Dynamic Avalanche in High Voltage Diodes during Short Circuit III

Inhalt:
A short circuit on a turned on IGBT and a conducting diode is called in literature short circuit type 3. The current commutates from the diode to the short circuit and the IGBT. After a reverse recovery of the diode a desaturation leads to an avalanche in the diode. Measurements on a 3;3 kV-IGBT with different DC link voltages and diode currents before the short circuit occurs show the impact on the avalanche. An increased DC link voltage and a higher current results in a higher avalanche which can be three times of the reverse recovery current. Simulating the diode behavior gives a similar voltage and current curve with the electric field strength, hole and electron current concentration and density. In a semiconductor simulation an avalanche at the anode and cathode occur.