The Troubleshooting and Repair for On-board Charger (OBC) Thread

[Carlossalinas]

[REPAIRED]
Hello all,
I hope I managed to repair my broken OBC. Many thanks to you guys on this forum. The symptoms were very similar to ChristopheFR's case, so I borrow his post, do some editing to save time and continue my story.

My name is Karel, and I am the proud owner of a C-zero in Czech Republic since 2015,
My Z totals 105,000 km, it is 2012, imported from Germany, used every day.

One morning in June, I realize that my “Z” is not ready . I think charger died due to the heat this summer, over 32 °C in the garden while charging. I was able to change on the Chademo socket nearby. No error on dashboard.

The apparent diagnosis: when I plug my charging cable, the green charging light on the cable box comes on for several seconds, I hear a few clicks to the cable and to the car, the car's blower starts a few seconds, then everything stops, no blower, no green light on the cable, and no fault on the cable or on the dashboard.

With the ignition key open, when I take the voltage across the auxiliary battery, I get 12.4 volts
With the ignition key closed, I get 14.5 volts.

At December 2020 my original accessory battery died, so I changed it.
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...while doing autopsy I found out one 4R7 resistor on the lower PCB in dog-house was broken and 2,2uF capacitor beside was partialy melted. So after connecting the charger the circuit was not charged through 2x4R7 resistors and charger ended the session without any visible error indication (i have no OBD error-diagnostics).
I did not want to waste time getting the PCB out and desolder the waffle plate, so i connected 4x 4R7 3W resistors in series between the "measure points", where you should normally measure 9,4 Ohm (pin N of waffle plate on white bar and cable named N00 connecting upper and lower PCB).
It started charging, but stopped after 1 hour. 1 blue 1nF/2000V capacitor got blown and 20A DC fuse in the MCU box got blown too.
So I disconnected my 4x 4R7 3W resistors set, took lower PCB out, desoldered waffel plate and replaced all components in dog-house but the coil: 2x 4R7 5W resistors, 2u2 310V capacitor, 2x 1nF 2kV capacitors, relay. Then I replaced 20A fuse in MCU box with 2 wires and a photovoltaic circuit breaker with fuse 15A/1000VDC.
It did not start charging, 2x 4R7 resistors in doghouse went blown. Then I almost ordered used unit for 1050 Euro from B-Parts.com, but I decided to give it one more try the next day.
Next day I connected again my 4x 4R7 3W resistors set and it started charging immediately !! But after 5 minutes charging stopped from powermeter's point of view. From user's point of view everithing was ok, charge cable indicating charging in progress, charging indication in car was on.
To be short, there was unexpected charging pause but then everything continued to happy end and fully charged pack.
Next day I added 5nF/5kV capacitor to those 2nF/2kV (C121, C122) in doghouse (not sure why...for more stability ??) and did 1 more power cycle: discharged battery by heater on, AC on, seat heating on and blower to max. At SOC 7% I plugged the original 14A charger and recorded the power session. There is 11minute charging pause at T0+25min. Do you think it is normal?

My conclusion up to now: only passive components went wrong due to overheat in combination with ageing
charger p.n.: 9499A437 v110 2011.04.02

Thanks again and good luck
Karel

 

[kiev]

Howdy Karel, Welcome to the forum and thank you for sharing your OBC details.

One thing of concern is that your 12V starting battery is really low at 12.4. Even though the DCDC Converter comes ON when in READY or the OBC is charging, the low battery really needs attention and maintenance, and a full charge with an external charger. i suspect that the weak, low 12V battery is a big factor contributing to your initial OBC failure and the second failure after repairs, and may cause it to fail again.

What was your reason to connect the string of resistors in parallel to the Neutral leg of the AC input (bypassing the doghouse, filter, ceramic resistors and relay)?

 

[Carlossalinas]

i suspect that the weak, low 12V battery ....

Agree. Someone with oscilloscope should measure transient response of the battery voltage when for ex. blower or water pump gets on when charging.

What was your reason to connect the string of resistors in parallel to the Neutral leg of the AC input (bypassing the doghouse, filter, ceramic resistors and relay)?

Laziness....2x 4R7 ceramic resistors are dead. The pads are accessible only from the waffel plate side of PCB. In advance the inrush current with 4x 4R7 is lower and in combination with coil in doghouse it forms LR snubber (until coil saturation). Energy possibly stored in the coil is negliable to enegry capacity of capacitors after diode bridge (no overvoltage danger). After relay gets on the resistors have no effect.

 

[Mucker]

Hey People,

Karel are you able to make a drawing, of what you did and with which parts?

Now my problem after changing D301 and checking, that the relay is fine, is that the ceramic resistor I used ( https://cdn-reichelt.de/documents/datenblatt/I200/vis_10w.pdf ) blowed 2 times while testing. (1 time before I repaired D301 and 1 time after the replacement)

So do anyone has an idea?

 

[coulomb]

So do anyone has an idea?

My guess is that the relay isn't being told to turn on, e.g. there is some sort of problem with the relay driver transistor or circuit leading up to it.

So then when the charger starts to draw significant current, the 4.7 Ω resistor is severely overloaded and fails open circuit. Or blows its internal fuse, if it has one.

