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Product Information => Product Reviews => Topic started by: lighthunter on April 26, 2021, 10:32:12 pm

Title: No brand/5500W inverter disaster porn
Post by: lighthunter on April 26, 2021, 10:32:12 pm
A couple years ago i bought one of these EGS002/8010 based inverter boards, great deal for a 48v backup inverter. Am sure i tested it after i got it cause a few of the necessary control wires had solder on and i faintly remember making sure it worked. Recently after several years my power jack control board quit. No blown fets just no output. Can be repaired i think but needed a quick solution so got this spare off the shelf, after all thats why it there.

It took a while to fit it into place secure it and arrange necessary connections that were not now on board terminals. All connected i decided to precharge and power on before closing the lid. Precharge took little time as the capacitor bank is only 8000uF. Charge indicator came on and i closed the DC breaker. I didnt even get a chance to turn it on before an explosion ensued, immediately, im thinking fets and usually theres no point in saving anything once the noise starts but then another horrendous bang!! Then another!! Like popcorn only x1000!!! By the time i got my wits together and tripped the 100A DC breaker 6  of 8 had gone off!! Of course i somehow hooked a wire up backwards i thought....  Double and tripple checked the wiring. No problems there. Polarity was correct. DC volt meter read 52, caps stamped 63V. Ive no idea why the caps blew the way they did other than they had been sitting unused for maybe 2 years and dried out. Or the obvious...dragon brand...  Fitted some suitable replacements to the board and it powered up the toroid with zero noise or hum and 121/242VAC
no adjustment necessary. Now to fix the PJ no wait... its spring time there are other garden/patio/building repair jobs to do first.
Fun times!!
LH
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on April 27, 2021, 03:40:55 am
Ive had that happen to a high frequency board... " 63v " caps and same result... probably find they are 35v caps " re-labeled " work for a short time sometimes, then boom... drying out a bit probably didn't help ether, but should not have mattered, unless temp extremes... same fix worked for me too, replaced and all good...
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on April 28, 2021, 02:11:00 pm
35v cap in place of 63, yeah that would do it. :P  Reminds me of a story years ago when a friend and i built a 4meter wind genny, first week of it being up his dog chewed the cord and unplugged it. Fortunately the caps and diodes all came apart shorting the 3/phase winding which brought it to a stop and saved the mill . Caps and diodes dont like limits disrespected Ha!

this is my first experience with the 8010/egs002 it uses less power to idle, like around 15w only which is great! Its also very unaffected by changes in load power.
The not so great is the AC output volts oscillates by a volt or so at about 2 hz and the AC output also changes with battery voltage.  At 52V the output is 121V and at 46.5V its about 115V.

Im sure those two issues can be corrected by tinkering with feedback loop a bit. Since battery volts changes very slowly and a plc already monitors battery volts I could simply drive a relay contact to adjust AC output volts based on batt level.

Its not a perfect solution but it is serving the purpose of a spare inverter which im grateful for!

LH
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on April 28, 2021, 02:56:49 pm
That's strange,  I've been using a bigger version of that board for years, and its rock solid, even pulling a solid 9kw for hours... i would change all the smaller feedback caps, check the solder for " dry joints " etc. , the eg8010 board is very good for feedback usually...

Specially if the bulk caps did what they did, i would suspect all of em...
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on April 28, 2021, 09:51:16 pm
. "i would change all the smaller feedback caps, check the solder for " dry joints " etc. ,"

Very good advice!

 it also occured to me that the resonant freq. Of the toroid and choke likely is not 90hz as it needs to be. I never checked this one. Never noticed an issue with the PJ boards driving it.  Maybe its much lower than 90  and causing the voltage to fluxuate as the wave is influenced by rolling addition and subtraction of the actual resonant frequency. Kind of like the volume of old am radios used to do under the right conditions.

 Courtesy to Poida's research or i wouldnt even think about it.

The wave shows a little distortion from incorrect LC filtering.
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on April 29, 2021, 02:56:04 am
I just bought a dead 8000watt 24 volt powerjack.
I have repaired the mosfet board, new mosfets and replaced the very fiddly 47 ohm surface mount resistors. The rest looks fine.
Just wondering if you folk who play with inverters lots can tell me what the waveform from the driver board should look like.
I read somewhere here that folks test the driver board output before connecting the mosfet board just to make sure that the smoke doesn't get out.
The man I bought this inverter from said he replaced the mosfets and it blew up on him again. I am guessing that the dead 47 ohm resistors may have been a big part of the problem.
This model I have does not have the removable mosfet boards, I would have to remove the whole heatsink and main power board to fix it if the smoke got out, so I am hoping to test the  driver board output first.
Anyone know the wave shape I am looking for and if it is possible to test without the mosfet board in place.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on April 29, 2021, 06:54:47 am
Hi Pete, yes it is and it does save a lot of grief and ruined fets. From memory  :P the procedure i used was to unplug the ribbon cable from the fet/heatsink board and then cut wires 9&10 and 1&2.  Connect negative 12/24/48 (your flavor) to wire 9 or 10 leading to control board and then connect positive to 1 or 2.

this allows you to power up the control board without energizing or connecting to the power board. If you can do the same thing without cutting the wires, go for it. You just need to get ribbon disconnected from power board and get power and ground to control board.  Next put scope probe on each pin 3/4/7/8 (i think these are the 4 H bridge drive wires. Of course ground pin on scope goes to negative on pin 9 or 10. You will also need to plug in the long flat connector so you can switch it on/off.  Since it wont be generating a sine wave for feedback it will fault within a few seconds of each power on cycle but immediately after each power on cycle you should see a decent square wave, it wont be a continuous duty cycle so it looks strange but the basic thing to look for is that the voltage goes high enough, the transitions look fairly square and all 4 are very similar. Usually all 4 do not have same problem so just comparing the 4 will get you there. Frequency is gonna be somewhere north of 20khz range i think. Its been a few years now so i'll see if i can post a photo and better info this eve. Good luck. One other cool solution is just to buy a driver daughter board for $25 and replace it. They still have those, i think the new version still uses the same board.
have fun!

