Author Topic: My 12kW powerjack build - Ozinverter Inspiration!  (Read 23543 times)

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Offline influence

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #30 on: October 06, 2018, 12:51:40 am »
Inside....emi filters etc....the monster toroidal core....

Offline oztules

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #31 on: October 07, 2018, 12:22:54 am »
Looks the goods. When ( if ) the controller gives up for any reason, there is always the newer 8010 boards on the net now, and just change some components on the fet card... and you will have a ozinverter. The control cards are very expensive now for the PJ... te 8010 are indestructable... really, three plugin chips  ( at most) and your going again, but the pj is a good thing too.

Well done.



.......oztules
Flinders Island...... Australia

Offline Wolvenar

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #32 on: October 07, 2018, 08:02:32 am »
Makes me want to attempt one of these now.
My inverter is getting quite old, and at this point it's just used as a backup system because it seems to have gotten unreliable.
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline Pete

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #33 on: October 07, 2018, 04:58:37 pm »
Hi Influence, well it looks great, I am a bit concerned that your cables are a bit small in the transformer. If you really intend to draw 12 kw through the inverter that will mean that the primary will have 500 amps through it.  3x25mm cables will get pretty warm carrying that current, especially within the confines of the transformer core. The secondary should handle the 50 amps fine but still I would suggest watching the heat. The cables are only rated at 90 degrees C.
Looks like a pretty neat job well done, I just don't want you to fry it.
I would de- rate it a bit. Generally 25mm cable is rated at around 100 amps with XLPE insulation. So I would limit your rating to around 6 kw for safety and longevity
cheers
Pete

Offline influence

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #34 on: October 07, 2018, 08:21:39 pm »
Looks the goods. When ( if ) the controller gives up for any reason, there is always the newer 8010 boards on the net now, and just change some components on the fet card... and you will have a ozinverter. The control cards are very expensive now for the PJ... te 8010 are indestructable... really, three plugin chips  ( at most) and your going again, but the pj is a good thing too.

Well done.



.......oztules

Thanks mate. Yes I plan to upgrade to 8010 when this board dies. I also want to upgrade the fets to hy4008...

Offline influence

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #35 on: October 07, 2018, 08:24:16 pm »
Hi Influence, well it looks great, I am a bit concerned that your cables are a bit small in the transformer. If you really intend to draw 12 kw through the inverter that will mean that the primary will have 500 amps through it.  3x25mm cables will get pretty warm carrying that current, especially within the confines of the transformer core. The secondary should handle the 50 amps fine but still I would suggest watching the heat. The cables are only rated at 90 degrees C.
Looks like a pretty neat job well done, I just don't want you to fry it.
I would de- rate it a bit. Generally 25mm cable is rated at around 100 amps with XLPE insulation. So I would limit your rating to around 6 kw for safety and longevity
cheers
Pete

Hiya Pete, erm the primary side is 3 x35mm2 not 25mm2 and 12kW at 48V is 250A not 500A. I have a DC breaker set at 300A on the input side.
Also the secondary side is 25mm2 and then it goes to the SB through a 63A breaker via 16mm2 TPE (5m run).


Offline influence

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #36 on: October 07, 2018, 08:31:25 pm »
@oztules
My next step is to get an SMA 5kW grid tie hanging off the end of this inverter. Im so glad you have done the leg work to control the grid tie wrt overvoltage.
Would an IGBT work in place of a FET?

Offline Pete

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #37 on: October 08, 2018, 01:37:15 am »
So going with a ratio of 1:8 (30V : 240V)

I ended up using a ratio of 6 turns of the primary : 48  turns of the secondary.

I decided to use what I had lying around (orange 4+E cabling).

So I set the primary coil gauge to 3 lots of 25mm2 olex 90C cable and
for the secondary 1 lot of 16mm2 olex 90C cable.

