Insulated Gate Bipolar Transistor (Igbt) Operation - Lincoln Electric Cross Country 300 Service Manual

LINCOLN ELECTRIC
SOURCE
n +
p
n -
n +
p +
DRAIN
A. PASSIVE
Insulated Gate Bipolar Transistor (IGBT) Operation
The IGBT is a type of transistor. IGBTs are semiconductors 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.
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. This is similar to turning ON a light switch.
Figure E.4 – Insulated gate bipolar transistor (IGBT) operation
GATE
n +
BODY REGION
DRAIN DRIFT REGION
BUFFER LAYER
INJECTING LAYER
Cross Country™ 300 Service Manual
SOURCE
n + n +
p
n -
n +
p +
DRAIN
A. PASSIVE
POSITIVE
VOLTAGE
APPLIED
GATE
BODY REGION
DRAIN DRIFT REGION
BUFFER LAYER
INJECTING LAYER
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