constant current charger
Posted by: bren
on
Good day! I would like to ask your help. I want to design a constant current charger using TOPswitch. The charger will use to charge 12VDC lead acid batteries. It should handle up to 4 batteries in series (4 x 12) = 48VDC. Do you have reference design for this? Steady state charging current is 4 amperes. Bren
Although a Flyback topology would work, at this level of power (200 W) you should really consider using a Forward converter. The closest design you can take a look at is the DER136 design which is a 75 W design
http://www.powerint.com/sites/default/files/PDFFiles/der136.pdf
This is a discontinuous mode flyback design with very small input capacitor which limits its overall power. Since you dont need PFC there is no restriction for you to operate in discontinuous mode and also use a larger input capacitor. Infact you should operate in continuous mode to limit ripple and RMS currents
This design will show the CC circuitry that you can use but the power level is only 75 W.