I am hellbent on turning my spare alternator into a motor and using my Arduino Uno to drive it. I guess I could get an already-available controller, but I want to play with how much voltage I can put through it, etc. I've been exploring this idea for a few days and this is how far I got in my search.
The rotor takes 12 volts DC. I have sweet access to the terminals of the stator. I have some high-capacity MOSFETs on the way. The Arduino should have the PMW capabilities to handle this, right? (I'm told that I need synced PWM channels and that Arduino has them. I don't know yet what exactly this means, but if I need them and the thing has then than it's all good, right?)
I can write the code, but I need detailed info to do it. I could also use a list of additional components that I will need and an explanation as to what exactly they do.
I suspect that an alternator (minus its rectifier) would behave like a brushless motor - except that it uses an electromagnet rather than a permanent magnet.
I also suspect that brushless motors need phased power rather than simple PWM.
Car alternators are 3 phase with a full wave diode bridge to produce the DC.
The only way to run one as a motor is to supply 3 phase AC at whatever frequency you want the motor to run at.
Its possible but a lot of work, and needs specialised electronics.
You can run an alternator as a motor by connecting the three wires from the stator to an relative inexpensive sensorless ESC for BLDC (electronic speed control for brushless DC). I have done this, and it works. However, because it's sensorless, the motor can't start under load and looses synchronization if your apply too much load to it while it's running. I would speculate that in order to make good use of an alternator as a motor (BLDC), you would need to add sensors to it and use a BLDC sensored controller. The supply voltage would probably need to be at least 24v, but ideally a lot more, like 48 - 96V. An alternator easily generates more than a 100V, without regulation. Also the controller needs to be able to supply a lot of current, probably at least 100A.
You should not supply the rotor with 12V, but instead something like 6V, or better use PWM regulation. With a regulated supply to the rotor you can get "electric gears". Hi power to the rotor equals hi torque and low rpm, and low power equals hi rpm and low torque.