See igbt operation and, Theory of operation, Insulated gate bipolar transistor (igbt) operation – Lincoln Electric V155-S User Manual

Page 30

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THEORY OF OPERATION

E-6

E-6

INVERTEC® V155-S

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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.

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 con-

nected to the drain terminal will allow the IGBT to con-

duct and supply current to circuit components coupled

to the source. Current will flow through the conducting

IGBT to downstream components as long as the posi-

tive gate signal is present. This is similar to turning ON

a light switch.

FIGURE E.6 – IGBT OPERATION

DRAIN

SOURCE

GATE

INJECTING LAYER

BUFFER LAYER

DRAIN DRIFT REGION

BODY REGION

p +

n +

n -

p

n +

n +

DRAIN

SOURCE

GATE

INJECTING LAYER

BUFFER LAYER

DRAIN DRIFT REGION

BODY REGION

p +

n +

n -

p

n +

n +

POSITIVE

VOLTAGE

APPLIED

B. ACTIVE

A. PASSIVE

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