Insulated Gate Bipolar Transistor (Igbt) Operation; Theory Of Operation - Lincoln Electric PRO-CUT 25 SVM149-A Service Manual

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INSULATED GATE BIPOLAR
TRANSISTOR (IGBT) OPERATION
An IGBT is a type of transistor. IGBTs are semicon-
ductors well suited for high frequency switching and
high current applications.
Drawing A shows an IGBT in a passive mode. There
is no gate signal, zero volts relative to the source, and
therefore, no current flow. The drain terminal of the
IGBT may be connected to a voltage supply; but since
there is no conduction the circuit will not supply
current to components connected to the source. The
circuit is turned off like a light switch in the OFF
position.
SOURCE
n +
p
n -
n +
p +
DRAIN
A. PASSIVE

THEORY OF OPERATION

FIGURE E.5 – IGBT
GATE
n +
BODY REGION
DRAIN DRIFT REGION
BUFFER LAYER
INJECTING LAYER
PRO-CUT 25
Drawing B shows the IGBT in an active mode. When
the gate signal, a positive DC voltage relative to the
source, is applied to the gate terminal of the IGBT, it
is capable of conducting current. A voltage supply
connected to the drain terminal will allow the IGBT to
conduct and supply current to circuit components
coupled to the source. Current will flow through the
conducting IGBT to downstream components as long
as the positive gate signal is present.
to turning ON a light switch.
SOURCE
n + n +
p
n -
n +
p +
DRAIN
B. ACTIVE
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This is similar
POSITIVE
VOLTAGE
APPLIED
GATE
BODY REGION
DRAIN DRIFT REGION
BUFFER LAYER
INJECTING LAYER