Repair of Axpert Inverters : A Journey Started

[wael_fathe]

On 2023/03/20 at 2:08 AM, BritishRacingGreen said:

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. 

 

but that  will put 48vdc  on the battery terminal?

the configuration i constanly see is   4 smps 

 

one  for ac 

one  from battery   "battery sps" and it produces voltage that will operate  the mains  smps 100vdc 

one is main smps 12 -12 5

one  soft start 

 

the trick is that battery sps  will  work from  battery produc  100vdc  input for that  main smps  

 

and  in that  100 vdc inpu for  mains sps  is  real  input  for  the entire  system!!!!!!!!!!!!

all other sps  are diode ored to  it  ,            ac sps  and mppt  

if  battery is non existence  or  so low   still  ac sps  and mppt can directly connect  "diode ored  to the 100vdc

input  for the mains  sps  tha  have to work  at all costs for  the system  to  turn on !

 

-----------

 

ofoucrse there are other ways  it can be done  but that mainy the most used 

[BritishRacingGreen]

2 hours ago, wael_fathe said:

but that  will put 48vdc  on the battery terminal?

the configuration i constanly see is   4 smps 

 

one  for ac 

one  from battery   "battery sps" and it produces voltage that will operate  the mains  smps 100vdc 

one is main smps 12 -12 5

one  soft start 

 

the trick is that battery sps  will  work from  battery produc  100vdc  input for that  main smps  

 

and  in that  100 vdc inpu for  mains sps  is  real  input  for  the entire  system!!!!!!!!!!!!

all other sps  are diode ored to  it  ,            ac sps  and mppt  

if  battery is non existence  or  so low   still  ac sps  and mppt can directly connect  "diode ored  to the 100vdc

input  for the mains  sps  tha  have to work  at all costs for  the system  to  turn on !

 

-----------

 

ofoucrse there are other ways  it can be done  but that mainy the most used 

Hi @wael_fathe I trust you are well . I have been quiet on this front for a while , apologies for that ,  and I owe you some answers to earlier posts as well, but lets start here.

The older generations of Voltronics Axpert inverters are dependant on battery operation . Therefore , the only way to power up the inverter's internal supplies is via the battery terminals , regardless if MPPT or Mains (AC input)  power is available.

The MAX range , as well as the later 5kW models are so called Battery Independent. So the system SMPS can be powered up by either Battery , MPPT or Mains (AC input). The MPPTs are therefore self-powered , as opposed to older MPPTs that relied on the host battery to power them. 

Please find below a crude schematic of the various power sources available to the main SMPS input. 

 

You will notice that a seperate SPS power supply board is introduced as shown in green. This board is separate to the main board and it has 3 connector cables.  The Mains input is rectified to create a dc bus and this dc feeds a 60V SPMS that produces a regulated 60V output .  A second SMPS are powered from the MPPT DC feed and also produces 60VDC. Note that the two seperate sources of 60vDC are wired or by the 2 steering diodes. This combined dc output is now fed to the main board (BAT+).

Inside the Main board the Battery+ is  internally routed to the SMPS input via a steering diode , and as you can see this is combined with the composite output of the SPS. 

This configuration allows MAx to operate batteryless. In other word you can generate 220VAC from only PV  if you want to.

So to bring up the MAX system supplies without powering the battery terminals , I merely remove the SPS BAT+ cable , and feed into the main board with my current limited power supply. You can of course power the main board via feeding the SPS that is 'hot- wired with mains input . In fact I have done so originally , but I do prefer to use a current limited bench power supply instead.

 

Below is an image of the MAX 1 SPS board .  On the top right is the MPPT / Solar DC input connector, just below it is the BAT+ 60VDC output that goes to the main board , and at the bottom of the board is the Mains (AC Input) input connector. You will notice that the board real estate is mainly occupied by the two 60VDC SMPSs as described earlier on.