(CAUTION pin numbers were edited if you read this earlier today, power and ground pins were reversed)

i had a couple wrong. If you want to get picky, the probe neg is different for the high side drivers, each has its own negative pin 6-and4+ are a pair,  5-and7+ also a pair. 9/10 are - for pins 8 and 3 which are the two bolted to the heatsinks with the AC connections. I dont think i fussed about the correct ground though. If you just use the 9/10 ground for probing all 4, two will be inverted and look a bit wierd but there will still be two symmetrical pairs that look alike if all is well.
LH
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on April 29, 2021, 04:50:19 pm
Even easier , take the bulk caps off board ( very important) and power it up through a 20 ohm resistor... if any issues there won't be enough juice to blow mosfets.. you can even hook up to a transformer,  but you will need to play with resistor value , start with 20ohm, then 10, then 5 etc....
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on April 29, 2021, 05:43:18 pm
Thanks Lighthunter, I do have a spare driver board for the running inverter I have, but unfortunately the dead one has a different driver board. The ones that powerjack sell these days have one row of pins underneath to plug in and the one on my dead 8kw inverter have two rows.
So far the transistors on it look fine, not sure about the optocouplers. Mine has a plug in cable that goes from the driver board to the heatsink/mosfet board so I was thinking of just unplugging it and testing the output of the opto's.
I will read your description through a few more times before I do that.
Thanks again
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on April 29, 2021, 05:46:07 pm
I just read the second way you suggested. That may be worth a try too. Like you say better than cutting cables etc.
I remember a tech at a place I worked who used to power up TV sets he repaired with an incandescent globe in series with the supply to rob the set of enough power to die if there was a fault.
Thanks will let you know how it goes
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on April 29, 2021, 09:38:07 pm
Sorry the second post was by Noneya.
I have removed the caps, will take the plunge later and see how it all goes then.
I realised that it appears the main board is fed battery power from the Fet/Heatsink board so my original plan would not have worked.
Did not mean to hijack the thread, it seemed that you folks have a lot of experience with these things.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on April 29, 2021, 10:03:18 pm
yeah, noneya's way may be easier what could be tricky is if you have one or more wounded fets, it will distort the wave shape. Thats still a win because youve found a problem but you dont know  its your driver or a fet. If you have removable fet boards that might be easy to separate though.
I dont remember if PJ is unipolar or bipolar in other words, bipolar is switching all 4 fet banks at 24ish khz, unipolar is switching  two banks at 60hz and the other two at 24khz. I thought the pj control boards ive worked on were bipolar.

So heres an example of a unipolar 8010 gate drive
First a photo of a 60hz gate drive then a photo of a 24khz drive
showing the pwm 60 hz component, then a photo of the 24 khz pulses. All you are really looking for is the full 12v drive strength and fairly straight square transitions.
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on April 30, 2021, 01:55:57 am
Thanks Lighthunter, I used Noneya's method, took out the large caps and put a resistor in series.
I  had already changed all the AC Mosfets over, i used Hy4008 mosfets. I also changed all the 47 ohm resistors on the mosfet board as well. Surface mount stuff sure is fiddly but I managed it in the end.
So firing it up all looked good until it screamed at me, No caps so no big bang. I checked the output ( pin6) of the optocouplers and it was rubbish. So delved a bit deeper and changed the 4 surface mount transistors on the driver board.
Then checked and found that there was a short still on two transistors from emitter to collector.
I pulled the TLP 350 opto couplers out of their sockets and the short went.
I have some on order so will have to wait until they arrive to go further.
I did order one of those inverter boards you talk about in the article and will play with it when it arrives. As long as we are not being punished too much for our politicians big mouths.
Thankyou both you saved me a stack of fets and lots of work
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on April 30, 2021, 02:09:28 am
Good to here that helped, not my idea, I was suggested it by Oztules years ago when I was playing with em... the PJ 's are bipolar, I would check the low side driver totem pole transistors.. by memory " MY " and " NY "  surface mount ...( nevermind you already did )

The PJ's are tough, but can be fiddly... why I changed to the Eg 8010 boards... simple and VERY tough
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on April 30, 2021, 03:01:41 am
Hi Noneya, yes I have changed the NY and MY transistors. I am keen to try the inverter module when it arrives. This powerjack has two transformers in it. As their 8000 watt rating is so far over the top I am toying with pulling one of the transformers out and using it as a test bed for the 8010 inverter board.
Haven't seen any posts by Oztules for quite a while, I wondered what happened to him.
thanks again.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 01, 2021, 07:35:50 am
Hey ya'all, hope your having a good weekend, supposed to be hot here today 80ish might try starting the AC on this 8010 inverter.

So at the beginning of this thread i mentioned a PJ inverter that had run for years and control board quit... no blown fets, I WAS VERY MISTAKEN, it was blown fets, i was not home to hear the sound and there was almost zero visible evidence. A close up photo of the end fet shows a hairline fracture i never noticed and there are others like it. HA ive never seen so very little visible damage. This one had run for at least 4 years and so i must add that i am suspicious since i had made a change to the cooling only a day prior. The change was from 25c setpoint to 30c setpoint. The thermostat probe was fixed to one of the heatsinks directly. 

So was it the temp change from 25 to 30C?  Or was it totally a coincidence. My boss reminds me every so often that theres no such thing as a coincidence. Personally i dont believe that as ive often seen two unrelated events happen at the same time.

Its really not important now unless someone thinks i SHOULD have fan thermostat at 25C.  Sorry for the drama queen stuff
its just kinda nice to understand failures. :)

LH
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 01, 2021, 05:44:04 pm
I would have thought that 35 degrees would be well within the design limits of the components. It gets hotter than that just at ambient temperature in summer in lots of places.
Can't explain why the fets only just cracked though, normally they go bang in a big way. Possibly something else blew just in time to stop the usual fireworks.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 01, 2021, 05:47:19 pm
I just had a look at the Hy4008 spec sheet they say that the maximum junction temperature is 175 degrees C, so 35 degrees sounds very reasonable.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on May 02, 2021, 04:34:03 pm
Just remember junction temp doesn't have a whole lot to do with CASE temperature only " steady " temperature rises come into play there... the data sheet will have to J to C coefficient,  but an instant temp rise will still blow it to smithereens before the case even warms...

Ive had that happen to mosfets , cracking like that under failure... your lucky the energy in those capacitors usually make em go boom...

I don't think the 5 degree change SHOULD have made any difference,  unless you were at the limits... which sounds like you were not... maybe re-set it back to 25 and get some readings, a no contact temp probe are not expensive off of fleabay, check case temperature ( not heatsink ) under load  and post it here, can back track the junction temp using datasheet, will only give steady temp, not instant,  but give you some more info to track the issue down... 
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 02, 2021, 05:28:15 pm
One thing that I have noticed on my powerjacks is that they don't use any heatsink compound on the mosfets. It may be fine if the inverter is not run too hard but with hard running and possibly an ill fitting transistor they could easily overheat.
I thought about adding heatsink compound during the repair I am doing on my 8000 but forgot , I may still undo the screws and put some compound on when I put the main capacitors back on.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on May 03, 2021, 01:05:45 am
Oz tested that at some earlier stage, said made no difference.. but up to you...
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 03, 2021, 02:22:28 am
Thanks Noneya, I trust that Oz was enough of a tinkerer and blew up enough stuff to know what he was saying.
Will save me trying to undo those soft screws on the mosfets .
Cheers
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: dochubert on May 04, 2021, 08:52:44 pm
Hi guys,
Pete, don't forget that it must be conductive heatsink compound behind those fets.
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 04, 2021, 09:31:24 pm
Thanks Doc, I have decided to take the advice of those more experienced and not bother to put heasink compound on.
Your point about conductive heatsink compound is probably why PowerJack don't put it on in the first place.
I should have realised that as the cables go directly to the heatsink that they are live
thanks
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 04, 2021, 10:10:02 pm
Good discussion on the heat sink guys! Very important.

