LDU temp reading problem (not logic)

[guillemonde]

Hi,

I've a problem with the tempm (motor temp sensor) return, when I start my trip the value is lower than the outside temp (output 6°c, inverter 6°c, motor -12°c) , after the temp growth progressively (as the motor warm) to 155°c and then go down to 85°C and continue to growth.
When the motor is cooling I've the same step : go down to 85°C go to 155°C and continue to going down.
As the stator temp is the most critical point for my vehicle ( 19T motorhome ) I don't know what to believe.
I had the same result with 3 different stator, and 2 different logic board, and it's the same on CAN and WiFi .
Is it a known problem ?
Any ideas to solve it ?
Can I trust the second sensor ?

Thanks

[tom91]

Did you graph the rise in temperature and it looks to be plausible?

Did you measure the coolant temperature as it circulates through your motor?

[P.S.Mangelsdorf]

The motor being colder than the inverter is odd. I have not seen that happen on mine.

Check that your snsm and snshs parameters match some of the example parameter sets.

Also, can you share a parameter dump and/or a data log of the temperatures?

[johu]

Check that your snsm and snshs parameters match some of the example parameter sets.

In fact these two are ignored when the hardware is detected as Tesla. So is it? (hwver=Tesla)

[guillemonde]

The motor being colder than the inverter is odd. I have not seen that happen on mine.

It's only on startup, just the ambient temp is seen differently by motor and inverter, I think the motor one is false.

In fact these two are ignored when the hardware is detected as Tesla. So is it? (hwver=Tesla)

I just checked, and yes hwver=Tesla

Also, can you share a parameter dump and/or a data log of the temperatures?

I'll manage to create a data log, but as my vehicle is a bus, the motor is 12m behind, so no wifi possible, I've to make something via CAN

Thanks all for your help

[P.S.Mangelsdorf]

I'll manage to create a data log, but as my vehicle is a bus, the motor is 12m behind, so no wifi possible, I've to make something via CAN

Thanks all for your help

This plus the latest firmware is your solution:
https://openinverter.org/shop/index.php ... duct_id=78

[guillemonde]

Hi,

I have some data, I'm pretty sure the good temp is the second one (I hope), but when I check the temp, I don't know if it's the good one displayed ....
Also the outdoor temp is upper than 10 degrees, so it's not possible to start at 1 degree, this is why I think the first values are wrong.

Thanks

[guillemonde]

And also my params

[P.S.Mangelsdorf]

Does your cooling system kick on and off, or stay on constantly? Those sharp drops look odd, even for a system that turns on and off.

Have you tried this with multiple temp sensors or just one?

[johu]

One unusual thing I noticed in the parameters is the high minimum slip (fslipmin). The default is 0.9 Hz or so, try dialing it back and check for changes.

It's certainly not a known issue. The LDU has two stator temperatures and the maximum of the two is displayed.

The most common temperature issue culprit is usually the cooling system itself, especially in a so demanding application. So flow rate, air bubbles, radiator size and placement, flow restrictions.

[guillemonde]

Have you tried this with multiple temp sensors or just one?

I had the same issue with 3 stators, and 2 logic board, so I think the problem is software,
My cooling system is always on.

If I drive at constant speed, I'll see the same : go to 150 and fall down to 90, and during the time I stay at this temp (pivot point) the display is blinking between 150-90. So I'm pretty sure that the temp is not changing really of +60 -60 degree in some seconds ...
So I see 2 way :
The good temp is the first one and I drive at 170 degrees or more, or the good one is the second one and I drive at 100-110 degree, it's not the same .
I noticed that the first temp is starting at 10 degree less than reality so maybe is not the good factor for the display, but it's the good comparison between the 2 sensor ?

One unusual thing I noticed in the parameters is the high minimum slip (fslipmin). The default is 0.9 Hz or so, try dialing it back and check for changes.

For the fslipmin I put this value due to regen, with lower value the regen is not enough. When I had the original gearset, I changed this dynamically to have smooth start, and strong regen.