 

 

EDIT : There are some additional steering control that is not shown in the schematic . The battery supply is only available to the SMPS if the  Inverter Switch is ON , while the SPS output powers the inverters regardless of the state of the switch. I think this is to allow PV and Mains to charge a connected battery with the load output remaining off. I am not too sure .

 

EDIT2 : I have never actually measured the voltage of the MPPT input to the SPS . All I can say is that the fly back transformers are identical in product number , in fact both smps's are identical. So I assume that the mppt feeds a dc input in the range of 300-400VDC into the smps , as does the ac input do via its bridge rectifier. But I am getting seriously off-topic now

 

 

Edited November 4, 2023 by BritishRacingGreen

[razmasoom]

14 hours ago, wael_fathe said:

why ?   we inject dc  to the secondery of the smps  ...it  is not going to  fed  back to battery ?

i attached to secondary after diode point and -12v regulator using two external 12v 2amp smps in series to make dual power supply to test the board. Any shorting makes the smps to stop its output. During this i used thermovision camera to look out any shorting component.

[BritishRacingGreen]

4 hours ago, razmasoom said:

i attached to secondary after diode point and -12v regulator using two external 12v 2amp smps in series to make dual power supply to test the board. Any shorting makes the smps to stop its output. During this i used thermovision camera to look out any shorting component.

on the 5kW machines its still easy to inject a single 35v-60v external power supply in order to power the main board SMPS without connecting power to the battery terminals. Have a look at this post :

 

 

so if you connect your external positive via the SCC connector pin 2 , then  it will power the SMPS but D63 diode will block the feed to the battery bus.

 

[BritishRacingGreen]

18 hours ago, wael_fathe said:

this is  probably why  we have   alot of  catastropchic   failures in such inverter ,    in most smps  current mode  control  have  an inhernint 

over  current protection  that will shutdown  smps   soon as   short happen ...they rarely  fail in  a way that blows 

thier   primary side  fet due  to short in output diodes  

 

but  with this  open loop   converter   the  short in secondery will reflect in primary  and blow   fets

the cpu no matter how  fast it still slow  to react to   this   very fast  failures

 

i have  my bench  power  supply  i  remember  shorting positive to negative millions of times

never  fail    ..

I tend to agree with you , there is closed loop control via the dsp but it is slower than a tight analogue close loop control. Further to this there is no dedicated current sensor on the battery side in order to rapidly detect short circuit currents. Wether such an addition may protect mosfets and igbts I dont really know.

[BritishRacingGreen]

18 hours ago, wael_fathe said:

why ?   we inject dc  to the secondery of the smps  ...it  is not going to  fed  back to battery ?

ok it is possible I have subsequently found a solution as described in the following link :

 

 

[BritishRacingGreen]

On 2023/11/03 at 8:49 PM, wael_fathe said:

i mean my question  why  would  any brand of   sg35xx would do  good  with this delay  ...if  fets  on immediately

agree with you here . All I can add is I have seen on most 5kW boards that I worked on , that the two filter components are not fitted.  The one that had it fitted caused severe short on -12V when I replaced the old SG3525 with a new one .

[BritishRacingGreen]

On 2023/10/14 at 12:44 AM, wael_fathe said:

that will make  a  rovolution in servicing this  inverters....  i appreciate your  work ...

a

you observed the current in resitor by observing the voltage  accross it

so   at last you  show  us  gate capacitance "in action"  studing something is  not

as nice as  seeing it    bravo sir 

 

 

you and colomb  made too many inventive  ways to test  all in one  solar inverters thank you guys

but with new designs   as you said  voltronic  now  make cpu  responisble  for  driving the primary fets

and no more sg3525  buiness 

do you have ideas in mind  for the these new designs 

yes , that is the main reason for the pico microcontroller. The DC-AC full bridge must be controlled from first principles via this pico in order to test the igbt switching. In the same manner will I individually switch the DC-DC mosfets and igbts on the new 5kW designs. I am currently developing a command line interface to control the pico controller from a serial terminal .  So you can for example inject a test pulse onto an igbt of arbitrary duration in order to verify that the frequency response of the mosfet/igbt driver is compliant.  So the pico will actually emulate the working of the 3525 pwm ic.

