Styx
Active Member
I have a couple of cct that detects when an IGBT starts to desaturate. Now previously when this happened I would just turn-off the gate and flag-back to the control that a DeSat event occured
I designed a gateboard for a 800A device and a type1/type2 desat concideration had to be taken into account (this produced a complex gate-board)
The new one I am designing is for a 400A device, so the complex protexction isn't justified BUT a simple-turn-OFF isn't enough.
What else exists? I have heard of dropping the gate voltage from +15V to +10V (before turning off to -15V) to move the IGBT charcteristic onto a different I-V curve (to limit the desaturation current).
I plan to put 18V zeners back-to-back across the gate-emitter to stop the millar jacking the gate potential up as well.
I designed a gateboard for a 800A device and a type1/type2 desat concideration had to be taken into account (this produced a complex gate-board)
The new one I am designing is for a 400A device, so the complex protexction isn't justified BUT a simple-turn-OFF isn't enough.
What else exists? I have heard of dropping the gate voltage from +15V to +10V (before turning off to -15V) to move the IGBT charcteristic onto a different I-V curve (to limit the desaturation current).
I plan to put 18V zeners back-to-back across the gate-emitter to stop the millar jacking the gate potential up as well.