Author Topic: Output voltage adjustment  (Read 5239 times)

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Offline lighthunter

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Re: Output voltage adjustment
« Reply #30 on: May 01, 2016, 09:38:21 AM »
Hi Doc! I made some changes to the 6000 pj this morning and seems like it was a winner.
Because of the info Oztules gave us about power control being done on the small metal current transformer (on board). I connected*edited* "maintx-L" and "P3" back up the way pj originally wired it. Then I connected the corrected feedback voltage to the maintx-N terminal. A pic from book for reference.
It doesnt seem to matter (it does matter see next post) to pj control card if you use red or black lead for N so i guess my concern for (proper) phasing was overkill. All in all, this makes the complete mod very easy and should maintain original power control functionality. My array size has just doubled now at 4400w and we may finally get sun today so i will try to confirm later today if original fans work again! Come to think of it im pretty sure the rest of my inverter can do 4k continuous but that little on board ct may be weak spot now. Oh well, i can always bypass some to allow more. The only cooling i need is for fets as the toroids are both out of the box. Generally my grid tie does all the work anyway. Now i need an electric car to use the peak power for charging :)

LH
LH

Offline oztules

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Re: Output voltage adjustment
« Reply #31 on: May 01, 2016, 02:45:38 PM »
The phasing is only an issue if using the onboard charger, otherwise it is as you say... inconsequential.
The onboard charger needs to match the mains freq to the inverter output, and connect them together to charge.... you can imagine what happens when it syncs them at the computer end, only to find out they are opposing sign when they meet at the transformer.

Running as inverter only makes no difference to the phasing arrangement.


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

Offline dochubert

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Re: Output voltage adjustment
« Reply #32 on: May 01, 2016, 09:39:07 PM »
Hi lighthunter and Oztules,
I did wonder why phasing seemed important, as I didn't think it should make any difference which way the new transformer's secondary was hooked up, especially since the battery charging 'feature' is a non-issue for me.  Nice to know something I thought might be right!  (Still, I was not about to question while still able to smell my first attempt - I left that transformer sitting next to the pj to remind me to be careful my connections are correct next time)
The current transformer CT1, as I understand it, just compares the output leg L1 at connection P3 to a fed back L1 potential from the toroids at Maintx L connection point P5, so the control board can adjust output as needed.  That it also allows monitoring of current/wattage is logical but how it uses that info is beyond me.  Just happy it works. (I'm assuming you meant L1 when you said P1)
I don't know why CT1 should be a weak point as it is just comparing voltage differences.  Seems unlikely it handles any significant load itself to become a weak link under heavy powerjack load conditions, or maybe my ignorance is showing again


Got my new transformer Saturday and hoping to have time to start unwinding secondary turns tomorrow and testing for proper secondary voltage reduction.
Lighthunter, glad you got your panels working with proper output.  2 strings?
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Offline lighthunter

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Re: Output voltage adjustment
« Reply #33 on: May 01, 2016, 11:16:12 PM »
Quote

     "(I'm assuming you meant ]L1 when you said P1)"

Your right Doc, I meant terminal marked "maintx-L and P3" I put connections back to original.

From looking at board it appears that the pj output load current flows from maintx-L terminal through the yellow metal ct to P3 then fuse and outlets. Similar on your split phase i should think.
This flow path allows the ct primary to see all the load current in this version at least while the secondary converts the current to a meaningful voltage proportional to the current so main control IC can throttle the duty cycle of fets to limit current.

Mine worked too well today, when it hit 2900 watts it started beeping and well shut off after a time limit. so i had to adjust that. The "weak spot" i meant was ct primary as it now has to run 30 amps through it. I just didnt know how heavy the wire is but i guess it doesnt matter since i bypassed half of it.

Thaanks for catching the error, i just saw the P3 next to the terminal in book but they were just marking the length of wire. 



