What is an integrated gate commutated thyristor?
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What is an integrated gate commutated thyristor?

Posted Date: 2024-01-20

Integrated Gate Commutated Thyristor (IGCT) is a power semiconductor electronic device used to switch current in industrial equipment. It was jointly developed by Mitsubishi and ABB. The basic structure diagram of IGCT is shown in Figure 2-90. IGCTs are similar to gate-off (GTO) thyristors, but have multiple gates connected in parallel.

IGCTs can be turned on and off controlled by gate signals, have lower conduction losses than GTO thyristors, and can withstand higher voltage rise rates, making them unnecessary for buffers in most applications. ‍

In an IGCT, due to multiple gates being connected in parallel, the turn-off current is greater than the anode current, which results in a shorter time to completely eliminate minority carriers, giving the IGCT device a faster turn-off speed; also because the gates are connected in parallel, the and The inductance and resistance of the gate drive circuit connection become lower. Compared with GTO thyristors, IGCTs have faster turn-off times, so they can operate at frequencies up to several kHz in a shorter period of time. IGCTs can be fabricated with or without reverse blocking capabilities. However, since a long and low-doping drift region is required to improve reverse blocking capability, the forward voltage drop will be increased. An IGCT that can prevent reverse voltage is called a symmetrical IGCT (S-IGCT). Its structure and electric field distribution are similar to that of a GTO thyristor, as shown in Figure 2-91. Usually the reverse blocking voltage rating of the S-IGCT is the same as the forward blocking voltage rating. A typical application of S-IGCT is a current source inverter.

IGCTs that cannot block reverse voltage are called asymmetrical IGCT (A-IGCT) and usually have a reverse breakdown voltage of tens of volts. However, because the drift region is shortened by adding an n-type buffer layer, its forward voltage drop is lower than that of S-IGCT. A-IGCT is used where reverse-conducting diodes are applied in parallel (for example, in voltage source inverters) or where there is no reverse voltage (for example, in switching power supplies or DC traction choppers).

If part of the p⁺ collector is changed to the n⁺ region, this part becomes a reverse conducting diode in parallel with the IGCT. An asymmetric IGCT manufactured with a reverse-conducting diode in the same package is called an RC-IGCT, which is an IGCT used for reverse conduction.

IGCT is mainly used in variable frequency inverters and is used in electric motor drives for drive and traction.

Review Editor: Huang Fei


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