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Delta, star, Jerry riged?
hiker:
nice draw up their JERRY.....
so you can use one rect for each phase and get the same results--as using a rect. for each coil..? seems like you would have a slight voltage gain by using one rect. for each phase..sence there is some loss using a rect..so the more rects you use = more loss in voltage--and i guess you could add a few more windings to couter act this..
damm guess its time to scroung up some wire and give it a try.............
scottsAI:
Hello Jerry,
Some more great testing.
I thought you were going to show the bridge per phase produced more power than star or delta.
But you changed the subject before anything was demonstrated??
What were the Battery currents of the three methods? The battery is what it's all about?
How can we decide what is better unless we know what was?
"to pass its current through a coil that is partialy an inductor only, or has current that is slightly in opsistion."
The generator is not an inductor. The impedance of the generator is very low, it does not behave like an inductor. A generator has some small inductance like any wire will have, major effect is not an inductor it's a voltage/current source.
"My proposal is to make each phase have 2 times the voltage as one phase. This solves the lost voltage isue. Then provide each phase with its own fullwave bridge rectifier. This keeps the voltage high (no phase to phase lose) The perelelling of the lower amperage higher voltage will provide the same amperage as the lower voltage higher amperage phases wire in sires."
Boosting the voltage can get you a low cut in speed. When the wind is in your power range, the generators efficiency is going to suffer. Lets assume the blade is large, can produce the power listed.
We have a 12v system, generators impedance is 1 ohm to keep the math simple. The batteries impedance is 0.0001 ohm, ignore it more than two order mag smaller.
Cut in 6mph we have 13 volts generated.
The current into the battery is 1 amp, or 12watts, power as heat in gen is 1 watt.
mph = 26v, (26 - 12)1 = 14a, 168wa into battery, 14x14 = 196w as heat in gen.
mph = 52v, (52 - 12)1 = 40a, 488w into bat, 40x40 = 1600w left as heat in gen.
Good idea to make a chart with wind vs calculated power into battery. Results are quite surprising.
The danger of boosting the voltage too high is generator burn out. The higher speed winds helps cool it and maybe the blade may be stalled by the excessive power the generator is trying to produce, which will make the machine noisy.
The use of the star to delta switch is trying to get the best of both worlds. Star or the higher voltage for low cut in speed, delta for the lower voltage with higher current at the higher speeds, switching configuration has it own problems.
I would love to see the three configurations tested?? (needs to be same coil)
Have fun,
Scott.
Flux:
Jerry
I like your drawings, modified Dancad. I may try it, much quicker than drawing things by computer.
It is inevitable that the 3 voltages of a 3 phase system add vectorially.There is no way round it.Rectifying the things separately doesn't get round this. There is no way to have all coils contributing current at the same time. Any 3 phase rectifier will have the coil with highest voltage conducting at any instant and neglecting overlap( doesn't happen here), the current is always carried by a pair of diodes, and with a full bridge, one diode swops to the next every 60 electrical degrees. The same conduction path will exist with your system but the diode conduction sequence will be more complex.
If you use 6 phase rather than 3, you can achieve the full twice phase voltage and the cut in speed is reduced. The ripple is also reduced but the operating efficiency is not, in fact it it is slightly worse. The winding has to supply a higher peak current for a shorter time to maintain the same average current.
If you look at a force commutated rectifier you may be able to improve things, but otherwise no.
Flux
oztules:
sorry jerry,
but before you head north for the patent office, connect the three coils in "The last pix is the diode bridge per phase." to delta. the voltages shown will remain identical........jerryrig equals= delta rig (without bothering to connect up the coils).... ie join the bottom of coil 1 to the bottom of coil 2. connect the top of coil 2 to the top of coil 3. join the bottom of coil3 to the top of coil 1. what do you have ....delta (coil 2 is inverted....ask ed (windstuffnow for the explanation).
All the voltages remain the same as in the "jerry rig" configuration.. if you hook them up in star, the ac voltage will become 36.98v. ring a bell 14.59v delta and 25.11v star....... now you simply have 29.18v delta ( or jerryrig) and 36.98 star.
in delta the minor changes in voltage dont push pull either, as it is the rectified voltage that is joined together, the diodes prevent looking back through the coils.
In both jerryrig and delta (effectively the same thing in this application really) the dc will pulse out of time with each other. ie for a 2 pole machine, there will three +dc pulses per cycle appearing at the output. they don't add together because they arrive at the output at different times and are not in series. Averaged over time you have three times the output of a single coil.
so all the advantages and disadvantages attributable to the star/ delta argument, are identical for the star/jerryrig arrangement.....hope this makes some kinda sense.....oztules
hvirtane:
I think that the whole issue is,
if it is better to connect coils
of different phases before or
after the rectifiers.
If you'll connect them after
the rectifiers
(the way of Jerry and Hugh),
the currents are
not fighting against
each other at any time, as
it is the case with the star
connection or even with
a delta connection.
So I'm thinking that
connecting them after
the rectifiers is better
as regards the maximum power.
The other thing is that
in practice you often need
high voltages at low RPM,
not the best power in Watts.
So in practice star is the choice
in many cases.
(Even if it is giving less
power at high speeds.)
The other problem is that
you would need more rectifiers
and put them on the top
of the tower, if you'll
do it the way of Jerry and Hugh.
- Hannu
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