Introduction

Thyristor technology is inherently superior to transistor

GTO with its snubbers and IGBT with is high losses

GTO drive technology results in costly dv/dt and di/dt snubber circuits

GCT combines the thyristor and transistor characteristics

IGCT- Combination of GCT and low inductance gate unit without snubbers

Circuit and Equivalent circuit

Two transistor equivalent circuit

Fabrication

IGCT combines power handling device and the device control circuitry

Permits integration of free wheeling diode and snubberless operation

Features of IGCT

Improved GTO switching characteristics

Reduced turn-off and on-state losses

Reduced gate drive requirements

High frequency operation for continous and dynamic condition

Integration of main switches

Development of antiparallel diodes

Improved GTO switching characteristics

Improved at high power with the hard driveo Integrated gate drive commutates

the cathode current to zero

The hard gate drive converts the thyristor from its pnp latching state to pnp mode within 1microseconds.

Reduced on-state and turn-off losses

Reduction in device thickness is achieved by introducing a buffer layer on anode side.

Table compares he improved characteristics of IGCT with GTO thyristor.

Snubberless turn-off with anti-parallel diodes

Upgraded high-power presspack diodes manufacture using irradiation process

Inverter operation

di/dt control is achieved with an inductor, clamped by a diode and a resistor

Capacitor in the input makes the input dc voltage constant. Also suppresses the harmonics fed back to the source.

Output Waveform

Application of IGCT

Main advantage is its ability to turn-off in 2 microseconds.

With IGCT it is possible to build less costly, more reliable & more compact power control systems including

oRailway power supply frequency changers

oStatic Var Compensator for power factor control

oPump and fan drives for chemical, oil and power sectors

oLocomotive drivesoStatic breakers

Conclusion

The IGCT combines all the important innovations needed for future power electronics applications. It enables simple and robust series connection to turn-off devices for high power applications. The additional advantages of IGCT is its low cost, low complexity and high efficiency.

Reference

ABB review on Power semiconductor, May 1998

Power electronics by B.S Bimbra

Power electronics by Mohd. H. Rashid

IGCT characteristics

Turn-on characteristics

Turn-off characteristics

IGCT-A new emerging technology for high-power, low-cost inverters

Presented by

Mohammed Jamshid S7-EEE

Under the guidance of,Mrs. Sobha.MAsst.Professor