Vin for calculation of number of turns in transformer pirmary

Discussion in 'The Projects Forum' started by kender, Dec 12, 2012.

  1. kender

    Thread Starter Senior Member

    Jan 17, 2007
    263
    0
    Subject: Input voltage for calculation of transformer pirmary number of turns

    Colleagues,

    I'm making calculations for a push-pull transformer and following equations in Microchip application note AN1207 (pp.51ff).

    {\Delta} B = \frac{V_P T_{ON}}{N_P A_{core}} eq.175

    N_P=\frac{V_{DC,min}-V_{Q,on}}{A_{core}f_{PWM} {\Delta} B}D_{max} eq.176

    where
    V_{DC} is the input voltage
    D_{max} is the max PWM duty cycle (between 0 and 0.5 for push-pull topology)

    Why do they use V_{DC,min} and not V_{DC,max} in this calculation?
    I though that higher voltage across the primary will cause higher magnetic flux. Higher magnetic flux can saturate the core.

    Any suggestion, insight or reference is really appreciated!

    Cheers,
    - Nick
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    I agree that it should be V_{DC,max}. Don't know why they used V_{DC,min}. :confused:
     
Loading...