boost convetor.

Discussion in 'The Projects Forum' started by studenttwo34, Feb 20, 2012.

  1. studenttwo34

    Thread Starter New Member

    Jan 5, 2012
    6
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    I am building a boost converter, for my final year project I require 300volts dc in 400 volts dc out. I have calculated my inductor to be 3mHENRY. And capacitor to be 1.25u farad . when i simulate this circuit. there is a surge to 480 volts . it then settles to around 410volts .My switch in the simulation is a Stw11nb80 mosfet (800volts 11amp). the current in the boost converter is 2 amps. Is this surge due to the mosfet? and what ways could this be maintained.also i have to do an interface for this boost with a pic does any one know anything about this . any help is welcome .Thanking you studenttwo34.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    We have no idea why the surge is occurring since you didn't post the circuit diagram. :rolleyes:
     
  3. jimkeith

    Active Member

    Oct 26, 2011
    539
    99
    Switching on the power to a series resonant circuit can cause the surge that you are viewing--this is also something that must be dealt with in real life--in some cases, pre-charge circuitry must be included limit the current during power-up.
     
  4. studenttwo34

    Thread Starter New Member

    Jan 5, 2012
    6
    0
    i believe i may have solved the surge problem by a snubber circuit still working on it. But the control circuit in the brief for my project it says build a boost convertor with input 300v DC and out put 400vDc for a danfoss inverter with a voltage and current control interface . any ideas where to start on control interface would be welcome.
     
  5. crutschow

    Expert

    Mar 14, 2008
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    Post the circuit you have so far.
     
  6. studenttwo34

    Thread Starter New Member

    Jan 5, 2012
    6
    0
    this is the circuit so far
     
  7. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    As jimkeith noted, you are seeing a resonant overshoot due to the resonant frequency between the inductor and the output capacitor (you see such an overshoot whenever you apply a step voltage to a resonant circuit). You need some way to slowly apply the voltage or limit the current.
     
  8. studenttwo34

    Thread Starter New Member

    Jan 5, 2012
    6
    0
    Thanks have put in a resistor seems to have sloved the problem . i need to use a microchip pickit 2 to control the on time of the mosfet.to keep the output voltage at 400 volts dc . i know i require some sort of circuit between the 400volts and pick as pick out is only 5volts . My question is what sort of circuit any ideas how this works? thanks for the help on the other part.

    :D
     
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