2017.09.05 - measuring IQ current and manually adjusting position_correction_value

I did the code to read the IQ current, is simple and seems to be working. I tested with my slow eRPM motor, with low, medium and max speeds (with power supply at 24V) and the motor was most efficient when IQ value was near zero - the motor was quieter and the power supply did show the lowest current value. I also verified that measured IQ value was near the rate increased value I saw on my lad power supply, when I moved the position_correction_value to wrong values.
At lowest speed (like just after startup the motor when angle interpolation is not running yet) the measurement of IQ current also seems to work ok as also the effect of changing position_correction_value.

I also verified that at higher speeds, a small change of position_correction_value have a high impact on IQ current/motor efficiency.

Code used to measure the ADC IQ current value and do a low pass filter:

switch (hall_sensors)
{
case 3:
(...)

if (ui8_adc_read_throttle_busy == 0)
{
ui16_ADC_iq_current = ADC1_GetConversionValue ();
ui16_ADC_iq_current_accumulated -= ui16_ADC_iq_current_accumulated >> 3;
ui16_ADC_iq_current_accumulated += ui16_ADC_iq_current;
ui16_ADC_iq_current_filtered = ui16_ADC_iq_current_accumulated >> 3;
}

And then the filtered value was printing with this code:

// Phase current: max of +-15.5 amps
// 512 --> 15.5 amps
// 1 ADC increment --> 0.030A
// RMS value --> max value * 0.707
#define ADC_PHASE_B_CURRENT_FACTOR_MA 21 // 0,030273437 * 1000 * 0.707

ui16_temp = (ui16_ADC_iq_current_filtered - 511) * ADC_PHASE_B_CURRENT_FACTOR_MA;
printf("%d, %d, %d\n", ui16_motor_speed_erps, ui16_temp, ui8_position_correction_value);


On the next images, you can see how the motor speed eRPM changes (speed can increase a bit, equivalent of field-weakening?) and IQ current change while I was manually incrementing/decrementing the position_correction_value. The motor was most efficient when IQ value was near zero, as expected.
Conclusion
• the low resolution FOC algorithm need to look at IQ current and increment/decrement position_correction_value until IQ current is near zero.

eRPM: 29


eRPM: 48


eRPM: 60 (max speed)