How to increase Field Weaking at runtime when flat road allows for higher speed ?

[RoboDurden]

Variant

None

Control type

FOC

Control mode

None

What can we do to make the firmware better?

Hello again :-)

My solar camper (max speed 10 kmh at 150-200 Watt flat) now has pedal assist so i would like to go faster when less then 10A (250 Watt) are drawn. So when my https://pionierland.de/hoverhack/?p=uartCar recieves a target speed of 15 kmh and current < 10A, the field weakening should be activated.

Describe suggestions or alternatives you have considered

I guess that is rtP_Left.b_fieldWeakEna and rtP_Right.b_fieldWeakEna :-)

Will this activate field weakening softly ???

And anyway, i would like to increase rtP_Left.id_fieldWeakMax and rtP_Right.id_fieldWeakMax up to 10 (amps) until the motors current (5s average) reaches 10A. (Don't want to waste my 2-3 kWh on not so efficient higher speed..)

So a little closed loop for rtP_X.id_fieldWeakMax :-)

Would id_fieldWeakMax = 0 (amps) be zero field Weakeing ? Then i would set FIELD_WEAK_ENA to 1 and let the closed loop control id_fieldWeakMax from 0 to 5 (or 10)

Should i also change FIELD_WEAK_LO and FIELD_WEAK_HI in that closed loop, or will 750-1000 be fine ? What is 750 anyway ? Milli seoncds ? A scalar number ?

I am currently on the road and 300 km far from home. So i do not want to kill my motors or the board.

Ideas welcome :-)

[RoboDurden]

Well that does not seem to work: config.h:

// Field Weakening / Phase Advance
#define FIELD_WEAK_ENA  1               // [-] Field Weakening / Phase Advance enable flag: 0 = Disabled (default), 1 = Enabled
#define FIELD_WEAK_MAX  5               // [A] Maximum Field Weakening D axis current (only for FOC). Higher current results in higher maximum speed. Up to 10A has been tested using 10" wheels.
#define PHASE_ADV_MAX   25              // [deg] Maximum Phase Advance angle (only for SIN). Higher angle results in higher maximum speed.
#define FIELD_WEAK_HI   1000            // (1000, 1500] Input target High threshold for reaching maximum Field Weakening / Phase Advance. Do NOT set this higher than 1500.
#define FIELD_WEAK_LO   750             // ( 500, 1000] Input target Low threshold for starting Field Weakening / Phase Advance. Do NOT set this higher than 1000.

main.c:

        iFieldWeakMax = CLAMP(iFieldWeakMax-1,0,500);
        rtP_Left.id_fieldWeakMax = rtP_Right.id_fieldWeakMax = iFieldWeakMax/100;

That param seems to be used in BLDC_controller_data.c:

      if (rtP->z_ctrlTypSel == 2) {
        rtb_Saturation1 = rtP->id_fieldWeakMax;
      } else {
        rtb_Saturation1 = rtP->a_phaAdvMax;
      }

If i do not touch that value by commenting out:

//rtP_Left.id_fieldWeakMax = rtP_Right.id_fieldWeakMax = iFieldWeakMax/100;

I can easily speed up to 12 kmh. With that line hover, i stay at 10-11 kmh.

Will do some more test driving today. Ideas welcome !

[RoboDurden]

Okay i had forgotten about that (FIELD_WEAK_MAX * A2BIT_CONV) << 4 integer to float conversion stuff that Emanuel had introduced with his great firmware here :-/ Instead of 5A i must set the id_fieldWeakMax to 4000. So no wonder nothing happened.

This code now works for my VARIANT_UARTCAR:

#ifdef VARIANT_UARTCAR // ROBO
  int16_t cmd2Goal; // 10* goal speed for VARIANT_UARTCAR
  int32_t iFieldWeakMax = 0;
  #define INPUTMAX 9900  // +-1000 do cause vibrations in my 350+ Watt motor :-(
  #define INPUTMIN -9900
#endif

 if (cmd2Goal < INPUTMIN)   // pwm at negativ full speed
    cmd2Goal = INPUTMIN;
  else if (cmd2Goal > iInputMax)    // pwm at full speed
  {
    cmd2Goal = iInputMax;
    long iSpeedKmh = (iSpeed * 36) / 1000;  // 60 = 6 kmh
    if (    (fCurrent < 12.0) && (iSpeedKmh >= 80)  )
    {
      iFieldWeakMax += 2;
    }
  }
 iFieldWeakMax = CLAMP(iFieldWeakMax-1,0,FIELD_WEAK_MAX*100);   // 300 = max 3A field weakening
 rtP_Left.id_fieldWeakMax = rtP_Right.id_fieldWeakMax = ((iFieldWeakMax * A2BIT_CONV) << 4 ) / 100;
 // rtP_Left.id_fieldWeakMax      = (FIELD_WEAK_MAX * A2BIT_CONV) << 4;   // fixdt(1,16,4)
 // #define A2BIT_CONV             50     // A to bit for current conversion on ADC. Example: 1 A = 50, 2 A = 100, etc

Have not tested it on the street but with my two wheels spinning freely i now reach max speed of 15 kmh at 5A field weakening and 14 kmh at 3A.

Thanks for this great firmware.