skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

Re: Troubleshooting and repair for On-board Charger, DC-DC Converter

Wed Aug 29, 2018 11:35 pm

Just got a phone call from another AEVA Member here in Western Australia that said her charger has also died in
here 2010 I-MIEV.
Looks like these are dropping like flies. She will be sending me a photo of the top of the charger so I can check
the part number and see if its same version as the other ones we have come across so far.
I'll post the details here once I get more info.

kiev
Posts: 942
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Location: The Heart o' Dixie
Contact: Website

@electronpusher

Sun Sep 02, 2018 11:44 am

Did you check the 20A fuse in the MCU? Open the small access cover to see it.
kiev = kenny's innovative electric vehicle

kiev
Posts: 942
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Thread Housekeeping

Sun Sep 02, 2018 11:51 am

i did a little work to tidy up the first post with links for the user names to their initial failure reports.

i also added links in the 2nd post for troubleshooting steps and an index of sorts with links to sketches, schematics, circuit descriptions and discussions, to help find stuff quickly. Thanks to coulomb for the idea to create this feature. Let me know if you would like something added to the index.

misspelling of charrger is on purpose to stop the addition of links by the forum bots whenever that word is used... :evil:
kiev = kenny's innovative electric vehicle

skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Mon Sep 03, 2018 8:04 pm

Hi KIEV / Coulomb:

This second charrger that I am now working on, has all of the symptoms that the first charrger had.
The 20 AMP 450V Fuse in the MCU was blown, and the SMD Caps on the vertical pcb in the dog house were blown up.
I've de-soldered the verticle pcb and replaced it with two 1000pf 3kv ceramic through hole caps, which is what the previous version used.
I've visually inspected all of the components on the top controller PCB, and on the bottom pcb for other burnt components, and trying
to spot and poor solder joints. I've particularly looked at the area around the 39k resistors near the flexstrip cable on the main board,
which is what the problem was on the previous charrger that I worked on, but on this one, all the resistor solder joints look good and ohm out ok. From what Electronpusher said, he seems to have a charrger with the same faults this one has.
I've replaced the 20 amp fuse in the MCU In preporation of testing back in the car, but have not put the charrger back into car yet till
I can come up with what the cause is that if blowing up caps and the fuse.

It is interesting that all of these charrgers have the caps on the output filter getting blown up. The 2x 1000pf caps are rated at above 3kv.
This part of the circuit normally does not go above 365 volts, so to take out a 3kv rated cap, it must be something generating a
spike in voltage.I am thinking that in the case of the first charrger that I worked on, The fault with the 39k resistor caused a failure in voltage regulation. The difference between charrger voltage and battery voltage caused the current to be too high and blew the 20 amp fuse.
When the fuse blows, the sudden vlotage chage causes a discharge of the inductors in the filter might be what causes a spike that blows the 2x 1000pf caps.
Last edited by skylogger on Tue Sep 04, 2018 6:36 pm, edited 3 times in total.

kiev
Posts: 942
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Mon Sep 03, 2018 8:31 pm

i'm working on jray3's charger which had the same symptoms--blown fuse in the MCU and blown snubber caps.

i'm thinking it is caused by a huge inductive spike when the boost stage switching gets interrupted. There are the two transformers plus the two inductors in the upper right corner.

Check all the little parts around T501 and T502. i haven't traced any of that yet but that will be my next target when i can get back to it.
kiev = kenny's innovative electric vehicle

coulomb
Posts: 170
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Tue Sep 04, 2018 12:19 am

skylogger wrote:I've replaced the 20 amp fuse in the MCU In preporation of testing back in the car, but have not put the charger back into car yet till
I can come up with what the cause is that if blowing up caps and the fuse.

Very wise to not just run the charrger with only the fuse and obvious failed capacitors replaced. It would be great to know what the cause is, but the more urgent question for now is what else has blown up. Kiev wisely mentioned parts around the pulse transformers; on the Elcon chargers and Axpert inverter chargers, the gate driver components often also fail. But this might be different, as the switching devices may not have failed.

