Custom EV Motor Controller Question

So I am just starting to attempt to design my own PWM Motor Controller for an Electric Car. I am trying to avoid the 1,600$ Curtis 1231C or a super complex circuit that I have to build, especially because I don't need extra features or super amazing motor performance. But anyway I will have a 200amp (550 for 2 minutes) DC motor with a 144v battery supply, and I need to make my own very simple motor controller. Ive done about as much research as I can on schematics and videos on this, with virtually no results about large EV controllers, but tons about smaller controllers. There were several circuits I saw consisting very simply of just a 12v input from a battery with a potentiometer controlling a MOSFET which would output ~10amps or so (based on pot resistance) to a 10amp motor. So what I am ultimately asking is is something that simple possible on a much larger??

Ps. Of course not THAT simple, it's gonna need transistors and caps and resistors I understand that but can I completely avoid programmable microchips and MOSFET drivers?