Connect with us

Gate Resistors used for IGBT's why? IGBT timing

Discussion in 'General Electronics Discussion' started by Danny Daviss, Mar 16, 2013.

Scroll to continue with content
  1. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    How does the Gate Resistor in series adjust the Timing of a IGBT?

    Why does using a small value Gate Resistor resistor cause IGBT to short out? or cause shorts?

    A small value Gate resistors changes the IGBT to have faster switching time?

    Example:
    IGBT drivers to Gate resistors to IGBT to Low Pass filter


    The IGBT driver sends High Frequency pulses to the IGBT transistors

    What kind of bandwidth an oscilloscope do u need to see these high frequency pulses?

    How does the Low pass filter change DC voltage from the output of an IGBT to an AC waveform?

    The IGBT output is high Frequency pulses right? and the Low pass filter cause high frequency pulses into an AC waveform?

    My oscilloscope is 300MHZ, the IGBT drivers signal is in the killohertz

    How can I view Killohertz signals?
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,513
    2,651
    Nov 17, 2011
    The gate of a MOSFET or an IGBT in your case has a noticeable capacitance. Add a series resistor and you get a low pass filter. YOu can evaluate the math for yourself.

    Set the timebase into the ms range. Read the manual, get a thorough understanding of the operations of an oscilloscope,
     
  3. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    So a 300Mhz oscilloscope can view Kilohertz signals?

    I can't view the signals because they are in the kilohertz, it just looks like scramble lines

    300Mhz oscilloscope = 300,000 Kilohertz?

    Kilohertz is must higher frequency than megahertz right?
     
  4. davenn

    davenn Moderator

    13,833
    1,950
    Sep 5, 2009
    of course :)

    your scope may not have a high enough resolution

    yes

    NO, why would you say that ?? you just proved ( correctly) in your last statement
    that MHz is higher than kHz

    1 kHz = 1000 Hz
    1 MHz = 1,000,000 Hz

    Dave
     
  5. davenn

    davenn Moderator

    13,833
    1,950
    Sep 5, 2009
    Your scope should have its bandwidth rating up by the brand of the scope

    10MHz, 50MHz, 100MHz etc

    Dave
     
  6. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    Are IGBT driver chips outputs in the kilohertz? or megahertz?

    Where do u find the resolution rating? how high should the o-scope be to view these waveform signals?

    Yes the 0-scope i'm using is 300Mhz
     
  7. davenn

    davenn Moderator

    13,833
    1,950
    Sep 5, 2009
    I have no idea --- what is the part number of the ones you are using???

    Dave
     
  8. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    IGBT drivers are M57959L
     
  9. davenn

    davenn Moderator

    13,833
    1,950
    Sep 5, 2009
    OK so do a google search for the datasheet
    it will tell you the ratings of the device :)

    Dave
     
  10. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    ! I Did, it's my 300mhz o-scope viewing the IGBT Drivers waveforms. The freq is high and the waveform is very close lines together because the freq is so high, is this a resolution problem?
     
  11. davenn

    davenn Moderator

    13,833
    1,950
    Sep 5, 2009
    do you know how to use a scope ? ... specifically how to adj the timebase setting?

    you were given a link by some one in another thread of yours on how to use a scope

    YOU STILL havent told us anything about your circuit!!

    its very difficult to help you when you dont give all the info
    You are still following your old ways that you showed on the forum many, many months ago

    Dave
     
  12. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
  13. Harald Kapp

    Harald Kapp Moderator Moderator

    11,513
    2,651
    Nov 17, 2011
    Obviously it doesn't so very well.

    Autoranging, autosetting or whatever is good for geeting a first grasp of the Signal. It doesn't replace knowing how to use an oscilloscope, including the limitations. Read the tutorial by Tek (I gave you the link in another thread of yours).

    Btw: The "300MHz" Rating for the scope tells you what max. frequency you can Analyse with reasonable accuracy. By no means does this signify that the scope cannot Display much slower waveforms. On the contrary.
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
    2,837
    Jan 21, 2010
    The autoset button might give a good first guess, but saying it does all the hard work for you is somewhat like engaging the cruise control on your car and having a nap.
     
  15. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    Is this correct tho about the IGBT driver datasheets that the IGBT drivers output signal waveform is at 20Khz? at 2us pulse width, 50% duty cycle?
     
  16. Harald Kapp

    Harald Kapp Moderator Moderator

    11,513
    2,651
    Nov 17, 2011
    It can´'t be correct, F=1/T, so with F=20kHz, T=50µs. So either the 20kHz are wrong or the 2µs pulse width.

    What are you trying to do? You seem to lack some very basic understanding but you want to work with IGBT drivers. To me thats like trying to drive a race car without knowing how to drive at all.
     
  17. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    Can you take a look at the IGBT drivers datasheets and tell me what the output frequency is please?
     
  18. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
    2,837
    Jan 21, 2010
    There is no specific output frequency.

    And what IGBT driver are you talking about? I can't look at a datasheet without knowing the part number.
     
  19. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
  20. Danny Daviss

    Danny Daviss

    67
    0
    Mar 16, 2013
    IGBT DRIVER IS M57959L
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-