Insulated Gate Bipolar Transistor (IGBT) is a semiconductor device used in high-voltage, high-current circuits, it is a combination of bipolar transistors and metal oxide field effect transistors, with the advantages and characteristics of both, insulated gate bipolar transistor has a low on-state voltage drop and high blocking voltage, widely used in AC modulation and converter, frequency converter, servo drive, lighting and other fields. In this article, we will introduce the working principle and application areas of insulated gate bipolar transistor in detail.

　　I. Insulated gate bipolar transistor working principle

　　Insulated gate bipolar transistor is usually composed of three regions: Drain, Collector, Emitter, drain is N-type semiconductor materials, base and collector area is P-type semiconductor materials, in the base area and drain separated by an insulating layer between the gate, the formation of a MOSFET.

　　When a positive voltage is applied to the gate of the MOSFET, the P-N junction between the drain and the collector region becomes inversely polarised, generating holes in the drain region and electrons in the collector region, at which time the holes and electrons diffuse from the base region to the drain and collector regions, forming a bipolar transistor structure between the drain and collector regions.

　　When the voltage applied to the gate of the MOSFET is zero or negative, the gate-drain junction of the MOSFET becomes reverse biased, preventing the gate current from flowing through it, so that the bipolar transistor is in an off-circuit state.

　　When a positive voltage is applied to the MOSFET gate, the gate-drain junction conducts, and the higher the conduction current, the higher the carrier concentration in the drain region, while the P-N junction's charge changes. Because of the involvement of a PNP-type bipolar transistor, we can emulate the operation of a P-N-P bipolar transistor to understand the conduction process of an IGBT.

　　IGBTs are the natural evolution of vertical power MOSFETs for high current, high voltage applications and fast end devices.Since achieving a high breakdown voltage BVDSS requires a source-drain channel that has a high resistivity, thus resulting in power MOSFETs characterised by high RDSon values, IGBTs eliminate these major drawbacks of existing power MOSFETs.

　　Although the new generation of power MOSFET devices substantially improve the RDSon characteristics, but in high withstand voltage devices, power conduction loss is still much higher than the IGBT technology, lower voltage drop, the ability to convert into a low VCEsat, as well as the structure of the IGBT, with a standard bipolar device compared to the support of higher current densities, and simplify the schematic diagram of the IGBT driver.

　　Second, insulated gate bipolar transistor application areas

　　1, power electronics field

　　Insulated gate bipolar transistor in the field of power electronics is widely used, such as in high-voltage DC power transmission, IGBT is used as a converter switching tube, the ability to convert alternating current into direct current, and will be transmitted to remote areas, power supply to tell a variety of equipment in modern society. In addition, IGBT is also widely used in inverters, frequency converters, electric rail traction, low-voltage power distribution systems and other fields.

　　2、Various industrial applications

　　IGBT is also widely used in machine tool industry, metallurgical industry, chemical industry, textile, food, transport, medical equipment and lighting, etc. IGBT is used to achieve proportional control, matching loads, transformer regulation, free running and become stable, etc. In the field of modern industry, IGBT is an important equipment to achieve automatic control and process control.

　　3、Automotive electronics applications

　　The application of electronic components in modern automobiles is becoming more and more extensive, and IGBT is one of them. In automobiles, IGBT is used for motor control, such as controlling the electric drive unit of hybrid vehicles, the electric drive system of electric vehicles, and the charging system of rechargeable vehicles.

　　IGBTs are also used in advanced automotive electronics to enable efficient power conversion and power storage. When automotive developers continue to improve the operating power and stability of IGBTs, the application prospects of IGBTs will be further expanded.

　　4, other application areas

　　IGBTs are also used in other fields, such as computer equipment, including servers, controllers, printers, and household appliances, such as refrigerators, microwave ovens, air conditioners, etc. The power of these electronic devices is usually low, but the requirements for their efficiency and reliability are high, so IGBTs are also used in these applications.

　　Overall, the insulated gate bipolar transistor is a widely used, powerful semiconductor devices, is used in a variety of high-voltage, high-current power electronic equipment, IGBT is currently undergoing continuous development and improvement, especially in improving its power and stability, has a wide range of application prospects.