Igbt <-> mosfet

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

is an off the shelf cheap chinese sh*t (CCS) grid tie inverter really that interesting... only when it explodes perhaps, but just the fuse exploded... just the TO247 igbt's just melted internally.

My custom SMPS for this system is nothing special, just needed something to connect a 1S1P panel parallel to a 2S1P system (because of the CCS grid tie inverter requires 2S and can't deal with 3S1P which would have been ideal, alas it just shuts down when it sees 3S). Of course the 1S1P with the SMPS can generate only half the amperage the 2S1P, but it's still more power to handle...

Technically I could have bucked the 3S to fake a 2S but then I'd need a toroid that could handle even more watts.

I suspect that dealing with solar panels, a bit of waste here and there doesn't show up as much as futzing with Li-ion batteries... but still, would be nice to dump everything towards powering the load instead of heating up toroids and transistors...

[sam_sam_sam]

Re: Igbt &lt;-&gt; mosfet

Sun came out today, so have some power to play with. The new IGBTs seem to be fine though will need to run them a few days (with a more optimized/better SMPS that I have) before declaring victory. One thing I noticed as far as I can tell, with IGBTs restored, the output power factor seems to be a bit higher and it seems to be producing less RF noise. Which kind of makes sense since IGBTs are slower, but still kind of surprising... Will need to monitor it more and really see if it really is better.

If you get this the way you want it to would you consider posting some pictures of your setup I would be interested in seeing what you have

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

Sun came out today, so have some power to play with. The new IGBTs seem to be fine though will need to run them a few days (with a more optimized/better SMPS that I have) before declaring victory. One thing I noticed as far as I can tell, with IGBTs restored, the output power factor seems to be a bit higher and it seems to be producing less RF noise. Which kind of makes sense since IGBTs are slower, but still kind of surprising... Will need to monitor it more and really see if it really is better.

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

Installed new IGBTs, inverter is now full once more with all G60N100s, crossing fingers...

Problem being tomorrow will be rainy and I won't have enough power to fully test... as if I had full power to begin with. However I need to see if that bigger toroid core would get me more power with that one homemade SMPS...

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

Finally got replacements from China.

I was a bit suspicious about the picture of the IGBTs that I bought off of fleabay but now I know why the photos were suspicious. I thought I was buying Fairchild branded units (which were the originals) but I got post merger On Semi units...
I think they look good enough... at least I hope I didn't get fakes.

Going to wait for a rainy day to put them in, the FDPF18N50's are still working however. But I think I'd rather have the G60N100 IGBTs installed instead of the tiny MOSFETs (or the tiny IGBTs), even better when the G60N100s at least have a metal back plate whereas the FDPF18N50s are plastic all around. I hope that the noise emission also goes down with the slower IGBTs, not to mention that they will be balanced with the two remaining working IGBTs.

Just so suspicious the old IGBTs had no failure marks on them, Still look fine, just shorted all the way.

While we're at it, MOSFETs are easy to parallel unlike BJTs. However, how about IGBTs? On the datasheet it says IGBTs are "easy to parallel" but is it?

(as an aside, I happened to have gotten the FDPF18N50s from the same seller as the G60N100s.... probably by coincidence. Hoping that if the 18N50's lasted these few days as temporary fixes, the G60N100s should also last a while...)

[CapLeaker]

Re: Igbt &lt;-&gt; mosfet

Interesting it survived that long. What’s the grid tie inverter brand? Any pics?

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

The 18N50s survived one day, peak current was 1.3A ...
still waiting on new G60N1000s...

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

I thought the RCP10N40 was a really obsolete device so no loss... probably could be replaced by a modern mosfet with nothing but upside ...

[CapLeaker]

Re: Igbt &lt;-&gt; mosfet

Well… I got curious when the these baby IGBT’s blew again.

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

I did not want to give part numbers as I wanted this to be completely theoretical...

but if you insist...