With my modified gearset I don't need to change this value to keep smooth start.
Today the vehicle work like a charm, but as I want to use more power, I want to be sure of the temp displayed, and it's very difficult when I just take a look on the temp to know if it's the first temp or the second one. At 120 on the second one I'll stop, but at 120 on the first one I'll just wait the temp falling at 90.

thanks for your help

[guillemonde]

I didn't read all the code but on the VehicleControl::GetTemps the isLdu is set to false on declaration and is checked inside the case 1 and 2 without possibility to be true.
I didn't know how work the input switch mux, but seems not necessary to check if we know the value.

my apologies, isLdu is a static, sorry.

[guillemonde]

So finally, I burn a stator again, maybe the first temp is the good one, because I'm pretty sure that 110 degrees is not that much for this stator ?
Or maybe it's due to too high Amp in the AC side, I only check the DC side power and I never exceed 300A 120kW
How to be sure of the temp reading ?

With the graph of my last trip, when my stator die, we can see that the temp output go 155 and fall down 90 to stay all the trip between 95 and 120 degrees. But I suppose that it's just a step error in the reading and I add 70 degrees to the value following the fall the curve seems to be logical as at the end the curve is linear.
So really the temp was between 160 and 190 degrees that is really high .
I can also suppose that I've to remove 70 degrees at start and end, but I burn the stator so .....

I

I noticed in the parameters is the high minimum slip (fslipmin)

I think that is the main clue, with my new gear set I use too much torque at startup, and as I don't want to exceed 100kW, I start in 3th or 4th speed, that was stupid, as the current on the AC side was certainly too high.

For the science I'll change the stator and keep this gear set, but this time I'll monitor all the spot values.
If I can have the true temp it'll be better.
I can considerate to never exceed 150 degrees, but if the problem is on the reading, maybe one sensor is never checked correctly, or maybe the scale is not good, finally it'll be better if we can understand why this step appear in the temp reading.

[muehlpower]

Perhaps it is a program error that no one has noticed until today, because the temperature remains below 120°C in most cases!

[guillemonde]

Perhaps it is a program error that no one has noticed until today, because the temperature remains below 120°C in most cases!

I think you're true, I'll check on the code if I can see something, but now I know how to estimate my stator temp.

My last interrogation is about the temp at the startup, before "start", is always under the inverter sensor, and under the outdoor temp.
On my last trip it was 10 degrees under the inverter temp, have I to add 10 degrees to the displayed temp ?
Somebody know the max temp for the stator ?

[jrbe]

Maybe you have a 12v connection issue messing with the temp sensor reading?

It's been asked a bunch of times but I haven't seen you answer yet. Have you measured actual coolant temp with something you know is accurate? You need a known good reference to figure out if the temps are accurate.

[guillemonde]

Maybe you have a 12v connection issue messing with the temp sensor reading?

I didn't notice 12v issues.
All other stuff in 12V seems to work, and also the inverter sensor work fine .

It's been asked a bunch of times but I haven't seen you answer yet. Have you measured actual coolant temp with something you know is accurate? You need a known good reference to figure out if the temps are accurate.

Yes when I start all the sensor outside the motor, for the input and output coolant, for the oil temp, far the DC box, and also for the batteries, all says the same (at +/- 2 degrees) than the outdoor temp, also the inverter sensor, but the stator say less (last check it was 10 degrees less). Now I've to change the stator, so I can't take new measurements, I think (I hope) I could take measurements on Thursday.

I noticed this problem a long time ago, 2 years, during this time I changed a lot (almost everything), include stator , inverter, logic board, 12v batterry, BMS, water pump, oil pump, HV wires. But I didn't change 12V DC/DC and signal harness

Finally, just to try to localize my problem, did you ever go upper than 155 degrees for the stator ? Did you ever seen 165 degrees at tmpm ?

[jrbe]

Yes when I start all the sensor outside the motor, for the input and output coolant, for the oil temp, far the DC box, and also for the batteries, all says the same (at +/- 2 degrees) than the outdoor temp, also the inverter sensor, but the stator say less (last check it was 10 degrees less).

Ambient temp is one thing but high temp is another. Are you able to put at least some of the sensors in boiling water and check their accuracy on the high end?

Coolant temp does not equal stator temp. Seeing you are very likely pushing a lot more weight there's extra sustained load and heat on everything. Considering your pile of failed parts it's worth considering how to get a temp sensor on the stator. Infrared is likely safest.

[guillemonde]

Are you able to put at least some of the sensors in boiling water and check their accuracy on the high end?

