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Circuit concept of DynamicActiveClamping

As alreadymentioned, adisplacement current can flow through theMiller capacitance of

the IGBT, charging the gate. This process may increase the voltage at the gate of the

IGBT. Especiallywhen switching over currents and short circuit currents. In the event of

a short circuit, the transfer characteristic of the IGBTmeans that:

) U(f

I

GE

SC

=

I

SC

: Short circuit current [A]

It is therefore important to limit the gate voltage to a certainmaximum value, so that the

value of the short circuit current is not too high and themaximum short circuit energy is

not exceeded. The relationship between the gate voltage, the short circuit current and

the maximum short circuit time for a 1.2kV IGBT is presented in

The gate

clamping limits themaximum gate voltage and therefore also themaximum short circuit

current.

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