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Repair of Axpert Inverters : A Journey Started

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HI  @Coulomb

I HAVE   list of  some  vital  question   hope you can  satisfy  my curiosity   

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1-from relay configuration of  solar inverters  i can see  that  ac  grid  is some  what conncted to  outut  of  the inverter 

this  should  explode the igbts  so  i assume that  synchronization process  happen  between ac  grid  and ac inverter?

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2- too many sps   configuration  but mainly  it can be like that   bttery operated smps that produce 160vdc  which can be diode ored  with 300vdc  of ac grid to fed both    main sps 12-12+5  and soft start  

 

or   in the second  configuration  

ac operated sps  that  produce 160vdc and battery voltage  both can be  diode ored to  spftstart  and mains smps 5+12-12??

----------------------

3- the soft start  circuit function  is to  fully  charge caps  at 370  or just partially?? how error 09  can be generated

low  bus voltage  or  no buss voltage or good bus voltage that have not  reached the target in the specified time!?

-----------------------

4- in the shot  uploaded  some windings  of the driver  are  not   refrenced  to the mosfet's   source  which they drive    ?

------------------------

5-  i read in a  book  there are  igbts  that used  for  zero current switching?  other  say there is  sorts of  active  snubber circuits  in solar inverters ? is that true?

----------------------

-6  some manual  says  some thing about discharge ciruit   is that same  as  the buck igbts  which mainly  used for  controling charging process or there is another  discharge  circuit  ?

-----------------------------------

 

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Edited by wael_fathe

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    Yesterday I nearly decided to stop my journey , pack my solar suitcase, delete my forum account, and walk off in the sunset. I have done so much homework in order to leave very little if any to t

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On 2023/03/17 at 10:40 AM, wael_fathe said:

1-from relay configuration of  solar inverters  i can see  that  ac  grid  is some  what connected to  output  of  the inverter 

this  should  explode the igbts  so  i assume that  synchronization process  happen  between ac  grid  and ac inverter?

Yes. The inverter synchronises with the AC-in (when present) even if it doesn't need to right now. That makes for a smoother switch to utility powering the loads if needed.

Quote

 

2- too many sps   configuration  but mainly  it can be like that   bttery operated smps that produce 160vdc  which can be diode ored  with 300vdc  of ac grid to fed both    main sps 12-12+5  and soft start  

or   in the second  configuration  

ac operated sps  that  produce 160vdc and battery voltage  both can be  diode ored to  spftstart  and mains smps 5+12-12??

 

The power supply configuration seems to vary a fair bit between models.

For all models, there is a "main" switching power supply that produces ±12 V and +5 V. This gets power from various sources. Sorry, that's all I know on that one. Perhaps @BritishRacingGreen could add?

Quote

3- the soft start  circuit function  is to  fully  charge caps  at 370  or just partially??

There is a calculation for what the minimum bus voltage to aim for. So it's not a fixed number like 370 V; it depends on the battery voltage, the transformer turns ratio, and the AC-in voltage if present.

Quote

how error 09  can be generated: low  bus voltage  or  no buss voltage or good bus voltage that have not  reached the target in the specified time!?

If the bus voltage doesn't reach high enough in a fixed period of time, fault code 09 is issued, but then the soft start power supply is turned off, so you would not get the second case.

Quote

4- in the shot  uploaded  some windings  of the driver  are  not   referenced  to the mosfet's   sources  which they drive ?

They certainly should be, and I see that there are some problems with the traced schematic. Thanks for pointing that out. Hopefully I can fix that later today.

Quote

5-  i read in a  book  there are  igbts  that used  for  zero current switching? 

I believe that's "soft switching". As far as I know, the Voltronics circuits are all "hard switching".

Quote

others  say there is a sort of  active  snubber circuits  in solar inverters ? is that true?

Sorry, that sort of design knowledge is outside my area.

Quote

-6  some manual  says  some thing about discharge circuit   is that same  as  the buck igbts  which mainly  used for  controlling charging process or there is another  discharge  circuit  ?

I think when they say "discharge circuit" they mean the DC-DC converter (MOSFETs, transformer, and DC-DC IGBTs). The buck transistor (only in very early models was this two transistors in parallel) is only ever used for utility charging in low-voltage PV models, but also for solar charging in high PV voltage models. So it's never "discharging", unless you consider charging the battery to be discharging the DC bus. When the power flow is away from the battery, I believe that the buck transistor is turned on solidly, reducing the voltage drop across its free-wheel diode and thus saving a little power that would otherwise be wasted.

