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Forum Index : Electronics : 6Kw Ozinverter build

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Warpspeed
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Joined: 09/08/2007
Location: Australia
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Posted: 09:01am 22 Feb 2019
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I was always pretty sure that a screen would fix the waveform kink problem.

Looks like you have now proved that Mark.

Another small step forward.
Cheers,  Tony.
 
renewableMark

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Location: Australia
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Posted: 09:36am 22 Feb 2019
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Yeah, having those two big chokes already made it pretty good, but adding the screen made it just that tad better.
Earlier attempts with crap chokes had prominent kinks, so yeah, it all needs to be just right and work together.
Cheers Caveman Mark
Off grid eastern Melb
 
renewableMark

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Posted: 10:11am 22 Feb 2019
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OK, having very weird voltage fluctuations now with the new toroid running the house.
Placing heavy loads and turning them off the system doesn't respond to fluctuations now, lights flicker and voltage takes quite a few seconds to respond sfter loads are turned off. It never did that before.

The current hall sensor got put on the wire close to the secondary outputs, but not as close to the secondary as last time, maybe only 5cm difference, other than that it's the same system.

Update, fridge just kicked in, all lights dimmed/flickered.
Thinking how it was wired differently, before it had the hall sensor direct on the secondary outputs, before it got connected to the caps and line going to the filters/RCD.
This time it was placed on the line after the connector which has the secondary caps.
Reckon I'll try it the old way tomorrow and see if it makes a difference.Edited by renewableMark 2019-02-23
Cheers Caveman Mark
Off grid eastern Melb
 
wiseguy

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Joined: 21/06/2018
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Posted: 01:42pm 22 Feb 2019
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Are the two chokes the same as what was in the original house unit ? Were they tested previously on the house setup with a non screened Toroid with similar loads but worked ok? I'll wait to hear back before saying more. But I also know you're quite resourceful and tenacious - you'll probably have it figured out before then. Edited by wiseguy 2019-02-23
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
renewableMark

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Posted: 08:57pm 22 Feb 2019
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Nah mate, didn't work it out yet. I had a few beers so didn't want to fiddle with things that spark till the morning.

The chokes and everything else is the same.
Only difference was my wiring of the hall sensor, can't see how that would cause it though.
I'll swap that around soon and let you know.
Cheers Caveman Mark
Off grid eastern Melb
 
renewableMark

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Posted: 05:16am 23 Feb 2019
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OK that didn't fix it.
What was your idea Wiseguy?
Cheers Caveman Mark
Off grid eastern Melb
 
renewableMark

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Posted: 08:49am 23 Feb 2019
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Ran the Ac today and it seemed to be surging, so put the scope on to see what was happening.
PHUK ME!!



This thing is not happy, it previously ran it totally fine. So had to switch the grid back on and pull the unit apart to remove this torroid with the screen.
Cheers Caveman Mark
Off grid eastern Melb
 
Revlac

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Posted: 10:49am 23 Feb 2019
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I Remember having a similar thing happening when I was playing with chokes, voltage would increase when load applied and wave went a bit horrible.
The transformer also had a shield in it, so perhaps it makes the choke behave a bit different than a transformer without one.? I can't prove that because I don't have a transformer here at the moment without a shield.

Ended up adding more air gap on the choke and it run happy.
Not sure if anything else was going on, but all I did was adjust the air gap.
Cheers Aaron
Off The Grid
 
renewableMark

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Posted: 11:22am 23 Feb 2019
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Thanks Aaron,
I already pulled the unit apart, will check it in the morning and fire it up with the non shielded toroid like as before.
Probably should have not tried anything different as the sine was pretty good any way, most likely better than mains..... so WTF was I thinking, if it aint broke don't fix it.
Cheers Caveman Mark
Off grid eastern Melb
 
renewableMark

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Posted: 09:18pm 23 Feb 2019
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Hey Aaron,
of course they will all be different, but how much gap did you use?
I had the standard spacer from the doubled up 3kw aerosharp choke, which is around 1.5mm.
Then on the doubled up E70 it had around 1mm.

They were nicely tuned for my previous setup.
Maybe those small gaps had no chance with the shielded toroid?

At this point it's a lot quicker to go back to a setup that I know worked well.
(And much smarter to keep the wife happy too).
Cheers Caveman Mark
Off grid eastern Melb
 
wiseguy

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Posted: 01:02am 24 Feb 2019
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Couldn't answer earlier, lots of distractions here at the moment.
Looking at your CRO trace, there appears to be ~ 500Hz harmonic thing going on in the background. In my opinion it is unlikely to have anything to do with voltage or current feedback.
It looks more like a tuning issue which has more to do with chokes toroids and secondary winding capacitors. Will be interesting to see if it goes away with an un-shielded Toroid I hope it does, but I suspect it may not. Look forward to your next exciting update.....Edited by wiseguy 2019-02-25
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
renewableMark

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Posted: 02:26am 24 Feb 2019
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OK unshielded toroid seems to have fixed it.
Voltage is more stable now, lights flick a tad after big fluctuations but not much, it's only the old style filament bulbs that do it.
AC running on full has a nice sine now.
Below pic was the inverter running at 1900watts or so.




