DC to DC converter design

Discussion in 'The Projects Forum' started by gobi615, Feb 24, 2013.

  1. gobi615

    Thread Starter Member

    Jul 26, 2011
    Hi , I am designing a charge controller for a 48V lead-acid battery . So i have to design a buck boost converter i selected inverting topology buck boost converter.[​IMG]
    I am using mosfet IRFP150N . PIC microcontroller for pwm pulse 5khz , and a3120 gate drive optocoupler to mosfet gate from microcontroller.
    design parameter are input voltage varies from 20V to 70V .fixed output 54V (including losses) . L=2mH, C=1.62mF . output current 5A.

    Problem is my capacitor burst for a input voltage of 25V and there is no boosting operation for duty cycle increment .
    I need some guidance
    Is this topology works fine with this power level.
  2. Papabravo


    Feb 24, 2006
    If your capacitor was an electrolytic type, I'm not surprised it failed if you connected the + lead to a - voltage. Why are you making an inverted DC DC converter? Also what is your input voltage?
  3. gobi615

    Thread Starter Member

    Jul 26, 2011
    It is two 660uF and one 330uF electrolytic capacitor connected in parallel to get 1.62mF.I connected negative of capacitor to anode of schottky diode , i connected it correctly.I didn't figure it out the problem.

    my input voltage varies from 20V to 70V dc and i want to get 54V constant at output .
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    Where is your feedback for output voltage stability?
  5. gobi615

    Thread Starter Member

    Jul 26, 2011
    First, i am doing it in open loop control with varying duty cycle via pot . once i get it successful then i going to install a divider network across the battery and give it to the microcontroller.