  • Author
On 2023/03/18 at 4:48 AM, Coulomb said:

For all models, there is a "main" switching power supply that produces ±12 V and +5 V. This gets power from various sources. Sorry, that's all I know on that one. Perhaps @BritishRacingGreen could add?

The inverters that has so called batteryless mode, can be powered by both grid input and/or pv in the absense of battery power. 

On the MAX family there is only battery supply for the SMPS on the main board. But in addition to this there is a seperate SPS module. This module features two switch mode power supplies, one for grid input and one for MPPT. The resultant isolated 60VDC outputs are wired-or and connected to the main board where it is wired-or again with the battery 48v dc. 

I am not sure how this is accomplished on the MKS3 and MKS4, maybe on the large flat MPPT board, but thats just a wild guess. 

EDIT :  the pv path does not require the activation via on/off button, it will bring the machine up regardlessly, of course given enough pv power to do so. This has the disadvantage of early morning sunrise chatter of the relays/power supply. But then again I dont think people are using the machine in pv only mode, as a single power source. 

 

Edited by BritishRacingGreen

  • Author
23 minutes ago, BritishRacingGreen said:

The inverters that has so called batteryless mode, can be powered by both grid input and/or pv in the absense of battery power. 

On the MAX family there is only battery supply for the SMPS on the main board. But in addition to this there is a seperate SPS module. This module features two switch mode power supplies, one for grid input and one for MPPT. The resultant isolated 60VDC outputs are wired-or and connected to the main board where it is wired-or again with the battery 48v dc. 

I am not sure how this is accomplished on the MKS3 and MKS4, maybe on the large flat MPPT board, but thats just a wild guess. 

EDIT :  the pv path does not require the activation via on/off button, it will bring the machine up regardlessly, of course given enough pv power to do so. This has the disadvantage of early morning sunrise chatter of the relays/power supply. But then again I dont think people are using the machine in pv only mode, as a single power source. 

 

Below is image of MAX SPS. Note the two main switch mode power supplies. Both switchers employs the standard Volronics SMPS design built around the UC3845,  the unregulated DC inputs  are in the order of 400vdc, and the output 60VDC. The grid input is merely bridge rectified and smoothed to provide unregulated DC. 

EDIT :the board is fitted on top of the MPPT modules via suitable standoffs. 

 

IMG_20230320_112315.thumb.jpg.e9804efae1ec6ed72ab4665bcc119620.jpg

Edited by BritishRacingGreen

  • Author
20 hours ago, BritishRacingGreen said:

Below is image of MAX SPS. Note the two main switch mode power supplies. Both switchers employs the standard Volronics SMPS design built around the UC3845,  the unregulated DC inputs  are in the order of 400vdc, and the output 60VDC. The grid input is merely bridge rectified and smoothed to provide unregulated DC. 

EDIT :the board is fitted on top of the MPPT modules via suitable standoffs. 

 

IMG_20230320_112315.thumb.jpg.e9804efae1ec6ed72ab4665bcc119620.jpg

This external plumbing to the main board SMPS has the extra benefit of connecting an external variable PSU  with voltage and current limit in order to debug a faulty mainboard SMPS, without the need to power up via the mainboard  battery rail. The latter may still produce too much destructive energy via its large capacitors, even when using psu with current liimit. 

And it also helps to debug battery side mosfet drives, without actually having power on the battery rail. 

Edited by BritishRacingGreen

  • Author

Hi @Coulomb, I had an F57 problem with an OG10 after I replaced a main board. It turned out that during dissasembly, I damaged a tiny 100R smd resistor on control board (🙈). It was open circuited.

After replacing the resistor, F57 was cleared. So it does appear that F57 can also be a function of failure on control card, not only limited to sensor failure on main board. While I had no time to trace the circuit on control card, it does appear that the DSP has a bias circuit that must be satisfied otherwise F57 will be raised. 

EDIT: during the process of debugging, I replaced the OG10 control card and big round display, with an  OG7. 2  control card with old type small square display.  The F57 was gone.  But most interesting is the hardware compatibility and inter-operability of MAX family hardware subsystems.  

It also appeared that the DSP is agnostic of the type of display, as I hooked the OG7. 2 display onto the OG10 control card. So I infer that the comms protocol between dsp and display module is sort of generic. 

Edited by BritishRacingGreen

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1 hour ago, BritishRacingGreen said:

It also appeared that the DSP is agnostic of the type of display, as I hooked the OG7. 2 display onto the OG10 control card. So I infer that the comms protocol between dsp and display module is sort of generic. 

