high frequency inverter based on igbt

Discussion in 'General Electronics Chat' started by amit_87, Sep 15, 2010.

  1. amit_87

    Thread Starter New Member

    Sep 15, 2010
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    I was trying a single phase full bridge inverter for 40khz frequency so i used igbt module CM150DU12NF than i had used polysterene capacitor .01uF, 630V for series type commutation with 100 ohms load (value has been selected by considering the charging time of capacitor so that pair of Igbt is turned OFF before the next pair of Igbt is triggered ) and then connected the 100 ohms resistor with inverter in series to dc supply to avoid shorting of dc supply if accidentally the pair of Igbt of same module is ON, to work as a inverter pair of Igbt of different modules is trigerred alternately with use of toggle IC 7473 and power driving IC LN293D.Now the problem faced by me is that i am receiving the 40khz freq at the gate and receiving only positive pulses of 60V at 80khz at series resistor this shows that pair of diff module Igbts are perfectly turned ON & OFF alternately (as whenever current is drawn from the dc supply voltage is measured across the resistor) but now i am not receiving any voltage across the load resistor plz help me
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    First, I have to try to break your block of text up into something more meaningful. A "Stream of Consciousness" style of writing does not work very well on these Forums.

    The L293D is a push-pull 4-channel driver capable of up to 1.2A peak current (non-repetitive), 600mA constant current per channel. It's absolute maximum limit for Vs is 36v.

    You did not read the specifications of the LN293D. You have exceeded it's absolute maximum Vs specification by quite a large margin. The L293D is fried to a crisp; dead, trash. You have let the smoke out of it.

    If you want to operate at 60v or higher, you will need to select components that are rated for more than the voltage and current than you will apply.

    While the L293 is rated for 600mA continuous current which would be the result of applying 60v across 100 Ohms, it is not rated for the 60v. I would not operate the L293D with more than ~32v for it's supply.
     
  3. amit_87

    Thread Starter New Member

    Sep 15, 2010
    3
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    Reply for ur quest asked above



    I was trying [simulate] a single phase full bridge inverter of 40khz frequency.

    I am using an IGBT module, CM150DU12NF as frequency required is high

    I am also using a polystyrene capacitor rated .01uF, 630V, for series type commutation required to turn off IGBT (because it requires external circuit to turn off thyristor i.e IGBT) with 100 ohms load.

    I selected values by considering the charging time of capacitor, so that a pair of IGBT is turned OFF before the next pair of Igbt is turned ON.

    Then I connected the 100 Ohms resistor with inverter (plz refer the new attachment fig for further clarification) in series to dc supply [to avoid shoot-through.]

    To work as an inverter, a pair of IGBT of different modules CM150DU12NF(from fig pair of 1,4 & pair of 2,3) is triggered alternately (with use of NE555 as a timer which o/p is given to J-K f/f DM74S73AN as clk pulse and J-K is used as a toggle switch by keeping its i/p J&K both high and its o/p is given to IC L293D push pull driver to drive the IGBT i.e its o/p is given to gate of IGBT in pair of (Q is given to g1,g4 & Q* is given to g2,g3))

    Quote:
    Now the problem faced by me is that i am receiving the 40khz freq at the gate and receiving only positive pulses of 60V @ 80khz at series resistor.(shown in fig volt across series resistor)

    This shows that pair of diff module Igbts(1,4 & 2,3) are perfectly turned ON & OFF alternately (as whenever current is drawn from the dc supply voltage is measured across the resistor)

    But now i am not receiving any voltage across the load resistor plz help me
    I have read the specifications of the LN293D but here it is used to give the gate pulses which is about 10 V to turn on the IGBT (and is not used as to supply the IGBT)
     
  4. amit_87

    Thread Starter New Member

    Sep 15, 2010
    3
    0
    hey guys plz help me out.......
     
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