It is interesting that all of these chargers have the caps on the output filter getting blown up. The 2x 1000pf caps are rated at above 3kv.
This part of the circuit normally does not go above 365 volts, so to take out a 3kv rated cap, it must be something generating a
spike in voltage.I am thinking that in the case of the first charger that I worked on, The fault with the 39k resistor caused a failure in voltage regulation. The difference between charger voltage and battery voltage caused the current to be too high and blew the 20 amp fuse.

My understanding is that these charrgers are all essentially current controlled. They set a current, and the voltage follows (the pack gradually rises in voltage as its state of charge increases. It's not like they can set the voltage, and if too different from the pack voltage, too much current flows. So I'm not totally convinced that your badly soldered 39k resistor was the main cause of your charrger failure.

When the fuse blows, the sudden vlotage chage causes a discharge of the inductors in the filter might be what causes a spike that blows the 2x 1000pf caps.

Yes, there is a huge quantity of energy stored in the inductors, and interrupting the current will make the inductors angry :o But what is interrupting the charrger output? I've not thought of a mechanism as yet. I suppose that a 39k resistor suddenly going open circuit might do it. Car charrgers do suffer a lot of vibration, so other parts might be shaking loose, or letting go due to heat after being shaken loose earlier with driving.

[ Edit : charger -> charrger, to talk like a pirrrate and to avoid the evil bot-links. Thanks Kiev, for that idea.]

electronpusher
Posts: 45
Joined: Sun Jun 25, 2017 3:11 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Tue Sep 04, 2018 1:52 am

skylogger wrote:From what Electronpusher said, he seems to have a charger with the same faults this one has.


Correct, we have to two SMD caps on the riser PCB blown as per your board. We will hopefully have the car moved out to our new house this coming weekend (8/9 and 9/9), we can then start working on our OBC, and inspect the fuses in the MCU and let you all know.

Will be replacing the caps with through the holes (do you have a link where I can buy the caps?).

I have a feeling that the caps that are blowing may be a weak point. I discussed this with my PhD supervisor (Biomedical Engineering/Electrical Engineering), and he suggested the caps may be the problem, and said that you could try putting in caps that have a higher voltage rating? Thoughts on that? Do we know what the original caps were rated at? Actually, reading further in your post skylogger, it appears that is exactly what you have done.

So I need to get 2 x 1000pF caps rated at 3kV.

Additionally, with the 20A fuse in the MCU, do you have a link for the replacement fuse, I want to purchase it before the weekend if possible to be ready for the cars arrival? Although we have not looked at that yet, from what I have read I suspect that it most likely has blown.

kiev
Posts: 942
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Tue Sep 04, 2018 2:31 am

The opamp went to the rail and the controller shut off the FETs immediately was my guess on how the loose resistor could cause the spike, back in Schema 7

With the twisted sister resistor going open circuit, then the op amp becomes a non-inverting follower with a gain of 1+(39/20) = 2.95, and now the output goes to ~4.72V, nearly to the 5V rail. The diode circuit on the ouput would clip that back down a bit, but the microcontroller would be seeing an abnormally high voltage reading. We don't know what it would do in response, but most likely shut down the FETs in an attempt to lower the HV. It may be a sudden shutdown could cause the snubber capacitors in the potted doghouse to see a massive overvoltage and this may have caused them to blow.
kiev = kenny's innovative electric vehicle

coulomb
Posts: 170
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Tue Sep 04, 2018 2:44 am

electronpusher wrote: Will be replacing the caps with through the holes (do you have a link where I can buy the caps?).