Based on the above, I would require:
3 lengths of 25mm2 cable - 3.8m-4.0m each
1 length of 16mm2 cable - 28m long

Hi Influence, I based my post on the above information from your post.
I assumed that you were using a 24 volt battery bank because you talk of having the transformer ratio of 30 volts to 240 volts.
Seems that you changed the cable size after the post
sorry
Pete

Offline oztules

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #38 on: October 08, 2018, 04:17:12 am »
Your scaring me now......
30v:240v is a 48v transformer for a PJ, a 8010 would be closer to 28v:240v.

For 24v ie 14:240V.

6 turns:48 turns @48v system.......is for a very big core, or your looking for saturation fairly early on I would think.

Rule of thumb is 2800mmsq is 1 turn per volt or thereabouts. 240/48turns=5v/turn????

So you would need a huge core of 14000mmsq cross section for the torroid I would expect.... serious core indeed.


6 turn primary on say a two core inspire or aerosharp for 48v system would be pretty heavy on the magnetising current I would have thought.

The 8010 has proven to be very tough in the field. I built a number of spares fearing the worst in the hands of neophyts... none have been used for years.... very happy.

The hy4008 is a very strong performer.. don't doubt the chinese on everything.. they really know how to do it if they want to. Never had a hy4008blow in the field. Testing is another matter... try to kill them then, still I can't recall one going then either on my boards..... very large number of 4110 though in the experimental stages. Mostly because I did not realise how rigid these big tranny's are magnetically.

......oztules
Flinders Island...... Australia

Offline Pete

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #39 on: October 08, 2018, 06:42:31 pm »
Hi Oz I misunderstood the transformer ratios and why the voltages are so much lower than the battery volts for the primary.
I am guessing that it has to do with the peak voltages of the waveform and also allowing for a bit of core saturation.
So if you stick 48 volts into a transformer designed as a 30:240 volt winding, I guess that you would end up with somewhere near 384 volts peak on the secondary  waveform. The electronics must throttle that back a bit to keep the peak at 339 volts
I did not take that peak voltages required into account.
I would still think that he would not want to run the inverter at full power ( 12kw ) for long. I would suspect the transformer would get pretty warm.
Also I would like to see what the idle current comes out to be. Seems that there would have to be a lot of back emf to keep the idle currents down to something palatable.
I have only been involved in rewinding motors and transformers in my working life, I did not do any designing of windings.
Pete

Offline oztules

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #40 on: October 09, 2018, 12:10:49 am »
I am not a transformer person professionally.... so don't really know what I'm on about .

But ripping apart the originals, it was not hard to get some simple rules together, so that designing something that will work from the get go, seems not that difficult.

I found that around the 2800sqmm of torroid core does 1turn per volt at 50hz.... thats all you really need to know. If you go conservative from there you will get even lower idle currents.

The next thing to notice is that contrary to popular belief, loading up a tranny does not saturate it if it was not saturated at idle... so the amp turn under load is not an issue, only at idle. Once you have got clear of saturation at idle, you cannot saturate the core unless you lower the freq, or raise the voltage.

Here we can raise the voltage .. or so it seems. The battey voltage can change, so that can cause saturation if you run at full tilt perhaps, other than that, you need to be mindful that at full charge and equalization, your at 60v, so your peak inputs on the scope will appear higher, but in practice this does not seem to matter much if your using the rule of thumb windings.

So I am not an expert on transformers, but I can make them work  ok. My normal run of the ,mill twin cores easily do 16kw-20kw on motor start ups, and pretty happy at 6kw cont with some cooling if we are running for 20 mins or more.

The 28:240v ratio seems to work perfectly at 230v ( where I am happy ). The lights don't dim or flicker with 2-3kw loads switched in or out at night time. which is just crazy for a 2 dollar chip. I still am amazed by the performance of this pretty innocuous chip.

I would like to think I deserved to get some recognition for the beautiful performance of these things, but really it is the little 8010 that does all the wizardry, and I'm really just an onlooker hanging on for the ride.

