I have a lathe that runs faster than what I would like on the slowest speed. Two answers seem to be available. Replace the motor with 3-phase motor and a VFD controller, or replace the motor with a DC motor and PWM controller.
The DC version, I think I understand electronically, although maybe not effective powerly (I've heard lower DC power motors effectively look like higher power AC motors -- ?).
The 3-phase VFD (Variable Frequency Drive) seems simple enough in principle, but I'm wondering what's in the best cost effective versions.
The one I want will take single phase 230V AC and convert it to 3-phase motor drive output that is variable in freq.
First question: what happens to the input? If it is single phase, I assume it goes through a full wave rectifier to get it as smooth as possible. Then what? Caps wouldn't help much at this kind of power I'd guess, and commercial units are small. Just ignore the bumps?
I think the drive to the three phases is a form of PWM, probably microprocessor generated, and done by IGBTs.
So, It's obvious I don't know a lot about this except my first-level assumptions. Can anyone provide a basic description of what is happening in these VFDs and what might make better or worser implementations?
Thanks. Hope it generates some interesting observations. I know this can get deep, but at a first level I'd like to hear the the basic theory about how the input power might be adapted and controlled.