Persistent OVERCURRENT error after installing SDU V8 board w/new sensors

[nubster]

Hey all. I ran into some trouble with my latest SDU board installation. The sensors really put up a fight this time. I ended up using the heat gun a little too aggressively, and long story short, they got too hot and melted out of the sensor rings. Could I have damaged to sensor rings themselves?

I had some new current sensors and installed them with a new SDU board. I buttoned everything back up, but now I'm getting persistent OVERCURRENT errors as soon as I hit START.

When powering up 12V, I hear the precharge contactor close and see:
opmode: Off
lasterr: NONE
status: WaitStart
udc: 83.31 V
udcmin: 0 V
udcsw: 50 V

No Errors

However, I'm not sure why it's showing udc of 83V, as I am using a 65V e-bike battery.

When I hit the START button, I see:
opmode: Off
lasterr: OVERCURRENT
status: UdcBelowUdcSw
udc: 2.4 V
udcmin: 0 V
udcsw: 50 V

[72592]: WARN - HICUROF2
[72602]: STOP - OVERCURRENT

For some reason, udc drops to 2.4V.

With HV disconnected, I see the following upon powering up 12V:
opmode: Off
lasterr: PRECHARGE
status: UdcBelowUdcSw
udc: 2.4 V
udcsw: 50 V
udcmin: 0 V

This is a V8 SDU board that I built and programmed myself.

The inverter & motor previously worked great with a V6 board and the original stock current sensors. I sold/traded that board+tray+sensors for their stock board+tray+sensors, so now I'm trying to get my motor back up and running with a V8 board. This is also my first time installing new sensors. I've read thru several related threads, but not sure if they apply to the V8 board.

Also, it's not clear if the Troubleshooting guide refers to the SDU boards, as the resistors mentioned are not on the bottom right side of the board. Are these still the correct resistors to test?

Any advice on how I should proceed with troubleshooting?

-Edited for clarity

[nubster]

I've been playing with the parameters but so far no luck. The udc is still showing an incorrect value of 83V when it should be 65V. I attached my parameter file in case I messed something up along the way.

I built this V8 board and programmed it myself. The V6 board that was working before was from the webshop. My understanding is that the latest parameters should have been set when I flashed the stm32_sine firmware. As a sanity check, I just ordered a new board from the webshop. If it works, then I know something is wrong with the board I built.

[johu]

These are not Tesla parameters, these are: https://openinverter.org/parameters/view.html?id=15

When flashing the firmware you'll get default parameters very unfit to the SDU

[nubster]

These are not Tesla parameters, these are: https://openinverter.org/parameters/view.html?id=15

When flashing the firmware you'll get default parameters very unfit to the SDU

I see. I must have misunderstood the reply in my other post. I will give these a shot. Thank you!!

[Pete9008]

I see. I must have misunderstood the reply in my other post. I will give these a shot. Thank you!!

Oops, sorry, the ones I described in that post are the overall default parameters in the OI code but not the specific parameter defaults for the SDU

[nubster]

Oops, sorry, the ones I described in that post are the overall default parameters in the OI code but not the specific parameter defaults for the SDU

No worries, man. That's totally on me, and thanks for all the help on that thread! I suppose I just assumed the firmware somehow knew what inverter it was in and, thus, which params to load by default. In hindsight, I guess that doesn't make much sense, and I now feel silly. I think I understand now.

So which DU are the overall OI default parameters meant for then if anything?

[johu]

So which DU are the overall OI default parameters meant for then if anything?

To be honest quite a few defaults date back to my Polo conversion

[nubster]

After loading the correct SDU params, I see the correct udc value, but I still got an OVERCURRENT error when I hit start.

I opened it up and found that I didn't quite trim the current sensor leads all the way down, and a couple were bent over and contacting each other. I trimmed them down to the board and put it back together, but I still got OVERCURRENT when I hit start. Could I have damaged the sensors?

