Controlled Parameter in IGBT

The controlled parameter in an Insulated Gate Bipolar Transistor (IGBT) is the collector current (IC). The collector current is controlled by the gate-emitter voltage (VGE) applied to the IGBT.

IGBT Structure

An IGBT is a three-terminal power semiconductor device that combines the advantages of both the Bipolar Junction Transistor (BJT) and the Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). It consists of a pnp bipolar transistor and an n-channel MOSFET connected in series.

Working Principle

The IGBT operates in three different modes: cut-off, active, and saturation.

1. Cut-off Mode: In this mode, both the MOSFET and the BJT are in the off state, and no current flows through the device.

2. Active Mode: In this mode, a positive voltage is applied to the gate terminal (VGE), which creates an inversion layer in the n-channel region. The formation of this layer allows current flow between the collector and emitter terminals. The collector current (IC) is controlled by the gate-emitter voltage (VGE) according to the MOSFET characteristics.

3. Saturation Mode: In this mode, the IGBT is fully turned on, and the collector current reaches its maximum value. The voltage between the collector and emitter (VCE) is at its minimum value.

Controlled Parameter

The controlled parameter in the IGBT is the collector current (IC). It is determined by the gate-emitter voltage (VGE) applied to the device. By varying the gate-emitter voltage, the IGBT can be operated in different regions, allowing control over the collector current.

Gate-Emitter Voltage (VGE)

The gate-emitter voltage (VGE) is the voltage applied between the gate and emitter terminals of the IGBT. It controls the conductivity of the n-channel region, thereby regulating the collector current. Increasing the VGE voltage enhances the conductivity, leading to a higher collector current, while reducing the VGE voltage decreases the conductivity and reduces the collector current.

Conclusion

In summary, the controlled parameter in an IGBT is the collector current (IC). It is controlled by the gate-emitter voltage (VGE) applied to the device. By varying the VGE voltage, the IGBT can be operated in different regions, allowing precise control over the collector current.