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motors their applications and limitations PMDC vs BLDC

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hi guys

i want to know for low voltage 24-72v what is the deciding factor between DC motor ? Brush or brushless

1- limitations in power can PMDC go as high as BLDC ex:10Kw or 20Kw ??
2- efficiency ?
3- magnets rare earth , or ferrite has to do anything ??
4- size to power ratio ?
5- cost to power ratio ?
6- availability ? future proof ?
7- difference in servo applications ?

plz discuss your valuable opinion :lol::lol::lol::lol::lol:
and if this post should be moved to another section please advise ! i posted here because i assume the engineers working in motors and controllers are usually power electronics experts

cheers
 

7. For servo application, accurate position of rotar required, PMDC is used AKA "stepper motor". because of the difficulty of manufacturing very large magnets, I doubt if these are available for a greater power then a couple of kilowatts. BLDC is normally 3 phase so the rotar can only lock at 6 positions , so the shaft position is only know to be +- 60 degrees.

1. Big magnets are difficult to make, so no.
2. Brush are better as commutation losses lower.
3. Ferrite would only be used for specialized motors with a very high commutation speed.
4. Brushed motors smaller - no driver module needed.
5. Brushed are cheaper.
6.To future proof, buy only motors with a specified frame size ( NEMA)
Frank
 
chuckey said:
7. For servo application, accurate position of rotar required, PMDC is used AKA "stepper motor". because of the difficulty of manufacturing very large magnets, I doubt if these are available for a greater power then a couple of kilowatts. BLDC is normally 3 phase so the rotar can only lock at 6 positions , so the shaft position is only know to be +- 60 degrees.

1. Big magnets are difficult to make, so no.
2. Brush are better as commutation losses lower.
3. Ferrite would only be used for specialized motors with a very high commutation speed.
4. Brushed motors smaller - no driver module needed.
5. Brushed are cheaper.
6.To future proof, buy only motors with a specified frame size ( NEMA)
Frank
Click to expand...

7- PMDC is not AKA stepper motors !! stepper motor are closer to bldc , and when u add enocder you can know the postion of the rotor anytime in both types

1- as i know even BLDC has magnets right ? so why is this a limitaion for brushed
3- as i know ferrite is the main stream and neoyduim is the specail version or is there another type ?
 

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