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How does current flow in IGBT?

How does current flow in IGBT?

Also the IGBT is a unidirectional device, meaning it can only switch current in the “forward direction”, that is from Collector to Emitter unlike MOSFET’s which have bi-directional current switching capabilities (controlled in the forward direction and uncontrolled in the reverse direction).

Why diode is connected across IGBT?

We know that MOSFET or IGBT is a unidirectional device, they only conduct current in forward bias and block the current in reverse bias. This reverse voltage may damage the MOSFET. For this reason, an external diode is connected across the MOSFET or IGBT or SCR to provide a path for reverse current.

Does IGBT have body diode?

When learning power electronics, we all discovered that MOSFETs can conduct in reverse (because they have a body diode) and IGBTs can’t (because they don’t). Because of their construction, some don’t have parasitic diodes. But they still have the same useful property as MOSFETs: They conduct in reverse when VGS=0.

Why IGBT has tail current?

When the IGBT begins to turn off, minority carriers are swept out to external circuitry. When the collector-emitter voltage (VCE) of the IGBT has risen to a certain level (i.e., after the depletion region has expanded), minority carriers contribute to internal recombination current. This current is called tail current.

How does IGBT convert AC to DC?

An AC-to-DC converter furnishing a regulated DC-output voltage from an AC-input supply voltage which is converted with a rectifier that utilizes, in at least two of its legs, IGBT (insulated gate bipolar transistor) devices, preferably of the kind that have no internal diodes.

Why IGBT is popular in recent days?

With its lower on-state resistance and conduction losses as well as its ability to switch high voltages at high frequencies without damage makes the Insulated Gate Bipolar Transistor ideal for driving inductive loads such as coil windings, electromagnets and DC motors.

Which are the terminals of IGBT?

The three terminals of IGBT are Gate, Collector and Emitter. The figure below shows the symbol of IGBT.

What is the function of IGBT in AC device?

The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device. The IGBT is used in medium to high-power applications like switched-mode power supplies, traction motor control and induction heating.

How does a IGBT work?

As defined by being a transistor, an IGBT is a semiconductor with three terminals which work as a switch for moving electrical current. Just as the word “gate” suggests, when voltage is applied to the gate, it opens or “turns on” and creates a path for current to flow between the layers.

How is the current of an IGBT diode controlled?

The current through the IGBT can be switched on and off through the gate-emitter voltage, whereas the diode is not self controlled. When it is biased in forward direction, the resulting current depends on external conditions.

How are IGBT and anti parallel fast recovery diodes different?

Po w er and product ivity for a bet ter wo rld™ ABB’s IGBT modules contain two different types of semiconductors, the IGBT and the anti-parallel fast recovery diode. The current through the IGBT can be switched on and off through the gate-emitter voltage, whereas the diode is not self controlled.

What’s the breakdown voltage of an IGBT junction?

The breakdown voltage of this junction is about 10 to 50V and is shown in the IGBT symbol as an unconnected terminal (Figure 2). For this reason IGBTs have an undefined reverse conduction characteristic, while power MOSFETs have a well de- fined diode behavior.

When does the IGBT turn on the reverse recovery current?

When the IGBT turns on load current is flowing in the antiparallel diode of a complementary IGBT. At turn-on the IGBT picks up the load current plus the reverse recovery current of the diode. See waveform later. Because of the reverse recovery of the diode turn-on losses are normally higher than turn-off losses.

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Ruth Doyle