Principle of U
monitoring as illustrated by the output characteristics
Accordingly, in the event of a short circuit the collector-emitter voltage rises well above
the nominal saturation value U
. The U
monitoring uses this to detect short
circuits. If the U
measuring circuit recognises an increase in the U
means of a previously set reference voltage being exceeded, the measuring circuit
interprets this as an error and turns off the IGBT gate drive unit or reports an error to the
microcontroller, which can also turnoff the other IGBTs in the power circuit.
Many commercial drivers have a measuring circuit like this. Almost all manufacturers
offer them. They are usually realised technically by using a driver with integrated U
recognition and simple external wiring, usually comprising an additional capacitor C
resistor anda diode.