does this IGBT have a negative or positive temp coefficient?

Discussion in 'General Electronics Chat' started by strantor, Sep 12, 2011.

  1. strantor

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  2. praondevou

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    From the POWEREX website FAQs comes this "answer":

    >>>>>>>>>>>>>>>>>>>>>>>
    Q: How do we use these devices in parallel configuration?

    R: Parallel operation requires that the parallel current paths are of equal impedances to ensure proper sharing. In the case of the semiconductors, those with a negative temperature coefficent need to be matched in order to ensure proper sharing. Bus bar or power cables must be electrically balanced as well. Finally, some level of derating is necessary to compensate for differences in the parallel paths.
    >>>>>>>>>>>>>>>>>>>>>>>>>>

    Haha. So if you consider using this device you will need to contact them.
     
  3. strantor

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    shoot man. another instance of datasheet uselessness. thanks praondevou
     
  4. strantor

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    btw if I used one of these, I would only need one. no need to parallel. only think I'm worried about is thermal runaway in the single IGBT
     
  5. praondevou

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    I didn't see the price of the one you posted, but we used Powerex lately in UPSs sucessfully without any problems. They where used as a replacement for the more expensive Semikron modules. If I'm not mistaken, especially the Powerex drivers are cheaper, they came in small hybrid component form and you could incorporate them in your own PCBs. However it's more than a year now that I left the company, and my memory is failing sometimes....:D
     
  6. strantor

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    The price is for used modules. price is very reasonable IMO 300$ for 4 of these modules. I had not taken much consideration for drivers. When I was looking at mosfets, it seemed the drivers were usually a single IC. I looked up the driver for this IGBT and they don't sell just a driver; it's a PCB you need to populate the components. 2 of these components are powerex ICs which start @ 20$; so it looks like using the IGBT wouldn't be as cheap and straight forward as I was hoping. Is it usually simpler & cheaper to drive MOSFETs than it is to drive IGBTs? or am I underestimating the MOSFET drivers?
     
  7. praondevou

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    Whenever I worked with these big modules, negative gate voltages were used to turn off the IGBT. For smaller IGBT's it wasn't always necessary. You can also build your own drivers , don't need to use the ones from the manufacturer, but in general I'd prefer them.
     
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