Anti cogging idea ?

[FreeEnergy]

i like this idea, might work.

[Airstriker]

It's the same idea as this one (not ever finished as I remember):
http://www.overunity.com/index.php?topic=8262.0

[helicoil]

 ran a few basic tests on this idea,probably incorrect, not sure about using wm2d,sorry cant post the file as its a
trial program.
  getting interesting results which i hope an expert user of wm2d can test.
Most of the test had the pin radius and friction set to 0.5, not sure what this friction is but its able to grab and rotate
a 4 meter bar with a 50kg weight on its end, this seems like a huge cogging force.I hope its overkill as this test the drive
motor used just over 10kw, with it driving 2 30kw gens at 100rpm.

The problem with this test is that i had the motor driven a a constant velocity to rotate at 100 rpm, don't know the settings
for the dc motor, (so the kw readings are probably incorrect).
frictions a problem as well, not sure if its set true, results are surprising, even when hanging a 500 kg weight off the 4
meter arm  the drive motor uses 37500 kw when arms(rotors)friction pin radius and friction is set to the maximum value of
1.0, and the axle friction set at 0.5.
when the friction on the arms or rotors are set to maximum it would grab and rotate a 255kg weight hanging at the bottom of
a 4 meter arm, i doubt the cogging force would come close to this.

ran another test with all friction settings at 0.5 and the main axle friction coefficient set to the max,1.0, drive motor
power was 21kw. 

lengthening the arms helps keep the weighted arm lower, as you can see on the pic, there almost at 45 degrees.
tested the idea with 2 500 w gens weighing 13 kg, lightening the weight of the frame and arms and weights, running at 500
rpm, used more power than it produced, just over 1100 w, but if there were frictionless bearings on the main axle it ran at
550 w, friction on the arms were set at 0.5, main axle set at 0.05. 

Just thought id post these details, i hope other members who are skilled at wm2d  post the correct results.

[helicoil]

Came across this motor, never heard of these before.
wonder if the same idea could be used to generate power.

quote from ThinGap Announcement

ThinGap
developed a patented technology, which replaces the
iron core and wire windings of conventional motors
with a precision-machined copper sheet. This has
eliminated such issues as hysteresis, iron losses,
and cogging torque, while substantially reducing the
impact of eddy currents and back emf. The copper
sheets allow higher copper density and a higher
copper to total volume ratio, making ThinGap a
performance leader in high efficiency and power
density motors.

DC Ring Motor Powers 600-lb. Thrust Ducted-Fan
VENTURA, CA â€" April 20, 2010 â€" ThinGap LLC, a leader in high power density DC motors, today
announced a TG14090 Brushless DC Ring Motor that delivers 122 kW of shaft power, allowing a
ducted-fan to generate 600 pounds of thrust, depending on the fan blade design. The motor
provides an exceptional power to weight ratio â€" 6.4 HP per pound; a compact package that fits
the control inside the motor and low thermal load characteristics.


“ThinGap’s 14-inch electric ring motor allows a ducted fan to develop as much thrust as with a
gas engine, which is a game-changing milestone,” said Rean Pretorius, president, ThinGap, LLC.
“At 6.4 HP per pound, its power to weight ratio has not been achieved by any electric motor
currently in production and exceeds the aerospace engineering threshold of 5 HP per pound. The
advantage is much quieter operation for stealth, and less weight, which can be critical for UAV
surveillance and close support tactical applications.”


http://www.thingap.com/pdf/technologypaper.pdf

http://www.thingap.com/pdf/tg14090motor45clean.pdf

http://www.thingap.com/pdf/tg14010ds.pdf

[Airstriker]

@helicoil
I've seen this before. Everything is correct, but the thing with BEMF is not quite what you think BEMF is still there but it's characteristics are a bit different. Here is what it's like:

The back EMF waveforms are sinusoidal
and with matching sinusoidal current waveforms, a
smooth low peak-to-peak A ripple is achieved.
A back EMF waveform with near-perfect sinusoidal
symmetry signifcantly reduces torque harmonics and
mechanical resonance over a wide speed range.