IGCT
Encyclopedia
The Integrated Gate-Commutated Thyristor (IGCT) is a power semiconductor
electronic
device, used for switching electric current in industrial equipment. It is related to the gate turn-off (GTO) thyristor
. Like the GTO thyristor, the IGCT is a fully controllable power switch, meaning that it can be turned both on and off by its control terminal (the gate). Gate drive electronics are integrated with the thyristor device.
An IGCT is a special type of thyristor
similar to a GTO
. They can be turned on and off by a gate signal, have lower conduction loss as compared to GTOs, and withstand higher rates of voltage rise (dv/dt), such that no snubber
is required for most applications.
The structure of an IGCT is very similar to a GTO thyristor. In an IGCT, the gate turn off current is greater than the anode current. This results in a complete elimination of minority carrier injection from the lower PN junction and faster turn off times. The main difference is a reduction in cell size, plus a much more substantial gate connection with much lower inductance in the gate drive circuit and drive circuit connection. The very high gate currents plus fast dI/dt rise of the gate current means that regular wires can not be used to connect the gate drive to the IGCT. The drive circuit PCB is integrated into the package of the device. The drive circuit surrounds the device and a large circular conductor attaching to the edge of the IGCT die is used. The large contact area and short distance reduces both the inductance and resistance of the connection.
The IGCT's much faster turn-off times compared to the GTO's allows them to operate at higher frequencies—up to several of kHz for very short periods of time. However, because of high switching losses, typical operating frequency up to 500 Hz.
IGCT capable of blocking reverse voltage are known as symmetrical IGCT, abbreviated S-IGCT. Usually, the reverse blocking voltage rating and forward blocking voltage rating are the same. The typical application for symmetrical IGCT is in current source inverters.
IGCT incapable of blocking reverse voltage are known as asymmetrical IGCT, abbreviated A-IGCT. They typically have a reverse breakdown rating in the 10's of volts. A-IGCT are used where either a reverse conducting diode is applied in parallel (for example, in voltage source inverters) or where reverse voltage would never occur (for example, in switching power supplies or DC traction choppers).
Asymmetrical IGCT can be fabricated with a reverse conducting diode in the same package. These are known as RC-ICT, for reverse conducting IGCT.
inverters
, drives and traction
.
Power semiconductor device
Power semiconductor devices are semiconductor devices used as switches or rectifiers in power electronic circuits . They are also called power devices or when used in integrated circuits, called power ICs....
electronic
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
device, used for switching electric current in industrial equipment. It is related to the gate turn-off (GTO) thyristor
Gate turn-off thyristor
A gate turn-off thyristor is a special type of thyristor, a high-power semiconductor device. GTOs, as opposed to normal thyristors, are fully controllable switches which can be turned on and off by their third lead, the GATE lead.-Device description:...
. Like the GTO thyristor, the IGCT is a fully controllable power switch, meaning that it can be turned both on and off by its control terminal (the gate). Gate drive electronics are integrated with the thyristor device.
Device Description
Thyristor
A thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current trigger, and continue to conduct while they are forward biased .Some sources define silicon controlled rectifiers and...
similar to a GTO
Gate turn-off thyristor
A gate turn-off thyristor is a special type of thyristor, a high-power semiconductor device. GTOs, as opposed to normal thyristors, are fully controllable switches which can be turned on and off by their third lead, the GATE lead.-Device description:...
. They can be turned on and off by a gate signal, have lower conduction loss as compared to GTOs, and withstand higher rates of voltage rise (dv/dt), such that no snubber
Snubber
A snubber is a device used to suppress voltage transients in electrical systems, pressure transients in fluid systems, or excess force or rapid movement in mechanical systems.-Electrical systems:...
is required for most applications.
The structure of an IGCT is very similar to a GTO thyristor. In an IGCT, the gate turn off current is greater than the anode current. This results in a complete elimination of minority carrier injection from the lower PN junction and faster turn off times. The main difference is a reduction in cell size, plus a much more substantial gate connection with much lower inductance in the gate drive circuit and drive circuit connection. The very high gate currents plus fast dI/dt rise of the gate current means that regular wires can not be used to connect the gate drive to the IGCT. The drive circuit PCB is integrated into the package of the device. The drive circuit surrounds the device and a large circular conductor attaching to the edge of the IGCT die is used. The large contact area and short distance reduces both the inductance and resistance of the connection.
The IGCT's much faster turn-off times compared to the GTO's allows them to operate at higher frequencies—up to several of kHz for very short periods of time. However, because of high switching losses, typical operating frequency up to 500 Hz.
Reverse Bias
IGCT are available with or without reverse blocking capability. Reverse blocking capability adds to the forward voltage drop because of the need to have a long, low doped P1 region.IGCT capable of blocking reverse voltage are known as symmetrical IGCT, abbreviated S-IGCT. Usually, the reverse blocking voltage rating and forward blocking voltage rating are the same. The typical application for symmetrical IGCT is in current source inverters.
IGCT incapable of blocking reverse voltage are known as asymmetrical IGCT, abbreviated A-IGCT. They typically have a reverse breakdown rating in the 10's of volts. A-IGCT are used where either a reverse conducting diode is applied in parallel (for example, in voltage source inverters) or where reverse voltage would never occur (for example, in switching power supplies or DC traction choppers).
Asymmetrical IGCT can be fabricated with a reverse conducting diode in the same package. These are known as RC-ICT, for reverse conducting IGCT.
Applications
The main applications are in variable frequencyFrequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
inverters
Inverter (electrical)
An inverter is an electrical device that converts direct current to alternating current ; the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits....
, drives and traction
Traction (engineering)
Traction refers to the maximum frictional force that can be produced between surfaces without slipping.The units of traction are those of force, or if expressed as a coefficient of traction a ratio.-Traction:...
.