Yes, it's all standard RS-232 commands at that point, just with different pinouts on the 8-oin RJ-45 connectors.

It makes me think again about why there appear to be different display firmware versions for Max E and Max II. But I think that there are subtle differences, perhaps for example the LED ring on the Max IIs may be able to do different effects than the LED bar on the MAX Es. So they would still be sending commands, just a slightly different dialect / command set.

But yes at the comms interface level they are the same.

Interesting, thanks for bringing this up.

This type of content is really Golden!! One thing is to buy an imported product. Totally other thing to know the deep engineering behind such product. 

Living in a place like SA I have realised that one needs to be self reliant. Not reliant on any big company or establishment. @BritishRacingGreenyou are making the Voltronics machine open source to repairs & troubleshooting. Now only if you & @Coulombcould  physically be in the same place hacking these machines together. 

One of these days a Deye inverter & Sunsynk will enjoy this same reverse engineering. Can't wait for that to happen. 

Been great following this thread & I think it will remain a very long lengthy thread of Golden content. 

this ic i fnd near tl494 in normal   inverter   not solar one     manufacture usually use lm358  this one is not  358  can you guess number out of  few  remaining letters?  image.thumb.png.b5506a1ef3d0117dc4affca60316ba91.png

Edited by wael_fathe

On 2023/02/02 at 2:40 AM, Coulomb said:

I'm wondering if we'll see a even more of a spate of these as these cheap capacitors reach their end of life. Though I have to wonder about the other dozens of electrolytics. Maybe they don't dry out as fast because they don't suffer the same repetitive surge currents that the high frequency power supply capacitors do.

Hi @Coulomb and @BritishRacingGreen

I seem to have be the latest victim to this type of failure. I am actually currently in the USA, but my cousin reported the error after the inverter failed and did the whole relay-clicking and blinking LCD screen on attempted start up. Purchased some capacitors and will recap upon my return to SA on Sunday. Your assumption seems to be coming true. I'll let you know if it does the trick or if I find any other issues.

Edited by Trick720
Spelling.

  • Author
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BritishRacingGreen was awarded the badge 'Great Support' and 25 points.

7 hours ago, Trick720 said:

whole relay-clicking and blinking LCD screen on attempted start up

Yep. Thats game over, that one capacitor has ran entirely dry. 

Make sure you procure 105 degree C rated caps. I have, in addition, replaced the 1000uf 16V with 25V rated ones, that also helps. 

Kindly let us know of your progress. 

So, update: I received the capacitors today, and installed them in the inverter.. MIRACLE! The inverter is back to life like nothing happened lol. Can't believe a tiny capacitor can do that. I replaced the two 16v 1000uF ones only as I found it very hard to find any other capacitor replacements. There was visual evidence that the capacitors (C78 and C79) were both goners. 

@BritishRacingGreen and @Coulomb Thank you so much for your valuable contribution to this thread. Saved me from needing to purchase a new inverter just due to two small capacitors.

  • Author
10 hours ago, Trick720 said:

So, update: I received the capacitors today, and installed them in the inverter.. MIRACLE! The inverter is back to life like nothing happened lol. Can't believe a tiny capacitor can do that. I replaced the two 16v 1000uF ones only as I found it very hard to find any other capacitor replacements. There was visual evidence that the capacitors (C78 and C79) were both goners. 

@BritishRacingGreen and @Coulomb Thank you so much for your valuable contribution to this thread. Saved me from needing to purchase a new inverter just due to two small capacitors.

Great news, happy for you, people like you getting value from threads like this, makes it worthwhile to carry on with this journey. 

2 minutes ago, BritishRacingGreen said:

Ok,  take an image of the inverter label on the side of the inverter, and post it. 

And I was just bragging how this guy had worked perfectly for 6 years. 

image.jpg

On 2023/03/26 at 10:52 AM, Steve87 said:

One of these days a Deye inverter & Sunsynk will enjoy this same reverse engineering. Can't wait for that to happen. 

Well @Steve87 perhaps you can donate one or two dead SunSynk Inverters to @BritishRacingGreen so that he can open them and get acquainted....

Hopefully he will not strip out the IGBTs and MOSFETs to use in his Axpert repairs. 😂

  • Author

Update on @Richyv inverter failure. As expected, its the dry capacitor on the 5V regulator input (1000uF 16v).  The esr of 1000uF  on the 12v rail suggest he would been the next to fail. As per esr, no other electrolytic suggest there is imminent failure. This is typical of all 6 machines i have serviced so far. 

