battery pack.
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