So far the 8010 inverter wins over powerjack in
1) efficiency
2) Quieter
3) Cheaper
4) Load volt regulation is better
5) power board design, compared to older pj


The only thing i dont like is the battery voltage regulation.
 ( i know AC volt regulation is load reg and bat reg, its all the same thing)
Maybe there is aomething i dont understand.

  49.0 thru 57.5 vdc = 120.7vAC solid
  48.2vdc = 118.7 vAC
  47.85 = 113.7vAC

   This might suggest the volt regulation range is
    at the lower edge, when below 48v it falls sharply,
    suggesting i need to add turns to the secondary of
transformer (or remove from primary)
 
What i dont get is the pj had no trouble
Holding 120v all the way down to 44v with this same transformer.  What could be the difference. Both are switching 48v through a transformer with an H bridge. Except,
one is using bipolar while the 8010 is unipolar. Maybe that explains the efficiency gain as well. Just guessin at this...



Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on May 04, 2021, 11:11:15 pm
Oz discovered that earlier on... it doesn't have as good " dynamic range " as the PJ, why for a 48v system, the PJ is happy with a 32v/240v transformer,  but the eg8010 requires 28v/240v to be able to keep the voltage consistent over the lead acid usual voltage range..

However,  it doesn't mean it won't work,  voltage will just sag at lower voltages... how I got around it, was to lower final voltage ( 225v on a 32/240 transformer) it will hold that happily and I haven't had any connected devices complain.. grid voltages can fluctuate way more than this anyways...
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 05, 2021, 03:20:52 am
Hi Noneaya , just wondering how you lowered the voltage on the 8010 unit. I have ordered one to try out and wondered how you went about adjusting it.
As the grid in Australia has aged and not been kept in such good condition then authorities have actually lowered our supply voltage guarantee to 230 volts anyway. Seems that they could not be bothered putting in bigger wires, cleaning connections etc.
So your 225 is well within the +/- 5% range that is required anyway.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on May 05, 2021, 03:50:27 pm
On my board, the variable resistor circled in pic is what adjusts the voltage.... yours may be different,  but the do come with a chinglish instructions which are easy to decipher...
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 05, 2021, 05:22:24 pm
Thanks Noneya, I will see what mine looks like when it gets off the slow boat from China.
Seems that as our pollies poke a stick in to the ant nest that is the Chinese government, the freight slows down even more.
Pity that Australia stopped manufacturing electronic parts many years ago. With all the stupid talk of war with China, and anyone else the west decides is worthy of bombing that we had better ramp up our manufacturing.
Maybe the government here doesn't understand that all the electronics that runs our millitary and civilian industries comes from China.
Oh well, the madder the place gets the more being mad looks normal.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 05, 2021, 06:35:53 pm
Ha! yeah what a mess. The crazies of facebook were gonna try to decide if Trump is still banned from their website today. Too bad everybody dont just delete their account and vaporize social media.

Nonya, you were fortunate to find directions on your inverter. Mine had zero, i ended up using my phone camera and translator to figure it out.Pete just ask if you have any questions when it arrives. I only use 3 two pin plugs, one for on/off switch on the left, one for power in the middle marked - +  and the third on the end far right for feedback. I dont know if i have any current limit though, ive fuses for that anyway.

Noneya, thanks for the clarification of "dynamic range" thats a whopping lot of difference between the two. I cant help but wonder whats different. The only thing the 8010 can do to change voltage is vary the duty cycle. Seems odd they would be so different. Unless the bipolar thing makes a difference.

If i did the math right the power  difference d 110 Vac vs 120Vac
is 16%. Thats kinda huge for a compressor in an air conditioner.
a 10 volt drop at 235 to 225 is 8% power change. So its not that things wont work but the AC unit will draw more current and cool less. This time of year its not a big deal but when compressors are running at maximum it wont go unnoticed.  I may have to wrap more copper in my transformer.

As for the 8010 inverter its pretty darn good an pete your gonna like the power board simplicity.


Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 05, 2021, 09:04:12 pm
Thanks LH, I will definitely ask if I can't understand the Chinglish.
Yep I agree on social media, all it seems to have done is speed people up more, so that their interactions are very short and not so sweet.
We don't do any of it at all.
Thanks for your help
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: dochubert on May 05, 2021, 09:27:52 pm
Hi Guys,
Here's some info you might not have;

[attach=1]
[attach=2]
[attach=3]
Title: Re: No brand/5500W inverter disaster porn
Post by: dochubert on May 06, 2021, 10:14:38 am

Should have mentioned that the info is for the 10kw unit that I have.  The 5500w may be different.
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 06, 2021, 05:31:48 pm
Thanks Doc, I did notice that the one you have is a little different to the one that is in the article but still good info to know.
I have saved the pics so that I can check when my inverter arrives.
Cheers
Hope the new system at your place is behaving well
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 07, 2021, 01:36:54 am
The good news is that after I replaced the MY and NY transistors and Optocouplers on the driver board that the inverter appears to be working fine.
Tomorrow I will put the capacitors back on the main Mosfet board and see how it goes then.
I have only run it with a 0.22 ohm resistor in series with the positive supply so far and it puts out 240 volts and doesn't scream at me.
So the signs are all aligned so far.
Thankyou all for your help, the ideas shared here saved me blowing up mosfets and a lot of work.

Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 07, 2021, 02:30:09 am
Good work Pete! sounds like your just about complete with repair. One thing that helped me out in past was to shut off the lights during testing to see if any tiny lights are flashing as carbon arcs around fets sometimes its hard to see all the carbon from the burned fets. Thanks for the photos on connections Doc! looks like i didnt need the middle one so only the switch and feedback are absolutely necessary. I really like this thing so far. Maybe its less prone to failure than pj!

I did a bit of reading up on bipolar vs unipolar sine wave synthesis. Its more complicated than it first seemed.  Turns out bipolar switching scheme uses rail to rail power supply voltage in both polarities to drive the transformer primary. (Max vout=.78 x vbat) which is 34.32vac when batt is 44vdc. And uses high frequency switching on all 4 fet gate drives.

This method is simpler and produces maximum voltage possible at the transformer primary but has drawbacks.

Switching losses are higher.
Significantly more distortion.
Harder on fets.
Needs larger inductor to smooth to good sine wave.

Two types of unipolar switching schemes exist, one uses high frequency switching on all 4 fet drives, the other uses low frequency for two and high frequency for the other two (8010 unipolar does this)

This type is significantly more efficient.
More accurate sine wave output.
Smaller inductor filter is needed.
Maximum output voltage is less than power supply.

   I couldnt find proof of lower output in writing but it seems obvious, as the wave simulation uses a different volt averaging scheme to minimize stress on the switches  and load. (the reason the transformer is quieter with 8010 unipolar)

The 8010 has capability to do bipolar so i may switch it as an experiment when i have a backup ready to use :)  switching 8010 to bipolar will involve altering the feedback loop to include freqsel pin on 8010 and making sure the other two drivers are capable of the high frequency gate switching. I'm pretty sure the egs002 is not capable of the 8010 bipolar mode simply by shorting the jumper.

