LAUNCHXL-F28069M: BOOSTXL-DRV8301 LAB2B RoverL get a negative value

a PMSM motor with parameter:

pole pairs = 10

rate speed = 180RPM

rate voltage = 36V

Rs = 5.0R

Stator inductance = 27mH

Time constance = L/R = 5.4mS

use lab02b to test the RoverL and Rs，

RoverL = -7415   not correct

Rs = 4.9R

power voltage = 20 -24VDC

Test codition set as followed

#define USER_IQ_FULL_SCALE_FREQ_Hz               (300.0) 
#define USER_IQ_FULL_SCALE_VOLTAGE_V          (24.0) // 24.0 Example for boostxldrv8301_revB typical usage and the Anaheim motor
#define USER_ADC_FULL_SCALE_VOLTAGE_V       (26.314)      // 26.314 boostxldrv8301_revB voltage scaling

#define USER_IQ_FULL_SCALE_CURRENT_A (20.0) // 20.0 Example for boostxldrv8301_revB typical usage

#define USER_ADC_FULL_SCALE_CURRENT_A (33.0) // 33.0 boostxldrv8301_revB current scaling

#define USER_MOTOR_NUM_POLE_PAIRS (10)
#define USER_MOTOR_Rr (NULL)
#define USER_MOTOR_Rs (NULL)
#define USER_MOTOR_Ls_d (NULL)
#define USER_MOTOR_Ls_q (NULL)
#define USER_MOTOR_RATED_FLUX (NULL)
#define USER_MOTOR_MAGNETIZING_CURRENT (NULL)
#define USER_MOTOR_RES_EST_CURRENT (1.0)
#define USER_MOTOR_IND_EST_CURRENT (-0.5)
#define USER_MOTOR_MAX_CURRENT (2.0)
#define USER_MOTOR_FLUX_EST_FREQ_Hz (20.0)

change power supply to 12V, the RoverL value still -7900

why the RoverL value is a negative value? 

so I could not finished the Ls test

wei liu：

#define USER_PWM_FREQ_kHz (20.0) //30.0 Example, 8.0 – 30.0 KHz typical; 45-80 KHz may be required for very low inductance, high speed motors

#define USER_R_OVER_L_EST_FREQ_Hz (100)               // 300 Default

#define USER_VOLTAGE_FILTER_POLE_Hz  (364.682)   // 364.682, value for boostxldrv8301_revB hardware

I use a motor with parameter under below to check the hardware and LAB02b got the right value

pole pairs = 4

rate speed = 3000RPM

rate voltage = 24V

Rs = 1.02R

Stator inductance = 0.59mH

that prove the hardware is ok and all the procedure has no fault.

,

Cherry Zhou：

Hi,

We're looking into this and please allow some time for us to get back to you.

Thanks

,

wei liu：

yes, I do use the TI origin launchpad and boostxl board. 

I do use another motor as listed to check the board and get the right value

the bias of course was set by the hardware get read the correct value

the question is that the motor identify prog work not correct at the pmsm low speed motor.

I'm confused why I got a negative value

Thanks

,

Cherry Zhou：

Hi,

Thanks for the information and we'll try to give you the feedback by Thursday.

Thanks

,

Cherry Zhou：

Hi,

Try to run the lab02c if the motor is a low inductance motor. And please don't add any load on the motor for identification, and set the correct identification variables value in the file of user.h according to the specification of the motor, to make sure the motor spin smoothly during Flux measurement and Ls identification states.

#define USER_MOTOR_RES_EST_CURRENT     (2.0)                               // A – 10-30% of rated current of the motor

#define USER_MOTOR_IND_EST_CURRENT     (-1.5)                             // A – 10-30% of rated current of the motor, just enough to enable rotation

#define USER_MOTOR_MAX_CURRENT           (20.0)                               // A – 30~150% of rated current of the motor

#define USER_MOTOR_FLUX_EST_FREQ_Hz     (40.0)                           // Hz – 10~30% rated frequency of the motor

Thanks