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CCS/DRV8312: DRV8312EVM - TMS320

Quang-Trung NGUYEN
Prodigy 40 points
Part Number: DRV8312

Tool/software: Code Composer Studio

Hello,

I'm working with the DRV8312EVM developped kit with the motor BLDC DT4260-24-005 24VDC 4000RPM (just starting). I ran the example code BLDC_sensorles, the motor runs just untill the level 4. AT level 5, when I close the loop, it didn't work. I think the problem coule be in the CMTN_TRIG module.

Below is the CmtnTrig and ZcTrig signal mesured. I think is not normal comparing with the guide file (which say that CmynTrig should appear 30° after the ZcTrig). the motor in this case still works.  

Thank you in avance for your support,

Trung

  • 0
    TI__Guru** 109730 points
    1. Could you please make sure that the connections and settings are correct on DRV8312-EVM board? Such as RSTA/B/C switch to MCU position.
    2. You may adjust the cmtn1.NWDelayThres and cmtn1.NWDelta based on your motor if you changed the default setting (pwm frequency...) and motor.
    3. Changed the BemfA/B/C_offset in project after you ran level 2.
  • 0 in reply to Yanming Luo
    Prodigy 40 points

    I keep using the default motor DT4260-24-055 24VDC 4000rpm. Below is the screen capture of my values while I run in level 4, I think Va, Vb, Vb are not normal.

    And here is my offsets:

    I have had tried to change cmtn1.NWDelayThres and cmtn1.NWDelta but the result is still the same.

    Thanks a lots,

    Trung

  • 0 in reply to Quang-Trung NGUYEN
    TI__Guru** 109730 points
    OK. Please keep the default setting and don't change anything, follow the lab guide to look if the motor run well, and use PwmDac to monitor the variables. Did you have any current and voltage waveform of oscilloscope to show the problem? You may adjust DFuncDesired to change the pwm duty.
  • 0 in reply to Yanming Luo
    Prodigy 40 points

    Yes, every code I have used till now is default, the motor is default also, I followed the lab guide and the motor didn't work at level 5 when I applied the CMTN_TRIG_MACRO, the output cmtn1.CmtnTrig is always zero and the motor is locked at a fixed position. I think the problem is located in the CMTN_TRIG_MACRO, the re-constructed Bemf is not good or the NOISE_WINDOW_CNT_MACRO doesn't work, I don't know. I cannot capture them to show you because the visualization doesn't work well and you see, the motor doesn't work so the Bemf is basicly zero.

    Below is the screen capture of PWM when the motor work at level 4 and doesn't work at level 5.

    Level 4 (PWM_A and PWM_B)

    Level 5 (PWM_A is kicked while two other are zero)

    Thanks for supports,

    Trung

  • 0 in reply to Quang-Trung NGUYEN
    Prodigy 40 points
    Can you explain a little bit your code in macro CMTN_TRIG_MACRO? so I can have some ideas to fix the problem.

    Thanks
    Trung
  • 0 in reply to Quang-Trung NGUYEN
    TI__Guru** 109730 points

    comtn_trig.pdfSensorless Trapezoidal Control of BLDC Motors.pdfTo compute the Bemf Zero Crossing Point by sampling the three phases voltage, and then delay 30 degree to commutate.  More detailed explain can be found in both lab guide and digital motor library guide. Attached it for your reference, please let me know if you have any further question.