Theoretically

[ChrisOlson]

The Jake itself is 40-180 VAC three-phase.  The inverter converts that wild AC to 240V split phase.
--
Chris

[oztules]

"The Jake itself is 40-180 VAC three-phase.  The inverter converts that wild AC to 240V split phase."

The 240v split phase I assume is 60 HZ?, or is it designed to be synced to a grid.... ie is it a free standing inverter, or does it require a grid to drive in order to operate.

I suspect from your quandry, it is a grid tie type inverter?

If it is a grid type, and your xantrex does not support reverse feed through the mosfets, then your dead in the water.

In your case the best scenario is to drop the xantrex and get the sunnyisland and be done with it. Loosen the springs on the jake to derate it to only a few KW with a big blade set, and you should have the best of all worlds...... and a protective dump load on the batteries.

Actually that would be a perfect system for a wind alternative....

If the jake could do a max 2kw (loosen springs), hour after hour because of your winter weather and it's massive diameter.... you've got a guaranteed 48kwh/day and no more, with not much plant and equipment.

Really because you have a jake with pitch control, it would be the best way for your wind power full stop. Your load is only 1kwh for the house, and a 2kwh charge regime will be over the top when the wind blows constantly in winter.

So.... the new  the Xantrex is the wrong inverter for you if it can't accept ac into the output............... with a jake in the back yard....if it is still serviceable, maybe you could trade it and all your classics in on  a sunnyisland.... they are not cheap.

You could use a cheap powerstar (less than $800 over here 6kw etc) and this would show you how it will work..... then either throw out the power transformers of the power star and replace with decent ones (gets the idle from 200w down to 30 watts or so... magnetising currents), or buy a sunnyisland or whatever else actually backfeeds.... but the power star is hungry on the juice to just idle.... good for intermittent loads then only 25w, but continuous,it can use 5kwh/day.




.................oztules

This is a powerstar w7over 55kgs



For the money it is a brilliant performer, but the idle current is .... wow...
But it can be fixed too.

[oztules]

OOps forgot..

Looking at the Xantrex block diagram, It is hard to see how they are really doing what they are doing.
If it was just three output transformers acting in unison, then the back feed should work... but they seem to be controlling them independently to have different emf in different transformers, depending how the wave step is to be produced on the seriesed output.

I don't hold out a lot of hope there.

...............oztules

[ChrisOlson]

No, the SW looks like it can't be AC coupled or backfed.  We put the new bigger one in so we can run our loads with one inverter instead of two.  And that works really good with a transformer to make the other leg of the split phase for us.

I spent most of one winter rebuilding that old Jake, and I thought I had a plan that would work to use it.  But then everything I tried didn't work.  The inverter for it requires the grid in order to "sync", and it won't work without it.  It seems with modern electronics and computers and technology, somebody could build a standalone inverter that can convert wild three-phase AC to stable 240 split phase without having to have a grid to "sync" with.  But nobody does that I've ever found.
--
Chris

[oztules]

"It seems with modern electronics and computers and technology, somebody could build a standalone inverter that can convert wild three-phase AC to stable 240 split phase without having to have a grid to "sync" with.  But nobody does that I've ever found.
--"

That might be because it would sag and/or over produce, and be unusable for anything but battery charging... and we only need diodes for that.

We need a load of some sort that we can add to willy nilly.... and the grid can do that... or a back fed home grid can do that if it can send the excess above demand to the batteries....

In short, you need another/better/different inverter..




...................oztules

[ChrisOlson]

Oz, if you think about it in the context of a standby generator with an AVR in it.  Now that standby generator has to run at a certain speed for frequency control.  Where a wind turbine is going to run at various frequencies.  But why can't it work?  The turbine puts out three phase wild AC and the "smart" electronics makes the steady and stable 240 split phase, just like an AVR does.  They already do this in inverter gens like the Honda EU3000 - wild three-phase AC into an inverter.

Why can't it work with a wind turbine?  If you don't need the power from it it just runs up against the governor and no harm done.  Plug something into it and it lugs it down and puts it to work.

I think I need a 10 kW inverter off a big inverter gen because they do exactly just what I want.
--
CHris

[oztules]

Well here is the schematic for the output stage of the W7 6kw unit I have.

All it needs is the 60hz pwm signal to drive  the H bridge.

