Yep copper losses, and the magnetic flux linkage. The iron in the bell’s magnets go through demagnetization and have losses as well depending on the magnet type (n42h n42sh n52sh etc)
The magnets don’t go through demag. If they do they are done. The only losses in mags are Eddy currents. Regardless of type
Demagnetization of the permanent magnets occurs to some extent whenever a current flows in the motor winding.
As well most of the magnets we use start to.demagnetize around 160-170F and are fine once cooled.
Yea mags will decrease their magnetism at high heat a bit n come back but its not a loss. It’s heat related. Not current related.
I always thought that once they’re demagnetized they will be unusable?(no magnetization afterwards) You learn something everyday around here…
But I think it right in that at higher temps when the mags are decreasig. Their strength then in compensationitscopper losses as the mag field is needed to be built theretoxontume same torque
But, and a big but, if the motor is badly designed the hysterisis loop that makes the magnet work can dive into the demagnetization region, even at ambient temperature.
I still didn’t get that part well enough to be certain, but from what i understood with a high enough flux, or with high flux concentration due to stator design you can make this happen, so each phase activation would demagnetize the motor a little
That being said I guess the flux intensity and materials that are used for our application don’t let this happen, but again, not sure yet
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I thought the mags would demanitize not ever a little but an instantly reverse polarity. with a bad hysteresis loop would that be an overlapping of polarity or something where the motor produced a strong enough field to reverse polarity?
Devin is that you?
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Devin? Not sure what your trying to imply…
To someone who doesn’t know a thing about motors he sounds just like him, no? (not to be rude, it was just a thought)
Not to be rude too, but the discussion is better if everybody try to add something. I’m expert in motors? No way, I know very little at the moment, but I’ve studying a lot in the past few months to manage to build my own and only now everything is starting to click
Cheers
I know. I wasn’t trying to be insultive(is that a word?). I just thought he reminded me of devin with all the technical stuff. @Hummie has definitely more knowledge than anybody else in my opinion. I could only dream to know as much as him about the subject.
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I’m not Devin, and no offense, but hummie doesn’t know everything.
Do a search, hummies been in alot of convos. There’s some surprising ones around that show how little hummie knows about these motors in a system, and yet he builds them…
http://vedder.se/forums/viewtopic.php?f=6&t=276
So hate on me all you want, but I don’t trust half the stuff he says…
Move along with that Devin nonsense.
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No use comparing me to someone I clearly am not… So just making that as clear as possible. Lol not trying to start anything, just don’t want to be compared to someone who has clearly been banned from theforums 5+ times.
I only share what I know, I’m not forcing my views in y’all or demeaning anyone when I share what I know. If x person doesn’t agree with what I’ve said, don’t agree and move along. Just because some dude(me or anyone else) in the internet said something doesn’t make it right, so take what you want, leave what you don’t. But I’m anything but this Devin character.
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100% with you DeckyBro!
struggling to believe that was a comment.
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From the first picture you can see the hysteresis loop in normal operation, as the external field (generated by the coils) gets more intense the loop goes down and two the left, if it goes down to cross the x axis you enter in the demagnetization region
The second picture show the influence of temperature, since the intrinsic field intensity goes down as it gets hotter, the external field intensity to cross the x axis gets smaller
The knee on the diagonal lines represent the non-linearity that is often discarded during design, so you can demagnetize sooner than expected
About the who knows what’s discussion, there’s two approaches to most things, practical and theoretical, @Hummie aproach is most practical and iterative, there’s nothing wrong with that
What’s better? Who knows, of course by an engineering stand point you should predict, design, simulate and etc before making something, but for a low volume market such as hub motors it may not be worth, a state of the art multi physics FEA software would set you back 30K or more, and if you have no knowledge of what’s happening on the background it’s worthless
@Deckoz sorry I wasn’t meaning to insinuate you were anyone, I was saying someone else here sounds a lot like Devin. Devin is a good friend of mine for like nine years so regardless it’s not an insult.
@RedEagle thanks for the compliment but I don’t know a lot of stuff that for many people is easy. Coming with endless repeated questions till I figure it out is probably how I do it.
that link thought @Deckoz,…I still didn’t get my question answered. its a basics electronics questions probably: how can the vesc make a complete circuit with the motor where there is created a high voltage, …so a circuit with a high voltage but not a high current. why? in my basic understanding if you have a high voltage in a circuit …current will go. unless there is some other circuitry bit which would just reduce it. if you know… I like to be in discussions above my head…like the present… In practice demagnetizing the motor’s magnets I still understand from either a high temp or an extremely strong field, and I’m guessing that what’s produced in the “hysteresis loop” above is an extreme field produced by the coils and iron. I’m guessing the stator would need both a very high current and also so much speed so as to have the peaks and valleys of the hysteresis loop overlap in a way to build the field strong enough…no?