I have been searching these forums for a good 6 months trying to soak up as much information as I can. I just now registered as Im coming up with questions the search bar cant give answers for (or I cant find, links appreciated)
that being said here we go.
1. I have read posts regarding magnetic weakening due to temperature and this causes a higher kv (that is rpm per volt applied) and lower torque output.
from that i would assume that the opposite is true (stronger magnets = less kv, higher torque)
is this a correct assumption ?
could instead of rewinding I put stronger magnets in a motor and get a lower kv (not practical just wondering if thinking is correct)
if it is, why?
does it have to do with flux lines? the reasoning being stronger magnets=more flux lines therefore more flux to grab (and more torque) but also more connections to break and reconnect therefore less kv.
2. I understand the idea of magnetic saturation in motors. Iron having only so many domains to line up and once a certain amount are lined up it becomes cost prohibitive to try to line up more, and after saturation is reached more amps just means more heat with and negligible power output.
my question is again why?
my cores are saturated and I pump more amps in where does it go? is it dissipated in the iron as heat as flux is trying to travel through saturated iron?
3. I believe magnetic pull is an exponential relationship with distance so when a tooth is attracting a pole from it furthest distance then per power applied, until they are right next to each other, not all of the full pulling strength is realized but at the same power cost. but yet motors achieve high efficiency. how when in a 3 tooth 4 magnet configuration the tooth distance to magnet is less than optimal for full pulling strength almost all of the time yet it achieves high efficiency. does anyone understand what i am talking about? i can post a picture if nobody does.
4. generally what are the characteristics of a 3 tooth 4 magnet compared to a 12 tooth 14 magnet motor ? or more simply less vs more pairs
i would assume the former (for best efficiency) likes higher rpms like rc motors while the later prefers proportionally lower rpms like hub motors?
with iron cores more hysteresis losses because of higher erpm per given speed
thats all i think i know
5. wondering where axial flux motors come into play? well I plan on building one but in trying to design it i run into options that without a understanding of the principles governing it i cannot make a informed decision
ideally i would like to make a air cored stator with 2 rotors sandwiching it, steel backing on the rotors, hall sensors, weird design that greatly reduces axial loading
(later) and a bunch of undecided things (like flat wire for 100% fill factor but not sure what that will do for eddy current losses I would assume the smaller cross sectional area would prohibit it more than round but still undecided).
not sure if it sounds lame but my goal is to have a pretty killer motor that could be made by a diy'er without to much fancy equipment.
but for now its just a idea hopefully a motor that will soon be something i will be posting
Thanks for reading this post I appreciate any ideas, help, advice, ect. you are willing to share
-John
that being said here we go.
1. I have read posts regarding magnetic weakening due to temperature and this causes a higher kv (that is rpm per volt applied) and lower torque output.
from that i would assume that the opposite is true (stronger magnets = less kv, higher torque)
is this a correct assumption ?
could instead of rewinding I put stronger magnets in a motor and get a lower kv (not practical just wondering if thinking is correct)
if it is, why?
does it have to do with flux lines? the reasoning being stronger magnets=more flux lines therefore more flux to grab (and more torque) but also more connections to break and reconnect therefore less kv.
2. I understand the idea of magnetic saturation in motors. Iron having only so many domains to line up and once a certain amount are lined up it becomes cost prohibitive to try to line up more, and after saturation is reached more amps just means more heat with and negligible power output.
my question is again why?
my cores are saturated and I pump more amps in where does it go? is it dissipated in the iron as heat as flux is trying to travel through saturated iron?
3. I believe magnetic pull is an exponential relationship with distance so when a tooth is attracting a pole from it furthest distance then per power applied, until they are right next to each other, not all of the full pulling strength is realized but at the same power cost. but yet motors achieve high efficiency. how when in a 3 tooth 4 magnet configuration the tooth distance to magnet is less than optimal for full pulling strength almost all of the time yet it achieves high efficiency. does anyone understand what i am talking about? i can post a picture if nobody does.
4. generally what are the characteristics of a 3 tooth 4 magnet compared to a 12 tooth 14 magnet motor ? or more simply less vs more pairs
i would assume the former (for best efficiency) likes higher rpms like rc motors while the later prefers proportionally lower rpms like hub motors?
with iron cores more hysteresis losses because of higher erpm per given speed
thats all i think i know
5. wondering where axial flux motors come into play? well I plan on building one but in trying to design it i run into options that without a understanding of the principles governing it i cannot make a informed decision
ideally i would like to make a air cored stator with 2 rotors sandwiching it, steel backing on the rotors, hall sensors, weird design that greatly reduces axial loading
(later) and a bunch of undecided things (like flat wire for 100% fill factor but not sure what that will do for eddy current losses I would assume the smaller cross sectional area would prohibit it more than round but still undecided). not sure if it sounds lame but my goal is to have a pretty killer motor that could be made by a diy'er without to much fancy equipment.
but for now its just a idea hopefully a motor that will soon be something i will be posting
Thanks for reading this post I appreciate any ideas, help, advice, ect. you are willing to share
-John