[WilliamH]

On 2022/12/12 at 10:18 PM, Andry91 said:

Guys I don't know if it can help you, I have a diagram of the axpert max 7.2kw model.  There are 29 pages I can't insert them here, write me on whatsapp and I'll send you the file

 

[WilliamH]

Hi Andy91, Ill be intertested? Could you perhapse send it to 0734963212? South Africa

Thanks

[Coulomb]

7 hours ago, WilliamH said:

Could you perhapse send it... 

Already in file section:

 

[kifo]

1 hour ago, Coulomb said:

Already in file section:

 

Hello everyone i got parts from digikey and replace them and after i tried the  battery to wake up inverter but still could"nt recognize battery ,guess i had to precharge first and voila everything started normal working right now as i am typing here thanks for the input just occaisionally this shit happe where my 110 v get knock and inverter switch to line mode even if battery still have like 58% soc and would tend to kind of knock off my 110v sytem in my house  i am thinking is the step down transformer don't really know but thats my only issue kind of have had that problem where it knock down my 110v side but it comes on failrly quickly like milli seconds don't really know whats the cause of this one.Might have to sell this inverter and get inverter with dual output i guess.Working like a charm whenever inverter try switching leading to the 110v supply issue the invert switches to line mode sometimes battery disappear i have had that issue from  the time i got this inverter so that wasnt a surprise but apart from that everything working back to normal a little better.

[flltech]

Hello everyone, I have Axpert VM II 5kVA-48V that gives 230V output when 500W load is given just on battery power. If I increase load to 800W, output voltage drops to 218V. If I increase the load further to 1.2kW, output voltage drops down to 204V. I have checked main board for components related to this but didn't find any abnormal values. 

I also checked with spare control card and it did the same. It seems the issue is on main board and not on control card. 

Any suggestions what to check to resolve this issue?

[razmasoom]

19 minutes ago, flltech said:

Hello everyone, I have Axpert VM II 5kVA-48V that gives 230V output when 500W load is given just on battery power. If I increase load to 800W, output voltage drops to 218V. If I increase the load further to 1.2kW, output voltage drops down to 204V. I have checked main board for components related to this but didn't find any abnormal values. 

I also checked with spare control card and it did the same. It seems the issue is on main board and not on control card. 

Any suggestions what to check to resolve this issue?

You may check for voltage across the big capacitor , is there any large drop in voltage then there is drive problem in DC/Buck section If slight drop then Check optocoupler for output igbt (most probable).

[AndrewF]

On 2022/11/05 at 9:00 PM, BritishRacingGreen said:

This time I did not have the luxury to cut the devices legs to desolder, so my solder wick skills was tested again , this time I managed well , but it takes a long time , and you need to be patient.

I also removed TX7 to check it...using a desoldering technique shown on You Tube where a thick 2.5mm dia piece of solid core copper wire is wrapped around All the pins in a row then with powerful Iron and added solder, the whole area is heated up to release the soldering of one side of the transformer, the transformer is then simply pulled loose carefully and same procedure is repeated on opposite side still soldered to board....the result was a perfect unsoldering of TX7...The last time I tried similar thing I destroyed tracks and pads so went looking for ideas...

[razmasoom]

33 minutes ago, AndrewF said:

I also removed TX7 to check it...using a desoldering technique shown on You Tube where a thick 2.5mm dia piece of solid core copper wire is wrapped around All the pins in a row then with powerful Iron and added solder, the whole area is heated up to release the soldering of one side of the transformer, the transformer is then simply pulled loose carefully and same procedure is repeated on opposite side still soldered to board....the result was a perfect unsoldering of TX7...The last time I tried similar thing I destroyed tracks and pads so went looking for ideas...

Try electric manual desoldering pump .. it work great and it's cheap then soldering iron

[Mischel68]

Hello.

I also have a problem with a MAX 2 11 kW. I am now the owner of 2 Max Mainboards for the inverter. The original board was imported from China during the warranty period.

