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DRV8303EVM: DRV8303EVM + InstaSPIN BLDC GUI => motor not spinning

frederic_c
Prodigy 210 points
Part Number: DRV8303EVM
Other Parts Discussed in Thread: INSTASPIN-BLDC, DRV8301, CONTROLSUITE, DRV8302,

Hello,

I spent many hours trying to spin my motor with very little success.

I am focusing on "PWM control mode"

#1:

The only way I can keep the motor spinning is to enable "Advanced Startup Options"

but even with this enabled, the control seems to stay in "Startup" mode (the main Knob=duty cycle has no effect).

The main knob only affects the spinning direction (CW or CCW) but has no effect on RPM

#2: The BEMF waveform (Vag = Second graph: Displays the PU Phase-A BEMF waveform) seems strange:

I am using

InstaSPIN-BLDC_GUI_DRV83xx_v104.exe

+

InstaSPIN-BLDC_GUI_DRV8301_v104.out            (reflashing the MCU with this did not change the behavior)

Can you help?

Thanks.

  • 0 in reply to frederic_c
    TI__Guru** 110620 points
    1. What motor are you using? Is it the default motor attached with the kit.
    2. What's the rated voltage of the motor? It seems like the input voltage is a little low for the kit and motor.
    3. Did you changed the "Flux Threshold"? It seems like the "Flux Threshold" is too high you showed in the figure. You might change to a small value that should be less than 1.0.

    Btw, the default target code in controlSUITE only supports DRV8301-Kit and DRV8302 kit if you didn't change the target code.
  • 0 in reply to Yanming Luo
    Prodigy 210 points

    Hello Yanming Luo,

     

    I switched to another motor which seems easier to control (and is also closer to the motor of my final application).

    (BTW, there is no motor provided with DRV8303EVM)

    The motor I am now using is maxon 323220 (4 poles).

    The spec is here:

    https://www.maxonmotor.com/maxon/view/product/323220

    For now, the only load is a gearhead (planetary gearheard probably).

    With this setup, I have no issue with the startup phase.

     

    For Duty Cycle=0.4 (RPM around 4600)

    Everything seems OK:

    Changing the flux threshold from 0.01 to 0.3 changes the DC current from 0.07A to 0.09A => OK

     

    This is for flux threshold = 0.01   (IDC=0.07A)

     

    And this is for flux threshold = 0.3     (IDC=0.09A)

     

     

    The issue I am having with this motor is the high DC current at higher Duty Cycle / RPM.

    For Duty Cycle=0.8 (RPM around 9800)

    Changing the flux threshold from 0.01 to 0.3 changes the DC current from

    IDC=0.2A   (acceptable???)

    to IDC=2A => OK   (not acceptable / motor very hot)

     

     

    This is for flux threshold = 0.01   (IDC=0.2A)

     

    This is for flux threshold = 0.3   (IDC=2A !!!!!!!!!!!)

    So in order to have an “acceptable” DC current I have to reduce the flux threshold down to the minimum (0.01).

    Any Duty Cycle above 0.01 will increase the DC current.

    Does this seems normal?

    About firmware:

    This page

    http://www.ti.com/tool/drv8303evm

    shows “Software: DRV8303EVM (Rev. B)”

    which contains InstaSPIN-BLDC_GUI_DRV8301_v104.out   (and InstaSPIN-BLDC_GUI_DRV83xx_v104.exe).

    So I assume that this should work with DRV8303EVM board.

    Is this correct?

     

    "Paste from Word" does not seem to work (no image) so I am attaching the MS word file:

    Hello.docx

    Thanks,

    Frederic

  • 0 in reply to frederic_c
    Prodigy 210 points

    Hello Yanming Luo,

    The main problem is the RC filters on the phase voltage measurements on DRV8303EVM.

    At high RPM, the delay of this filter cannot be compensated with the adjustment of the GUI flux threshold.

    I changed the 100nF cap to 10nF.

    I can now run my motor at high RPM.

    Could you comment this:

    "

    This page

    www.ti.com/.../drv8303evm

    shows “Software: DRV8303EVM (Rev. B)”

    which contains InstaSPIN-BLDC_GUI_DRV8301_v104.out   (and InstaSPIN-BLDC_GUI_DRV83xx_v104.exe).

    So I assume that this should work with DRV8303EVM board.

    Is this correct?

    "

    Thanks,

    Frederic

  • 0 in reply to frederic_c
    TI__Guru** 110620 points
    Hi Frederic,

    It could work well in the most case, but you might change the filter capacitor to a small capacitance since you are using the instaSPIN-BLDC algorithm, and need to run the motor to a high speed. The 100nF value is better for the instaSPIN-FOC algorithm.