Also, I watched Damien's latest video, which inspired me to open it back up and test the IGBTs. I followed the procedure per this thread, and the lightbulb does not light up on any phase, so I hope this means I didn't manage to fry the inverter. Please let me know if I can perform any other tests to verify this.

The new board I ordered from the webshop is still stuck in customs but should be arriving soon, so at this point, I plan to just put that in with new sensors and see what happens.

[nubster]

OK, I received the new board from the web shop, installed it with new sensors, and got the same symptoms as before. I.e., Everything seems fine until I press start. opmode says Run for a fraction of a second; then I get OVERCURRENT. udc is showing the correct value.

@johu - Thanks for posting the testing steps in the Electronics Basics page you made.

When I perform the first step, the voltage rises to a value over 2V (~3V), but then goes to 0V.
When I do the second step, it starts off negative and then rises to 0.6V.
Here's a video of me performing the test for clarity: https://photos.app.goo.gl/LfAy5VqAycMMVLuz9.

Can you please clarify if the 0V is ok to see after the multimeter maxes out (in my case ~3V), or should it stay at the maxed-out value? The wording is a bit unclear to me. If there were a failure, would I not see any rise in voltage at all and only ever see 0V right from the start?

Also, I noticed the parameters that came pre-loaded on the new SDU board I just received are not the same SDU parameters found in the parameter database. Can you also help me understand this discrepancy? I assume the preloaded parameters are preferred, but let me know otherwise. Attached for reference.

Thank you so much!!

[johu]

0.6V sounds fine. In the other direction it doesn't go to 0 but to OL, overload All good.

I think you're not going to get around some probing on the control board while it's powered. Most likely culprit is the interlock which you can override by closing CONN2/HVIL Disable with a solder blob or jumper wire.

Above said jumper you will find 4 capacitors side-by-side. These all need to read around 5V on the upper side.

Finally you can measure the voltage on the left side of R15, it should also be 5V. Also check the voltage on the left side of R1 and R3 (current sensor outputs). Should be 2.5V

The parameter discrepancy is easily explained: you're comparing SDU to LDU parameters

[nubster]

Here's a video of me performing the tests above: https://photos.app.goo.gl/b4rpCbvxkmJiQU2Q8

I performed the measurements both with and without the HVIL jumper shorted and got the same exact results.

0.6V sounds fine. In the other direction it doesn't go to 0 but to OL, overload All good.

Ohhh, haha thx for explaining that now I understand! I was really worried the inverter was toast.

Above said jumper you will find 4 capacitors side-by-side. These all need to read around 5V on the upper side.

They all read 0V.

Finally you can measure the voltage on the left side of R15, it should also be 5V. Also check the voltage on the left side of R1 and R3 (current sensor outputs). Should be 2.5V

R15: 3.75V
R1: 2.45V
R3: 2.45V

The parameter discrepancy is easily explained: you're comparing SDU to LDU parameters

Sorry, I uploaded the LDU params by mistake like a dum dum. Please compare to the actual SDU params online, they are indeed very different from what came preloaded.

[johu]

So all is well except those 4 signals that should read 5V but read 0V. Those are the error signals from the gate driver board. Could there be a dodgy connection? Either in soldering or in the actual connector. Does the gate drive board look clean or are there signs of heat damage or something?

R15 3.75V is fine also.

[nubster]

I assume the gate driver board is the one underneath the logic board that's encapsulated in clear plastic? If so, the only thing I can see are two pads marked G that have a little black around them. The 24-pin IGBT connector looks good to me. Pics here: https://photos.app.goo.gl/j5P5TPSmvoksicUJ8

Also, I only had 12V connected. Should I also have HV connected when doing the measurements?

[nubster]

FWIW, I retested everything with the HV connected but got the same results.

However, after seeing THIS post today, I took a look at C13.

