just a basic idea, if this wheel is powered by a motor, and the smaller wheels in the pic are generators, does the larger wheel feel the effect of cogging ?

 the generators have a heavy weight that always sit at the bottom during rotation of the larger wheel with a much greater weight than the cogging force.
 

Your drawing is not entirely clear, but it should be safe to say that inductors
take time to fill and empty; and so, Gyula's caveat about speed is useful.

...
  The question is can a motor use less power to drive the wheel than the generators output, and will the drive wheel notice the cogging on each generator.
...

Yes, and your question can be answered only by building a prototype setup.  Do not worry about the big wheel cogging question, it is not that important (I mean it would be small).
For the test, for the generators,  you could use some stepping motors because they can work nicely as generators too. OR some DC motors with magnets, they also can work as generators. Unfortunately the DC motors efficiency at low RPMs are low. (Stepping motors are better in this respect.)  Have you got already thoughts on building such setup?

  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

 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.

i like this idea, might work.

 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
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.