But also if the IGBTs are shorted, or there is some other short on the "DC bus", that could cause the pre-charge resistor to experience massive overload. Have you checked for a short from bus positive to bus negative? You could check across the large electrolytic capacitors. Edit: Or P1 to N1.

 

[Mucker]

Thanks for the answer,

but where is N1 and P1?

 

[coulomb]

but where is N1 and P1?

These are labels on the printed circuit board near the pads that connect to the Waffle Plate™.

 

[Mucker]

There I have 0 ohms.

Is this correct? https://drive.google.com/file/d/1XYomfgxXeNNFBK4Zmhx9RPsMWrmOYoY3/view?usp=sharing

 

[kiev]

The gogle drive document can't be viewed without an account--maybe change the settings so it is public and not private?

That reading is not normal and indicates there is a short in the transistors of the waffle plate as coulomb mentioned; it is damaged

 

[Mucker]

Okay people,

I hope this time the drive document is working.
I desoldered the waffleplate once again and measured with the LCR T4 Mega compents tester the like I draw in here.

https://drive.google.com/file/d/1RyrtwHsqNcXm7RupEmI4fn5AaVpQ3-yx/view?usp=sharing

So does someone knows, if there is something crashed?
That would be really helpful.

 

[coulomb]

I hope this time the drive document is working.

Works for me.

I desoldered the waffleplate once again and measured with the LCR T4 Mega components tester the like I draw in here.

https://drive.google.com/file/d/1RyrtwHsqNcXm7RupEmI4fn5AaVpQ3-yx/view?usp=sharing

The 0,07 Ω across the IGBTs is very bad. I assume that short comes from the Waffle Plate™. If so, it means that your IGBTs are shorted. I can only recall one very minor repair of a waffle board; they are very hard to deal with, and we don't know the correct replacement parts. Likely and DPAK 600+V 50A+ IGBT would do, but it's not known. Gate driver components on the PCB may also be damaged.

 

[kiev]

Yes the google documents show up now, you did a good job measuring the waffle plate values in the second document; unfortunately it is badly damaged as coulomb mentioned.

It cannot be repaired but the entire waffle plate could be swapped out from another OBC after checking all the diode drops first to verify it is not damaged. The 2011-2012 nissan laefs also use this exact same plate in their OBC, so that opens up a wider source for a replacement.

 

[shuma89]

I am beginer.
i want to know wich type of IGBT swiching control is used to control WAFFLE PLATE IGBT-s? 8 IGBT for inverter and 3 IGBT for power conditioning.

 

[kiev]

The 3 IGBTs used in the power conditioning section are driven by signals from an IC located on the power board. This ic performs a PFC function, that is Power Factor Control, which is the alignment of the voltage and current to be in-phase, by the switching action of the transistors of the Boost converter.

The 8 IGBTs of the inverter section are just 2 H-bridges using PWM, Pulse Width Modulation switching to create an alternating current thru the windings of the step-up transformers to control the voltage and current of the OBC output to the pack.

 

[shuma89]

The 3 IGBTs used in the power conditioning section are driven by signals from an IC located on the power board. This ic performs a PFC function, that is Power Factor Control, which is the alignment of the voltage and current to be in-phase, by the switching action of the transistors of the Boost converter.

You can point on the power board this IC?

The 8 IGBTs of the inverter section are just 2 H-bridges using PWM, Pulse Width Modulation switching to create an alternating current thru the windings of the step-up transformers to control the voltage and current of the OBC output to the pack.

and what controlls the PWM for IGBT-s of inverter?

 

[kiev]

The PFC chip is IC312, located on the bottom side of the power board, UC2845. There is a picture of this in the first post on page 1.

The microcontroller on the upper control board sends the signal for the H-bridges.

Are you trying to make a repair?

 

[nnasskoo]

Hi, I have a broken charger with error Code No. 17: Inside Ambient Temperature Abnormal (boost circuit rectifier temperature abnormal) which is permanent. Any idea where this sensor is located?In hybrid fet boart?

 

[kiev]

Howdy nnasskoo and welcome,

i think it is in the hybrid fet board, aka waffle plate, on the pair of solder junctions labelled 17 and 18 in the silkscreen of the power board. Located on the right column, third row from the bottom.

My notes show it measured 90k resistance, i didn't try heating or cooling to see how that changes but could if needed.

 

[Foreb]

Greetings. I have broken charger. DC-DC works, charging does not. I am getting these error codes from my OBC:

15 Power factor correction (PFC) circuit temperature abnormal
16 Temperature in increasing voltage area abnormal
17 Inside ambient temperature abnormal (boost circuit rectifier temperature)
31 Temperature in increasing voltage area abnormal 2

Car does not even start to charge, but I am getting all these errors. Hard to believe that all is overheated without charging.
Any idea where this sensors are located ? What could I try or look for ? Maybe some fuse, which is responsible for all these sensors.

 

[Virusman]

Hi guys, I have on my desk a broken charger. Cups and resistors are ok, I replace them before.
My question is, is it possible to connect ac power line to charger and measure voltages? I don't have car, I just looking some tests to he sure that charger can work.

Second questoon: p1a12 any solution for this error?