IGBT RBSOA non-destructive testing methods: Analysis and discussion

The investigation about RBSOA limits and the study of the instabilities in high power IGBT devices, during clamped and unclamped operations can be executed by means of non-destructive experimental test circuits where the power device is switched in the presence of a protection circuit able to save it in the case of a dangerous condition to take place. This work, starting from the main non-destructive tester (NDT) proposed during the past years, supplies critical considerations and discussions about the main problems and difficulties that arise when a non-destructive experimental set-up is used for the IGBT RBSOA characterization. The authors demonstrate that the characteristics of the protection circuit must be chosen accordingly to the device that must be characterized and the possibility of saving this device may be significantly improved by a proper choice of the circuit parameters. Considerations about the influence of the parasitic stray elements in the circuit operation and the possible solutions to these problems are also investigated.