Thanks also oztules for the phasing info. I may try to use that to tie two of em together one day.
LH

Offline dochubert

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Re: Output voltage adjustment
« Reply #34 on: May 02, 2016, 10:56:44 AM »
So does that mean that the transformer we are adding is carrying full load current?  I sure hope not as that changes everything.  The transformer now needs to be rated at least as high as the powerjack's toroids or its not going to last too long, if at all.  First time a significant load is put on the pj, there's gonna be smoke...
I remember you saying your first 10w transformer smoked after a short time.  What is the power rating on the one you are using now?

It must not be full load current or that little CT1 current transformer wouldn't last long either.  The transformer I just got is a 50w, which I thought would be big enough, without getting too physically large, but maybe not?
Maybe Oztules can clarify current to and through CT1 (which would include the added transformer)?
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Offline oztules

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Re: Output voltage adjustment
« Reply #35 on: May 02, 2016, 03:21:23 PM »
I have not followed this thread very closely, so I don't know exactly what your up to.

I think your trying to use a second transformer to tell the AC input a new voltage that is not the same as the voltage from the main transformer... in order to trick into thinking it is doing something it is not actually doing.

If so,

1. Your little 50watt or whatever transformer.... it  would  be nice to be in  phase with the main transformer. It is not strictly necessary as it should be floating above the main transformers N output.... so..

2. The little transformer goes to N and L on the control card. This provides control voltage to control card

3. The main transformer line ....goes to the L input, and  then through the CT and out to the load. So the controller can see the current through CT.

4. The neutral lead from the main transformer does not go anywhere near the control card. It floats... or actually goes directly to load point on your power receptical. This way your little transformer is only used for control voltage, and can be as small as you like. It will see no load, even though it is connected to the CT, the N rail is going nowhere other than the N terminal on the board.

5. That leaves the shaping capacitor. It needs to stay where it is to shape the voltage transformer wave, but a new one needs to go across the main transformer output... or go across the output receptical, so it can shape the power coming from the main transformer...

This means the little transformer is only connected to the main one at the L terminal only.... so it sees no load, the CT and the main will, as the CT is in series with the main L output.

So the new tranny is basically isolated from the load because the N rails are not connected to each other or the load N. It provides the new voltage reference only. It is connected to the CT L terminal, and the N terminal, but only to get access to the voltage dividers that control the output voltage.. it has no other interaction.

I expect the new tranny is connected primary to the main output, and secondary to the control card... ie a 220:240 or whatever transformer. This way, your load can drop the output voltage, and the new tranny will give a lower voltage to the controller to do the compensation.

Seems like a hard way to control the output, but it is your choice. I expect messing with the divider will achieve the same results..... but your show.

The CT has only 2 turns of pretty heavy wire, have not seen it suffer in all my usage so far..... but a current bypass wire will help too if you are going for high power continuous.

Is that how you want to do it, or did I get it wrong.


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

Offline dochubert

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Re: Output voltage adjustment
« Reply #36 on: May 02, 2016, 04:16:12 PM »
Thanks Oztules,
And yes, the new transformer is to trick the control board into bumping up the normal 230v output to about 240v. 

Relieved to hear it won't see full load current.  Thanks.  Lighthunter's first attempt was a 10 watt transformer which burned out in a short time (not sure how long it lasted, and not sure what wattage he's got working now - large I think) His works now and with good steady regulation, which is why I'm about to try it.  He and I both previously tried adding resistance to the voltage divider network with  almost identical same results.  It boosted voltage up where we wanted it but for some reason, made voltage regulation sloppy.  My output randomly drifted from 232v to 241v  under steady (light) load, which never happened before the mod.

Is the shaping capacitor you referred to the large brown one at C20 across the maintxL and maintxN connections?  If so, another of same specs across output makes sense since we have now isolated C20 from output with our new transformer.
Thanks again
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Offline oztules

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Re: Output voltage adjustment
« Reply #37 on: May 02, 2016, 04:30:36 PM »
Actually, the 4u7 cap can be removed from the control card, and placed at the main transformer outputs on the receptical, as the small one is seeing this filtered output as it's input, so  it's wave will be fine anyway.... forgot about that ....

