What is IGBT and the principle of IGBT
Time:2024-01-27
Views:352
IGBT stands for Insulated Gate Bipolar Transistor, which stands for Insulated Gate Bipolar Transistor. It is a power semiconductor device that combines the advantages of MOSFET and bipolar transistor, and can operate under high voltage and high current conditions, making it widely used in the field of power electronics.
Compared with MOSFETs, IGBTs have lower driving voltage and higher switching speed, as well as the forward conduction ability of bipolar transistors, allowing them to withstand higher currents and voltages. At the same time, IGBT also integrates the insulation gate control function of MOSFET, which can achieve safer and more reliable control.
IGBT typically consists of a PN junction and an N-channel, with three ports: collector, emitter, and gate. When a forward voltage is applied to the gate, a PNP type structure is formed, polarizing the PN junction between the collector and emitter, thereby conducting. When the forward voltage is no longer applied to the gate, the PNP junction will return to an open circuit state and the IGBT will stop conducting.
The work of IGBT can be divided into four main stages:
Off state (off state): When no voltage is applied between the gate and emitter, the IGBT is in the off state with no conducting current flowing through. In this state, the PN junction between the collector and emitter of the PNP bipolar transistor is positively biased, so it is in a conductive state.
Open transition state: When a forward voltage is applied to the gate, electrons in the insulating gate layer between the gate and emitter form a conductive channel. The formed conductive channel can control the current between the collector and emitter of the PNP bipolar transistor, causing it to start conducting.
On state (conduction state): After turning on the transition state, if sufficient forward voltage is applied between the collector and emitter, the PNP bipolar transistor will enter the saturation zone, and the IGBT will be in a conduction state, allowing current to flow.
Closed transition state: When the gate no longer applies forward voltage, the conductive channel closes, the PNP bipolar transistor returns to the cutoff region, the IGBT enters the off state, and current cannot pass through.
IGBT combines the advantages of MOSFET and bipolar transistor, with low voltage control characteristics (MOSFET) and high current driving capability (bipolar transistor). It has lower switching losses and higher switching speeds, making it suitable for high-frequency applications. Meanwhile, the use of an insulating gate layer isolates the gate from other parts, improving insulation performance and reliability.
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