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

Question asked by Peter Dufault on Jun 24, 2014
Latest reply on Jun 24, 2014 by Peter Dufault

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?

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