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DRV8316-Q1: CSA output waveform

Jeffrey Chung1
Genius 3300 points
Part Number: DRV8316-Q1
Other Parts Discussed in Thread: DRV8316

Tool/software:

Hi Team,

There is an issue on CSA output waveform of DRV8316. Please check the waveform/schematic below and let me know the cause of this issue.

CSA output waveform.pdf

Regards,

  • 0
    TI__Genius 12231 points

    Hi Jeffrey,  

    Thank you for your question!

    I am a bit confused regarding the waveform provided-- can you help to explain which outputs are being shown? 

    I see the increasing peaks are circled, is this the are of issue? Is the SOx output not following the OUTX voltage and current form? 

    Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    Genius 3300 points

    Hi Joshua,

    As I checked it with customer, SOx waveform is not following the current output waveform over around 1.7A. But in case of low current condition(under 1.7A), SOx waveform is following the current output waveform. Please check the attachment below and let me know the solution.

    CSA output waveform_02.pdf

    Regards,

  • 0 in reply to Jeffrey Chung1
    TI__Genius 12231 points

    Hi Jeffrey, 

    Thank you for the additional clarification! To be clear, CH1 is the current probe measurement of a single phase (A, B, or C)  and CH2 is the SOx voltage of the same phase? 

     May I ask which control algorithm is being used (trapezoidal, sensorless FOC)? The current waveforms do not appear stable/cyclical-

    From the two provided waveforms it appears the SOx voltages increase appropriately with the phase current, but can we decrease the gain to the lowest setting (if not already) and increase the waveform timescale so that we can get a closer and more accurate view of the PWM cycle and current changes?

    Thank you and Best Regards,

    -Joshua 

  • 0 in reply to Joshua Maize
    Genius 3300 points

    Hi Joshua,

    I uploaded the updated waveforms below. CH1 is input current of DRV8316 and CH2 is SOA waveform of U phase. SOB(V phase) and SOC(W phase) waveform are same as SOA. Also, It is same when changing Vref from 2.5V to 4V. Please check it and let me know the cause of this issue.

    CSA output waveform_03.pdf

    Regards,

  • 0 in reply to Jeffrey Chung1
    TI__Genius 12231 points

    Thanks Jeffrey,  

    Please let me look into this and follow-up tomorrow with additional feedback. 

    Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    TI__Genius 12231 points

    Hi Jeffrey, 

    Can you help to provide the driving conditions used for the application? (PWM, duty cycle,  voltage,  commutation algorithm) 

    Can we also set the gain setting to the lowest setting if not already set? 

    Regarding the channel-1 current waveform, is the current probe measuring the actual output (OUTX) motor current, or the device input current as labeled?  The c1 and c2 waveforms do not appear to track each other in either case. 

    Lastly,  do you have an additional motor to cross-check the current waveform with to rule out motor/algorithm efficiency (current spike) issues?

    Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    Genius 3300 points

    Hi Joshua,

    Joshua Maize said:
    Regarding the channel-1 current waveform, is the current probe measuring the actual output (OUTX) motor current, or the device input current as labeled?

    The CH1 is device input current.

    Also, let me check other questions above with customer and will let you know that.

    Regards,

  • 0 in reply to Jeffrey Chung1
    TI__Genius 12231 points

    Hi Jeffrey,  

    I believe we should be monitoring the phase output current with a current probe on OUTA. OUTB, or OUTC, as SOA, SOB, and SOC is the current sensing correlating to the motor phases, not the input current (I_VM).  

    To determine if the waveform is truly abnormal, we will need to very the current of the motor phase is not following the voltage/current of the phase.

    Thank You and Best Regards,

    -Joshua