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Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 19 2019 3:51pm
by arber333
Lebowski wrote:
Jul 19 2019 12:32pm
Dont thjnk parallelling two output stages is a problem, but I would definitely use all 6 current sensors then ! You can add the current sensor outputs using resistors.
Hm... so i could just connect sensors in the same order they are connected to outputs. I.e. sensor A1 of one IPM would be parallel with sensor A2 on the other IPM and same for sensors on phases B and C. Where do the resistors come in?

See here i already use Volt connector J1 so sensors could be directly paralleled. Do you think i would have to add anything?

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 19 2019 5:03pm
by Lebowski
I think i used 1 kOhm and 10 nF in the (single) current sensor lines... for two sensors each sensor would need its own 2.2kOhm resistor in series with its output and then connect to the 10 nF. The resistor is a bit higher because two 2.2kOhm's in parallel is roughly 1 kOhm.
This way by using equal resistors the current sensor output voltage averages out... effectively in the controller IC you can then enter half the V per Amp of a single sensor.

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 19 2019 5:20pm
by Arlo1
Lebowski wrote:
Jul 19 2019 3:48pm
You dont, just have to match wiring length and trust inductance and ptc to equalize the currents...
What if they don't share current properly?

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 19 2019 8:35pm
by kiwifiat
It has been done by some guys in the Ukraine I think. A video on YT showing an Ampera/Volt inverter running a Nissan Leaf motor in a Peugeot van. There are a couple of videos showing the inverter, it is hard to be certain but it looks like they are driving the 6 half bridges in closest pairs ie 1 and 2, 3 and 4, 5 and 6. It makes sense even if it does mean you have to rewire the the bridge outputs, in any case that is how I plan on doing it.


Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 20 2019 3:24pm
by arber333
Hah, great minds truly think alike.
I see he used some lenght of cable before he attached in paralel. I wonder if this is what Paul was describing when he told about his AC controller being used as DC motor controller. He paraleled uppe and lower IGBTs to get like 1000A push pull unit. He told he had to use some length of cable because of some IGBT vibration/pulsing damping? I didnt quite follow, but now it seems i see another iteration of this.
Bas, you have any comment on what to use? Either very short clamps to paralel IPMs or some 400mm cable lenght before paralel connection, similar to what they use.

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 20 2019 3:42pm
by arber333
Lebowski wrote:
Jul 19 2019 5:03pm
I think i used 1 kOhm and 10 nF in the (single) current sensor lines... for two sensors each sensor would need its own 2.2kOhm resistor in series with its output and then connect to the 10 nF. The resistor is a bit higher because two 2.2kOhm's in parallel is roughly 1 kOhm.
This way by using equal resistors the current sensor output voltage averages out... effectively in the controller IC you can then enter half the V per Amp of a single sensor.
Nice one!
I can lead additional wire from lower connector and i can solder 2K2 inline. I have split sensor lines with holes just for that :).
I will have to split driver connector leads to command both IPM. I think i will just design a new board and put everything what i learned on it.
What about 4K7 GND drain caps? Those i should use for each sensor line yes?

A

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 21 2019 2:55am
by Lebowski
Maybe show a quick schematic of your intentions wrt the current sensors and the 2k2 resistors ? And I dont understand the bit about the 4k7 capacitors ?

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jul 21 2019 6:34am
by arber333
Lebowski wrote:
Jul 21 2019 2:55am
Maybe show a quick schematic of your intentions wrt the current sensors and the 2k2 resistors ? And I dont understand the bit about the 4k7 capacitors ?
Sorry not caps, but resistors. 4K7 per channel is what Volt main board has installed just after the connector. So i replicated it and it does seem to drain most of the hash away.

Well schematic is mainly yours with a separate branch from the 10nF cap. Also i will have to branch driver signals into each IPM connector.

Re: Ampera/Volt inverter with Lebowski brain

Posted: Dec 16 2019 8:44am
by arber333
I am on to tuning out the rumble and shaking in the Leaf motor.
I am using Chevy Volt inverter with 600A 600V IGBTs

Leaf motor should pull out with power, but it doesnt happen. We keep getting the shaking and surge just before driveoff into a steep hill. Are that position sensors or bad settings?
Motor does drive off with gentle throttle, but with rougher handling it conks out.

I tried changing lots of parameters. Mostly i got a good behaviour with motor parameters 178uH and resistance between 42mR to 76mR. Outside that parameters motor does not behave good.
I attach parameters for our fallback settings that work.

When i started to try other parameters i watched Arlos videos. He says i would have to cycle through parameters to update them. Can you explain that to me? How to update parameters after i change some current or motor settings? What parameters are to be updated at that time and how?

tnx

Re: Ampera/Volt inverter with Lebowski brain

Posted: Dec 16 2019 2:23pm
by Lebowski
Do the current sensor offset values make sense ? And the hall sensor results, are they reasonable ?

Re: Ampera/Volt inverter with Lebowski brain

Posted: Dec 27 2019 1:35pm
by arber333
Current sensor offsets are some -/+13pt
Hall sensors are at value 6 in general. I cant get them to be 7. And RLS sensor was set to 0 position using current through 2 adjacent phases as per RLS procedure. Do you think 6 is not confident enough?