In conclusion unipolar has some serious advantages. I do think  the highest reliability inverter is to add (or subtract) the necessary turns to transformer and go with unipolar.  *note, if reducing primary turns, you are increasing flux density and you dont want saturation, safer to add secondary turns)  Factory wound units generally have primary low volt side on inside layer so theres no risk of me going there HA! ::)


 
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on May 07, 2021, 05:46:23 pm
https://www.anotherpower.com/board/index.php?topic=1116.15 (https://www.anotherpower.com/board/index.php?topic=1116.15)

Oh and make sure you make the modification above that OZ referred to on first post, VERY important for no blown  mosfets on low frequency inverters...

Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 07, 2021, 09:00:25 pm
Yes, good point!! i did do that just in case it mattered, the people who designed these boards may have their own clever way of fixing that issue but i didnt wanna find out the hard way they didnt. Its kinda neat, the 8010 has a bit of protection built in like under volt and overvolt of the AC feedback overtemp as well, then the egs002 board has protections built in and the makers of this power board added overcurrent and short circuit over and under battery volts. I wonder if that isnt how the problem Oz found came about, the old saying, too many cooks... well you get it!!

The thing just works way too good not to like it or want to change it. Best part if something did happen the plug in egs002 board is only about $7.00 and beyond that. repair would be just the normal resistors and fets we are used to.
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 08, 2021, 08:53:49 pm
Hi guys, In my spare time, Ive been trying to understand the switching sequence to synthesize a pure sine wave from a digital pulse train. The whole thing used to seem simple to me until i started looking at it closer.

The two most popular techniques of generating a sine wave are called bipolar and unipolar. The meaning of bipolar implies that you are supplying energy in both polarities throughout the positive and negative half cycles.  Unipolar on the other hand implies that you are supplying energy of only one polarity for each half cycle of the AC wave.  Just knowing these facts raises an eyebrow as to whats going on with the fets, inductor and transformer.

Theres always lots of inductance in these circuits and one principle of an inductor is it always opposes a change in current. Like a flywheel so to speak it has electrical inertia. So for whatever reason, maybe simplicity, bipolar switching technique pulses energy through the transformer primary in both directions as it makes a half cycle.There are only two possible switch conditions yielding v+ or v- at the primary. It would be a bit like driving down the road in forward gear for a short distance then reversing directions for an even shorter distance then forward again further than the first time. With very short pulses of timed energy the wave is shaped properly. One concept i never realized is except for dead time between switch events, the load (xfmr pri) is always connected to the power source either positively or negatively. Theres no "off" time with bipolar. The reverse polarity has a braking effect on the current flow through the inductor. By controlling the duty cycle any desired resultant current flow can be achieved. Just the concept of it doesnt seem nice to the switches or anything else in the way.

Unipolar switching also pulses energy to shape the half cycle but it doesnt use reverse gear until the alternate half cycle where it is needed. Between the energy pulses (wait time) both fets on top or bottom are turned on to allow inductor current to continue to flow.

Im doing some interpreting and reading between the lines here but im pretty sure the reason bipolar switching always has a pair of fets ON so the load has a conductive path is because of what happens if you try to stop a flywheel in motion or inductor with current. (Spark plug ignition uses that principle)
So unipolar is described as a 3 voltage level +Vd -Vd and 0, basically the 0 volt state is when both upper fets are on (or both lower) when the inductive energy can bypass the power source but still continue moving.  If you ask me,  unipolar just makes a lot more sense and seems much easier on switches.  I still do not understand fully why the voltage output of unipolar should be less but i expect theres a good reason for it. Some articles i read were very clear the unipolar switch technique is very superior to bipolar  with much less distortion and very low harmonics and much smaller inductor needed and more efficient. I guess its easy to see why.
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 08, 2021, 09:14:27 pm
Nice explanation LH. Like you say an inductor resists current direction changes. It is a challenge when trying to switch the inductor current in reverse as the inductor stores energy in the core and the back emf can be pretty horrific.
The designers must have some way of dumping that back emf safely or the mosfets would just go bang.
I am guessing the mosfets are turned off just in time to soak up the inductors stored energy before reversing the output.
Beyond me how to design that, I just fix things when they break. As long as they once worked then fixing them is possible with patience.
Nice thread some great info here
thanks
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 09, 2021, 05:08:43 am
" It is a challenge when trying to switch the inductor current in reverse as the inductor stores energy in the core and the back emf can be pretty horrific."

Yes indeed, once the FETs are switched on, the inductor is now connected opposing the source voltage and the stress is  between the inductor and the source, so the current is braked and excess inductor power charges battery or capacitor bank rather.  Thus one of the reasons for the much larger low esr capacitor bank in the bipolar inverter.  Its not horribly inefficient because energy is not wasted but theres a lot of whiplash creating distortion that the filters need to remove. One of the reasons Oztules inductor modification helped efficiency. Id like to assume the added inductor increased the life of the FETs as well. The working inverter in some ways is similar to a combustion engine where timing and counterbalance are extremely important to the smoothness of the cycle and longevity of the machine.
Title: Re: No brand/5500W inverter disaster porn
Post by: rossw on May 09, 2021, 05:29:45 am
Like you say an inductor resists current direction changes.

Clarification. It's not changes in DIRECTION.  It's simply changes.
If you try to go from 3A to 5A, (no change in polarity) an inductor will resist it.
If you try to go from 20A to 15A, an inductor will still try to resist it!

It's the change (variation) in magnetic field that is the effect at play, not a complete reversal.
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 10, 2021, 10:58:54 pm
Hi rossw! Thanks for pointing that out. I'm still puzzled as to why the 8010 unipolar has less voltage building ability, almost seems like it must be a software limitation since its the same hardware circuit. Yet unipolar is described as switching between +V and 0 wheras the other is +V and -V perhaps thats the difference.

Ive also noticed one other major benefit to this unipolar inverter. We have a 3.5kw grid tie connected to two arrays, most days that thing is pegged out at 3650W, its programmed to skip one AC cycle every second and monitor the grid its connected to. This (skipped cycle) would always cause the lights to flicker every second. Now with the unipolar there is no flicker. Also when the wife would use a space heater on low, ( uses 1 diode for half wave) the grid tie would go offline. Now with this 8010 unipolar, the heater can be on low using 750 w of lopsided load and the GTI is fine with it. So i guess the wave accuracy and low distortion claim is true.
Title: Re: No brand/5500W inverter disaster porn
Post by: rossw on May 11, 2021, 10:55:36 pm
You might find http://www.ijirst.org/articles/IJIRSTV1I7111.pdf (http://www.ijirst.org/articles/IJIRSTV1I7111.pdf) to be useful...
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 23, 2021, 08:29:07 am
Yes, good article! not new information compared to others i had read but very informative nonetheless. I was hoping to find one that states unipolar has max output voltage .64VDC vs bipolar maxvout of .73vd.  Instead of stating the relationship between vd and vout vs switching type, they do infer the concept by pointing out the unipolar driven Hbridge drives the load between VD and 0 while the bipolar Hbridge drives the load between +Vd and -Vd. I suppose most who read such articles dont need it spelled out any further :) Ha! Eventually i will test and prove the theory but havent as yet.