We are talking about the stators sensor, they are inside the winding, so no I can't take it out, and I can't put another sensor in.
Sorry, I don't understand what you want to check by this way ?
The main problem is that the temp returned by the logic board has a step in the rise and in the fall, whatever the accuracy is.
During the rising temp, while I'm driving, so it's not possible that the temp fall, at 155° the returned value fall of 70° so the returned value is 85°, and this value continue to rise to something between 95° and 115° during my trip.
During the falling temp, while I'm not driving, so real temp in the stator don't have to rise, at 85° the returned value rise of 70° so the returned value is 155° and continue to fall to something +- close of the ambiant temp.
So I think that is the returned value that have a mistake, because if at the rise step I add 70° and at the fall step I remove 70°, the curve seems to be logic


I sent the graph of the reading value and the supposed real value. it's an extract so it doesn't start at 0, but it's easier to understand the steps
I'm sorry, I think I should have sent the 2 curves separately
As you can see during the falling, it's linear.


thanks for your help.

and to avoid a hardware problem, I got the same result with 3 stators and 2 open inverter cards
and also to avoid a software problem on my side I had the same result by using an access point to read the value by the WiFi

As muehlpower said maybe nobody noticed this problem because nobody gone to this too high temp, this is why I asked if somebody already seen 165° or more at the tmpm value. I burnt 3 stators and I never seen this number.

[jrbe]

We are talking about the stators sensor, they are inside the winding, so no I can't take it out, and I can't put another sensor in.
Sorry, I don't understand what you want to check by this way ?
The main problem is that the temp returned by the logic board has a step in the rise and in the fall, whatever the accuracy is.

You have a few things interacting and it's hard to figure out what is causing the odd readings.
The temp sensor could have been damaged from overheating.
The hardware / voltage divider could be off at these higher temps.
The code could be getting wonky up there.
This could be the typical behavior of the Tesla sensor for unknown to us reasons.
If it's a NTC sensor it could start self heating at elevated temps and distort the reading. https://www.ti.com/lit/pdf/slyt774

My suggestion was to check the temp sensors when heated. Water is the typical way unless it's built in. Do you have a non food oven you could carefully heat the stator with a couple other temp sensors to watch their temp rise over time to compare?

You could also use a potentiometer to simulate the temp sensor value for the oi board to read to see if something odd is going on with that side.

Basically trying to isolate the potential issues, breaking it down into smaller chunks until you find it.

[P.S.Mangelsdorf]

The sharp changes in the graph remain odd, but I'd also agree with the point that +150C is not something that others have seen. I've hit a thermal derate, but only from the inverter running a bit too hot.

Two related questions:
- Are you running the drive unit in it's original packaging/configuration? i.e. the inverter still in the case, with coolant fed from the motor side?
- if so, can you graph motor and inverter temps together?

[guillemonde]

Do you have a non food oven you could carefully heat the stator with a couple other temp sensors to watch their temp rise over time to compare?

No badly I didn't yet . This could be the best way to figure how the sensor react.
I'll search for an oven.

I already try with 3 stators (so 6 sensors) and I never seen 165° , so I don't think it's a sensor failure as it seems to be able to go up to 200°.

[guillemonde]

i.e. the inverter still in the case, with coolant fed from the motor side?

I've try (not intentionally) in the reverse way, and I think it's a bad way as the inverter doesn't warn so no way to know there is an issue, but same in the good way, I had the same reading problem.
I'll manage to reduce the temp, it's not the main subject, for me the main subject is the step on the value, because derating is based on this value and also when you check your temp if you read 100° is not the same than reading 170° and if you don't look every minute how to know if you have an issue or not ?
Maybe the solution is to set derating at 150° by default.

I think it's a bug or a limit on software or hardware, maybe it's interesting to solve it or to workaround it. To not return false value.

I'll make the try with an oven to reproduce this problem without burning stator. and with only the openinverter board and the sensors

[guillemonde]

if so, can you graph motor and inverter temps together?

This the inverter and stator temp, but I fed coolant by inverter side, next week I'll send the graph in the other way.

[P.S.Mangelsdorf]

I'd try running coolant from the motor side as it's designed to do, then graph again.

For reference, I have my limits set to:
"tmphsmax": 85,
"tmpmmax": 300,