On my V8 board, C13 is populated with a capacitor. I tested it with 12V power enabled, and the top of C13 reads 4.85V, and the bottom reads 0V. Would this indicate that the capacitor is bad or perhaps backward? Could it explain my issue? Or is that expected because the neg terminal is grounded, so I'm basically measuring the potential diff between gnd and gnd?

[johu]

4.83V seems a little low. I wonder if the 5V rail sits too low. It should be at 5.3V. Can you confirm R56=56k and R58=10k ?

[nubster]

4.83V seems a little low. I wonder if the 5V rail sits too low. It should be at 5.3V. Can you confirm R56=56k and R58=10k ?

R56=51k
R58=10k

I double-checked C13 again, and the top is now reading 4.9V after restarting my multimeter (and adjusting my power supply to exactly 12V). The supply indicates the inverter is drawing ~4.6W @ 380mA pretty steadily.

This inverter worked great with a V6 earlier this year, so I'm tempted to make some V6 boards just to see if I get the same issue. It would be cheaper than buying a whole new unit. Would that be a worthwhile test, or can you think of anything else to try?

I really appreciate all the help.

[johu]

Ah yes, that's indeed what I've got in the BOM. That would result in about 4.9V. Don't think this would be a problem but you could try replacing it with a slightly higher value (like 56k). Or stick 330k in parallel to R58
The differences between V6 and V8 are just that: smaller 5Vvoltage regulator, esp32 instead of esp8266 and pull-down resistors for the gate signal driver

[nubster]

Don't think this would be a problem but you could try replacing it with a slightly higher value (like 56k). Or stick 330k in parallel to R58

Ok, I ordered a 56k. In the meantime, I measured all 24-pins of the IGBT connector in case it might hint at the issue:

1=0.003V
2=0.295V
3=1.126V
4=1.132V
5=1.124V
6=11.71V
7=4.9V
8=0.811V
9=4.9V
10=11.78V
11=0V
12=4.9V
13=0.001V
14=3.205V
15-24=0V

I figured if the voltage coming out of the connector is 0V, maybe one of the inputs is bad (or not), and thus determine if the issue is on the logic board or the gate driver board.

[johu]

All looks good up to pin 14.
The inputs for faulta,b,c and uvlo all run via 1k resistors into the logic gate. Can't see much going wrong. Can you increase your 12V a bit to like 14V?

[nubster]

Sure. @ 14V:

1=0.002V
2=0.289V
3=1.103V
4=1.108V
5=1.102V
6=13.74V
7=4.9V
8=0.811V
9=4.9V
10=13.74V
11=0V
12=4.9V
13=0V
14=3.212V
15-24=0V

Should 15-24 be above 0V? Is that an indication of an issue with the gate driver board?

I uploaded pics of the top of my gate driver board. Not sure if you had a chance to take a look, but I can't tell if anything looks out of the ordinary.

[johu]

Sorry forgot this. Not all pins above 15 should be above 0V, but certainly FAULTA-FAULTC and UVLO.

I can't see any bubbles or black stuff on your pictures, so not sure what is wrong. Can you pull up one of the fault pins say with a 470 Ohm resistor to 5V? Or is it forced low? E.g. pin 22

[nubster]

No worries. I know you're super busy; thanks for getting back to me.

OK, I used a 470 Ohm resistor to connect the 5V pin of CONN8 (reading 4.9V) to pin 22/FAULTC of CONN5, and I'm measuring 0.255V at the pin. Does this mean it's being forced LOW? Implications?

[nubster]

So, it would seem my inverter's power electronics indeed got damaged.

I bought another SDU, took off the inverter, installed the original V8 board I built & programmed myself w/new sensors (the one giving me the weird voltage readings), and put it back on my original SDU, and it's happily spinning again! I checked the four capacitors (C9,10,12,15) again, and they all read 4.98V with the new inverter...

Did I find a new failure mode that is hard to detect since it seems to pass the lightbulb and diode tests just fine?

It sucks that I had to spend so much money fixing it, but at least I know now that I built the V8 board correctly!

Thanks again for all the help.