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Discussion Starter #1
I can’t remember where I read it but I thought I read somewhere that essentially- “larger permanent magnet motors generally have higher iron losses in terms of percent of total losses or watts per pound.”

Anyone know if it’s true or where I can find info one way or the other? Do larger permanent magnet motors generally have more watts of iron losses at a given torque per pound than smaller motors?

For example for a given torque per pound, does a smaller motor have less iron loss per pound?
 

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I would be fairly sure that many factors affect electric motor efficiency but I leave this detailed work and experimentation to the clever guys who design and make them. I'm sure they have a much better understanding of such matters than you or I.
 

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Discussion Starter #4 (Edited)
I would be fairly sure that many factors affect electric motor efficiency but I leave this detailed work and experimentation to the clever guys who design and make them. I'm sure they have a much better understanding of such matters than you or I.
It so happens I’ve been involved with the design and made smaller motors...

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my point is in this electric motor efficiency chart, at low torques (below 100nm), at low rpms, and at high rpms, the efficiency dives off a cliff, presumably due to high iron losses at low torque.
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So I was wondering whether many smaller motors working in parallel have improved efficiency at lower combined torques from reduction in iron loss?
 

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You seem to have a particular interest in this, so I suppose it falls to you to answer your own question. Do the maths and if it looks promising try and develop an experimental set up.
I suspect, if you add in cost, you may find that a piddling increase in efficiency comes at considerable increase in cost. But, it's your baby.
 
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