Re: Ampera/Volt inverter with Lebowski brain

Posted: Dec 28 2019 5:15am
by Lebowski
Confidence at 6 shows there is a lot of noise on the hall signals, if you scope them theyll probably look messy..

Calibrating the sensor to 0 is not necessary, as the controller IC can deal with offset. The number of pole pairs in the RLS and motor should match though.

Re: Ampera/Volt inverter with Lebowski brain

Posted: Dec 31 2019 8:49am
by arber333
Certainly, Leaf motor is 8 pole design. I purchased 8 pole encoder simulation, so the signal is correct.
I can scope signals but only on the inverter side. They are connected inside motor. Cable shield is connected to car GND on the inverter side. Do you think the problem is the sensor? Would different decoupling caps on sensor lines help anyhow? I use 10nF caps now.
RLS encoder has its own output drive. Each output can drive 24mA. Would that interfere with the system as a whole? I could add additional pullups on the controler end if you think that would be good.

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jan 07 2020 9:08am
by arber333
Lebowski a question if you please.

What would functionally happen inside controler if i pressed reset button while motor would turn at 8000RPM?
I consider this rather high hazard because i would have a battery of 380Vdc nominal and motor backEMF voltage will be higher at that RPM.
To protect against inadvertent power section failure I decoupled DC contactor from controler brain, it is enabled by another uC when votlage goes past some value
Is there something more to be done?

tnx

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jan 09 2020 3:33pm
by Lebowski
When reset is pressed it will shut down the output stage, turning off all FETs/IGBTs .

If you are using field weakening and motor speed is higher than the battery would normally allow, roughly the at that moment used field weakening current will be delivered by the motor to the battery (via the FETs freewheel diodes). This will amount to braking the motor as if you are running regen.

I would say normally nothing needs to be done...

The danger is when the motor voltage (due to high speed) is much higher than the FETs of the controller can take, AND the main battery fuse blows. Normally with field weakening the FETs do not see the high motor voltage, only the limited battery voltage. But the main fuse blowing would show the high motor voltage to the FETs, probably blowing all of them in an instant. If they all short out your motor at high speed would be completely shorted out... to protect against this you can put a high amp fuse in each of the motor wires coming out of the controller.

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jan 15 2020 10:59am
by Arlo1
Guys be careful with this.

I read the last 2 posts and have a couple comments.

1 Most EV fuses are slow blow so take that into consideration
2 You should use a smart fuse (Tesla Pyro fuse)
3 The instant regen if you fault the controller is brief and you will be surprised how its a non issue.

You can do a couple other things 1 keep the RPM limits low so you don't use a lot of Field Weakening also if it looses sync and you are driving the car at the time hit the breaks hard and get it out of that zone where Motor voltage is higher then battery voltage.

When we were shooting the discovery channel episode. I was going about 200km/h and Max speed with no field weakening was 130km/h so it was a LOT of FW. Needless to say it konked out and lost sync. It almost slammed my head into the steering wheel I knew what was going on and it lost sync so I slammed the breaks and thought I was going to be running from a car on fire. But once it slowed down to ~ 130 it recaptured the motor and was back running again and everything was fine. I was lucky. But its suprising how many times I lost sync above 130km/h

This testing stuff is why I build a new dyno!

Re: Ampera/Volt inverter with Lebowski brain

Posted: Jan 15 2020 5:07pm
by arber333
Tnx Arlo i really need to hear this from someone with experience with PMSM. I only done this with ACIM and however you rev that motor is a piece of iron if you turn off excitation.
The way you are saying it i identified couple of hazards.
1. DC contactor dropout when in FW region. This would blow my PS for sure
2. Conking out at high speed with massive regen. All power goes straight to the battery.
3. un/intentional controller reset by EMGCY button. What exactly would happen here? Would it regen through IGBT reverse diodes? How much?
4. Main pack fuse is not so much of a consideration since i will use oversized fuses anyway. Fuses are there to protect car against battery short circuit fire not to protect equipment on DC link against overload.

1. I can fight that with 3rd IC keeping the DC link alive above some preset voltage (usually precharge threshold)
2. I can try to fight that by trying to decouple and tune out sensors. Or in case of instance to apply the brakes.
3. Would it change that story to freewheel the core? I mean what if we would setup controler so watchdog would not drop it out but would rather freewheel it at last valid speed which would slowly taper out? Like having a small amount of reverse slip. Could that be done in current setup? I belive this would drastically lower the energy at such event.
4. I would fight that by preparation and not going there at all.

For now i would like to make a daily driver with speeds up to 160km/h and stock battery voltage. This will be for learning. Later i would try and double the power stage with both sides of Volt inverter. Then i will consider point 4 further.

Re: Ampera/Volt inverter with Lebowski brain

Posted: Feb 13 2020 8:58am
by SlowCo
Came across this thread and just wanted to say: great work so far. :thumb:
I will follow this thread. Good luck with the build.