I must clarify something i said earlier though. I mentioned something to the effect of unipolar inverter is more reliable and less prone to failure than bipolar counterpart. While i still think this is true, I havent proved it, its only a guess based on the switching emf. It turns out, the reason my bipolar pwrjck bit the dust a while back was because of a failing transfer relay. Not the inverters fault. If we get two consecutive cloudy days i have to switch over and though i synchronize the two sources before a switch. I have on occasion pushed stop button on controller which transfers all without regard to phase alignment.  Thats a fatal error, it wounded a relay and later caused the failure. I am thinking instead of transfer scheme. I can get an even better seamless solution by grid powered charger to 48v battery at about 1kw set to come on at some min battery V. I have an old transformer and rectifier with caps from a plasma supply that will work perfect. Not quite as efficient but zero risk of inverter failure from a relay. How do you guys do this? I know those with gensets just charge the battery but wondering if anyone else uses transfer relays and have inverter failure because of it. Seems like a cool idea but i cant recommend it. If someone insists on it i would say make sure your relay has 1/8" between poles and never switch without synchronizing.



Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on May 23, 2021, 02:25:03 pm
https://www.ebay.com.au/itm/ARC-220Amp-Stick-Welder-DC-Inverter-MMA-Welding-Machine-IGBT-Portable-10A-Plug-/272834881672?_trksid=p2349624.m46890.l49286 (https://www.ebay.com.au/itm/ARC-220Amp-Stick-Welder-DC-Inverter-MMA-Welding-Machine-IGBT-Portable-10A-Plug-/272834881672?_trksid=p2349624.m46890.l49286)

One of these with a couple of extra turns on the secondary side of transformer... again, OZTULES brilliant idea,  current controlled and everything... Ill try and find the thread later if you want
Title: Re: No brand/5500W inverter disaster porn
Post by: rossw on May 23, 2021, 04:11:03 pm
though i synchronize the two sources before a switch.

Quote
I have on occasion pushed stop button on controller which transfers all without regard to phase alignment.  Thats a fatal error


Quote
How do you guys do this? I know those with gensets just charge the battery but wondering if anyone else uses transfer relays

I'm not using PJ or similar (no insult intended) "low end, very basic" inverters.
My scenario is using commmercial "generator-interactive" inverters. When transitioning to generator mode, they initiate generator start based on various conditions (but typically SoC or DC volts). When generator input is detected, the inverter drifts its frequency to match the generator over a second or so, adjusts its output voltage to match the generator, and then drifts its phase to match the generator. When all three are "very close", a large contactor pulls in to join generator output and inverter output together with the load.

The inverter can then gently adjust its voltage/phase to gently transfer the output load to the generator, and indeed can go a little further to start pulling power from the generator to charge the batteries (using whatever headroom is left). Similarly, it can change it's output the other way to assist the generator allowing the pair to drive loads larger than either alone can.

When disconnecting, the contactor simply opens and 100% of the load is supplied from the inverter.

I've never had problems transferring to or from generator, the relay doesn't introduce a break (even briefly), and can be of a simpler "normally open" construction rather than change-over.

Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 24, 2021, 06:19:38 pm
Ross, thats high tech. I didnt even know they made one like that. Very nice, probably higher end than i'd wanna go. I know, buy cheap and pay more later... :) can be very true. I think for some of us at least, grid power is so cheap its really hard to justify high quality equipment. Either way you do it, even if it costs more, its worth it to run RE equipment. My minor misfortunes havent cost much more than fets and drivers in most cases and provides plenty of hobby adventure along the way! Ha! probably why some of us are here anyway is the fun of making your own mistakes.

Ihad the parts for a simple charger so i put together yesterday. 12Amps at 49v 17A at 46.5V, this will do just fine and no more switching. I considered the option years ago, being an efficiency nut i hated to down convert and then upconvert when its already there, not a big deal though if you rarely use it. 

Noneya, i have two inverter welders, i just like em too much to repurpose. Great ideas though! thanks!
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 25, 2021, 01:42:55 am
As we are totally off grid, I use a motor/alternator for charging my batteries on the very rare times we don't get enough sun.
Now that I have upgraded to 24 volt batteries I will get a 24 volt alternator to fit to the motor.
Years ago I used two alternators in parallel to weld with , they worked great but the noise was bad from the motor.
Firing up the inverter welder off the solar is so much more conducive to a peaceful time welding.
On another note.
Do any of you good gentlemen know which parts to delete on the powerjack inverter to get rid of the charger section.
I would like to tidy up the box and get rid of extraneous parts.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: rossw on May 25, 2021, 06:00:04 am
for some of us at least, grid power is so cheap its really hard to justify high quality equipment.

Some of us live 100% offgrid, with no practical option otherwise.
When you have a family to keep comfortable in todays high-tech, over-connected world, and your income is entirely from IT-related persuits, unreliable power simply isn't an option. Lose power, you don't have water pressure, you can't get in and out of the building, you can't even flush the loo, much less do the income-generating work that keeps food on the table.

In these circumstances, unreliable equipment isn't a mere inconvenience. You can't just "flick the switch and use the grid". It really is critical to our way of life, so the extra effort (and cost) is really "insurance".
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 25, 2021, 05:34:23 pm
Hi Ross, I agree with the practicality of having good gear. We live off grid, we did have grid power when we moved to our mountain but got rid of it and cut the poles down.( they make good gate posts). The grid here was unreliable and expensive.
I have one good inverter that is the spare ( an Australian made Latronics) and use a PowerJack as the main inverter.
I now have another Powerjack too that I bought as a dead inverter and repaired.
I have overcome my fear of surface mount components, but still prefer through hole ones.
I have set our place up with backups , got rid of the Pressure pump for water, and put tanks on the hill above the house so gravity supplies the water for a few weeks if the transfer pump dies.
Fortunately I have retired so there is no need to have electricity to earn money.
It is hard for me to come to grips with spending too much on power as I  have had solar now for 40 odd years and have gradually got bigger and bigger systems. I have never had the spare cash to spend on really expensive inverters. I can see the value in them reliability but fortunately having skills and spares helps.
Cheers
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 30, 2021, 08:48:12 pm
Some of us live 100% offgrid,

Yes, totally understand, Ive no doubt i would do the same. It why i used "some"  Im so spoiled my dad grew up without electricity till the 40s.

Speaking of expensive equipment, theyve now changed the code here in US to require PV mounted to buildings to rapid disconnect to 80v in 30 sec within 1 foot of the array. I use panasonic 400v relays for my strings. A solution might be move relays from inverter box to the arrays but they also have a sentence stating "all rapid disconnect equipments must be listed" i dont know if a listed relay in a listed weatherproof box is ok or not but i ordered a listed remote switch to be on the safe side. Youd think they would give you the option of running array wires in schedule 40 pipe. ;D (i doubt fireman ax would go through it.) Its good stuff but a challenge to keep everyone happy.

Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 31, 2021, 01:46:51 am
Hi LH, what you describe sounds like what we had here. Here the regulators decided that every solar array had to have a disconnect switch on the roof. The problem was not may fire people want to climb onto the roof to turn the switch off. In the event of a solar panel fire climbing up to turn the switch off sounds pretty precarious.
One other problem is that many of the switches were not up to switching high voltage and current DC and they caught fire.
So one so called solution became a problem that is still being looked into.

Just wondering with your inverter board ( the aliexpress one) did you have to make any modifications to it to get it to be reliable.
I am in the process of building a ground mount for another 2kw of panels so after that is done I will look at the inverter board that I bought and see how it works.
Cheers
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on May 31, 2021, 04:39:14 am
Hey Pete,I did do the current disable Nonya referred to a few posts back. The people who designed the board might have found a way around the issue i cant say for sure. It did work fine without the mod though. Seems like they had the low voltage shutdown already set somewhat close. I never touched it but i did set my low volt shutdown a bit higher so it would never use on board one. The reason i didnt care for theirs is it automatically retries in a few seconds. Doesnt seem to give up either. The last thing you want is to shut compressors off and on repeatedly. :P
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on May 31, 2021, 05:18:00 am
https://www.anotherpower.com/board/index.php?topic=1116.15 (https://www.anotherpower.com/board/index.php?topic=1116.15)

At least do this one as OZ describes... remove/bypass the 393... check all caps as well...
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on May 31, 2021, 05:19:32 pm
Thankyou LH and Noneya, I will check my board and if it has the LM393 will do as suggested.
Still a way to go with my new panels.
Next step is to dig a 40 metre trench for the cables to get to the shed and regulators.
The only problem I have here is that whenever I dig a hole I have to remove rocks twice the size of the hole I want.
The joys of living in the mountains with lots of beautiful boulders around.
Thanks again
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: rossw on May 31, 2021, 08:58:43 pm
whenever I dig a hole I have to remove rocks twice the size of the hole I want.

You should write a book.
"DIY Trenching with detcord"
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on June 01, 2021, 02:34:41 am
Good idea Ross. Many years ago when the world was a simpler place, I went and bought some gelignite. I was digging a well on my land in Southern NSW and hit rock at 3 metres down. So the shovel and crowbar were very slow then.
I had to go to the police station to get a permit to buy explosives, well a few simple questions later I had my permit.
Strangely enough one of the questions was " you are not going to do anything illegal with it are you?"
Now I did wonder who would answer yes to that and expect to get a permit.
Well blasting was hard too, as I had to make the holes for the gelignite with a hammer and a star drill, slow work.
These days explosives are not so easy to get legally .
So this trench will be built with the same idiot sticks ( shovel and bar) that the well was dug with.
Seems that 46 years has not taught me much about hole digging. Time passes, some methods stay the same.
Cheers
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: rossw on June 01, 2021, 05:56:34 am
I was digging a well on my land in Southern NSW

Where in Southern NSW? grew up in Young in the Riverina, and have been in Albury on the NSW/Vic border for the last 45 years or so.

Quote
So the shovel and crowbar were very slow then.

Alas, they were then and still are now.
I have a hydraulic post-hole digger which was a great idea, but 2/3 of the strainer posts we needed still hit rock and needed the bar to get far enough, and far too many of the roughly 900 trees we planted had to have their holes dug in a second or third spot to avoid rocks.


Quote
So this trench will be built with the same idiot sticks ( shovel and bar) that the well was dug with.
Seems that 46 years has not taught me much about hole digging.

I recently bought a small (1.2 ton) excavator to go with my old bobcat.
Next trench I hope will be far less taxing on my tiring bones and muscles!
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on June 01, 2021, 06:05:55 pm
Hi Ross , I grew up in Sydney, but moved to St Georges Basin near Jervis Bay when I was 21. I bought 10 acres there then and lived there for 5 years. After a long stint on the NSW north coast I moved and now happily live in Tasmania. (where we have seasons).
I did have a powered post hole digger at my last property in Tas, but it would not work here. We live on a mountain that has boulders of Grandiorite everywhere and above us the rocks change to Dolerite. Powered post hole borers just end up in a wild ride in this country.
Would love an excavator but not enough work for one, and I don't like the damage they do in the hands of the inexperienced.
That would be me and most of the people I know who own their own machines.
So as I am still young (66) it is idiot sticks for me.
I have nothing but time anyway.
Cheers
pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on June 13, 2021, 08:29:48 pm
Hey guys!  I have some new? 245w panels i want to put on a tracker i havent built yet and watts are wasting so since my main 2 channel grid tie is no longer maxed out at 3600 because of the heat its running at 2560w in the hottest parts of the day, i thought i'd add a few (5) of the panels to one of the arrays.

I started by measuring the mppt voltage at 255v and current at 6A. Then i added 5 245w 60 cell panels which shouldve bumped voltage up to 380v (30-5v each for heat=25) and current relatively unchanged. That isnt what happend. The grid tie mppt somehow choose to run it at 428v and 3.5A to 4A.  The gti output went from 2560w to 3200W so output improved but not like it should have.  I saw it at 3600 even a couple weeks ago when it was cool. The other string was running between 6 and 7 amps at 210v today and the currents are usually similar.

So im guessing its because i have a mixed group of panels in a string but its wierd ive never had that issue before. I was gonna throw on a different grid tie inverter to see it missed the correct mppt voltage like this one but it wouldnt turn on... frequency fault. Now after all the rambling... the relevance to this thread. So the 8010 48v inverter in the original post is making sine wave at 60.2hz. Kinda odd, i knew it was slightly off because my phase align detector relay switches on and off like every 3-5 seconds and the pj i used to use took over a minute sometimes 5 minutes for the phases to align meaning the frequency was matched to grid very close.

I dont need to change this immediately but i will at some point, guessing the 0-100hz adj mode would be easiest, i also thought about adding a cap to the crystal to slow it down a bit but might make it less stable.

So has anyone else had an mppt lock in at the wrong voltage? I tried dropping panels out one by one, nothing resolved it. I even checked max current of the entire array which was over 7 amps proving all connections were good and every panel was carrying current.  *edit* i realize somethin about the numbers dont add up. The current shouldnt have dropped so low though which i think indicates a problem.

