Dividing Wall Power Frequency

[b-rye-an]

First, apologies for my newbishness, my electronics knowledge only extends as far as getting LED's to flash on micro controllers.

I have a motor that plugs into the wall and runs at 60 Hz. There's no controller inside of it, so I know it's just running at the frequency of the power it receives from the mains. I was wondering if there's a good way to halve this frequency (to 30 Hz) and get the motor to run at that speed. I've seen some other posts here where people discuss halving the frequency of signals using flip-flops and counters, but if I understood them correctly, to do so requires significantly reducing your voltage. Is there a way to halve my signal and keep my voltage?

Thanks!

 

[crutschow]

Reducing the frequency at low current and voltage is not a problem. But changing 60Hz AC to 30Hz AC for a motor would require a power inverter circuit which has high power semiconductors and large transformers. And you would have to operate the motor at half the voltage to avoid saturating the magnetic core which would cut it's maximum power output roughly in half.

 

[b-rye-an]

Hmm. It sounds like there's not a relatively straightforward way to do it. Another thought was to step the power down to ~24 V DC and use a PIC to create my own wave. I can potentially increase the number of windings on the motor, so I might be able to get back some of my losses there. Thanks for the reply, I'll keep poking around and see if I can come up with any other ideas.

 

[jbeng]

A device called a VFD operates this way. They're usually used on industrial motors to control the speed.

en.wikipedia.org/wiki/Variable-frequency_drive

 

[ben7]

Know what's fun?

Run a 60hz AC motor on 5000hz AC, and it will sound like a jet engine.