You want to build a 12vdc push pull smps and get around 250W with a +-35vdc output. So lets start gathering some data. First we will assume a poor 60% efficency because of no output inductors.
250W x 1.4 = 350W input power.
Assume 14.7 volts max input.
350W / 14.7vdc = 23.8A, max primary current.
BTW, I am not perfect and i make mistakes. If anyone see’s a mistake speak up!
Hi, I noticed that this is the max primary current @ max primary voltage, like when the car is on, but if the car is off, and maybe battery is a bit low, shouldn't we calculate the max primary current
@ minimum primary voltage
of around 11.5 to 12.1 V? In this case the current would be in the range of 30.44 to 28.93 A, allowing for a better safe margin
Thank you for all the clear explanation!