Some folks have taken a slightly different route than I did, and seem to have met with some ugly problems. I don't know why. They seem to well know what they were doing, but it all turned up side down for them, their reliability was shot to hell, and just getting it to work seemed out of their reach. It is only that they knew I had over a dozen working unit/s out in the field that they persevered with it I think.

So I don't know what I did right, but it is very right somehow...... just lucky I guess.



.........oztules
Flinders Island...... Australia

Offline influence

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #41 on: October 09, 2018, 04:09:47 pm »
Indeed my core is huge....its 230mm diameter with a 100mm core hole and is 210mm tall giving a cross sectional area of 13650mm2 which gives us (at 2800mm2) 4.875V/turn

The idle consumption came in at 85-90W with a test supply of 50V and clamp current of 1.7A-1.75A.

A little high ?

I ran some extended time tests with a 40W incandescent and checked the temperatures...

The first 3 are temps of the heatsinks. The last is the temps of the transformer at the centre....and its a larf :)

...seems acceptable to me.



Offline influence

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #42 on: October 09, 2018, 04:12:06 pm »
Btw fishing through some of the alipress links for the premade egs002 inverters, Im sure you guys have seen the little chart the chinese sellers have made....

Is it just me or does it not give sensible numbers?

Offline oztules

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #43 on: October 09, 2018, 08:15:26 pm »
Yep... that be a plenty big core.... big....huge, mmonster core...
You have the luxury of plenty of room, so to get the idle current down to reasonable levels you would do well to put more turns on both the primary and secondary... maybe one more turn on the primary, and 8 more on the secondary. The further you are from saturation, the better for magnetizing currents.  You will note my quick calculation up further was 14000 slightly more than you have... which may explain the slightly higher idle currents.... plus it is a lot of steel to magnetize too.

With such a huge core, less then 40 watts will be pretty difficult, but not impossible. 100w is over 2kwh/day, and thats  a fair slug on a dark day. If you can get it down to 40w, it is a bit more manageable on short dark winter days.

All in all, you can power just about anything, and 12kw for 20 mins is probably easily achievable if you have the battery for it, and the heat sink/fan combo for the fets.

If your going all in with hy4008, remember 6 fets / leg will probably do well to have totem drivers designed onto your fet board. I have not had a problem with it, but others have. Four fets/leg seems very manageable without extra driving power... thats what I use. I have had no problems with 6 either.....

Re the charts, 1.4t will be heavy on the magnetizing current I would think, better to go for 1 or less to save power. Yes more turns will have higher resistance, but idle power is all the time, full power is very rare.... I vote for low idle power.

The curves for saturation will show you that there is a portion of the graph, where an extra turn makes a big difference to magnetizing current, but then the advantage of more turns drops away fairly quickly... so experiment. The 2800mmsq/volt turn seems fairly conservative, and yields fair results, but more turns is always good for the idle figures.... but too many will crimp the power handling.... always a compromise.....


......oztules

Flinders Island...... Australia

Offline influence

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Re: My 12kW powerjack build - Ozinverter Inspiration!
« Reply #44 on: October 09, 2018, 10:08:50 pm »
I'd love to throw more turns on...but there isnt any room left...I think Im ok with the 90W...perhaps I can try to squeeze some by adjusting the gap on the choke ferrite ecore?

Hey btw oztules, I was looking through the backshed forum at the gti control board you made, I was wondering...where are the totem drivers on that board with the nano?

This one:
https://www.thebackshed.com/forum/uploads/oztules/2017-07-25_105729_Screenshot_at_2017-07-25_20-56-50.png

And another question the nano has a pwm frequency of 490hz, I looked at the fet's datasheet and that corresponds to a pulse with of 2ms approx...do you reckon we need to increase the pwm frequency to move further into the SOA of the fet? I have some 20N60C3 fets out an a grid tie I gutted to use as an enclosure for a battery charger....

Here is a pic of the layout of my CC CV battery charger...using tx out of a 3000VA APC ups...
Basically I rectify the 32V output of the tranies and feed it into the 1800W boost converter which I set to 57.6V and 30A.