Hope everyone is having fun and enjoying the sun :)
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on June 14, 2021, 03:39:55 am
Hi LH , my take is that it will depend on the current that the new panels are able to produce. Their maximum current will be the maximum current in the string,
I don't have a grid tie so don't know how that stuff works, I tend to mix panels by wiring them to separate regulators in parallel.
That way I can mix different string voltages and currents.
Then my regulators only handle 100 volts max and 50 amps out. So that is my limit on each string.
There is a possibility that you have a high resistance joint on one of your connectors, if you are using those plugs and sockets that the panels come with they can sometimes not be seated properly and not make good contact.
Hope you find the problem
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: dochubert on June 14, 2021, 12:18:38 pm
Hi guys,
I think Pete may be right about the new panels limiting your max string current, making the mppt voltage go up instead.  What's the current rating on the added panels versus the current rating on the original panels?  Just guessing here but sounds similsr to what happened to me adding panels to my grid tie string back in San Diego.  In my case the panels I added were higher wattage but output didn't increase as much as I figured.  Don't remember what the actual numbers were, but the results of adding dissimilar panels was disappointing.
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on June 14, 2021, 06:48:52 pm
Yeah, i agree, I need to split the new ones into their own group. Since they are 60 cell i can move them to another spot that already has 2 strands awg6 or 13.3mmsq wire and direct connect to 48v battery, others have mentioned this works well. Im wondering aboutthe heat compensation. 2 x 30v panel -5 each for heat = 50v mid day max pwr volts. Battery volts is usually 54-56v mid day, wont that hurt output? Lets see, 50 vs 55 is 2.5v above max power per panel. String configuration error is 428v - 380v = 48v ÷ 16 = 3v mpv error per panel. Both errors are same direction. Maybe i better get busy like Pete an build the array rack n pivot an put all 12 together an see if the inverter can find the 340-360v sweet spot. All the fancy mppt stuff i wish they were just designed to adjust array volts manually with a temp compensation. Thanks guys!!
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on June 14, 2021, 10:29:14 pm
Hello again LH. Remember that the voltages on the panel label that relate to maximum voltage at full power will change. As the load decreases the panel voltage will rise towards the open circuit voltage.
I have never seen my panels at full output. The sun sneaks up and the panels start to charge the batteries long before the full sun gets on them. So the regulators are throttling back well before the panels are putting out their maximum power.
I think you are on the right track with splitting up the odd panels. From the labels they seem to have very different specs.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on June 14, 2021, 11:08:59 pm
Here are a couple of pictures of my new panel rack. We get very strong winds on the mountain so it is (hopefully) solid enough.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on June 16, 2021, 06:19:01 pm
 Beautiful work Pete! It would take a lot of wind to bother that mount! Looks strong, you got some good materials and fair bit of work into that project. Guessin you have a reason they are off the ground a bit. My solution to wind is to be back against a grove of trees and the front down low so wind cant get much lift. We have deer but so far they havent run into my panels. Seems like someone here mentioned Emu can be troublesome.

Keep up the good work! It pays off, i know i sure enjoy a good hot shower from solar heated water each morning!
Title: Re: No brand/5500W inverter disaster porn
Post by: dochubert on June 16, 2021, 07:45:23 pm

Pete!
That's an awesome panel mount!  Stronger looking than a lot of buildings.  In fact you could probably close in the front and back, put a door on the end and use it for storage! :)
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on June 16, 2021, 07:55:00 pm
LH ,No Emu here but we do have Wombats ( think miniature bulldozers). Wallabies and Possums abound here too, but the Wallabies don't climb and the possums are too light to do much damage. Also being off the ground allowed me to easily clip the wires along the wood frame. The panels are off the ground to stop them climbing on them and to ensure that I don't have to keep brushcutting the grass that is in front of them too often.
There are trees and bushes behind the water tanks to the West and South (which is where our strongest wind comes from) We regularly get winds up to 100 klm in winter but our house and where the panels are is protected a bit.
I usually over build, I only want to do a job once if possible.
Hi Doc , I just saw your post. Yes I did think about that, but I have enough storage space and yep I basically built it to the standard a small building would have.The rocks are so big here that pulling one out of the ground required a winch, and a friend levering it up at the same time. Some of the post holes had to be moved a bit to miss rocks that I could not get out. The joys of living on a Granite mountain. We love it here and are not planning on leaving, except in a box
Cheers
Pete
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on June 27, 2021, 10:51:20 am
Good morning guys, I wanted to update the solution i had questions on in post 63 "string of various brand panels running wrong max power point for the mppt channel" The grid tie mppt channel was targeting 428v at 3-4A. The whole inverter was maxing out at 3200w in full sun with two strings. (the other string output normally runs 1750w by itself)

A week ago i got a new grid tie inverter and needed to test it to make sure i didnt get a lemon. So i moved the low amp problem string to the new inverter and wow what a difference. String volts went to about 400 and output from that string alone was more than both strings were putting out on the other inverter. This at 10:30 am with a 30 deg light angle err.
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on June 27, 2021, 11:14:16 am
No doubt cloud edging was involved with that kind of power
because i think the panel string only
adds up to 4kw.

In addition the other inverter was still running other string at 1350w.

So thats a pretty big improvement by switching mppt volts.

Like i said, those numbers hardly add up, (why i attached photos) im sure later today when the clouds clear and it heats up the numbers will be more realistic but the point is, an mppt can choose the wrong numbers and its worth a check. Ive no doubt the other inverter has nothing wrong with it. It just somehow chooses the first power peak it sees without sweeping the range.
While troubleshooting I thought maybe im overloading it causing it to choose an incorrect voltage to manage power but no sir, i even removed the other string and removed a few panels from string. The real problem of course being mismatched panels but sometimes thats all weve got to work with.
All in all was very happy with result and happy inverter worked!
 
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on June 27, 2021, 11:55:44 am
 Those numbers are wonky. I knew something was up but still very confused why they would display REACTIVE power on a grid tie display meter rather than REAL power. evidently, this is one of those fancy power factor correcting inverters and it doesnt like my phase angle and is trying to correct it...

I thought of deleting the previous posts out of embarassment but maybe its good for humor.... or drama.... if your into that kind of thing. So am waiting for the clouds to clear so i can measure current and volts of the array to give me actual real power HA!
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on June 27, 2021, 12:18:25 pm
These are the ACTUAL values, seem to agree with my clamp meter too.  So 398v x 9.5A = 3781W from the array. The rated stamped values are 16 panels 5x250w + 5x200w + 5x245w +
 1x320w= 3795w rated and 10 of those panels are 5 yrs old.
Still illustrates the mppt tracker on the other inverter was a problem. Not the only one of course.

The power meter on the new inverter sure is misleading. What are they tryin to impress somebody??? Yeah yeah sure fooled me ::)

Oh well as long as it works and hey it can correct all the problems it wants with the power im all for that!!

Cheers hope everyone is doing well!!
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on June 27, 2021, 05:51:30 pm
Good to hear that you have sorted it out. Seems that creative accounting spreads to other situations too.
I guess that the manufacturers are trying to copy Volkswagen and fudge the figures to sell more inverters.
Cheers
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on August 12, 2021, 06:54:58 pm
Update,   there has been a bit of discussion about disabling the overcurrent protection on the egs002 board (which is used on this inverter).  The reasons for disabling were to do with poor shutdown control when triggered sometimes resulting in blown FETs. The disable procedure i think went something like, remove 393 SOT and jumper pad 1 to 4 and short  pads 7 to 8.

If you find that procedure difficult to maneuver and really dont want anything to do with current limit there is an option. Just snip or break pin one (IFB) off of the egs002 board and plug back into its edge connector taking care to line up with original hole positions and your off to the races, no overcurrent trouble to worry about, use fuses or breakers.

Why do i know this and why did i do it? 