Now that the replacement board is showing error 52, I examined the original. An IGBT and several Mosfets at the battery input burned out (short circuit). They're already unsoldered.

The question is, where is the greatest chance of repairs?

The board with error 52 is charging the battery from the solar and mains. Everything works in line mode. F52 only comes when power is to come from the battery. And in standby and sunshine it feeds into the power grid.

And thanks to the experts in this forum. I understood somewhat how the inverters work through the circuit diagrams. 

I'm an electrician and hope to get a board to work.

Greetings

[razmasoom]

26 minutes ago, Mischel68 said:

Hello.

I also have a problem with a MAX 2 11 kW. I am now the owner of 2 Max Mainboards for the inverter. The original board was imported from China during the warranty period.

Now that the replacement board is showing error 52, I examined the original. An IGBT and several Mosfets at the battery input burned out (short circuit). They're already unsoldered.

The question is, where is the greatest chance of repairs?

The board with error 52 is charging the battery from the solar and mains. Everything works in line mode. F52 only comes when power is to come from the battery. And in standby and sunshine it feeds into the power grid.

And thanks to the experts in this forum. I understood somewhat how the inverters work through the circuit diagrams. 

I'm an electrician and hope to get a board to work.

Greetings

check and change the pnp and npn  transistor in dc and igbt drive section. Hope will resolve your problem. Due failure of one of transistor (partially shorted) leads to such type issue. Will work flawless in solar directly as it charges the big capacitor near 380-400v. Also check three pin BAT schotkey diodes and always check for the resistance in igbt and mosfet side. Change if not in range. look for any broken path ie, track, dry solder joints etc.

Edited November 7, 2023 by razmasoom
suggestion

[Mischel68]

2 hours ago, razmasoom said:

check and change the pnp and npn  transistor in dc and igbt drive section. Hope will resolve your problem. Due failure of one of transistor (partially shorted) leads to such type issue. Will work flawless in solar directly as it charges the big capacitor near 380-400v. Also check three pin BAT schotkey diodes and always check for the resistance in igbt and mosfet side. Change if not in range. look for any broken path ie, track, dry solder joints etc.

Thanks for the quick reply.

I will remove the board and examine it. I think the board with F52 has a better chance. You may be able to see something visually on the components. I'll have a go at it this weekend. I'll report back then.

Greetings from Germany.

Update:

I just looked at the original board of the Max II 11 kw. The component labels are identical to your circuit boards. The resistance values differ slightly. But the plans are a great help to me.

Edited November 7, 2023 by Mischel68

[Coulomb]

7 hours ago, Mischel68 said:

I think the board with F52 has a better chance.

The only mention of fault code 52 in the AEVA Axpert repair topic is this one, which says that one reader corrected his by replacing the battery capacitors. It's a good idea to replace the battery capacitors with longer-life high ripple rating types anyway, and it's a fairly easy repair.

[Mischel68]

4 hours ago, Coulomb said:

The only mention of fault code 52 in the AEVA Axpert repair topic is this one, which says that one reader corrected his by replacing the battery capacitors. It's a good idea to replace the battery capacitors with longer-life high ripple rating types anyway, and it's a fairly easy repair.

Thanks for the tip.

The board is only 3 months old and we don't have such high outside temperatures in Germany. But one idea is to swap it. The board with error 52 is the replacement board. And when transported from China it was poorly packaged. At the corner where the control transformers for the battery mosfets are located, the circuit board was cracked. I looked without a magnifying glass and saw nothing. No conductor track in place. But I have to take a closer look at that. Maybe something is broken.

[WilliamH]

On 2023/11/06 at 3:17 AM, Coulomb said:

Already in file section:

 

Yes , thanks I saw your message after the fact- thanks, got it, now seareching for the RCT 3kW sevice manual...

[Mischel68]

As promised, feedback on error 52.

I was able to repair the inverter.
3 battery mosfets were burnt out (short circuit).
This also causes damage to the conductor tracks.
I swapped the mosfets and added wire jumpers to the conductor tracks.
The inverter works again. Let's see how long.

