IGCT: Insulated Gate Commutated Thyristor

The IGCT is a specialized type of thyristor that combines the characteristics of a thyristor and a gate-turn-off (GTO) thyristor. It is designed to address some of the limitations of traditional thyristors, particularly their inability to turn off once they are turned on. The IGCT offers the ability to control both the turn-on and turn-off processes, making it suitable for high-voltage and high-current applications where fast switching and controllability are essential.

IGCT circuit symbol

IGCT structure

IGCT characteristics

IGBT: Insulated Gate Bipolar Transistor

The Insulated Gate Bipolar Transistor (IGBT) is a power semiconductor device that combines the characteristics of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and a bipolar transistor. It is widely used in power electronics and high-power applications due to its ability to handle both high voltage and high current.

 

 

IGBT circuit symbol

 

IGBT structure 

 

Characteristics of IGBT

IGCT vs. IGBT:  What are the differences

Structure

IGBT is composed of N-type Metal Oxide Field Effect Transistor (MOSFET) and PNP-type Bipolar Transistor (BJT). This structure enables it to perform current amplification under the control of MOSFETs, thereby achieving high voltage and high current switching capabilities.

The IGCT is composed of two PNP bipolar transistors to form a bipolar structure. This structure determines the special switching performance and reverse blocking ability of IGCT. Due to the bipolar structure of the IGCT, its area is relatively large, causing a certain manufacturing complexity.

Voltage level and application field

Due to their bipolar structure and special design, IGCTs are suitable for high-voltage, high-current applications and can withstand higher voltage levels, usually in the range of several thousand volts.

IGBT is suitable for medium and high voltage applications, and the voltage level is generally below 1200V. It is used extensively in drive motors, inverters, welding equipment, and various industrial applications.

Switching Speed and High Frequency Applications

Due to the special nature of its structure, the switching speed of IGCT is relatively slow, suitable for low frequency and intermediate frequency applications, and the switching speed is generally above hundreds of microseconds.

The structure of the IGBT makes it have a fast switching speed, which is suitable for high-frequency applications, and the switching speed can reach tens of nanoseconds, which is suitable for occasions that require fast switching.

Efficiency and conduction loss

The conduction loss of IGBT is relatively small, so it has high efficiency in the on state, and is suitable for applications requiring high efficiency.

Due to its special structure, the conduction loss of IGCT is relatively large and the efficiency is relatively low, but its advantages are still obvious in specific high-voltage applications.

Switching capability

IGCT has high switching capability, can withstand large current impact, and is suitable for high-power applications and high-current environments.

The switching capability of IGBT is relatively weak, especially in high-current and high-power applications, which require reasonable current limitation and heat dissipation design.

Reverse blocking ability

Due to its special bipolar structure, IGCT has better reverse blocking ability, can realize bidirectional switching, and is suitable for applications where bidirectional current flows.

IGBT requires an external anti-parallel diode to achieve reverse blocking, which is relatively less flexible than IGCT in reverse blocking.

Switch Control

IGCTs offer inherent turn-off control, which means they can be turned off by applying a negative gate signal. However, their turn-off performance may not be as fast as IGBTs.

IGBTs require external gate control to turn on and off. Their switching performance can be controlled more precisely than IGCTs.

Short-circuit Protection

Due to their robust construction, IGCTs generally have better short-circuit withstand capability. They can handle short circuit conditions for a limited time without damage.

Compared with earlier power devices, IGBT has improved short-circuit protection mechanism, but its short-circuit withstand capability is generally lower than that of IGCT.

Life and Reliability

IGBTs generally have a longer lifetime than IGCTs. The increased lifetime is generally attributed to improved IGBT switching characteristics and reduced thermal stress. The long lifetime of IGBTs is especially valuable in applications where maintenance and replacement are challenging or costly.

On-state voltage drop

IGCTs exhibit a lower on-state voltage drop during conduction than IGBTs. This reduces conduction losses and improves overall efficiency in IGCT-based systems. The low on-state voltage drop of IGCTs is beneficial in high power applications where minimizing energy loss is critical.

Electromagnetic Emission

IGCTs are constructed similarly to traditional disk devices, resulting in relatively high levels of electromagnetic emissions. Such emissions may cause interference to other nearby electronic components and systems.

Dimensions and Packaging

IGCTs may require special packaging and cooling arrangements due to their larger size and structure. This can affect integration and layout considerations in electronic systems. IGBTs are smaller and available in a variety of packaging options, allowing greater flexibility in system design and layout.

 

Final Words

IGBTs and IGCTs have their own strengths and are selected based on the application. IGBTs are commonly chosen for their fast switching and efficiency, while IGCTs excel in high-voltage and high-current scenarios where controlled turn-off is critical. The choice between the two depends on factors such as voltage levels, power requirements, switching speeds, and application constraints.

 

Read More:

Difference Between BJT, MOSFET and IGBT: BJT vs MOSFET vs IGBT

IGCT vs. IGBT: What Are the Difference

IGBT vs GTO: Difference Between IGBT and GTO

IGBT Structure, Characteristics and Working Principle
Application of IGBT and IGBT Application Examples
IGBT Symbol Diagram, Characteristics, Circuit
Global IGBT Shortage: Cause & Future Outlook
IGBT Rectifier: All You Want to Know
IGBT Types: Understanding the Basics
How to Test an IGBT with A Multimeter
Difference Between IGBT and MOSFET (IGBT vs MOSFET)
What is the Advantage of IGBT

Difference Between IGBT and Thyristor 

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