Scoping Parallel IGBT's Gate-Emitter Voltage @ 400khz
zzz_julian_zzz, Fri May 08 2015, 04:05AMHi Guys,
I'm rebuilding my QCW, but I'm a bit concerned and worried on the G-E driving waveform of IGBTs connected in parallel with different Gate Resistors. I'm driving them with 24v with a driver based on UDs.
I have a video here to share with you guys to know if these waveforms are "OKAY" for driving 400khz QCW bridge. because I don't want to damage any more IGBTs.
As you can see they're not "snappy square waves", but when I disconnect the load (IGBTs) from the GDT secondaries the waveform looks nice, without the curves and with almost no ringing on tops.
I'm welcoming any comments / thoughts for this. Thanks!
Re: Scoping Parallel IGBT's Gate-Emitter Voltage @ 400khz
loneoceans, Fri May 08 2015, 04:54AM
They won't be snappy square waves with the IGBT gates and reverse diodes - in fact the waveform shape looks about right. Is the division 500ns? At first glance the only thing I see is that it seems that the rise and fall times could be a bit better. What transistors are you using now?
You mentioned you previously blew some IGBTs? What IGBTs were they and do you know what they failed?
loneoceans, Fri May 08 2015, 04:54AM
They won't be snappy square waves with the IGBT gates and reverse diodes - in fact the waveform shape looks about right. Is the division 500ns? At first glance the only thing I see is that it seems that the rise and fall times could be a bit better. What transistors are you using now?
You mentioned you previously blew some IGBTs? What IGBTs were they and do you know what they failed?
Re: Scoping Parallel IGBT's Gate-Emitter Voltage @ 400khz
zzz_julian_zzz, Fri May 08 2015, 05:34AM
yes the division is 500ns. I am using stgw60h65dfb IGBTs. [these are in the vid]
I am already using thin isolation magnet wire(awg 24) to even reduce Leakage inductance to the minimum so to make rise/fall even snappy, the core I am using is with AL 7000(value taken by doing tests, though I am not sure of its part number / material type).. With the conventional UTP cables, the slope is much more slower/longer that might lead to device heating.
I blew some IGBTs before and I am suspecting that one of the cause is improper(or rather slow) turning on/off of these switches.
Any suggestion to even improve the slopes(rise/fall) of G-E?
also, do you have photos of G-E waveform running at 400 khz? thanks!
zzz_julian_zzz, Fri May 08 2015, 05:34AM
loneoceans wrote ...
They won't be snappy square waves with the IGBT gates and reverse diodes - in fact the waveform shape looks about right. Is the division 500ns? At first glance the only thing I see is that it seems that the rise and fall times could be a bit better. What transistors are you using now?
You mentioned you previously blew some IGBTs? What IGBTs were they and do you know what they failed?
Hi Loneoceans,They won't be snappy square waves with the IGBT gates and reverse diodes - in fact the waveform shape looks about right. Is the division 500ns? At first glance the only thing I see is that it seems that the rise and fall times could be a bit better. What transistors are you using now?
You mentioned you previously blew some IGBTs? What IGBTs were they and do you know what they failed?
yes the division is 500ns. I am using stgw60h65dfb IGBTs. [these are in the vid]
I am already using thin isolation magnet wire(awg 24) to even reduce Leakage inductance to the minimum so to make rise/fall even snappy, the core I am using is with AL 7000(value taken by doing tests, though I am not sure of its part number / material type).. With the conventional UTP cables, the slope is much more slower/longer that might lead to device heating.
I blew some IGBTs before and I am suspecting that one of the cause is improper(or rather slow) turning on/off of these switches.
Any suggestion to even improve the slopes(rise/fall) of G-E?
also, do you have photos of G-E waveform running at 400 khz? thanks!
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