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 Post subject: Re: Rotary attraction motor
PostPosted: Thu Feb 17, 2011 3:24 am 
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Ok.

With available meter, do the consumption increase with mechanical load?

Your goal now is to improve efficiency?

Do you think if you improve the efficiency, the consumption pattern change?

I mean, currently, your motor is not no BEMF motor yet?


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 Post subject: Re: Rotary attraction motor
PostPosted: Thu Feb 17, 2011 12:07 pm 
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I started with an induction motor. It is designed to use induced EMF to our advantage when using AC current.

The induced EMF in the rotor plates is channelled into the squirrel cage where it flows forcing the rotor to turn when AC is applied to the coils. My experiment on torque shows that even though this motor uses induced EMF to our advantage, it still suffers the problems of BEMF.

I expect that there will be increased current draw when this motor is loaded.

If I could remove the squirrel cage this situation would improve, the same as removing the rotor windings in a universal motor; however it is not practical to remove as it is cast into the rotor.

I will do the current draw tests as soon as I get a suitable shunt resistor for my analogue meter.

My theory on an ideal motor had a power of 24w with one coil powered; I was powering two in parallel so the power would have been ideally 48w. My measured mechanical power was only a tiny fraction of this so it is important to find out the current draw and compare it to theory.

What this test does show is that just milling slots in an induction motor will not get you anywhere near where we need to be.


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 Post subject: Re: Rotary attraction motor
PostPosted: Fri Feb 18, 2011 5:34 am 
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I see. thanks. Will look forward for your result :).


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 Post subject: Re: Rotary attraction motor
PostPosted: Sat Feb 19, 2011 2:04 pm 
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I have Rebuilt the motor and run more tests.

All measurements are + or - 3% except torque as the scale has no tollerance on it
Timing and RPMs done with the scope
Two coils in parallel in all tests
24v 10A power supply unregulated (Hence 32v)
10% duty cycle

Test1

470uF cap across the points
Duty cycle 10%
Motor driven at 32v
Amps = 1.32A
Watts consumed = 42.24w
Unloaded speed = 1333rpm
Torque needed to overcome friction in the bearings = 0.56Kg-cm
Mechanical power consumed by friction = 7.66w
Measured Torque = 0.6Kg-cm at 750 Rpm
Torque required to reverse the motor = 12.6Kg-cm
Amps rose when speed dropped below 750
Mechanical output power = 4.62w
COP = 0.109

The motor was stripped again and as much of the squirrel cage removed as possible. This involved machining off the aluminium at either end of the rotor. The remaining aluminium bars remained in contact with the laminations of the rotor forming a circuit between them.

Test2

Timing and RPMs done with the scope
Two coils in parallel in all tests
Duty cycle 10%
Motor driven at 32v
Amps = 1.28A
Watts consumed = 40.96w - I don’t regard this small drop as significant.
Unloaded speed = 1395rpm
Torque needed to overcome friction in the bearings = 0.56Kg-cm
Mechanical power consumed by friction = 8.02w
Measured Torque = 0.9Kg-cm at 750 Rpm
Torque required to reverse the motor = 12.6Kg-cm
Amps rose when speed dropped below 750
Mechanical output power = 6.94w
COP = 0.169 -Over 50% increase

Torque needed to overcome friction in the bearings = 0.56Kg-cm
Torque required to reverse the motor = 12.6Kg-cm
Expected torque = 12.6 x 10% = 1.26Kg-cm
Motor torque loaded down to 750RPM = 1.2Kg-cm
Torque efficiency during rotation = 0.9 / 1.26 = 71.4%

Charging on a 60Ah battery was seen when the capacitor was in place at about 0.02v instant rise.

When the capacitor is removed a bright spark is seen at the points but not as bright as when there is no battery connected. Current consumption rose by 0.4AThe voltage of the charge is soon 2v above standing voltage. I think we need a larger capacity battery.

I know there is BEMF in this rotor because the speed drops by 10% when the output from the diode is shorted and amp draw increases. There must also be drag reducing the speed and so the power. No drop in speed when connected to the battery.