Thanks again for the help and all the work you did.

greetings from Germany

Mischel

[Mischel68]

I've got one more question.
I still have a motherboard that I want to repair.
There is a component in the battery MOSFETs that I can't find on the wiring diagram. Every mosfet has one of these. TVS 1 to 12. It looks like a diode? Does anyone have any information?

Greetings

[wael_fathe]

On 2023/11/04 at 11:00 AM, BritishRacingGreen said:

Hi @wael_fathe I trust you are well . I have been quiet on this front for a while , apologies for that ,  and I owe you some answers to earlier posts as well, but lets start here.

The older generations of Voltronics Axpert inverters are dependant on battery operation . Therefore , the only way to power up the inverter's internal supplies is via the battery terminals , regardless if MPPT or Mains (AC input)  power is available.

The MAX range , as well as the later 5kW models are so called Battery Independent. So the system SMPS can be powered up by either Battery , MPPT or Mains (AC input). The MPPTs are therefore self-powered , as opposed to older MPPTs that relied on the host battery to power them. 

Please find below a crude schematic of the various power sources available to the main SMPS input. 

 

You will notice that a seperate SPS power supply board is introduced as shown in green. This board is separate to the main board and it has 3 connector cables.  The Mains input is rectified to create a dc bus and this dc feeds a 60V SPMS that produces a regulated 60V output .  A second SMPS are powered from the MPPT DC feed and also produces 60VDC. Note that the two seperate sources of 60vDC are wired or by the 2 steering diodes. This combined dc output is now fed to the main board (BAT+).

Inside the Main board the Battery+ is  internally routed to the SMPS input via a steering diode , and as you can see this is combined with the composite output of the SPS. 

This configuration allows MAx to operate batteryless. In other word you can generate 220VAC from only PV  if you want to.

So to bring up the MAX system supplies without powering the battery terminals , I merely remove the SPS BAT+ cable , and feed into the main board with my current limited power supply. You can of course power the main board via feeding the SPS that is 'hot- wired with mains input . In fact I have done so originally , but I do prefer to use a current limited bench power supply instead.

 

Below is an image of the MAX 1 SPS board .  On the top right is the MPPT / Solar DC input connector, just below it is the BAT+ 60VDC output that goes to the main board , and at the bottom of the board is the Mains (AC Input) input connector. You will notice that the board real estate is mainly occupied by the two 60VDC SMPSs as described earlier on.

 

 

EDIT : There are some additional steering control that is not shown in the schematic . The battery supply is only available to the SMPS if the  Inverter Switch is ON , while the SPS output powers the inverters regardless of the state of the switch. I think this is to allow PV and Mains to charge a connected battery with the load output remaining off. I am not too sure .

 

EDIT2 : I have never actually measured the voltage of the MPPT input to the SPS . All I can say is that the fly back transformers are identical in product number , in fact both smps's are identical. So I assume that the mppt feeds a dc input in the range of 300-400VDC into the smps , as does the ac input do via its bridge rectifier. But I am getting seriously off-topic now

 

 

I THINK The  configuration i  am talking about is like  shown  in my picture

 

i remember  i once   opened  the fuse of  the battery sps   and   the main sps  is  dead ....its  dead not bevcause it is  dead

 

but  because   the  battery sps   is  actually  dead and  its  the battery  sps  is  the one  the  feeds  the main  sps  ...

this is  some   thing  that i  personally  experinced ....but  i assumed  that  the  pv and ac are feeding ored  at the  output 

of the  battery  sps  ..i have not actually  followed  it so am not sure  but  its more logically to  feed the output of  battery sps  ...........i  even   met   an inverter that have only  2  smps  ....one  if  soft start and other  the main  i guess  that one  evey thing   is ored to the mains  

 

your confiiguration is  quite interesting one     and  very  logical   all fed into   battery  bus  ored   using   diode's   simplest   application ....diode  as valve