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Motor ID process fail and unstable.

Junji Takiguchi
Prodigy 250 points

Other Parts Discussed in Thread: DRV8301, MOTORWARE, DRV8312, INSTASPIN-BLDC

Good day.

We are trying to use DRV-8301 Evaluation board with our high speed and low inductance motor.

Our power supply voltage is 24V and maximum speed will be up to 50000rpm.

Based on suggestion of Japan TI, we modified DRV8301 board as below.

Shunt resistor value : From 0.002 to 0.01.

ADC_Vhb filter setting capacitor. : From 0.1uF to 0.047uF.

 

Our Motor Symptom

In process of motor ID, sometimes it stops Rated_flux EST process.

So CTR_State_Error and EST_State_Error message appear.

Sometimes we can pass ID process. But in that time, Ls value is unstable. If we tried 3 times, it has so big difference. Rs value is every time stable.

How we should do to get stable result?

Please advice.

  • 0
    Guru 13185 points

    Hello Junji Takiguchi,

    While waiting the TI expert replying you, please confirm that:

    1. You set the correct switches for your ControlCard (once this was happened to me that I didn't set the ControlCard switch based on its hardware user guide and I got unstable ID results)

    2. Are you using CCS or GUI to evaluate your kit? If you use CCS, please make sure you use CCS Compiler (Code Generation Tool) v 6.2.3 or above.

    3. Are you using Motorware? Please use Motorware 12 and make sure you try Project Lab 2c (for low inductance PMSM)

    Best regards,

    Maria

  • 0 in reply to Maria Todorova
    TI__Guru** 119680 points

    Follow Maria's post.

    See the sticky post "setting your user.h"

    After following the spreadsheet on the 2nd page try again. 

    Then attach the user.h to your next post so I can review. 

  • 0 in reply to ChrisClearman
    Prodigy 250 points

    Thank you yor reply.

    Yes, I use CCS and follow Lab process.

    And I have already confirmed spread sheet parameters and no error found in it.

    Thus I worry that we could not set any parameter as best value.

    So I want to know a relation between hadware modificationand parameter setting.

    (If I changed filter setting capacitor and shunt resistor, whta parameter I shold change. I could not found any document that mentioned about this point.)

    As I wrote, TI Japan member said that we should modify hardware to use for our motor.

    By their confirmation, our motor could run with "DRV8312" board.

    Then they suggested to modify our board to make it close to DRV8312 board.

    But our target is higher power motor, so we had to change from DRV8312 to DRV8301.

     

     

  • 0 in reply to Junji Takiguchi
    TI__Guru** 119680 points

    Junji Takiguchi said:

    (If I changed filter setting capacitor and shunt resistor, whta parameter I shold change. I could not found any document that mentioned about this point.)

    This is mentioned in detail in SPRUHJ1

    Yes - if you are using your own HW or modified HW you need to update the user.h ADC Scalings. You also need to confirm the ADC pin mapping is the same (or change in the hal.c / hal.h files). 

     

    Are you trying to ID a motor with known HW, or trying to debug if your HW modifications are correct?

     

  • 0 in reply to ChrisClearman
    Prodigy 250 points

    Hello Chris.

     

    1. TI Japan and we failed to run our motor with original DRV-8312 evaluation board.  (We could not identify motor.)

    They suspected that it comes from too low inductance.

    1. In 8312 board, Voltage filter capacitor changed from 47nF to 10nF.
    2. At the same time, Voltage filter pole setting is changed from 714.14 to 3356.48.
    3. By this condition, we succeed to run our motor.
    4. We changed evaluation board to DRV8301 due to our motor performance.
    5. To make 8301 board setting close to 8312, we changed shunt current resistor and filter capacitor values based on TI suggestion.

    So I believe our modification of HW is correct. But at the same time, we should adjust some parameters in user.h not only ADC scaling, like a filter pole. But I could understand how to change it.

    As the result, I just want to know how to improve parameters in user.h. 

     

  • 0 in reply to Junji Takiguchi
    TI__Guru** 119680 points

    Junji Takiguchi said:
    • In 8312 board, Voltage filter capacitor changed from 47nF to 10nF.
    • At the same time, Voltage filter pole setting is changed from 714.14 to 3356.48.
    • By this condition, we succeed to run our motor.

    You only make this change for InstaSPIN-BLDC (where you don't want the voltage signal filtered).  Making this change and trying to run InstaSPIN-FOC will not / should not work.

    What values were you able to identify?

    Junji Takiguchi said:

    As the result, I just want to know how to improve parameters in user.h. 

    Most critical is getting the ADC_ and USER_VOLTAGE_FILTER_POLE_Hz  DESIGNED correctly, then setting these values in user.h

    Attach your user.h and I will take a look.

     

    I suggest reading chapter 5 of SPRUHJ1 again to check the current and voltage scaling and filter pole design.