On 11/03/2008, Jinx <joecolquitt@clear.net.nz> wrote:
> A friend is developing wind turbines and needs some advice
>
> The output of the turbine is 3-phase. Below 400rpm the coils
> are configured as star. Above that, delta (I think I got that the
> right way around - he took his notes). The 3-phase presently
> goes to a converter to make several amps of 12V for battery
> charging
>
> At a certain point, roughly 400Hz, the delta configuration gives
> a lot more wattage
>
> To make the switch from star to delta, he has a circuit based
> on the LM2917 V-to-F chip, and that operates a relay. The
> circuit needs at least 50mA
>
> What he wants to do is take a tap from the 3-phase terminals
> to get 12V-ish volts to run this circuit. Although the circuit has
> a 16V zener clamp and 7808 regulator on V+, so actually 8V
> would do. He doesn't want to have an extra wire coming back
> from the converter output to supply the 12V
>
> I suggested taking two of the 3-phase terminals on the turbine
> head and feeding them into a bridge. He tells me that at high
> speed, the turbine can put out up to 110V (he didn't specify
> pk-pk or RMS). At low speed, just a few volts, obviously
>
> Is what I suggested safe/practical ? Also, how would I cope
> with such a wide range of input voltages into perhaps a SMPS
> or linear regulator ? Bit out of my comfort zone
>
> TIA
>
> ===============================================
> If you aren't part of the solution, you're part of the precipitate
>

Jinx,
Re wide input voltage range - I've just got some sample LT3437 SMPS
chips. Input voltage 3.3V to 80V. (Buck regulation only). Something
like that may be applicable.

Or the Black regulator or Russells SMPS circuit (can't think of the
name). I've used both for a fairly wide range of input voltages, with
additional mods they should be able to go wider still.

RP
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