Wind Generator - Star Delta Controller

[simoin]

I am looking for a star/delta controller, I am happy to put a kit together but designing it is beyond my current skill level, but I am still learning.

I have found this circuit diagram ( http://www.dsgnspec.com/StarDelta.html ) and know one or two people that can give me a hand with putting everything together, but just want to make sure it is an appropriate sort for a fisher and paykel wind gen ( http://www.thebackshed.com/windmill/FPRewire.asp )

I have the stator all wired up as per the second link advises for star delta, I just need help setting up some sort of switching board. Anyone done something similar or at worst know where i can buy something like this/willing to sell me....

 

[Hero999]

One question, why?

Aren't there more effective ways to regulate the voltage like altering the field current?

I'd have to search the forum but there's a standard IC used in most auatomotive alternators that you might be able to use for this application.

 

[things]

so what are you looking for? a voltage regulator, charge controller?
Can you please give more information.

 

[simoin]

sorry should have said that too really.

The basics: This is a wind generator.

Delta will produce more power at high revs.
Star will start making power at lower rev's.

What I need is a switch that will change from the default Star configuration into Delta mode when there is a significant increase in wind speed, this could work off voltage or revs or anything I think.

**broken link removed**

In the diagram I found this is user adjustable in 32 rpm steps:
The user has the ability to control at what rpm ( windmill blade speed) the switch
takes place and the duration the windmill must maintain a specific rpm before that
change takes place. This is done with a 10 pin 5 switch DIP that is located
on the main control board. This give 32 rpm selectable options from 25 to 800
rpm in 25 rpm steps.

**broken link removed**

What else do you need to know, have you ever heard of this sort of thing? Worst come's to worst, i would settle for a manual switch...

 

[mneary]

Looks like a fairly complete system already. Which parts do you think are missing?

 

[HarveyH42]

The program for the microcontroller...

 

[Oznog]

Delta will produce more power at high revs.
Star will start making power at lower rev's.

What I need is a switch that will change from the default Star configuration into Delta mode when there is a significant increase in wind speed, this could work off voltage or revs or anything I think.

That's not quite the situation. Y vs Delta produce different voltages for a given RPM, just like changing the number of windings. More voltage means less current. The power available before slowing the rotor too far will not change with delta vs Y.

There is no reason to switch between them. If you wanted to change voltage, different windings- or selecting a portion of a leg's winding rather than the whole leg- will do it easier. But it makes much more sense to rectify it to DC and use a DC/DC converter, or use an SCR to lower the effective voltage to the load. The SCR has funny reactions to inductive and capacitive loads though that take awhile to understand.

 

[simoin]

I want to use it to charge a 12volt battery... So aside from the program for the wonderful little microcontroller most of the stuff seems to be there?

The other question was is this still an appropriate switch to use for a 6 wire star/detla configuration... I think it is but I am still a newb.

so I understand that the voltages will change and the amperage as well, but surely there must be a reason for the switch, does it keep the blade spin rate more constant? (guessing?)

 

[Hero999]

Look at how an automovtive regulator works.

It adjusts the DC rotor current to keep the output voltage the same at different engine speeds. At high speeds the rotor current is reduced lower speeds the current is increased.

Switching from star to delta can be useful for varying the voltage but it isn't as effective as varying the rotor field current.

 

[HarveyH42]

I think I understand why. When the wind is weak, the RPMs are low, and the generator barely produces the 12 volts needed to charge the battery. When the wind is strong, a much higher voltage that isn't too healthy for that battery is produced, and needs to be reduced (usually wasted). Switching the windings produces lower voltages and higher current, less is wasted through a voltage regulator.

Seems like this could be done without the microcontroller. There should be tons of circuits that count RPMS and activate a switch. You can replace the 3 relays with just one with 3 contacts. I don't know, but think relays would tend to fail after a year or two.

 

[mneary]

A regulator on an alternator doesn't have to waste power. As Hero999 said, it regulates the field current.

The star configuration alone, with a good field regulator, should be able to provide a regulated voltage over a wide range of speeds.

Switching to delta increases the current carrying capacity of the windings, which at higher speeds can give you more current. This is only useful if your storage system has enough capacity.

 

[Hero999]

Also note that to generate the same amount of power at low speeds requires more torque which will slow the turbine even furthe. There comes a point where the current required to generate the fild is higher than the current supplied by the alternator; at this point you should disconnect the alternator as it won't be doing anything except for draining the battery.

 

[simoin]

what the stator looks like

okay so I get the impression most people agree what the star/delat controller is for but think that a field line generator would be better? (I don't think that is the right terminology, for varying the rotor field current)

so just to make things clear here, we are talking about an old washing machine motor that is wired up and looks like this:

**broken link removed**

So what do people think the best way to proceed is? Continue with building a star/delta controller to get the most out of the wind generator in all conditions, or something else? I have a 300 Amp Hour 12volt battery to charge up here.

 

[mneary]

Is the field in your washer motor controllable, or would you need to switch to an entirely different design?

 

[Nigel Goodwin]

okay so I get the impression most people agree what the star/delat controller is for but think that a field line generator would be better? (I don't think that is the right terminology, for varying the rotor field current).

I certainly wouldn't agree that you need a variable field current - not for what you're trying to do - varying the field current wastes the mechanical power captured from the wind. Presumably you're looking to gain the maximum amount of power from it?.

You need a number of things:

1) As much charging current as possible at slow speeds, by changing the configuration you can get higher voltage at less current, which means that it's high enough voltage to charge the battery, even though it's lower current (some is better than none!).

2) At high speeds switch it to lower voltage and higher current, the higher speed voltage will be enough to charge the battery, and you'll get much higher current from it.

3) It 'may' be an idea to disconnect the generator entirely at extremely slow speeds, or not moving at all, as having zero load will mean it will start easier.

 

[simoin]

you've nailed it Nigel, that is exactly what i want to be doing, it is just coming up with a circuit that is on the market or indeed deigning something that can do this for me.... Any idea's there? I am willing to contribute towards costs etc, I would do it but simply do not have the experience necessary.

I do not believe the field is editable, but indeed I do not really know, what you were looking at in the last picture is basically it, there is that and the magnets on the outside, that's about as technical as this generator gets...

 

[Nigel Goodwin]

For a start I would suggest making accurate measurements on what the generator actually provides in the different configurations, at different speeds. Make sure it's viable, and find what speed is the optimum changeover point.

 

[simoin]

i will do my best to make mesurements but assuming it did make a reasonable difference what then. I would like to be able to adjust the changeover point to set it at the optimum after the control board is in place perhaps with a trim pot controller or something...

 

[Nigel Goodwin]

i will do my best to make mesurements but assuming it did make a reasonable difference what then. I would like to be able to adjust the changeover point to set it at the optimum after the control board is in place perhaps with a trim pot controller or something...

Depending how you design it you could certainly use a pot to adjust the switching point, or you could do it in software if you use a micro-controller for the job.

 

[Hero999]

I certainly wouldn't agree that you need a variable field current - not for what you're trying to do - varying the field current wastes the mechanical power captured from the wind. Presumably you're looking to gain the maximum amount of power from it?.

The field current doesn't take much power and it's required anyway providing it doesn't have a permanent magnet rotor. Therefore it makes a lot of sense to reduce it at high speeds so the voltage doesn't exceed the battery's maximum and increasing it at lower speeds will make the alternator more efficient since it will be producing power that would otherwise be wasted.