igbt

Discussion in 'The Projects Forum' started by arunpradh, Sep 3, 2014.

  1. arunpradh

    Thread Starter Member

    Dec 11, 2013
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    where can i get deeper data about igbt. usually it's switching at higher frequencies
     
  2. crutschow

    Expert

    Mar 14, 2008
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    A good place to start is the data sheet for the IGBT you want to use. IGBTs are fairly slow switching as compared to MOSFETs and BJTs.
     
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  3. ScottWang

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    Aug 23, 2012
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  4. DerStrom8

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    Feb 20, 2011
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    An IGBT is effectively a MOSFET switching a BJT. It's not ideal at high frequencies (like MOSFETs are), but is often used in high-power applications as there is usually less of a voltage drop across the collector and emitter. A MOSFET is an ohmic device, meaning the power that is wasted due to the voltage drop increases exponentially with current (P = I²*R). A BJT, on the other hand, has a fixed voltage drop based on the semiconductor properties (0.7v, for example), so the wasted power is linear (P = V*I) and in high power applications, this is the most efficient.

    Equivalent circuit:

    [​IMG]

    Please note that this is only a representation, and does not accurately show what the inside of an IGBT really looks like.
     
    Last edited: Sep 3, 2014
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  5. crutschow

    Expert

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    An IGBT actually has over a two diode drop which is typically about 2V (as noted here).
     
  6. DerStrom8

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    I was just using 0.7V as an example because everyone knows that's the diode drop of a regular silicon diode. You're right though, there's more to it than that. Thanks for bringing that up!
     
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  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Here is something from IR
    Max.
     
  8. ScottWang

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    Aug 23, 2012
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    If I want to using mosfet and bjt to simulate the IGBT in the real world, do you have any suggestions numbers for them?
     
    Last edited: Sep 3, 2014
  9. crutschow

    Expert

    Mar 14, 2008
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    Use the equivalent circuit that Max showed (with a resistor in series with the BJT base to give a base current 1/10th of the maximum collector current) and add a silicon junction diode in series with the emitter output terminal.
     
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  10. ScottWang

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    Aug 23, 2012
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    Thanks.
    But I was asked for the parts numbers of mosfet and bjt.
     
  11. DerStrom8

    Well-Known Member

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    That depends entirely on your circuit.
     
  12. ScottWang

    Moderator

    Aug 23, 2012
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    How about for a AC110V 500W application?

    The Vce =60V for bjt, Vds=200V for mosfet, those voltages of parts are what I have and usually use.
     
    Last edited: Sep 4, 2014
  13. DerStrom8

    Well-Known Member

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    Well first of all you really should not use BJTs or MOSFETs to switch AC. For that you really ought to use a TRIAC.

    You must make sure that the transistor that is carrying the full current can handle it. In an IGBT the main current-carrying transistor is the BJT, so your BJT must be able to handle the full voltage and current that you're trying to switch.
     
  14. ScottWang

    Moderator

    Aug 23, 2012
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    Normally I will use TRIAC, but I'm trying to use a diode has big current and in series with the output of bjt.

    If I want to make a dimmer using triac for AC110V/500W , do you have any TRIAC number in hand?
    I was thought maybe use parallel method to increase the power, the dimmer I had can be adjust the fan, 100W lamp, 60W solder iron.

    I knew that, as I mentioned that the bjt I had only 60V as 2N3055, if I'm trying to use in 200Vdc/2A, 400Vdc/2A, do you have any bjt number to try?

    Why I want to try this, because the IGBT is too expensive, so I want to use the mosfet and bjt to simulate.
     
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