Clarification on the bad IGBT turn-on ( 2SC0535T2A1-33 driver)

Dear Mikeh

thanks for approaching us

to answer your question, first we need to have a common understanding about what the "good" gate voltage is and what the "bad" gate voltage is.

I will not spend so much time on that topic here, since everyone/company can have its own opinion/rules based on the actual application.

to make it simple, here are some points you can check if the gate voltage is ok or not during your low voltage evaluation

1- check the negative voltage value before turn-on according to datasheet

2- check the positive voltage value before turn-on according to datasheet

3- choose the right equivalent load for your measurement 

4- calibrate the probe before the measurement.

5- check the driver delay according to datasheet

general feedback for "oscillation" on gate voltage

• oscitation is cause by stray inductance in the whole gate loop and the capacitive load from IGBT 
• another import factor is the slew rate of the applied voltage source for this loop, which is defined by gate driver chip and gate resistor 
• assuming the gate loop design and gate resistor are fixed, the higher the slew rate is, the more oscillation you will observe from the gate voltage, while it is rising.