inverter H tree driver imbalance in an AC inverter

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • eccerr0r
    Solder Sloth
    • Nov 2012
    • 8709
    • USA
    #1

    inverter H tree driver imbalance in an AC inverter

    My cheap crappy 1KW grid tie inverter (GTI) seems to keep blowing IGBTs. When I first got it, it had two failed IGBTs. It used four 60N100's (TO264). I bought 5 from a dubious source (fleabay) and replaced just the two that were dead. The GTI worked for almost two years but recently one of the two that I replaced failed. Since I had three spares, I replaced the dead one. Then a few weeks later it failed again. Weird. Well since I bought dubious China-sourced IGBTs from fleabay it could very well just be a mixture of fakes. I replaced it, but then a day later it failed again! I put in the last spare I had and the inverter works again... but then two weeks later it failed again. I'm all out.

    The weird thing is that there are 4 IGBTs in the H-tree and one would imagine that it should be a fairly even distribution of which one fails but it was always the same one, implying perhaps I got fakes, but that high side seems to be okay...

    Well, since I was out of spares I went and fleabayed more IGBTs, this time 80N60's (TO247) as at 120VAC I don't need 1KV isolation and apparently the inverter was likely populated with 60N100s because that's what they had on hand as the same FR4 PCB was used for both 220V and 120V variants. Once again this is fleabay and chances of fakes are high. (BTW, it seems that China once again has a new scheme dealing with the tariffs...)

    Anyway, as a proud ghetto mod poster, I was even cheaper than just getting possible fakes from China. Instead of replacing all the IGBTs I replaced just that one failed 60N100 IGBT with the new 80N60.

    Now who wants to make bets or at least some theoretical discussion:
    - When will the GTI fail again. Not only am I using dubious transistors, I have a mismatched H-tree now. Heck since that one transistor failed in a day, it could also fail in a day!
    - which IGBT fail: options are
    1. The (smaller TO-247) 80N60 I just put in which could be fake.
    2. The other (TO-264 giant cheap fleabay possibly fake) 60N100 I replaced two years ago. AFAICT the two failed transistors were of the same half bridge, so the remaining possibly fake transistor is the high side driver and the one that keeps failing is the low side.
    3. One of the other two 60N100s on the other half bridge that were in there the whole time and were never replaced.

    I was wondering how good TO-264 was compared to TO-247 and TO-3P for that matter. Seems manufacturer and bonding differences may affect ultimate thermal resistance and the smaller TO-247 looked better on paper... Alas there's more to it than just this. Who knows.

    BTW the 80N60 is *significantly* faster than the 60N100, and slightly more efficient. As of posting this the GTI is working even with the mismatch...
    Last edited by eccerr0r; Today, 12:39 PM.
    Tags: None
    • Agent24
      I see dead caps
      • Oct 2007
      • 5091
      • New Zealand
      #2
      I don't know a lot about IGBTs but my brain immediately jumps to something wrong with the gate/base drive circuit - poor switching waveform, wrong voltage, low voltage, slow rise/fall time, etc etc...
      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
      -David VanHorn

        Comment

        • eccerr0r
          Solder Sloth
          • Nov 2012
          • 8709
          • USA
          #3
          I've been meaning to see if I can probe the base drive though not having an isolated scope meter would be problematic. Then again I think I can run the GTI through an iso transformer just fine, though not at full power, my iso transformer can't handle it, and I think all the times it failed there was a portion of the day where it was probably running full blast as it was sunny...at least after the clouds moved away for a short period of time. The clouds and sun mixture is probably the most difficult situation to handle...

            Comment

            Previous template Next

            Related Topics

            Collapse
            • ahmedtou
              HOW CAN I UPDATE HL-DT-ST BD-RE GGW-H20N XA02
              by ahmedtou
              Hi everyone,
              help me please


              I have an HL-DT-ST BD-RE GGW-H20N with ROM version: XA02.



              When I tried to burn a 25GB Blu-ray disc using ImgBurn, I got an error.
              I will share all the details with you, including the disc information.



              Code:
              HL-DT-ST BD-RE  GGW-H20N XA02 (ATA)
Current Profile: BD-R

Disc Information:
Status: Empty
State of Last Session: Empty
Erasable: No
Free Sectors: 12,219,392
Free Space: 25,025,314,816 bytes
Free Time: 2715:27:17 (MM:SS:FF)
Next
              ...
              08-27-2025, 08:49 AM
            • x_orange90_x
              Vizio E55-E1 bad backlights or bad inverter?
              by x_orange90_x
              I just got this tv today and it appeared to have no backlight on. After taking off the rear cover and checking again in the dark I can see that MAYBE one quadrant is lit.. But still it's quite dim. I was going to check the LEDs with my tester, and I found LED 1 and LED 2 + pins on the wire from the inverter, but I couldn't identify a ground. Nonetheless I tried using a mounting screw on the inverter board and also the chassis as ground but regardless my tester reads 300 which is what it reads when there is no voltage draw.

              I don't know how exactly to test the inverter itself. Is it...
              01-29-2025, 09:24 PM
            • Gentian
              APSINT3636VR 3600W APS INT Series 36V DC 230V AC Inverter/Charger schematic
              by Gentian
              I have a tripp-lite aspint 3636vr inverter charger which blow some of mosfet transistors. I replaced them repaired also the driver circuit and tested but the mosfets burn again.

              It work very well as inverter and also as charger if I let the rear switch in auto mode (inverter) and charger only(charging) but in auto when I connect the feed line 220V AC first time it pass ok to line and start charging the batteries but when I remove the feed line it pass to inverter mode and if I do it again the second time when passing from charging to inverter the Main transformer start making a...
              03-06-2023, 07:07 AM
            • valvashon
              Insignia NS-LCD19-09 (PS OK, Inverter problem?)
              by valvashon
              For some reason I'm just not going to let this 19" TV defeat me. I guess because I have a schematic to work from I feel like I'm oh so close.

              History- while adding a turn-on circuit I let a small screw roll under the power board. Worked through all of that circuitry, probably replacing a MOSFET and PWM controller that were not bad but I was following the service manual. Finally figured out that the power supply is in working order when the inverter section (for the backlights) is disconnected. When the +12 supply to the inverter is disconnected the +12 and +5 will come up...
              1 Photo
              01-04-2024, 01:44 PM
            • eccerr0r
              A modified sine wave inverter + a grid tie inverter?
              by eccerr0r
              If I had a solar fed grid tie inverter (GTI), a modified sine wave inverter, and a power outage occurred, what would happen if you disconnected mains, backfed the modified sinewave inverter (MSI) into house power, and hooked up the GTI to the output of the MSI, would it work?

              Next thing is trying to charge the batteries using solar power, but that's another issue ...
              08-31-2023, 09:14 PM
            • Loading...
            • No more items.
            Working...