Which is better for fan speed control, V Mod, or PWM?

[Karaethon]

Ok, Which is a better way to control a 12Vdc fans speed? Voltage Regulation, or Pulse Width Modification? Please provide an explanation of why you think one is better than the other.

 

[Styx]

Depends what the motor is

IF it brushed then either, or depends if you want the extra complexaty of a PWM stage

IF it is a brushless-DC but fed from DC (control on a PCB) then it really needs to be regulated DC since it already has a PPWM stage, you PWM the voltage applied to it, it aint gonna like it

 

[Someone Electro]

And most of the fans in a PC are brushles becose there quieter and last longer.But meaby you could make the fan like PWM by sticking an big cap on it to smoth the pulses a bit.

 

[DigiTan]

I find variable voltage more difficult to work with. But then again, I'm new to feedback controls, so I find everything difficult to work with. :lol:

 

[Karaethon]

And most of the fans in a PC are brushles becose there quieter and last longer.But meaby you could make the fan like PWM by sticking an big cap on it to smoth the pulses a bit.

well further study shows that by using a PWM signal, to a Mosfet connected to the Neg Line of the fan, you can control the fan speed. So i guess this becomes a question of which is more economical? Voltage regulation (doesnt this generate heat lots of heat), pr PWM(does this requre some fancy chips to do?)

 

[akg]

And most of the fans in a PC are brushles becose there quieter and last longer.But meaby you could make the fan like PWM by sticking an big cap on it to smoth the pulses a bit.

well further study shows that by using a PWM signal, to a Mosfet connected to the Neg Line of the fan, you can control the fan speed. So i guess this becomes a question of which is more economical? Voltage regulation (doesnt this generate heat lots of heat), pr PWM(does this requre some fancy chips to do?)

i'll prefer the 'styx' suggestion..

Voltage regulation (doesnt this generate heat lots of heat),

Yes ofcource

or PWM(does this requre some fancy chips to do?)

no 'fancy' thing is needed.

 

[Optikon]

The term "better" is a very subjective term. The poll question is bogus.
What one person thinks is better another may not for good reasons. Better how, noise-wise? Simple circuit wise? Programming code wise? Cost wise? size wise? and on and on an on....

The correct answer to your poll is: It depends. Or should I say that is a definite maybe! Instead of fishing for what other people do, try and grasp an understanding of the constraints you need to work in and choose based on those. Everyones situation is different.

 

[Karaethon]

There are no constraints, this post is simply a brainstormer for me, i just wanted to get a bunch of opinions, for future projects. hencd:

Please provide an explanation of why you think one is better than the other.

 

[Nigel Goodwin]

There are no constraints, this post is simply a brainstormer for me, i just wanted to get a bunch of opinions, for future projects. hencd:

Please provide an explanation of why you think one is better than the other.

There's no real contest, for almost any purpose PWM is FAR better, but, it might not work on a DC brushless motor - some might be OK, but others certainly won't.

 

[Styx]

There are no constraints, this post is simply a brainstormer for me, i just wanted to get a bunch of opinions, for future projects. hencd:

Please provide an explanation of why you think one is better than the other.

There's no real contest, for almost any purpose PWM is FAR better, but, it might not work on a DC brushless motor - some might be OK, but others certainly won't.

ALL BLDC machine/motor can handle PWM.
The problem exist because ppl sell BLDC motor-drive (ie the machine and the PCB) as a BLDC motor, when it isn't it is a motor-drive

 

[Nigel Goodwin]

ALL BLDC machine/motor can handle PWM.
The problem exist because ppl sell BLDC motor-drive (ie the machine and the PCB) as a BLDC motor, when it isn't it is a motor-drive

I see what you mean, but it's probably just confusing the issue more than anything?.

Certainly there would be no trouble doing PWM between the controller and the actual windings of the motor - but there's probably not as much point though?, you could do speed control with the controller itself, which is how it's done in VCR's etc.