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Froddo123
Newbie

Joined: 23/02/2016
Location: United Kingdom
Posts: 1

Posted: 11:07pm 23 Feb 2016

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Hi All

I am currently building a windmill using a F&P Smart Drive and I will be wiring with a star & delta configuration. I am looking for a programmable Star Delta automatic switch as described in the below link from Your Green Dream. Any help or advise is welcome. Thanks

DaveP68

Senior Member

Joined: 25/11/2014
Location: New Zealand
Posts: 292

Posted: 06:59pm 12 Mar 2016

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Hi

I just posted this earlier today on another question relating to Star/Delta switching.

Electronic Switching is best done with delta wiring from my experiments.

The idea is to cut a 36 pole stator (not 42 pole older versions) into quarters or sixths depending on how much switching is required over a wide RPM range.

Each delta set of winding's is terminated into it's own 3 phase bridge rectifier. These 4 or 6 rectifier outputs can be switched using fast FET's into series and/or parallel depending on the RPM for a given voltage output range. Series for low RPM then Parallel for high RPM.

Example;
At 100 RPM with a 36 pole stator 4x delta winding's all in series would produce 50V, .62A, giving 31W output power.
At 200 RPM with same stator 2 sets of 2x in series put in parallel would produce 50V, 2.42A, giving 121W output power.
At 450 RPM with same stator all delta winding's in parallel would produce 50V, 9A, giving 450W output power.

Note the big jump in current after each switch, this is due to the load matching better with the stator so it's not going into saturation.

The FET's need to be fast switching and very low on resistance, with a make before break switch over so stator doesn't see an open circuit condition.

The switching can be done at different RPM's to produce lower or higher voltage as required.

The 36 pole stator is the best to use with a black rotor cap as stronger magnets. Also it can be cut into more configurations 1x 12, 2x 6, 3x 4, 4x 3, 6x 2 allowing a wider range of switching points. The stator can also be used in star mode for higher output voltage but less current. Difference is 1.732 times so delta volts 200 RPM uncut 100V 1.21A vs star 173.2V 0.7A same RPM.

I prefer delta wiring as better current output for the Voltage I'm wanting at a given RPM.

What do you think?

Cheers

David

There are realities if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow! The Dunning Kruger Effect :)

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