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CCS/BOOSTXL-DRV8301: Hard to identify motor - high inertia

Filipe Terra
Prodigy 20 points
Part Number: BOOSTXL-DRV8301

Tool/software: Code Composer Studio

Hello guys,

I'm trying to identify a motor using Instaspin-FOC GUI for the past couple days with no success. I've used several different configurations, such as different pwm and L estimation frequencies and also different voltage and current scales.
It's a turntable direct drive motor that runs at about 20V, star connection and abour 40ohms per phase. The shaft is directly connected to a 3kg heavy metal plate that can't be removed. Normal speed is 90 rpm maximum, and current does not exceed 300ma. The high motor inertia seems to be the problem.

Could someone gime a hint on what parameters to tweek in order to get this motor to succesfully identity?

  • 0
    TI__Guru** 115480 points

     You have to disconnect the shaft to a load and identify the motor without loading. 

    You may try to tune the identification variables in the file of the user.h according to the motor.

    #define USER_MOTOR_RES_EST_CURRENT     (1.0)                               // A - 10-30% of rated current of the motor

    #define USER_MOTOR_IND_EST_CURRENT     (-1.0)                             // A - 10-30% of rated current of the motor, just enough to enable rotation

    #define USER_MOTOR_MAX_CURRENT           (5.0)                               // A - 50~150% of rated current of the motor

    #define USER_MOTOR_FLUX_EST_FREQ_Hz     (20.0)                           // Hz - 10~30% rated frequency of the motor

  • 0 in reply to Yanming Luo
    Prodigy 20 points

    Hello Yanming

    Unfortunately the heavy load is built in to the shaft (rotor magnets are part of the heavy plate structure).
    The motor stator looks like this 

    During identification, Rs identification goes well, but inductance and flux steps do not work, I belive because instaspin is not able to estimate the speed accurately enought. Sometimes the motor doesn't spin and estimated speed is high (thousands of rpms), then estimation kind of work for a short period, the motor spins quickly and speed estimation goes bad again.

    Can I measure R and L with multimeter and try to work flux value from instaspin?

  • 0 in reply to Filipe Terra
    TI__Guru** 115480 points

    Understand. You might try to tune the parameters to identify again. If still failed, you have to ask the motor manufacturer to get the motor parameters and refer to chapter 6.8 of the user's guide to set the motor parameters.

    InstaSPIN-FOC and InstaSPIN-MOTION User's Guide (Rev. H)

    http://www.ti.com/lit/ug/spruhj1h/spruhj1h.pdf

     6.8 Setting PMSM Motor Parameters in user.h