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DRV8312-69M-KIT: DRV8312-69M-KIT

Part Number: DRV8312-69M-KIT

Hello,

I am using DRV8312-69M-KIT with 2806xISO control card. I am running sample code BLDC_Sensored from ControlSuit. All build level (LEVEL1 to LEVEL6) are running successfully. My question is as per PWM configuration PWM switching frequency is set 20 kHz but the actual PWM frequency in output waveform is in Hz. How this frequency is changing?  

  • Do you have any waveform to show this question? And post the configuration code for the System Clock and PWM. What's the EPwm1Regs.TBPRD?
  •  Please find below path of the example code and attached waveforms of EPWM2A and EPWM2B.

    C:\ti\controlSUITE\development_kits\DRV8312-C2-KIT_v128\BLDC_Sensored

  • Do you required any other information?
  • You might zoom in the waveform of channel "1" to check the PWM frequency as the first figure you posted. It seems like the PWM frequency is correct. The second figure shows the frequency on channel 2 is the commutation frequency of the motor, not PWM frequency. You might have a look at the application guide in the folder of example project in controlSUITE that should help you to understand the concept of BLDC control.

    Please check the configuration code for CPU clock and PWM if the PWM frequency is not right as you want, or post these code if you have any further question.
  • This is the code path.C:\ti\controlSUITE\development_kits\DRV8312-C2-KIT_v128\BLDC_Sensored

    How do I calculate this commutation frequency?
  • The commutation frequency is based on the motor speed, it's 6 times to the motor electrical frequency. Please have a look at the application guide in the following folder of controlSUITE.
    C:\ti\controlSUITE\development_kits\DRV8312-C2-KIT_v128\BLDC_Sensored\~Docs

    And the documentation of its related blocks that could be also found in below folder.
    C:\ti\controlSUITE\libs\app_libs\motor_control\math_blocks\v4.3\~Docs
  • I have already gone through these documents, But still I have doubt. Please answer the following question:
    1. Is motor electrical frequency is same as f in the motor speed equation that is RPM = 120f/P?

    2. In the macro namely BLDCPWM_MACRO six steps are generated and this macro is called at 40 kHz ISR frequency, Whereas actual PWM frequency which I have observed in the oscilloscope is same as hall sensor frequency. Kindly clarify this, if steps are generated at fixed frequency then how this commutation frequency is changing with hall frequency in sample code.

    3. Kindly provide me the information for the motor DT4260-24-055-4H-PT, I have tried to search it out and I have found TelcoMotion DT4260-24-055-04H-TI.pdf from one of the post. is it same for DT4260-24-055-4H-PT if not then what is the difference between PT and TI mentioned in the part number?

    4. In the code hall1.HallGpioAccepted is mapped into pwm1.CmtnPointer, how this mapping is done considering non-inverted hall logic?

  • 1. Right, this is the relationship between the electrical frequency and mechanical rotation speed.
    2. Different concepts. As replied to you above, the signal frequency from the hall sensor is 6 times of the electrical frequency of the motor.
    3. You may find the information from the website of the motor manufacturer directly.
    Btw, about Q2,3&4, all we can reply to you should be the same and covered by the documents recommended above, hope you could have a look again that should help you to find the answer more clearly.
  • Thanks, by reading again I got the answer. imp1.period = 168 for LEVEL2, imp1.counter incremented by 1 from 0 each 25 us (40 kHz) and when imp1.counter reaches the period it will trigger MOD6CNTR which generates the sequence. so the total time for a complete cycle of 6 steps = 168 x 25us x 6 = 39.68 Hz.