For Westralians, this should do:

https://www.altronics.com.au/p/r2889-0. ... capacitor/

[ Edit: the image shows a 10 nF part (0.01 μF) part with capacitance code 103; you want a 1 nF (1000 pF) part with capacitance code 102. It will likely be smaller than the one in the photo. It's common to use one photo for hundreds of different valued parts. ]

However, the lead pitch is 5 mm, and it looks like the PCB hole spacing is some 10 mm (maybe 7.5 mm). [ Edit: but you can just bend the leads to fit the wider hole spacing. ]

If you want to order on-line, since it's such a small order, you'd want someone with free shipping with any sized order, which in Australia means RS-Online:

https://au.rs-online.com/web/p/ceramic- ... s/7167324/

You have to buy a bag of ten, but that's still under $10 including GST and the free shipping. Plenty of spares.

I have a feeling that the caps that are blowing may be a weak point. I discussed this with my PhD supervisor (Biomedical Engineering/Electrical Engineering), and he suggested the caps may be the problem, and said that you could try putting in caps that have a higher voltage rating? Thoughts on that? Do we know what the original caps were rated at? Actually, reading further in your post skylogger, it appears that is exactly what you have done.

So I need to get 2 x 1000pF caps rated at 3kV.

Well, there's no reason that there should be even 2 kV in there, so it's not clear that 3 kV parts will solve the problem. Plus, how are other parts going to react with >2kV spilkes in there? But at least a 3 kV part should be a little sturdier than a 2 kV part.

Maybe a film capacitor would be more appropriate? Much bulkier, though.

Perhaps X rated safety capacitors would be better; they are designed not to explode in extreme over-voltage situations. But they do this by fusing to open circuit. I think that considering their cost, it's better to have these cheap things explode and save other, far more expensive parts. If indeed they can do that.

Additionally, with the 20A fuse in the MCU, do you have a link for the replacement fuse, I want to purchase it before the weekend if possible to be ready for the cars arrival? Although we have not looked at that yet, from what I have read I suspect that it most likely has blown.

That's also a problem. We haven't found an on-line source for these that is drop-in. I mention the nearest one I could find on-line in this post. JRay3 has the Mitsubishi part number in this post. But it seems that it's difficult to source in the USA; it might be a lot harder to find in Australia. But it might be worth a phone call or two. My guess is that it will have to come from Japan, which might take weeks, or months considering other posters' experiences . If that's the case, you may as well wait till you know you need it.

skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Tue Sep 04, 2018 3:07 am

Hi Electropusher:

The Mitsubishi part number for the original fuse is: #9499A656 I bought this from the local Mitsubishi dealership for $24
There was no stock in WA but there is some stock in SA, it it may day a few days to get to your location also.
While I was waiting on the original 450v rated fuse to come in, Just for testing, I used a standard 20 AMP fuse 240v rated in an INLINE
fuse holder that I bought from Altronics. I put half moon ring terminals on the wires of the fuse holder so they would slide under the
mounting screws of the original fuse that had metal tabs. I also kept a fire extinguisher handy in case the fuse holder melts since
the fuse and the holder are not rated to 450v, and I was just doing this during a test ;-)

I used some dentist scraping and picking tools that I bought from the chemist, to dig out the rubbery potting around the vertical PCB in the doghouse. The original caps in the dog house were 10% rated. I could have waited to get the original Murata parts from Element14 or Digikey, but did not want to wait for them to come in, so I bought some 20% caps from Altronics (Altronics did not have 10% ceramic 3kv, only 20%), but I checked a few with a meter while at the stores bin, and matched two that were actually within 10% of 1000pf before I paid for them at the counter at the store. The Altronics part number I bought was R2889
There are pins that come up from the main board that the vertical PCB is mounted to. There are pins on both top and bottom of the vertical PCB, so you have to de-solder 8 connection pins, and ending up with two pins forming a fork coming out of the via of the main board.
I formed the leads of the through hole caps so it would slide between the two pins forming the fork, and soldered them back together.
This way, I could do all of the rework on the top side of the main PCB without even removing the PCB.

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