106Views6Replies

Author Options:

Converting AC to DC Answered

I have a single phase 3.5 hp AC motor,

I would like to convert to a 12 volt DC.

I'm no electrical expert but I think it can be done.

From watching youtube vids and asking Mr. Google

I understand a DC motor runs slower say 1750 rpm,

where my AC motor spins at 3,450 rpm.

I also understand a DC motor has brushes.

Besides the speed being different, and changing the cord out,

is there any reason WHY this couldn't be done?

Any potential drawbacks?

Any help or knowledgeable advice would be much appreciated.

Thanks guys,

skip

6 Replies

user
-max- (author)2018-01-26

There are many types of AC motors. AC induction motors can probably be rewound to operate at a lower voltage, but you will not be able to do this easily or practically. They require polyphase AC, so forget DC.

Universal (brushed) motors can be operated from DC supplies as well as AC supplies, but the larger ones require a controller to regulate the speed. Unloaded universal motors can get very very fast and self destruct when no controller is used to limit the RPM. Rewinding them would also be practically impossible.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)-max-2018-01-26

Look at the OP's power levels ! 23A on 110V, 230A on 12V !

Select as Best AnswerUndo Best Answer

user
-max- (author)steveastrouk2018-02-04

I didn't intend to imply that a hacked/rewound motor would operate close to its original rating, I probably should have mentioned that. The sheer amount of magic smoke that we would see with 230 amps tho.... :D op would end up with more of a smoke bomb lol.

Select as Best AnswerUndo Best Answer

user
Toga_Dan (author)steveastrouk2018-01-28

thats assuming rewinding for equal power. in practice, 1/10th v means 1/10th current, and 1/100th power. of course, impedance etc will change that, but - its rough numbers for a brushed motor.

Select as Best AnswerUndo Best Answer

user
iceng (author)2018-01-26

A DC motor needs to create a shifting magnetic field by non-electronic means image #1..
A better detail of a DC motor components are depicted in image #2 if you ignore the gearing..
Now compare the armatures with the solid metal AC motor armature image #3 and
The wired MMF field AC coils in place of the permanent magnets in the 4th image..

I think the only way to make a DC motor out of the AC motor is to slide the field out of the machine shell and replace the armatures which is very much more work then getting a DC motor in the first place, even if you know certain advanced electrical Secrets that come from lifelong experience..
BTW,
Belief in YouTube laughable fake vids is a poor exchange to a proper education at a real school !

Select as Best AnswerUndo Best Answer

user
sdtag (author)2018-01-26

I don't think this is possible.
Totally different animals.
To convert ac to dc you run the ac through a bridge rectifier then clean it up with some capacitors.
I don't think you can convert an ac motor to dc, and vice versa
be careful - you're playing with fire

Select as Best AnswerUndo Best Answer