Today I finally managed to make this thing work. It is a normal pwm you would find at any ebay like shop based on LM324 chip. But instead of driving a "tiny" IRF 540, it drives a mosfet driver lol, which consists of 2 simples transistors in series, one NPN and one PNP. And this driver then drives 4 IRF3205, much "stronger" than the 540, capable of 110 amps. Ok probably they would melt with that current continuously, but they can take it for a short time.
All this is used to control the speed of a car engine starter motor which was a bit modified. I removed all the the front part of it, cover, "bendix"?, pinion, solenoid, that lever or arm, the clutch. Then I got another cover like the rear one and fitted on the front with a ball bearing. Also installed a sprocket on the axle. I plan to use this on a electric bike. I just don't like these electric bikes available. They are too expensive for a thing that is a bit .
Well it is in my language, but you still can see the result if you want.