My guess is it around 32 x 0.4 = 12.8w so lets add up what we know

Input 40.96w - Mechanical output power = 6.94w - Rotor BEMF = 12.8w. So with an Ideal rotor we have a COP of (6.94 + 12.8) / 40.96 = 0.482

Next I played with the dwell angle and found that a duty cycle of 7% gave highest speed

Test 3

Timing and RPMs done with the scope
Two coils in parallel in all tests
Duty cycle 7%
Motor driven at 32v
Amps = 0.98A
Watts consumed = 31.36w
Unloaded speed = 1666rpm
Torque needed to overcome friction in the bearings = 0.56Kg-cm
Mechanical power consumed by friction = 9.578w
Measured Torque = 0.6Kg-cm at 1000 Rpm – Below 1000RPM the motor stalled under load
Torque required to reverse the motor = 12.6Kg-cm
Amps rose when speed dropped below 750
Mechanical output power = 5.683w
COP = 0.177

Test 4

Timing and RPMs done with the scope
Two coils in parallel in all tests
Duty cycle 7%
Motor driven at 44.7v (car battery in series)
Amps = 1.4A
Watts consumed = 62.58w
Unloaded speed = 2011RPM
Torque needed to overcome friction in the bearings = 0.56Kg-cm
Mechanical power consumed by friction = 11.56w
Measured Torque = 1.2Kg-cm at 1000 Rpm – Below 1000RPM the motor stalled under load
Torque required to reverse the motor = 12.6Kg-cm
Amps rose when speed dropped below 750
Mechanical output power = 12.33w
COP = 0.197

The COP does not include any recovery at this stage, and at these COP figures I can see why Peter was quiet about the results having said that Jrtijs motor was much better than this. I will need to make a new rotor to approach his figures before I set about cutting the stator. What is obvious is that the drop in speed does not equal the torque when the motor is loaded so there is significant drag or counter EMF in this motor.


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 Post subject: Re: Rotary attraction motor
PostPosted: Mon Feb 21, 2011 4:45 am 
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Many thanks for sharing results :).

There is someone else also complaining about poor efficiency too. Here:
http://www.hereticalbuilders.com/showpo ... stcount=20

Laurent's method:
Quote:
So the idea in the Lockridge device, is to decrease the effect of the BEMF acting against the EMF by applying 1 pulse per revolution of the rotor. Than dump the energy in a flywheel in order to spin a generator, which should provide enough electric energy to feed a capacitor. And finally to discharge the cap in the 1 pulse motor , and so on.


I will look forward for your progress :).


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 Post subject: Re: Rotary attraction motor
PostPosted: Tue Feb 22, 2011 12:54 am 
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If I am correct, the energy that would normally take the easiest path, a short, in a motor is trapped in the rotor and stator causing drag. If we use a non conductive rotor, I believe some of the energy will become recoverable but not all as the stator is an easier path. If we then use a non conductive stator, again will be able to recover more but will the rest of the energy find another way out?

Using mathematical models that are flawed, we will never know; we have to experiment.

Have you seen the PPMT motors?

http://peswiki.com/index.php/Directory: ... technology

Notice they have a split stator.


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 Post subject: Re: Rotary attraction motor
PostPosted: Tue Feb 22, 2011 3:09 am 
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IIRC, Ted Ewert and Jetijs already tried flunn motor with unsatisfying results.

Have you ever read tewari motor? It utilize unique design to alter magnetic flux on the run:
Image
http://www.rexresearch.com/tewari/tewari.htm
http://www.tewari.org/Test_Results/test_results.html


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 Post subject: Re: Rotary attraction motor
PostPosted: Tue Feb 22, 2011 10:20 am 
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Complicated, maybe you want to start a tread on it?


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 Post subject: Re: Rotary attraction motor
PostPosted: Wed Feb 23, 2011 1:43 am 
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Maybe not. I never see replication and I don't think I can replicated too.

I once see harold Apsden explain it clearly and show why it can produce gain. but unfortunately I forget where.

IIRC it work by changing magnetic flux path, where the magnetic flux is interrupted and forced to go trough the new path.


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