I am trying to build a power bank that has 3 output USB ports that can provide 2.1 amp each; it has 8 LiPo cells. So total of 2.1×3=6.3amps so basically 7 amps at 5.1v out.
I have built the setup on breadboard but cannot get more than 2 amps out of even one USB port. I have tried making the inductor bigger, in size, triple wire for lower resistance and larger diode and N channel MOSFET.
PWM is with STM8S microcontroller at switching speed of 64kHz using 3mH inductor. I thought that paralleling the inductor, diode and switch would be enough to give more amperage but I'm not seeing that as a result. Instead the result is just 2.1 amps total. Then Schottky diodes starts to become hot or the 3 logic level MOSFETs.
Can the boost converter be useful for low voltage, high amperage or do I have to use transformer based circuit? Or do I need 10 diodes and 10 MOSFETs and a huge inductor for greater current?