Anti cogging idea ?

[helicoil]

 Need to do some research before building this.
Found some details on wind power generators.

The specs on this generator states Required Torque at Rated Power (NM) is 150 NM. (Is this the cogging ?).
If its the cogging force, hanging a 50 kg weight on a foot long lever should do.
generator weighs 78 KG.
At a guess, the frame to hold 4 generators would weigh at most 100 KG. (2- 1M long beams, no need to have a complete wheel).
4 generators 320 kg, Cost, probably out of my reach.
4 weights + arms 250 kg
Frame 100 KG
Total 670 kg.

generator output power at 100 rpm = around 600 W
Open Circuit Voltage at 100 rpm about 160 V

at 200 rpm output is over 2000 W and 325 V.

Now need help from other members, is there is a motor that could rotate this 670 kg wheel, using less power than the combined generators output.
looks promising at the moment, could even gear down a 3000 rpm 1000 W motor to a 15 to 1 ratio, to give 200 rpm, (i wish).

[gyulasun]

The specs on this generator states Required Torque at Rated Power (NM) is 150 NM. (Is this the cogging ?).

No it is not the cogging. It is a needed torque (150Nm) the wind should provide for the shaft via the blades so that the output power of the generator give out the specified electric power.  Cogging is explained here (and elsewhere if you google it):
http://wiki.answers.com/Q/What_is_cogging_effect

I agree on doing some research, however I would not suggest starting with as 'big' as you outline, (unless someone can afford the cost). For generators I mentioned stepper motors they are relatively cheep and could be obtained from old computer printers. See this for instance:
http://www.reuk.co.uk/Electricity-with-Stepper-Motors.htm
http://www.youtube.com/watch?v=KypzdIMxF6Q

There are many other links (both video and description) on stepper motor generators if you use search engines.

Stepper motors do have cogging because they use strong permanent magnets inside so the weight for their shaft is also needed of course. But this is not a big drawback. And the advantage is that they give good output already ar 150-200 RPM.

And for rotating your big wheel with all the hanging weigths on it, you could use the rotoverter principle which can minimize the input power for the big wheel rotation. See this description on the rotoverter principle:
http://www.panaceauniversity.org/RV.pdf   Your idea of using gears to step down RPM (if it is much higher than 200 RPM)  is good.

Regards, Gyula

[helicoil]

 Dam, i used to work at an e-recycling center, motors and transformers were just thrown in the scrap metal bin , what a waste of good copper wire.

will check out the stepper motors, and i couldn't afford the big gens, just posted the details hoping someone could answer if its feasible, I don't know how to calculate the power needed to rotate the mass of the wheel.
I'm in no rush, as the chances are that it wont work, its too simple an idea that it couldn't work.
Came up with the idea trying to create a gravity wheel, and on paper it seemed more  efficient to place numerous gens on the wheel, using the weighted arms to reduce or stop the cogging force being transfered to the driven wheel.
much simpler than numerous complicated mechanical devices trying to drive the wheel, to power 1 gen.

[helicoil]

 could wm2d be able to calculate the torque or power needed to rotate the drive wheel,at certain rpm, including friction on bearings and the lever arms to mimic cogging.
Was looking at a video today and looks like 100 rpm would be too quick.
probably need around 30 rpm to stop the arms flying outwards,
Will placing the gen rotors close to the center drive wheel reduce the centrifugal force, so rpm can be increased ?
have been searching for very low 30 -50 rpm gens, have only found massive 30KV units. can not find slow small units to test the idea, unless i gear them up which would require more weight on the arms.
How do i calculate cogging force of a fully loaded gen, without this imformation its impossible to calculate the wheels total weight.
Looks like the bigger you go the more efficient it gets, better power to weight ratio of the power gens, and a 100:1 ratio of a 3000 rpm drive motor.

[gyulasun]

Hi,

I mainly agree with what you wrote above on the smaller RPMs etc  but I do not agree with your thought: if there is a simple idea then it necessarily does not work or cannot be useful etc.  What I like in you idea is that the input power needed for turning the big wheel does not seem to be influenced to much from the actual load on the several generators.
I do not know wm2d whether it can calculate the needed input power for a give wheel mass etc, but there are several members here who have this software and already used it for different problems. Hopefully they will turn up in this thread too.