run 6V DC motor @ 12V w/ PWM ?

[1jam]

If I run a 6 volt dc motor at 12 volts, using less than 100% PWM, will it be
ok? or will it still burn out.

thanks

 

[Sjouke Burry]

1jam wrote:

If I run a 6 volt dc motor at 12 volts, using less than 100% PWM, will it be
ok? or will it still burn out.

thanks
PWM frequency should be high enough(50khz-1mhz), AND DUTYCYCLE < 50% ,

the induction of the motor should provide enough smoothing.

 

[bw]

"1jam" <com@example.net> wrote in message
news:i8al2b$ggs$1@news.mixmin.net...

If I run a 6 volt dc motor at 12 volts, using less than 100% PWM, will it
be
ok? or will it still burn out.

thanks

Depends on how hot it gets.
How hot it gets depends on load, time at load aka duty cycle, ambient temp,
etc. etc.

 

[Rich Grise]

On Sun, 03 Oct 2010 11:21:40 -0800, 1jam wrote:

If I run a 6 volt dc motor at 12 volts, using less than 100% PWM, will it
be ok? or will it still burn out.

If your drive circuit limits the current to the rated current of the motor,

you'll be fine, except you'll be dissipating some power in your drive by
regulating the current.

I'd have qualms about hitting a 6V motor with a 12V supply, even if you're
absolutely sure that you'll never go over 50% duty cycle - I'd worry about
the instantaneous currents.

If you know the spec - the motor is 6V at X amps, that's 6/X ohms - put
a 6/X ohm power resistor in series, and you'll be safe for sure, but
you'll waste a lot of power.

The last time I did a PWM controller, I used a current sink at a regulated
current and a supply that could be anywhere from 24-36V; I had to heatsink
the output Xsistor because it was dissipating some watts.

Good Luck!
Rich

 

[Jasen Betts]

On 2010-10-03, 1jam <com@example.net> wrote:

If I run a 6 volt dc motor at 12 volts, using less than 100% PWM, will it be
ok? or will it still burn out.

depends on the mechanical load, the capabiites of the commutator,
etc.

PWM: 50% 12V,50% shorted should, give similar mechanical perfromance to
a 6V supply, but the load on the commutator will be higher etc...


the easiest way to kill a motors is too much heat in the windings
due to much current. this can be caused by too much mechanical
load, over or under voltage etc.

--
¡spuɐɥ ou 'ɐꟽ ʞooꞀ

 

[whit3rd]

On Oct 3, 12:47 pm, Sjouke Burry <burrynulnulf...@ppllaanneett.nnll>
wrote:

1jam wrote:
If I run a 6 volt dc motor at 12 volts, using less than 100% PWM,...

PWM frequency should be high enough(50khz-1mhz), AND DUTYCYCLE < 50% ,
the induction of the motor should provide enough smoothing.

The frequency range can go lower, maybe 500 Hz. You can easily
add a series choke (and maybe a capacitor to shunt commutator noise)
or, if you're really energetic, can use switchmode power supply
control
circuits with current-overload-sense features. The important thing,
is
that there be an absolute current limit (because at 12V, the motor
winding resistance no longer performs that function).