Hi Danb,
Thanks for your response. I am deliberatly going for transformers, hence my choice of stator. They seem the least electronic way to tackle max power out for min stator heat.
Am I sure the resistance in the stator is 15R.... I thought I was. Measured with ohm meter.. 15R... However I have a problem.
I mounted it in the lathe and got these results which I don't think I understand... maybe you can shed some light on this.
In the lathe: About 92Hz,(550rpm) I measured 1 open phase: 242Vac
On the second phase I loaded 300W of flood lights (2x150w) (240v) The voltage on the loaded phase was 230v (I had a 1R resistor in series with this and got 1.3v drop ie circuit was running 1.3A
So I had dropped 12v@1.3A across this 1 star coil. If E=IR then r=9.2 ohms. not the 15R I measured in the star winding ?... what have I done wrong? Is it looking like a root3 thing is happening here.
More surprising however. I dropped 12v on a stator that measures 15R so Watts lost in the stator should be 12x12/15 ie 144/15=9.6W. if I use the 9R2 calculated figure it is 16W lost in the stator.
In three phase, I would loose just 30W or 48W for a combined output of 900W... The coils stayed very cool. One of these figures is probably correct, but either way, the stator sees very manageable losses for close on 1kw output.
By changing the load through changing the behaviour of the transformers, I hope to give the stator a fairly matched load over a large range. Different coupling techniques and winding ratios (not switching taps)should allow me to match the alt with little electronics at all.... thats the plan anyway.
I'm thinking that I need available 1.5kw of wind power at about 400rpm. This will give 180v @1kw, 340w/phase or 1.9A A loss of about 100w total in stator. This looks possible with a high tsr 3.6m set.
If I try to pull 1kw @300rpm, (130v)I will loose about 300W in the stator on those figures... starting to get high.
There is much testing to be done I think regarding primary turns (transformer)to get the best match to the stator impedance.
Or have I got this all messed up?
confused again
.......oztules