But when the Ac isn't of full boar it seems to mess with the sine, below pic was with the inverter running at 1100w



Bit worried it might stuff the AC unit, is it horrible enough to cause damage???

Any other loads like heater, oven etc have nice sine.
It's just the inverter AC unit that messes with it.
Cheers Caveman Mark
Off grid eastern Melb
 
renewableMark

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Posted: 02:47am 24 Feb 2019
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Something is still not right, I can hear the machine humming slightly louder and softer and the voltage goes up and down a few volts, it does this for 30 sec or so then resumes as normal.
When it does this the lights look like someone it playing with a dimmer on them.
Cheers Caveman Mark
Off grid eastern Melb
 
wiseguy

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Posted: 03:17am 24 Feb 2019
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Cant offer any further help from here Mark. I recommend Poida & Warp as your best resources and being more local to you.

I suggest the harmonic visible in the background is messing up the peak to peak voltage seen by VFB and it keeps hunting - this is when the inverter tries to make an adjustment for the output voltage, the shape of the harmonic on the fundamental 50Hz also probably changes a bit so it is hunting back and forth till things eventually settle down.

There is interaction going on between the 2 chokes, the toroid inductance, the secondary tuning capacitor and any load or lack of it, even the primary winding and primary side reservoir capacitors on the power board (they are fitted aren't they ?) could be playing a small part.

I wish you good luck sorting it.Edited by wiseguy 2019-02-25
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
renewableMark

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Posted: 04:51am 24 Feb 2019
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OK tried a new control board, no change.

Tried new caps across the secondary, no change.

Pulled the ferrite choke apart checked wires and increased the gap to around 3mm, no change.

I have another steel choke that could be swapped out (big job on my layout) That's probably what I'll do next.

First might try just running ferrite by itself to rule out the steel choke.

Caps on the power board, hmmmm big job (yes they are in place)

Funny thing is it's only Air Con that sets it off, you can see the CRO surging and the wave slightly increases and decreases in height slightly faster than once every second, you can hear it go hmmm hmmmm hmmm just surging like that.
If you turn on the oven or heater the sine stays stable, volts stable and no hum hum hum from the torroid.

I have a second power board to swap out too.

BTW the Air con is fine running off mains, so that's not it, the problem is in the inverter.Edited by renewableMark 2019-02-25
Cheers Caveman Mark
Off grid eastern Melb
 
wiseguy

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Posted: 05:42am 24 Feb 2019
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Is the air conditioner an inverter style or maybe an Actron style scroll compressor ?

Leave the primary capacitors alone at this stage. My next guess would be that the inverter appears it may not have a low enough impedance for the requirements of the A/C. Maybe more gap or less turns in the aerosharp ? (If it goes bang I apologise in advance - its hard to fault find remotely) But each bit of extra information helps towards the right diagnosis.

The humming variation might be reduced by using a smaller capacitor on the VFB signal after the bridge rectifier try halving the value first (or maybe even doubling the value) to see if it varies the effect.

But before worrying about driving the load, I thought unloaded (or low load) it had the terrible wave form - it should look good at low load/idle before going further.Edited by wiseguy 2019-02-25
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
renewableMark

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Posted: 06:41am 24 Feb 2019
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At idle sine is fine.
Running 2000w oven sine is fine.
Blowheater 2400w sine is fine.
Air con (inverter type) running on boost sine is fine.
Air con running at half speed sine turns to crap and the surging starts.

I turned on the old window type air con in the shed and it makes it surge too.

I fitted 3x 2uf caps across the secondaries to copy the other torroid, perhaps that is too much for this one so will remove one, then go to 4 if that doesn't help.

It's done my head in for today, went back to mains and opened a beer.

Thanks for the ideas.

Edit, I did think of putting on the nanoverter control card, but asking it to fix a non working system is a bit much, there is a problem that needs to be found first.Edited by renewableMark 2019-02-25
Cheers Caveman Mark
Off grid eastern Melb
 
Revlac

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Joined: 31/12/2016
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Posts: 1026
Posted: 10:27am 24 Feb 2019
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The double C Core I have at the moment has a 2mm air gap, it is laminated grain orientated material.
Only had rough wire around that one and is waiting for some proper stuff to wind up.
This doesn't mean that it is the correct air gap/turns for any other transformer/toroid as I'm seeing different results for different transformers, no two builds seem to be the same? Well not exactly anyway.

So I think the toroid and choke would have to be tested and matched up on a test rig to make some adjustments (Experiment a bit) until it all runs happy... without upsetting the rig already running the house.


I wrote the above earlier, and now after reading the the rest of the post, I don't think I was of much help.

Always need a backup/second inverter when going full off grid.

Our Changeover switch used to be GRID/GENNY, It is now labelled INV/GENNY.
Cheers Aaron
Off The Grid
 
renewableMark

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Posted: 10:58am 24 Feb 2019
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Ahhh, yes 6 months of no problems and bam, glad I kept the grid connection now.
Would have had a very pissed off wife otherwise.
Cheers Caveman Mark
Off grid eastern Melb
 
renewableMark

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Posted: 12:14am 25 Feb 2019
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Well I went to 7uf, looked better so added another 2uf
BANG!
Cheers Caveman Mark
Off grid eastern Melb
 
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