topic Re: Setting up scaling etc. for PMSM vector control on eTPU with customer motor in Other NXP Products

Setting up scaling etc. for PMSM vector control on eTPU with customer motor

peterdufault — Tue, 24 Jun 2014 13:57:45 GMT

I'm trying to control a customer motor using the approach in AN3206, but I'm having trouble scaling the quantities and setting things up.

I have controlled the setup as a BLDC motor using Hall detectors, so the setup is working, but I can't get past the ALIGN part of the example.

The ADC Vref is set to 2.5V, so below 0V corresponds to 2.5V VREF.

The currents come in with {-3.125A ... 0 ... 3.125A} mapped to {-2.5 ... 0V ... 2.5}

The bus voltage is 24V and is comes in with {0V ... 24V} mapped to {0V ... 2.4V}.

The way I thought this should work is:

Phase current range in mA: 3125 (3.125A is 7FFFFF);
DC bus voltage range in mA: 25000 (25.0V is7FFFFF);
Phase current option should be FS_ETPU_ASAC_PHASE_CURR_USE_AB_CALC_C (I assume the demo board uses 2 shunt resistors?)
CFIFO update should be FS_ETPU_ASAC_CFIFO_UPDATE_OFF (since I'm calculating C from A and B)
Sign extension should be turned on in the ADC conversion? It isn't in the example program.
Negate phase currents should be FS_ETPU_ASAC_PHASE_CURRENTS_POS (example program is NEG).

However, I never get any output during the ALIGN_START ... ALIGN_FINISH steps. The duty cycle is always 50%.

The u_dq D output is a reasonable value, but the u_ab output is always {0, 0}.

Any suggestions on how to debug this or additional info I can give?

Re: Setting up scaling etc. for PMSM vector control on eTPU with customer motor

peterdufault — Tue, 24 Jun 2014 17:18:33 GMT

I said:

"However, I never get any output during the ALIGN_START ... ALIGN_FINISH steps. The duty cycle is always 50%.

The u_dq D output is a reasonable value, but the u_ab output is always {0, 0}.

Any suggestions on how to debug this or additional info I can give?"

The second PMSMVC thread that does the backward park transformation and the DC bus elimination isn't running. That might explain why I see u_dq non-zero but u_ab zero. If I then force an align finish I see the second thread run, but of course the motor isn't aligned.

What lets the second thread run?

Re: Setting up scaling etc. for PMSM vector control on eTPU with customer motor

peterdufault — Tue, 24 Jun 2014 21:19:11 GMT

I said:

"The second PMSMVC thread that does the backward park transformation and the DC bus elimination isn't running. That might explain why I see u_dq non-zero but u_ab zero. If I then force an align finish I see the second thread run, but of course the motor isn't aligned.

What lets the second thread run?"

I found the source code for the eTPU function at the Ashware site and see that when PMSMVC_PID_OFF is in effect it jumps directly to the PMSMVC_INV_PARK_TRANSFORMATION section of the code in the first thread, so all work is done in a single thread. I'm still stuck with the 50% duty cycle during the ALIGN_START state of the application.

Any suggestions would be greatly appreciated.