Boost DC-DC Converter troubles in simulink

Discussion in 'Homework Help' started by hunterage2000, Jan 21, 2012.

  1. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    Hi, I have set-up a Boost DC-DC Converter the way my lab sheet shows and Im getting an incorrect Output waveform.

    I have used the following parameters:

    DC Source = 100V
    I = 0.001H
    C = 0.0001F
    R = 50 ohms
    Pulse = T = 0.001sec, Pulse width = 10% for a duty ratio 0.1
    2 IGBT's with default parameters and a NOT gate

    So for Vout, it should be equal to 100/1-0.1 = 111.1V
    But the graph shows the wrong value and the form of it is wrong.

    Our lecturer showed us his and the set-up was exactly the same but when he ran the simulation he got the right amount and right form of the output.

    I can't figure out what is causing this. Can anyone tell me how this is possible to use the same set-up and parameters and not get the same output? It is very frustrating and there is about 12 of us who are getting the same results.
     
  2. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    Anyone know why?
     
  3. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    If you are getting a higher voltage it means it is operating in DCM. Try it in CCM by decreasing the output resistor.
     
  4. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    The parameters of L, C, R and Vin are set in the lab. The pulse generator parameters were just randomly chosen so I think it might have something to do with the value of T
     
  5. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Yes, switching frequency can affect operation in CCM or DCM because the ripple current in the unductor is frequency dependent.

    Decrease T to 0.00001s.
     
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