Interestingly, the failed caps have been of different makes, and the machhines have been of different brands (rct and mecer)) , so the degrading of esr I can only attribute to ripple current, especially in the case of the 5v rail cap. In the case of the 12v, the operating voltage is also  too close to 16v rating.  Temperature does play a role, of course, but it is a common mode factor, which should affect all electrolytics in close proximity equally. 

Owners of MK2 axperts that has been in service for 5 years or longer, brace yourselves. But good news is the fix is not a major one.  

EDIT: a question that has been posed is wether one should proactively upgrade non compliant (esr) caps  per these models, while the machine is still good. I dont think so, the failure mode does not cause secondary damage, although the symptoms are scary. Fortunately the DSP fails during its startup phase where it start enabling its power to on-cpu subsystems. That increase causes the 5V to sag, so everything else related to the main board is pretty dormant and no harm affected. Or at least thats my theory. Havent had additional failures except the 5V rail failure. 

EDIT :  of course, further to above, one must also take in consideration that the very first failure is actually when the machine is on and delivering power, and the DSP cuts off abruptly. That is ungracefull and could probably lead to igbt / mosfet failure. But this does not seem to happen, insofar the machines I had serrviced. 

 

 

 

Edited by BritishRacingGreen

  • Author

Enters the Infinisolar Inverter 5kVA Single Phase

I have now entered unknown territory , the Infini series. @ChristoSnake delivered the above model for repair.  Nice guy , good to meet . I think he was aware of Germiston roads being terrible , because he arrived with a larger than life Nissan Patrol , absolutely beautiful vehicle , which amongst other amazing things  , he has done several upgrades.  Offloaded the machine , so this gives us the opportunity to try and learn the inner working of this grid tied beauty. 

After opening the bonnet , I am very impressed with the layout and overall quality. Its slightly offending with its presence  , like the Nissan Patrol , because I am so used to the Axpert by now . But here is the beautiful thing   , one start to relate to the machines subsystems as you expect nothing really out of the ordinary. The analogue power train is as expected , obviously all the intelligence lies with the DSP control board , and the latter looks like a complicated beast just looking at it.  Its even got a slave DSP controller , along with the Master controller, ouch , this is @Coulomb territory  ,big time.

Its a double story layout , with the power supplies (SPS) and DC-DC converter on top . In the basement is the large DSP controller board as well as the DC-AC converter (main board). Now this I love to no ends , the DC-DC  and DC-AC all-in-one on the Axpert , but on Infini  they are modular , separated . Interestingly , the high voltage DC bus caps are not on the main board , but separate cluster of capacitors. I would like to know why there are so many ( i think there is  6 or 8  large 470uF 500V caps).

The SPS is your typical SMPS's 12V , 5V -12V  concentrated from PV, Grid and battery.  The DC-DC converter looks pretty straight forward , 2525 PWM controller . Interestingly there is 2 sections in parallel , each delivering 2.5kW.  The mosfet and igbt drivers also onboard , as expected.

I have disassembled nothing so far . Only thing I have done is I tested for short circuit on the battery side , and low and behold , 0.2 ohms !  . So I will be starting with the DC-DC board , which I am  going to remove as a standalone circuit board.  I will be taking it slowly and easy though , but looking forward to  this part of our repair journey .

Circuit diagrams are non-existent , and I don't think @Coulomb has partial schematics . There exists not even a service manual for the 5KW (I see Coulomb has uploaded a 10kW one , which has given me some insight already). But guess what , these are the rules of engagement , and we will see how the knowledge we have gained from other power trains , will help us here .

 

 

6 hours ago, BritishRacingGreen said:

I don't think @Coulomb has partial schematics .

No, sorry.

6 hours ago, BritishRacingGreen said:

There exists not even a service manual for the 5KW (I see Coulomb has uploaded a 10kW one

No 5 kW manual, but I did find an EASun Igrid SS service manual, which I've just uploaded:

The 3 kW model might be closer to the 5 kW model than to the 10 kW model. Good luck with the repair.

6 hours ago, BritishRacingGreen said:

After opening the bonnet , I am very impressed with the layout and overall quality.

The Infinis before the Infini V series so seem to have higher quality, and even somewhat of an overkill. I wondered for a while whether Voltronic might have acquired the rights (or just outright copied) some French brand, whose name escapes me at present; perhaps it was Imeon. With the Infini V series, they seem to be using almost completely identical hardware to the Axpert; in fact it may be possible to convert one to the other (except if you convert it from off-grid to on-grid, you don't have the certifications legally required in many countries). 

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