critique my circuit with some questions

Discussion in 'The Projects Forum' started by lokeycmos, Nov 16, 2012.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    hello, im planning on building an inverter. i found a simple schematic(attached). ive made a few unique changes and am looking for a critique. i am upgrading the small transistors with some 200GAL173D IGBTs. they are rated for 1700v and 220A. one important question i have is, on the datasheet of the IGBT the max gate voltage is 20v. now i cant figure out if i put 12 volts to the gates from the output of the IC, will the IGBT be turned on sufficiently to stay within saturation voltage? also on another post someone said i dont even need gate resistors because IGBT gate work on voltage not current. is this true or do i need some sort of resistor? incase you need them i have the datasheets for the IC and bricks attached. one more thing, what would be a good starting value for the inductor? thank you!
     
    Last edited: Nov 16, 2012
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    That's not a good transistor for your application. If you look at the data sheet you will see that the saturated ON voltage (Vce(sat)) is nearly 4V. That will give you very poor efficiency with a 12V supply. IGBT's work best with a high supply voltage since then there ON resistance is a smaller percentage of the total voltage.

    Much better would be to use a bipolar or MOSFET transistor.
     
    Last edited: Nov 16, 2012
  3. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    What inductor?
    What's its purpose?
     
  4. bundick

    Active Member

    Dec 19, 2007
    97
    1
    Maybe 3055's would work better. I think....hmmm that any load on the 220 side will cause two loud POP's as those power transistors blow the lids off!
     
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Do you have a heater or incandescent light bulb that works from the square-wave output of your horrible old inverter circuit? Many electronic products and motor speed controls need the higher peak voltage of a sine-wave or modified sine-wave inverter circuit.

    Lousy old 2N3055 transistors are used in an old square-wave inverter circuit in The Philippines.

    You should use Mosfets at the output.
     
  6. bundick

    Active Member

    Dec 19, 2007
    97
    1
    Owoooo that hurts.:p

    I'm old, and ignorant, but I can still hear good.
    If I recall, 3055's were fast enough and heavy duty enough to be used in Switcher Pwr Supplies. No?
     
  7. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    200 Amps.

    1000uF + 0.1uF.

    Do you believe the 0.1uF will have ANY effect?

    Also the circuit is not good for IGBTs at all.

    It is a primitive transistor converter.

    Much bigger currents = much bigger problems.

    What is your location?
     
  8. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    the .1 is for transients on the ic side of the regulator. im in the states. i am using a 12 to 120v transformer. could someone recommend a better circuit?
     
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