Deleted
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Post by Deleted on Oct 15, 2011 15:20:07 GMT
Is a brushless motor supposed to be better? I see that some advertise the fact that they are brushless so wondered what the advantage was.
Do they last as long as normal motors?
Ian
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xerxes
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Post by xerxes on Oct 15, 2011 15:47:17 GMT
Here you go: en.wikipedia.org/wiki/Brushless_DC_electric_motorBasically, the motor is built on reverse, so the permanent magnets are fixed to the rotating part, while the coils remain stationary. Therefore there's no need for brushes to supply current to the coils as these are stationary and can be directly connected.
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Post by Deleted on Oct 15, 2011 15:52:32 GMT
Is a brushless motor supposed to be better? I see that some advertise the fact that they are brushless so wondered what the advantage was. Do they last as long as normal motors? Ian In many ways yes. Firstly, in a normal motor the brushes make physical as/with moving parts. Obviously this means the brushes will wear out, on a sealed motor that's game over, on a servicable one the parts may or may not be available as a seperate item. It is more common to replace the complete rotor or armature. On some larger motors softer "carbons" are fitted as the physical contact with the armature, allowing these to take the wear rather than the armature contacts. The carbons are replacable without dismantling the motor. Brushless motors also run quieter and smoother with more accurate speed control possible. not just due to lack of physical contact within the motor but also the possibility of having many poles. A bit like a 12 cylinder engine compared to a four cylinder of equal capacity. More specifically to RC heli usage, the motors cool better, as the electromagnet is to the outer part of the motor rather than the centre, hence those natty finned heatsinks you see on clipped onto such motors. That's just some of the basics, hope it helps. PS you were quicker than me Owen! I was still writing
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Deleted
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Post by Deleted on Oct 15, 2011 15:59:39 GMT
Here you go: en.wikipedia.org/wiki/Brushless_DC_electric_motorBasically, the motor is built on reverse, so the permanent magnets are fixed to the rotating part, while the coils remain stationary. Therefore there's no need for brushes to supply current to the coils as these are stationary and can be directly connected. Thanks for that. It never occurred to me to check Wikipedia!! So there is an advantage then. Quieter and more efficient plus extended wear. I saw helis being advertised making a biog point about 'brushless motors' so I thought they must be better than a normal motor!! Ian
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Post by gommer on Oct 15, 2011 22:10:23 GMT
If i'm not mistaken, every brushless motor needs a controller to make it run. A DC motor with brushes commutes on it's own, whereas for fixed coils, electronics will need to create the rotating field.
So: advantages of brushless motor as in the posts above, but more complex electronics are needed.
Oh and i think another advantage is higher torque and (with very clever electronics) possibility of very small torque ripple (although i doubt you'll find this in cheapish RC models).
Cheers, Marc
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Post by Deleted on Oct 16, 2011 6:18:38 GMT
Thanks Marc,
That's what surprised me. The helis with brushless rotors (which are quite small) aren't that much more. They seem to be known as better quality models as well.
Ian
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