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TMS320F28069M: summing noise lab11e

Daniel Mueller
Intellectual 905 points
Part Number: TMS320F28069M

Hello guys,

 

I have a question about lab11e. It works great in our application but there is one little thing I would like to solve. If the motor isn't spinning, there is a “summing noise”. (In other labs like 5a/b for example is it also there but barely audible)

 

I think this is needed to estimate the angle before the motor is spinning?
Do I need this if I start with hall sensors? If not can anyone tell me how to disable this noise?

To get rid of the noise I tried two things:

 

1.I disabled force angle, but this only reduced the noise a bit.

I think I do not need force angle with hall sensors at start-up, is this right?

 

2. I wanted to set PwmDuty to zero if no signal comes from the throttle but that does not work either.

// BLDC current loop
PID_run(pidHandle[3],gHall_BLDC_Is_ref_pu,gHall_BLDC_Is_fdb_pu,&gHall_PwmDuty);
if(gMotorVars.IqRef_A == 0)// gMotorVars.IqRef_A comes from throttle
   gHall_PwmDuty=_IQ(0.0);

HALLBLDC_Ctrl_PwmSet(gHall_PwmState, gHall_PwmDuty);


Thank you

  • 0
    TI__Guru** 114520 points
    The pwm output should be disable in most example lab projects of InstaSPIN by default if the motor stop without spinning, so there is no any "noise" source. I guess you are using different stopping mode, right? And what "summing noise" do you mean? Do you have any waveform to show it?

    1. You are right. The force angle is just used to provide a good start from zero speed if using sensorless instaSPIN-FOC, especially motor starts with a heavy load. The force angle will be disabled if using hall sensor.

    2. The pwm will output 50% duty waveform if you set gHall_PwmDuty=_IQ(0.0), because lab11e is using complementary pwm mode for both instaSPIN-FOC and BLDC.
  • 0 in reply to Yanming Luo
    Intellectual 905 points

    Thanks for your answer,

    I just tried something, usually I use torque control therefore I changed the lab11e to torque mode.
    e2e.ti.com/.../687037

    I changed it back to speed control and there was no noise!

    I assume the speed controller turns the pwm down or something.
    This are my changes HALLBLDC_Ctrl_Run():

    if(gHall_Flag_CurrentCtrl == true) // Torque Control Mode
    {
                    gHall_BLDC_Is_fdb_pu = gAdcData.I.value[gHall_BLDC_Flag_Is_fdb];

    if(FS_flag_enableSpeedCtrl == true)
                    gHall_BLDC_Is_ref_pu = speed_pid_out;
    else
                    gHall_BLDC_Is_ref_pu = FS_Iq_ref_pu;

    // BLDC current loop
    PID_run(pidHandle[3],gHall_BLDC_Is_ref_pu,gHall_BLDC_Is_fdb_pu,&gHall_PwmDuty);
    //gHall_PwmDuty=_IQ(0.0)   -> For testing I enabled this and there was no noise.
    HALLBLDC_Ctrl_PwmSet(gHall_PwmState, gHall_PwmDuty);
    }
    else // Speed Control Mode
    {
    gHall_PwmDuty = speed_pid_out;
    HALLBLDC_Ctrl_PwmSet(gHall_PwmState, gHall_PwmDuty);
    }

    Here is the screenshot:

     

    And a soundfile:

    Click here to play this audio clip

  • 0 in reply to Yanming Luo
    Intellectual 905 points

    It works, I did something wrong with the changes from speed to torque control.
    sorry about the circumstances