IGBT｜Basic
Principles of Operation of IGBTs
2023.07.19
Points of this article
・In an IGBT, when a voltage that is positive with respect to the emitter is applied to the gate, the device enters the on state, and a collector current flows.
・As indicated in the equivalent circuit, upon turn-on of the N-channel MOSFET, a current IB flows in the PNP transistor, so that the PNP transistor turns on and conduction between the IGBT collector and emitter occurs.
Principles of Operation of IGBTs
The following equivalent circuits and cross-sectional diagram are used to explain the principles of operation of an IGBT.
Equivalent Circuits and Schematic Cross-Sectional Diagram Clarifying Principles of IGBT Operation
In an IGBT, when a collector voltage VCE that is positive with respect to the emitter is applied, and similarly a gate voltage VGE that is positive with respect to the emitter is applied, the on state is entered, there is conduction between collector and emitter, and a collector current IC flows.
Applying this operation to the equivalent circuit, when a positive VGE is applied the N-channel MOSFET turns on, consequently a base current IB flows in the PNP transistor, and as a result the PNP transistor conducts, so that a current IC flows from the IGBT collector to the emitter.
The cross-sectional diagram indicates the movement of electrons and holes in the interior. When a positive VGE is applied to the gate, electrons accumulate in the P+ layer immediately below the gate electrode, and a channel is formed. This is basically the same as the principle of conduction in a MOSFET. As a result, electrons supplied from the IGBT emitter move from the N+ layer to the channel, then to the N- drift layer, to the P+ collector layer. On the other hand, holes from the P+ collector layer are supplied to the N- drift layer. This layer is called the drift layer because both carrier types, electrons and holes, move in it. In other words, movement of electrons from the emitter to the collector results in the flow of a current (IC) from the collector to the emitter.
【Download Documents】 Basics of IGBTs
IGBTs are one of the typical power devices and are used in a wide range of applications including motor drives. This handbook provides a basic understanding of IGBTs, including their application scope and application picture based on their features, their structure and principle of operation, and how they compare with and use other power devices.
IGBT
Basic
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About IGBTs
- Applications Using IGBTs
- IGBT Structure
- Principles of Operation of IGBTs
- Range of Application of IGBTs
- IGBT Features: Comparisons with MOSFETs and Bipolar Transistors
- Selective Use of Power Devices in Motor Applications
- Short Circuit Withstand Time (SCWT) of IGBTs
- IGBTs Incorporating Fast Recovery Diodes (FRDs)
- About IGBT IPMs （Intelligent Power Modules）
Application
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IGBT IPM: Protection Functions and Operation Sequences
- Short Circuit Current Protection (SCP) Function of IGBT IPMs
- Control Power Supply Undervoltage Lockout（UVLO) Function of IGBT IPMs
- Thermal shutdown（TSD） Function of IGBT IPMs
- Analog Temperature Output（VOT）of IGBT IPMs
- Fault Output（FO）of IGBT IPMs
- Control inputs （HINU, HINV, HINW, LINU, LINV, LINW）of IGBT IPMs
- Protection Functions and Operation Sequences －Summary－
Product Information