I am designing a motor system that has to run in a vacuum chamber (sub mbar). I am a little bit worried about the heat that would not dissipate at all in the vacuum. Therefore, I want the least amount of energy wasted to heat(high efficiency). Some people advised me to get a big motor that is much more capable so that it can withstand the heat generated under low load.
The rpm I need ranges from 30 rpm to 600 rpm. So I need PWM on top of gearbox+motor. PWM and speed input will be controlled using Arduino. Also I realised that there are brushless and brushed motors. I figured that brushless motors are a bit more efficient which means less wasted as heat.
So in conclusion, I want a setup that is, big brushless motor + gearbox + PWM. Am I thinking correct? I have never gotten a chance to do any electrical engineering so I might be missing obvious flaws. Please let me know if there are any better ways to achieve this.
Additional info) I chose dc motor because the important part is to run continuously and smoothly at a set constant speed without bumps or jittering. One session of running time would be ~10 minutes. Torque is not so much of a problem, probably maximum of 1000gcm needed I guess.