IGBT Information

What is IGBT?

IGBT, short for Insulated Gate Bipolar Transistor, is a fully - controlled voltage - driven power semiconductor device. It combines the advantages of a Bipolar Junction Transistor (BJT) and a Metal - Oxide - Semiconductor Field - Effect Transistor (MOSFET). It has a high - impedance gate like a MOSFET, enabling easy control with a small input signal, and low - on - state voltage drop like a BJT, making it efficient for power - handling applications.

History of IGBT

• Initial Invention: In 1979 - 1980, Professor B. Jayant Baliga from North Carolina State University in the United States successfully developed the IGBT. This was a significant milestone in power semiconductor technology.
• Early Production: In 1982, RCA and GE produced the first - generation IGBTs. These early devices were the starting point for the wide - spread application of IGBTs in various electrical systems.
• Evolution of Technology:
  • In 1988, the first - generation planar - gate (PT) IGBT was released. It laid the foundation for subsequent improvements.
  • In 1990, the second - generation planar - gate punch - through (PT) epitaxial - substrate IGBT with a buffer layer, precise pattern control, and minority - carrier lifetime control was introduced, enhancing performance.
  • In 1992, the third - generation trench - gate IGBT was launched, bringing new design concepts and better characteristics.
  • In 1997, the fourth - generation non - punch - through (NPT) IGBT was released, which had different structural and performance features compared to previous generations.
  • In 2001, the fifth - generation field - stop (FS) IGBT was introduced, further improving the device's performance in certain aspects.
  • In 2003, the sixth - generation trench - type field - stop (FS - TrenchI) IGBT was released, representing continuous innovation in IGBT technology.

Purpose of IGBT

IGBTs are mainly used in frequency - conversion and inversion circuits. They can convert DC voltage into AC voltage with adjustable frequency. They are widely applied in various electrical fields such as rail transportation, smart grids, aerospace, electric vehicles, and new - energy equipment. In electric vehicles, for example, IGBTs are used in the motor - drive system to control the speed and torque of the electric motor. In power grids, they are used in power - conversion stations to adjust the power flow and voltage levels.

Principle of IGBT

When a positive voltage is applied to the gate (G) of the IGBT, an inversion layer is formed on the semiconductor surface below the gate. This is equivalent to creating a conductive channel between the P - type semiconductor and the N - type drift region. As a result, the IGBT turns on, and current can flow from the collector (C) to the emitter (E). When the gate voltage is 0 or a negative voltage is applied, the channel disappears, and the IGBT turns off, blocking the current flow.

Features of IGBT

• High Input Impedance: Similar to MOSFETs, IGBTs have a high input impedance. This means that only a small control current is required to turn the device on and off, reducing the power consumption of the control circuit.
• Low On - State Voltage Drop: When conducting, IGBTs have a relatively low voltage drop. This is beneficial for reducing power losses, especially in high - current applications. For example, in high - power industrial motors, the low on - state voltage drop of IGBTs can save a significant amount of energy.
• Fast Switching Speed: IGBTs can switch between the on and off states in a short time. This makes them suitable for high - frequency applications. In applications such as high - frequency inverters, the fast - switching speed of IGBTs enables efficient power conversion.
• Large Current - Carrying Capacity: IGBTs can handle large currents. They are designed to meet the requirements of high - power applications, such as power - generation systems and large - scale industrial equipment that require substantial current - carrying capabilities.

Types of IGBT

• PT (Punch - Through) IGBT: The PT IGBT has a relatively simple structure. It has a thin N - type drift region, which allows for a lower on - state voltage drop. However, it may have some limitations in terms of reverse - voltage blocking capability and switching speed.
• NPT (Non - Punch - Through) IGBT: NPT IGBTs have a thicker N - type drift region compared to PT IGBTs. This gives them better reverse - voltage blocking capabilities and faster switching speeds. They are often used in applications where high - speed switching and high - voltage blocking are required.
• FS (Field - Stop) IGBT: FS IGBTs incorporate a field - stop layer. This layer helps to improve the device's performance in terms of both on - state voltage drop and switching speed. They are suitable for applications that demand a balance between power - handling efficiency and switching performance.