...........oztules
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Offline dochubert

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Re: Output voltage adjustment
« Reply #38 on: May 02, 2016, 04:40:37 PM »
Thanks again!
Saves me waiting for a new one to get here.
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Offline lighthunter

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Re: Output voltage adjustment
« Reply #39 on: May 02, 2016, 05:41:40 PM »
Nice explanation oztules!  :) Thanks! the 10w transformer i used didnt actally die it just smelled hot and since it ran for a month that way i'm pretty sure it was because i was using it in a buck fashion and the little 6v winding it had wasnt up to the task. The transformer i now use is larger yes 100w but there is very little current going through it.  As oztules pointed out the load current will pass through the ct but not the add on transformer.

I just got some new panels and didnt want to write about them yet because i wasnt sure they would be good.  I paid $135 each and they are rated at 305w 37v 45voc. I couldnt be happier, I measured output current close to 10A. They ran steady at 358w Thats 17% over rated pwr. I would not trust measurement but i happen to know inverter pwr reads on the low side and the current clamp x volt gave same pwr reading. Frameless panel some company i never heard of before. Was an ebay seller, i got the mono panels, he had poly even cheaper.

LH

LH

Offline dochubert

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Re: Output voltage adjustment
« Reply #40 on: May 02, 2016, 11:50:19 PM »
Lighthunter, that's a great price on those panels.  Panels seem to be getting cheaper all the time (or you're a heck of a wheeler-dealer!).
I love getting that higher than rated output with new panels for the first couple of months until they settle down to rated range.

Transformer;
Primary is wound on top of secondary in my new transformer, so considering using it backwards; primary as secondary and secondary as primary.  Since its 1:1 anyway and current flow will be small, shouldn't matter, I hope.  That way I can still unwind some of the 'secondary' (now accessable on top) to get my reduced output.
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Offline lighthunter

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Re: Output voltage adjustment
« Reply #41 on: May 03, 2016, 02:43:48 PM »
Quote

"I love getting that higher than rated output with new panels for the first couple of months until they settle down to rated range."

No kidding, i didnt know they changed that fast! i learn something every day :) Now if i cud just remember the things i learn ;D.

I think pri vs secondary is defined by user anyway.

LH
LH

Offline dochubert

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Re: Output voltage adjustment
« Reply #42 on: May 03, 2016, 05:04:30 PM »
Hi Lighthunter,

Honestly, I can't remember how long it takes for output to drop back to rated, and I think it depends on the panel brand as well.  Maybe as long as 6 months.

Its been many years since I studied transformer theory, but think I remember that there's no reason I can't redefine primary and secondary, especially since we're talking minimal loading.  Glad you agree.

Btw, did you add or move the capacitor (C20 on control board) on your setup as Oztules suggested?  Just wondering.
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Offline lighthunter

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Re: Output voltage adjustment
« Reply #43 on: May 04, 2016, 09:51:46 AM »
Quote

 "Btw, did you add or move the capacitor (C20 "

No i didnt. I remember thinkin about it. Oztules is right, it should stay with the toroid secondary.

Yeah transformers dont care what you do with them so long as you dont exceed current or voltage ratings.

LH
LH

Offline lighthunter

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Re: Output voltage adjustment
« Reply #44 on: May 10, 2016, 12:25:19 AM »
My first PJ casualty.Fets blown. Replaced with irf4110s some new resistors and swapped control board. All working again! Looked deeper into reason failure happend. Sump pump switching between inverter and grid power. It was a cheap dpdt relay with very narrow gap between contacts. You get the picture. Two power sources had a fight,  pj lost. Anyway. The spare control card i had still has a quirk, it powers on cold really hard with noise and high current. In 30 sec or so it warms up and is fine. This control card manages output at 230 instead of 240. The grid tie doesnt like it. It is back to shutting off frequently. I had to order totem pole drivers. Mouser had one but not both. Amazon of all places had both and 20 irfb4110 for $15.

LH
LH