G60N100 was the original big honking IGBT
RCP10N40 was the baby IGBT that died, well of course it's way too small, albeit I was using 1/6 the rated power of the whole device before it failed which incidentally is 1/6 the current rating of the original...
FDFP18N50 is the MOSFET in now since that's what I have on hand. Going to see if the sun kills them tomorrow.

I am not going to bother trying: 75N06 ... IRF640 ....

I'm thinking I should buy some more FDFP18N50's too....seems like a good MOSFET to have on hand.

[CapLeaker]

Re: Igbt &lt;-&gt; mosfet

What were the IGBT’s that blew and what mosfets are you going to use as a temporary replacement?

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

Well, on a bright sunny day today, the baby IGBTs blew... LOL
I put in MOSFETs this time, still nowhere near the current capacity of the original IGBTs but a bit ... bit closer. Unfortunately I simply do not have high current devices...

... and so far it's holding up at least for now... Let's see how these work.

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

Indeed I was concerned the IGBT would be slower than the mosfet. At the very least, coupled with the transition time and threshold, the MOSFET will turn on sooner. Nevermind turn off, these IGBTs are dastardly slow compared to even MOSFETs which have ways of mitigating shutoff. Was hoping there was enough dead time designed in for this so that they could sub in whatever part was cheaper at the time of manufacture.

So far the "baby" TO220 IGBT is surviving at 130W or so tie-in. The remaining IGBTs that weren't fried are rated for 2.5x the voltage and 6x the current of the ones I subbed so I'm definitely not going to get anywhere near the original design target. Luckily power is fairly stable around here...

New hopefully exact match IGBTs are coming through the mail...and hope I don't get baby IGBTs in TO-247 packages...

[redwire]

Re: Igbt &lt;-&gt; mosfet

Mosfets are fast switching compared to IGBT's, which can give new grief if the design has really time deadtimes or compensation added for that. They can turn the IGBT on in advance, while turning another off.

Another aspect is HV mosfets have high RDS(on) and at some point IGBT's end up more efficient. They have a huge 1.7V VCE drop but once a mosfet is above this, it's cheaper to use IGBT's. IGBT's are also much tougher when partially on, if your inverter has poor gate drive.

Not sure what voltage/current this inverter is or the old part numbers.

Mains transients can be huge at Cat. IV that's why many smart meter fires were happening, they couldn't take the 8kV+ spike. It's worse if you are at the end of a long run of distribution power lines and/or near the pole pig.
Utilities are putting MOV's on the pole pig input bushing.

I think I would use latest generation IGBT's and their voltage ratings are up too. Would have to do an autopsy on the old IGBT's top see why they failed.
Apparently it's very common for companies to purchase raw IGBT dies and do your own packaging/bonding wires.

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

Possible, but unlikely... would need to get a lot of panels whereas a LiFePO4 pack could wreck havoc.

[CapLeaker]

Re: Igbt &lt;-&gt; mosfet

Or someone put too many panels on a string.

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

oh. I think I figured out how this thing failed while I was perusing the web.
This GTI is MPPT and doesn't know when to quit. So if MPPT exceeds the design limits, so be it, exceed the design limit.

MPPT of some batteries will far, far exceed the design limits - so I think someone tried using a battery instead of solar panels.

This is sort of a let down though not totally unexpected. It was meant to be MPPT and anti-islanding after all. Really need a regular inverter for that though it's a shame this can't be double duty...at least without a hack...

And may well cut off MPPT at its design limits. (and even less with my ghetto fix, then again it was meant to be a band-aid until I get real componets.)

[eccerr0r]

Re: Igbt &lt;-&gt; mosfet

Actually I leave that as an exercise to the reader

The hint: if you don't like where you're at, define your own zero!

[sam_sam_sam]

Re: Igbt &lt;-&gt; mosfet

It's unfortunate my Kill-A-Watt doesn't deal with back power, but I think I have an idea on how to deal with that...

Did you find a solution to this dilemma with what you want to do here

[sam_sam_sam]

Re: Igbt &lt;-&gt; mosfet

I am glad that you found a solution to your dilemma with this repair