Why do you think it´s a problem? To high or to low?I think the reason of burning is dv/dt.
I don't agree. Your wiring is not as short as it should be.Lines are short and does not have any loop.
If the mosfets are dead it is likely the driver ic's will be too ... buy a variac to allow the HVDC to come up slowly ...
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Also try 220 ohm gate turn on resistors to limit dv/dt for starters until you gain confidence, if it works at 24VDC and not higher, dv/dt ( or di/dt) is always the issue ...
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what frequency are you trying to switch at?
Only to give you an impression:
View attachment 147963
It's IR2110 with two IRF4020
That's what I call an optimized layout.
Hi,
I don't agree. Your wiring is not as short as it should be.
And every signal needs to be a loop.
Always think as signal path and it's return path.
Klaus
Yes, thought you have seen them on the layout ;-) R/C225 and R/C226Does your circuit have snuber on mosfets?
Still quite fast, but much better than before.Now I measure rise time and fall time.
Rise time (turning on mosfet time) = 180 nS (R gate(on) = 22 Ohm)
fall time (turning off mosfet time) = 90 nS (R gate(off) = 10 Ohm)
Is it good?
1.) t-on is most important due to Body Diode Recovery restrictions. See my last post.1) Which is important Rise time or fall time or both?
2) should always be rise time more than fall time ( It means R gate ON bigger than R gate OFF)?why?
Can't agree. In bridge topologies you can not rely only in the "toff" and "ton" times, one needs to add additional dead time.Let's assume upper FET is closed, lower FET open. Then the upper should open (=toff) before the lower closes (=ton), and vice versa.Therefore you usually design toff shorter than ton.
:roll: I never said this ton-toff tailoring is sufficient to ensure break-before-make in any conditions...Can't agree. In bridge topologies you can not rely only in the "toff" and "ton" times, one needs to add additional dead time.
What you are suggesting is to turn the lower FET ON at the same time you turn the upper FET OFF i.e. apply control signals at the same time without any dead time and rely on the fact that you have tuned the "toff" and "ton" times correctly. That is playing with fire and therefore not a good practice. Dead-time is a must. Review standard literature.
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