The voltage feedback uses isolation transformer which insulates control circuit from any ground loop problems that might influence the sensitive voltage control circuit. If you omitted the tiny Vfb isolation transformer you would have all kinds of miserable problems.

The IFB doesnt have a means of isolation, (though you could make one) my system developed a problem where the overcurrent protection would trip out at random. When this happend it would shut off power to the house and my controller would switch to grid then after 16 sec the inverter would start up and do it all again. There is a small delay like 44/100 of a second for an unplanned power failure transfer this of couse isnt friendly to some appliances. Too much info i realize but you get the point. Having your main battery inverter switch off randomly through the day isnt good. I tried figuring out the real source of the problem, finally thought i nailed it when i noticed it occured instantly when relay contact closed for array 1 to grid tie 1. Great i thought now i have it cornered. Very little rain this summer but i noticed this problem only occured after a rain. So i grab a meter thinking the array has high voltage leaking. A 10mohm input meter showed 6v max of leakage between either hv terminal to ground. Scratching my head i thought, i dont need the power right now, ill just leave the array unplugged. Believe it or not that afternoon the inverter did it again even with the offending array unplugged. So id had enough, had wasted a good 4 hrs, had pulled new wire in underground conduit to the array etc. Shut power off to everything, removed board busted pin off, plugged back in and hasnt been a problem since. I might do something with an optoisolator later but for now i like it. I dont think overcurrent shutdown ever saved mosfets from a screwdriver across the output leads anyhow but could be nice if you use yours to capacity. Mine usually only runs at 1/2 capacity.

Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on August 13, 2021, 05:42:15 pm
ok, removing the 393 does NOT remove over current control,  it gives it BACK to the eg8010 chip... the 393 was causing problems with blowing mosfets in oztules inverter ( and others including mine ).  it was as oz explained fighting the eg8010 current control ( which works perfectly fine) as it would " trip " in a instant and re-enable too fast, which with a tight toroidal transformer means certain death for primary mosfets as it introduces a non-constant waveform..  why he ended up building his own board to start with.

the eg8010's current control is VERY good, shuts down smoothly and never caused issues,  again with oztules and others ( including mine), as it takes its sample from the negative DC side there should be no " earthing " issues like the VFB side ( as that is sampled from the AC side) .. oztules thread on these boards is a treasure trove of information that is worth the read if you are interested, he explains things so much better..
Title: Re: No brand/5500W inverter disaster porn
Post by: lighthunter on August 13, 2021, 07:18:07 pm
"ok, removing the 393 does NOT remove over current control,  it gives it BACK to the eg8010 chip... the 393 was causing problems"

Correct, i knew that and wrote it wrong.  Thanks for the correction.

As for isolation, my HV arrays are both ungrounded but to troubleshoot this i tried grounding both of them neg to earth. Didnt help. The battery + and - are floating not earthed but they are connected to a low V array which could act like an antenna. Ive no idea. I know it is an isolation problem but was not able to resolve in any way. So removing pin one helped me out. The only reason i  refered to the removal of the 393 is because deleting pin one of egs002 will solve that problem too but you would loose current shutdown wheras removing 393 doesnt. For some of us old fellers messing with surface mount stuff and ending up with a working board is quite a challenge.



Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on August 13, 2021, 09:36:36 pm
Hi LH, I get what you are saying about surface mount boards. I have take two of the 393 chips off my 8010 boards, In the end I used a sharp knife and prised one leg of the chip off at a time while heating it with the soldering iron.
I tried first using solder braid but that did not take enough off to allow the chip to lift easily.
So reverted to mechanical force and heat.
So far the inverter I accidentally blew up is working now. The only odd thing is that to get the relay to pull in I have to short pins 1 and 2 of the op amp, then once the relay comes in all is good. I can turn off and it will start fine as long as I haven't disconnected the battery supply.
So I will run it for a while and see if it keeps behaving.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on August 13, 2021, 11:04:01 pm
another good way is using a  Stanley blade , cut hard against the 393 chip body,  both sides so actual chip falls away... then just use a blob of solder to remove " legs " ...
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on September 04, 2021, 02:04:32 am
I have two of those Aliexpress type 8010 boards now. I used two transformers that came from an 8kw powerjack. One for each inverter.
Just wondering I have read that it is really important to get the right size inductor for the transformer to prevent blowups.
Both the transformers I have, used a torroidal core with a couple of turns of the primary winding around them as inductors.
Have any of you people who have used these boards had experience with inductors and do you know if the PowerJack ones are OK to use.
So far the inverters appear to be working fine, nice sinewave but I have not tried any massive loads on them yet.
I wanted to know that there is a fair chance that they won't blow up before I went for the full load tests.
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: noneyabussiness on September 04, 2021, 06:53:42 pm
reading Oztules thread, the pj ones were fine... however Warpspeed has improved on em dramatically by other peoples experience...
Title: Re: No brand/5500W inverter disaster porn
Post by: Pete on September 04, 2021, 09:35:01 pm
Thanks Noneya, will read up on Warps inductors
Pete
Title: Re: No brand/5500W inverter disaster porn
Post by: solarnewbee on October 25, 2021, 06:50:54 am
Recently installed A Sunyima labeled 8010 based unit with lcd that allows settings from a menu if you get there fast enough before the screen whites out. 2 trim pots on the board without a clue what they’re for. Definitely not for voltage out. I connected this to my old 15kW 30v transformer and got 201v. I was able to raise that to 227v to match the grid thru on screen menu so no voltage surge or drop when switching ATS.

This same transformer on the PJ boards was a lot louder. This thing is really quiet. Seller was useless but did gave a hookup diagram in the ad.

You’ll notice on the board right side there are 3 connectors, one has a plug with 2 wires and they are tied to voltage output from transformer. Without that feedback it goes into error. Next connector up has .47vdc maybe 4.47vdc can’t remember at the moment . Hoping it’s a standby power connector. Further up is a 12vdc connector and assuming it’s for a cooling fan.

And a pic of a an SSR ATS that works! My PJ didn’t like and blew up but probably was my bad coding. This has been re-wired right to left with the theory that zero cross may block the triacs from being forced open?

Title: Re: No brand/5500W inverter disaster porn
Post by: solarnewbee on October 25, 2021, 10:00:57 pm
It occurred to me suddenly to check the hertz rate,(slapping forehead rapidly) and of course it’s 50hz not 60 and I’ve no idea how to change that. What’s going to fry in the house if anything. Some things just adapt others just doesn’t matter but I’m not well versed in hertz. My Sony tv is versatile in that sense but my fridge is 120vac 60hz on a step down xfmr. The pots have no effect. Any hints? I have read this thread but must have missed it or need to read a different thread.

If I hadn’t mentioned before, I left the high voltage AC board in place to allow it to filter and make use of the lcd’s on the front panel. I took a 12vdc wall adapter and attached to the ribbons cable to power the lcd’s and voila! All the info I need according to PJ algorithms.
Title: Re: No brand/5500W inverter disaster porn
Post by: solarnewbee on October 25, 2021, 10:43:08 pm
So I found the answer thru Pete and Aliexpress. It’s jp1-60hz jp5-50hz

Thanks Pete!