Capacitor energy discharge using IGBT

Discussion in 'The Projects Forum' started by captainssbn, Sep 24, 2012.

  1. captainssbn

    Thread Starter New Member

    Sep 24, 2012
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    Hi All I have a dual syetm with one set of caps at a positive 1000vdc and the other set at neg 1000vdc. I would like to know if anyone has a working circuit that I may use to discharge the pos & neg caps into a set of motor coils. Position of the rotor will determine when the energy needs to be dumped.

    Email me with schematic or what ever. I'm on You-tube as captainssbn and have the first section of my project done.
    Gary
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    I don't understand what you are trying to do. What kind of motor and how are the caps connected to the motor and how do the caps get charged up again? What does the position of the rotor have to do with anything?
     
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    I too don't have a clue what he's trying to do. But if it is a BLDC or a switched reluctance motor, the rotor position is very important to the commutation of the stator coils.
     
  4. Papabravo

    Expert

    Feb 24, 2006
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    Thing is that a capacitor is a really lousy current source for a motor. This sounds like some kind of hair-brained noob scheme based on complete ignorance of the way motors work.

    We prohibit discussion of circuits that connect directly to the mains. IMHO a capacitor at 1000V is almost as dangerous and can weld a dropped screwdriver to the terminals while spitting smoke, flame, steam, and hot oil.

    I vote for banning this thread.
     
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  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    I agree. I was just commenting on rotor position sensors for some motors. To me it sounds like a over-unity motor scheme.
     
  6. Papabravo

    Expert

    Feb 24, 2006
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    A BLDC (Brushless DC Motor) will generally have at least 3 poles and possibly more and usually has hall effect sensors for rotor position. Maiking it move is a matter of sequencing the current in the correct phases. As far as variable reluctance motors I'm less familiar with them. It sounds like the OP has single winding that he wants to switch between a large positive and a large negative potential, like with and H-Bridge made of IGBT parts.

    I note that he doesn't seem too interested in continuing the discussion.

    BTW a 2200 uFD capacitor at 1000 Volts has 1100 Joules which is enough to knock him into the middle of next week.
     
    Last edited: Sep 25, 2012
  7. wayneh

    Expert

    Sep 9, 2010
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    This one got me thinking about the safety boundaries here.

    It makes sense - to me - to place limits where lethality is possible because of the voltages involved OR because of the magnitude of a potential energy release.

    This project seems to be over the line on voltage, involves a boat load of energy, and involves suddenly moving machinery.

    Unless the OP for such a project can convince us of having the skill and sense to handle all this safely, I can't see how we can keep this thread open and yet come down hard on itty-bitty rail guns and the like.
     
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