Hi,i am an engineering student i want to vary the speed of a dc motor without varying its power. Plzz help me!!

 

to vary the speed of dc motor without varying its speed

First off you may wish to correct this thread's title

i want to vary the speed of a dc motor without varying its power

The required input power will be a function of AV (i.e. 'speed'), load and efficiency --- I'm uncertain as to your meaning with 'not vary the power'...

IOW -- More info please!

Best regards
HP

 

Hi,i am an engineering student i want to vary the speed of a dc motor without varying its power. Plzz help me!!

Plzz explain your problem better (whatever plzz means ).
What type of dc motor?
You can vary the speed of a shunt-field dc motor by varying the field current.

 

Hi,i am an engineering student i want to vary the speed of a dc motor without varying its power. Plzz help me!!

Vary the burden as well.

 

Vary the burden as well.

FWIW I'm guessing the OP's intent is that he/she wishes to vary the AV sans 'static' adjustment of the feed EMF --- Still, who knows...

Best regards
HP

 

Sounds like they want to alter the speed without altering the voltage or current through the motor,

Its a job for Super-hamster!!!

 

Pulse width modulation allows you to control the 'speed' of a motor without changing the voltage by changing the duty cycle - but in an AC setting. If you use an ac power source and a filter circuit (Google is your friend) to prevent it from dipping below 0V, you might have some luck.

 

Pulse width modulation allows you to control the 'speed' of a motor without changing the voltage by changing the duty cycle - but in an AC setting. If you use an ac power source and a filter circuit (Google is your friend) to prevent it from dipping below 0V, you might have some luck.

@narinder kaur -- Pursuant to the above - Please consider, for instance, a 'phase control' circuit but employing an SCR (as opposed to a triac) as the power switching device... Be advised, however, that a (monopolar) PWM controller is the standard (and, in most applications, optimal) approach...

Best regards
HP

 

The OP probably means "how do I vary the speed of a DC motor without varying its torque". One word: Pulse Width Modulation.