Motor pulling high current at startup [SOLVED]

[Isaac96]

Hi,
I have a Rev2 inverter kit with a DMOC645 power stage - CM600DY-12NF IGBTs.
I have a Siemens 1PV5135 motor. This is a ~60kw industrial style ACIM, nominal voltage about 250V. I don't have any other specs on it.

I've been trying to work through the Schematics and Instructions guide on the wiki. Current sensors are calibrated, voltage is calibrated, but I cannot get the motor to spin smoothly at a low voltage. I'm testing using a 16S LG Chem module - about 57V.

As according to the wiki, I do the following:

Code: Select all

set fweak 10
start 2
set fslipspnt 10
set ampnom 100

And at that point the motor jumps a bit and instantly shuts down due to overcurrent. This happens with any ocurlim setting up to 800A - at 800A the motor sometimes spins but is very jerky.
Encoder is not yet connected.

How can I make the motor spin smoothly? Do I need more boost or different fslip values?
I could also increase voltage in increments of 60V or so.

Parameters:

Code: Select all

{
  "boost": 1700,
  "fweak": 10,
  "fconst": 180,
  "udcnom": 0,
  "fslipmin": 1,
  "fslipmax": 3,
  "fslipconstmax": 5,
  "polepairs": 2,
  "respolepairs": 1,
  "encmode": 1,
  "fmin": 1,
  "fmax": 200,
  "numimp": 64,
  "dirchrpm": 100,
  "dirmode": 1,
  "syncofs": 0,
  "snsm": 13,
  "pwmfrq": 1,
  "pwmpol": 0,
  "deadtime": 63,
  "ocurlim": 200,
  "minpulse": 1000,
  "il1gain": 1.56,
  "il2gain": 1.65,
  "udcgain": 2.15,
  "udcofs": 147,
  "udclim": 540,
  "snshs": 0,
  "bmslimhigh": 50,
  "bmslimlow": -1,
  "udcmin": 24,
  "udcmax": 520,
  "iacmax": 5000,
  "idcmax": 5000,
  "idcmin": -5000,
  "throtmax": 100,
  "throtmin": -100,
  "ifltrise": 10,
  "ifltfall": 3,
  "chargemode": 0,
  "chargecur": 0,
  "chargekp": 80,
  "chargeflt": 8,
  "chargemax": 90,
  "potmin": 0,
  "potmax": 4095,
  "pot2min": 0,
  "pot2max": 4095,
  "potmode": 1,
  "throtramp": 100,
  "throtramprpm": 20000,
  "ampmin": 10,
  "slipstart": 50,
  "brknompedal": -50,
  "regenramp": 100,
  "brknom": 30,
  "brkmax": -30,
  "brkrampstr": 10,
  "brkout": -50,
  "idlespeed": -100,
  "idlethrotlim": 50,
  "idlemode": 0,
  "speedkp": 0.21,
  "speedflt": 5,
  "cruisemode": 0,
  "udcsw": 45,
  "udcswbuck": 540,
  "tripmode": 0,
  "pwmfunc": 0,
  "pwmgain": 100,
  "pwmofs": 0,
  "canspeed": 0,
  "canperiod": 0,
  "fslipspnt": 0,
  "ampnom": 0
}

Thanks!

[johu]

Try higher fweak, like 100 or so

[Isaac96]

That got it working!
With fweak = 100, I can run at 57v and 114v at ocurlim = 200. The motor spins up very smoothly and quietly.

With encoder connected, however, the motor begins to jump a bit every rotation. It also draws 3 times the phase current (measured with clamp meter over phase cables - 30a instead of 10a).
It is an AB encoder, 64ppr. I scoped the signal lines and they swing nicely between 5v and 0v.
After reversing the encoder lines the motor does not spin at all, just instantly hits current limit.

I just tested the motor again with 600A ocurlim and reversed encoder and the motor instantly spun up to some very high RPM (10000+) before hitting current limit again. I am thoroughly confused with the encoder.

I have all the components populated on A, B and Z inputs except J1. Encoder is powered, signals look good; they are connected to A and B signal lines.

What can I test or change?

[Jack Bauer]

The first thing you want to do for testing the encoder is turn the motor by hand with the hv turned off and inverter logic powered. Check on the pins of the stm32 that the signals are reaching the processor.

[johu]

I just tested the motor again with 600A ocurlim and reversed encoder and the motor instantly spun up to some very high RPM (10000+) before hitting current limit again. I am thoroughly confused with the encoder.

That is what you expect. In manual mode there is no rev limiter. Once the motor is loaded it will be perfect.
Try with fslipspnt=1 and ampnom < 50 to limit revs a bit

[Isaac96]

The first thing you want to do for testing the encoder is turn the motor by hand with the hv turned off and inverter logic powered. Check on the pins of the stm32 that the signals are reaching the processor.

Yup I've verified that. Signals look nice.

That is what you expect. In manual mode there is no rev limiter. Once the motor is loaded it will be perfect.
Try with fslipspnt=1 and ampnom < 50 to limit revs a bit

Motor will not spin at fslipspnt=1, but works at 3. Still runs away very quickly.
Ampnom needs to be at 100 to get it moving.
I'm raising boost which seems to be helping. Was at 100, motor starts more easily with boost = 500.
Now with boost = 1000 motor starts at ampnom = 80.
Going to keep testing with higher boost. Is there an upper safe limit to boost?

EDIT Boost of 3000 works great. Ampnom of 40 to get it started and it holds steady at 4500rpm @ ampnom = 5.

Thanks for the help! Now to test regular mode with the pot...

[johu]

Thanks for reporting back - solved!
Can you add your question here or extend the documentation here?

[Isaac96]

Well... It looks like I'm having more issues with slip control mode. I will document my previous problem and its fixes.
In slip mode, the motor will not spin until I reach a potnom of 60%. And about 50% of the time it instantly hits overcurrent when I send "start 1" even when at zero throttle.
I'll do more testing when I can, and add my previous issue to the FAQ.