IGBT Design Beginnings

Discussion in 'The Projects Forum' started by mpatterson557, Jul 3, 2010.

  1. mpatterson557

    Thread Starter New Member

    Jul 3, 2010
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    I have been playing with the idea of building my own power supply and I believe that I have finally got all the specs together.

    I know this will be a large and expensive project...I know mom I know

    My input power will be 480 Volts three phase rectified to dc at around 70 amps per phase

    I will need two banks of igbt one set 180 degrees out of sync with the other
    the output will be variable depending on computer program, thinking of interfacing a small netbook to control the programming of the IGBT controller

    Circuit will also include snubber to control output voltage when not in use

    and a frequency overlay to induce a high frequency pulse that can be program controlled. The program will also have to control shape of dc and ac waveform outputs

    output amps is 4 to 700
    output is dc or crossphased dc = ac
    hertz is 10 - 360
    voltage is 10 to 160

    finished machine will have two options one is to sense voltage and modify amperage to compensate for load (like a voltage regulator) and the second is to sense amperage and modify voltage to compensate for load
    where to start and direction to where i should concentrate my energy would be appreciated.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Let's see - 480 volts times 70 amps = 33,600 watts. Times three phases is 100,800 watts. What do you have in mind that will use this kind of power?

    Kinda enthusiastic for a first-time project? Do you have any electronic background?
     
  3. retched

    AAC Fanatic!

    Dec 5, 2009
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    Strap-on nuclear reactor?
     
  4. mpatterson557

    Thread Starter New Member

    Jul 3, 2010
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    I would like to build a welder,
    Every one sells CV/CC DC or
    CC AC/DC
    Some made transformer based CC/CV AC/DC machines but no more.
    Its ambitious but I have two welders using IGBT tech that each output 680 amps I want to cannibalize these two for parts like the reactor, the main transformer, the hf transformer and the IGBT's, Absorption Capacitors, Filter Capacitor, I will use existing heat sinks but convert these to water cooled to up capacity. No my back ground is good old analog systems.
     
  5. mpatterson557

    Thread Starter New Member

    Jul 3, 2010
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    oh ah 480 is voltage between phases so its more like
    270 times 70 times 3 which should be around 60000 watts ok a little much
    lets cut that back to 270 times 40 times 32400 watts or lets design for 40000 watts input
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
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    Last edited: Jul 3, 2010
  7. mpatterson557

    Thread Starter New Member

    Jul 3, 2010
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    The input of 480V 40 amp three phase is right off the name plate of my welder, You can also look up the specs on a Dynasty 700 welder from miller. It is a 700 amp output ac/dc machine, but with no CV provision. I weld with both of these machines every day. And yes they do suck down the power.
     
  8. mpatterson557

    Thread Starter New Member

    Jul 3, 2010
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    Not bad on the inverter we use a 62 KW generator to power these welders
    for the inverter drive add cooling capacity and a reactor core to smooth output and that would be close, price is close too. I spent 16000 on my current welder, for this project I have bought 5000 worth of hardware. I really need help with the IGBT driver circuit
     
  9. retched

    AAC Fanatic!

    Dec 5, 2009
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    Youch!

    Yessir, I guess I was close with the plasma.

    This is going to be a toughy. You realize this will cost exponentially more to build than to buy, right? Especially if you value your time.
     
  10. mpatterson557

    Thread Starter New Member

    Jul 3, 2010
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    I have spent three months corresponding with oem manufactures in China Italy and Japan, all come back with same response why would you need such a machine, What I don't understand is a AC/DC constant current machine simply needs a output voltage sensor and some additional programming to use it as a constant voltage machine. When you look at the schematics of a DC CC/CV machine it has a set of 2 IGBTs each supplying a lead of the primary side of the main transformer, and then a set of diodes leading to the positive lead with a voltage sensor and a amperage sensing coil, along with a fairly massive reactor to stabilize arc and on the negative a small transformer to overlay a high frequency wave into the weld. If you look at the schematics of a AC/DC CC machine it has all the same parts minus the voltage sensor, and it has twice the IGBTS(4 or two banks of 6 each) and main transformers(2), it applies a positive charge to bus a then shuts off while second bank applies positive charge to bus B, creating a ac wave of sorts.
     
  11. mpatterson557

    Thread Starter New Member

    Jul 3, 2010
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    Meybe I should concentrate on building a driver for a small set of igbts then upsize circuit to meet my requirements. In a smaller size i am sure that there exists what I need skipping the massive input I need a power supply to provide dc pulse current and ac pulsed current with ability to control ramp and wave shape, sharpness, square and triangular including true sine
     
  12. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    check out Semikron's website. Excellent technical references.
     
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