So, yes If you can get the Jakes output, rectify to dc, and then feed this H bridge with it, the Xantrex should be able to through put, or enhance depending on load. easy... not

To feed the bridge, we need to know what load is, so we can feed it the right pulse information. If we divide the positive going  sine wave up into three sections (for example) then we can pulse the thirds with different width pulses, and let the transformer "shape it" for us, and we have our power. Normally this would be done is 30-50 steps, and so we can see how to make the wave, and how we can slip more steps into it to get more power out in a the same unit time.

Now if we have a vast reservoir (battery etc) it is easy to match the load, but if the input is slippery, and the output is vague, how can we do the algorithm for the next pulse.

Driving a grid is easy, the voltage won't sag as the grid carries it when the sun/wind dies out a bit,  but driving a load needs a solid power plant behind it, to stop the voltage saging.

If the Xantrex can provide a flexible input, then there is a chance, but I have never seen a wild input device drive a wild output device with true sine wave behaviour.

Best bet is to rectify the jake (use transformer if necessary) and drive the batteries as in the days of old.... or buy an inverter that back feeds.

You will see in the schematic, that is is a property of the H bridge that it WILL do this. It does not even need the fets to pulse, it will feed through the body diodes if you look at the circuit... so it is Xantrex programming stopping you. ( the body diodes create a full wave bridge rectifier.. independent of what the fets are up to at the time)

I don't think an inverter from a genny will get you there. As it increases the steps/pulsewidth, it expects the driving power to increase as well, and if it doesn't keep up, then it all falls over as the output sags, the pulse width will increase, and we may saturate the output transformer.

A decent program may get you there, but I'm not up to it. An analogue D class amp may do it... but I have no hands on with those as yet.

..........I've been wrong plenty of times before too, this is a bit left field for me to fully guess the outcomes.
"
I think I need a 10 kW inverter off a big inverter gen because they do exactly just what I want.
--"... the proper inverter is even better. sunny island etc...



..........................oztules

[ChrisOlson]

Oz, I got hold of a 12 kVA inverter for a big Cummins inverter-style genset that converts wild three-phase AC to 60 Hz 120/240 split phase without requiring any AC coupling or syncing with another AC source.  If it works, I can just feed the AC1 Grid Input on the Xantrex with it.  It happens to require the same three-phase AC voltage input as it does in the diesel generator.

Now I got a winter project to see if I can get it to work   
--
Chris

[fabricator]

Anybody else smell electrical smoke?

[oztules]

That sounds like a plan Chris. I will depend on how the input stage expects to see the wild AC.

I'm all ears to see how you do with it, and know you'll give it a good go.

For me, I'd go with the cheap inverter to test it all out, then migrate to the sunny island or similar... or just replace the transformer in the cheapie, it's a tough easy to work on unit for remote places (here).... thats why I chose it.

Best with it.


.........oztules

[Frank S]

I'm going to make a prediction here, Chris will take the Jake and hook it up a PTO  from one of his tractors to give it a spin  or if he has a lathe big enough he'll use that but he will need about 20 HP or more with RPMs from 100 to 200. He'll connect the Cummins inverter  not sure what he will use for a load maybe he will use a 15 hp irrigation pump motor & pump They make a great load test bank, easy to check voltages Amps and increase the load just by closing the valve a little at a time

[ChrisOlson]

That sounds like a plan Chris. I will depend on how the input stage expects to see the wild AC.

I don't have the inverter yet - have to go to Minneapolis tomorrow and get it.  It accepts 50-200 VAC three phase input and will output 60 Hz 120/240 as long as voltage is in that range.  The Jacobs is 40-180 VAC three phase, so I think it will work.  It requires the higher input voltages to full rated output from the inverter.

The generator itself in those inverter gens is just a permanent magnet three phase outfit.  The engine management system increases engine speed to meet increased power demand on the inverter's output.  There is no connection between the inverter internal controls and the engine management system.  They are modular units.

I'll have to hook up my rheostat I used to drive the field when I was trying to use that turbine for battery charging because the Jake's grid-tie inverter controls the field current.  But otherwise I see no reason why it won't work.  I got the inverter for basically free by calling a guy I know that works for Cummins there.  He said it got replaced in the field under warranty and when they tested it in the shop there ain't nothing wrong with it.  So he said it could use some further "testing" to make sure it's good, and if it is I can have it.  And if it ain't no good I can still have it   
--
Chris