AC Permenent Magnet Motor

[Michelinho]

@ gotoluc,

The motor is at my son-in-law's lab but I will try as soon as he brings it back. I will try it with my Simpson 1701 analog lab ammeter.

Take care,

Michel

[jadaro2600]

AC is indeed different from square waves.

I assume he has the coils setup to oppose one another? ..to pulse in opposite directions as the rotor spins?

..and then..

Hi jadaro2600,

thanks for looking at this topic Can you explain more on your statement "AC is indeed different from square waves" because my understanding AC is square wave, triangle wave or sine wave. If a wave form is alternating polarities at every pulse I though this was AC. I would not want to make a mistake and I'm open to learning.

The coils are not setup to oppose one another. They are both in the same direction and connected in series in the 2 last tests of the video.

Luc

....you cited me above, quoting; which was in reply to....

That is why we use 3 phase AC which has a 120 degree offset that will more easily determind the rotation direction. A 1 phase AC will by accident turn the rotor one or the other way as you use 180 or 360 degree offset. I know of 3 phase brushless motors, small ones, with magnet rotor, and coil stator, with a efficiency of 95% or more. Your motor probably are better synced with load and lower speed, and therfor the efficiency gets much higher, and the amps goes down. Load it more and the amps will go up again.

Vidar

And I should have quoted it.  Was a mistake of context.  Thank you for dissecting the truth.

What I should have said was that conventional AC ( conventional being a sinusoidal wave ) is indeed different from square waves.

[IotaYodi]

"AC is indeed different from square waves" because my understanding AC is square wave, triangle wave or sine wave

Normal AC power is sinusoidal . Square and triangle waves are non-sinusoidal. A triangle wave is closer to a sine wave than a square wave. A sine wave will keep its wave shape when added to another sine wave of the same frequency and arbitrary phase. It is the only periodic waveform that does so. As far as my limited knowledge goes you must have a certain amount of harmonic distributions in square or triangle waves to emulate a sine wave. Im not familiar with the harmonics of it.

[gotoluc]

http://en.wikipedia.org/wiki/Brushless_motor
If you want one, you can go here: http://www.hobby-lobby.com/brushless-axi2814.htm
I use this particular motor on a RC-plane - 110mph average, with 50 amps flowing through the coils at most. These motors are very powerful to its size. They are so called outrunners, as the 14 pole magnetic rotor is surrounding a 12 pole stator winding.

Vidar.

Hi Vidar,

thanks for taking the time to reply and post this information.

I looked at the wikipedia link and it looks to me that these motors seem to have metal core (not Air Core coils) and would have a very different behavior then the motor I'm demonstrating.

Please do correct me if I'm not understanding this correctly.

Thanks for sharing

Luc

[gotoluc]

..and then..

....you cited me above, quoting; which was in reply to....

And I should have quoted it.  Was a mistake of context.  Thank you for dissecting the truth.

What I should have said was that conventional AC ( conventional being a sinusoidal wave ) is indeed different from square waves.

Hi jadaro2600,

I understand now!... thanks for the explanation.

The motor works with sine wave but since my SG output is limited I was using square wave since it has more energy and made a better show for the video.

I think ideally sine wave should be used.

Luc