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Cannot reach nominal speed of BLDC motor with InstaSPIN

Eduardo Rhod
Prodigy 50 points

Other Parts Discussed in Thread: BOOSTXL-DRV8301, MOTORWARE

Hello my friends,


I am part of a team working in a project to control a BLDC motor which electrical characteristics are shown in figure below:

We are using the CSS and the GUI Composer to code and program the BOOSTXL-DRV8301 hardware connected to the C2000 Piccolo Launchpad. Our problem is that we cannot reach the nominal speed with no load of our BLDC motor, indicated inside the dashed yellow rectangle of the picture above.  

We started by connecting our motor to the kit and run the GUI Composer to identify the motor dynamic. The Gui Composer identified the KPs and KIs motor parameters and when we set the desired target speed (16,900 rpm) the GUI Composer shows us that the motor has reached only 6,800 rpm. We then connected a Tacometer to our motor to measure the real speed and to our surprise the measured speed was around the double, 13,672 rpm.

How can we reach the 16,900rpm we want to? What are we missing? Should we change directly at user.h file with different values for USER_IQ_FULL_SCALE_FREQ_Hz, USER_IQ_FULL_SCALE_VOLTAGE_V, USER_VOLTAGE_FILTER_POLE_Hz e USER_PWM_FREQ_kHz?

What references do you suggest for understanding the user.h parameters?

Sorry for the big number of questions. We are kind of lost here.

Thank you in advace,

Regards,

Eduardo

  • 0
    TI__Guru** 119680 points

    please attach the user.h you are using

    use proj_lab02c to ID this motor. it will have low inductance and needs this lab

    then use proj_lab10a to run the motor and try the different modulation levels.

    the speed KpKi gains will be too big, you will need to reduce.  try /10

    this motor is really low current....you aren't using much resolution of the +/- 17A scale of the BOOSTXL-DRV8301. Better HW will be a benefit.

  • 0 in reply to ChrisClearman
    Prodigy 50 points

    Thank you for your quick answer. In attach follows our user.h.

    What kit do you suggest we use instead BOOSTXL-DRV8301?

    Thank you,

    Eduardo

    user_modified.h
  • 0 in reply to Eduardo Rhod
    TI__Guru** 119680 points

    never mind, I misread the current on the datasheet.

    5A nominal and 2-2.5 continuous under load is fine for this board....70A start-up?  That is really strange...really?

    regarding user.h:

    1. why did you change this value?

    #define USER_VOLTAGE_FILTER_POLE_Hz  (416.67)

    2. set this to a maximum of less than 4x the pole, so something like

    #define USER_IQ_FULL_SCALE_FREQ_Hz        (3.9 * USER_VOLTAGE_FILTER_POLE_Hz)

    3. you didn't set up your own USER_MOTOR, you are just using the default
    #define USER_MOTOR Anaheim_BLY172S

    set-up something like

    #elif (USER_MOTOR == ESCON_311536
    #define USER_MOTOR_TYPE                 MOTOR_Type_Pm
    #define USER_MOTOR_NUM_POLE_PAIRS       (2)
    #define USER_MOTOR_Rr                   (NULL)
    #define USER_MOTOR_Rs                   (0.17)
    #define USER_MOTOR_Ls_d                 (0.000015)
    #define USER_MOTOR_Ls_q                 (USER_MOTOR_Ls_d)
    #define USER_MOTOR_RATED_FLUX           (0.003)
    #define USER_MOTOR_MAGNETIZING_CURRENT  (NULL)
    #define USER_MOTOR_RES_EST_CURRENT      (2.0)
    #define USER_MOTOR_IND_EST_CURRENT      (-2.0)
    #define USER_MOTOR_MAX_CURRENT          (10.0)
    #define USER_MOTOR_FLUX_EST_FREQ_Hz     (60.0)

  • 0 in reply to ChrisClearman
    Prodigy 50 points

    TY Chris,

    we will try your suggestions and reply here the results. Is there some 101 literature that explains the meaning of each user.h parameters?

    Regards,

    Eduardo

  • 0 in reply to Eduardo Rhod
    TI__Guru** 119680 points

    attached QSG was accidently left out of MotorWare release, it belongs here

    C:\ti\motorware\motorware_1_01_00_13\docs\guis\universal

    there is also the QSGs for the "frozen" GUIs

    C:\ti\motorware\motorware_1_01_00_13\docs\guis\hvkits_8312s_8301s

    and the InstaSPIN Lab UG

    C:\ti\motorware\motorware_1_01_00_13\docs\labs

    and of course the main UG SPRUHJ1

    qsg_gui_universal.pdf
  • 0 in reply to ChrisClearman
    Prodigy 50 points

    Good morning Mr. Chris,

    I'm Yuri and I work in the same project than Eduardo.

    So I will try manifest what is happening.

    When I configured the motor using USER_MOTOR == MYMOTOR and I changed the parameters to the parameters that you sent.

    Then when I use the GuiComposer the flag Enable System is rested, I have setting it in code too but it not works.

    When I use the GuiComposer I can see the flag resetting. Please check out below: 

    I don't know why that is happening... then I found some parameters of motor manufacturer like NUM_POLE_PAIRS, MOTOR_Ls, MOTOR_Rs. The same happens...

    Then, I looked that when I don't select the check box "user.h Params" I saw that gui composer calculate all params of motor, that is awesome! But doesn't work...

    Only the same happen... The strange is we use the wrong motor like Anaheim_BLY1725 it works. but the motor lock and don't spin...

    Why it work? that motor have more pole than I really use, the all parameters is different.

    It look like that some wrong calculation and some protection don't let the motor spin...

    Please, can you help me?

    I would like to add you on skype or call you for finish it. Can I do it?

    thanks for all

    best regards

    Yuri Rodrigues

  • 0 in reply to Yuri Andrade Rodrigues
    TI__Guru** 119680 points

    Yuri Andrade Rodrigues said:
    I would like to add you on skype or call you for finish it. Can I do it?

    no

    Yuri Andrade Rodrigues said:
    When I use the GuiComposer I can see the flag resetting. Please check out below:

    If the Enable flag is resetting it means you have an Error. Read the Error Code in the top middle of the GUI

    Yuri Andrade Rodrigues said:

    NUM_POLE_PAIRS, MOTOR_Ls, MOTOR_Rs. The same happens...

    Then, I looked that when I don't select the check box "user.h Params" I saw that gui composer calculate all params of motor, that is awesome! But doesn't work...

    Those aren't your motor parameters. Those are the active USER_MOTOR parameters from the user.h that you compiled into the .out

    You need to follow the user's guide to ID your own motor parameters

    C:\ti\motorware\motorware_1_01_00_13\docs\labs\instaspin_labs.pdf