• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 82 subscribers
  • Views 358 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TMS320F280040: Adding deadband delay for ePWM

TMS320F28379D: Applying rise and fall delay dead-band to both ePWM input sources

Jin Gao1
Prodigy 90 points
Part Number: TMS320F28379D

Hello,

I have a question that I would like to be clarified. Due to the way the dead-band submdule is, there is no way to have a rise delay on ePWMxA and both rise and fall delay on ePWMxB, correct?

For example my B signal is exactly the same as A input signal. 

My goal is to have :

  1. Add only rise delay to input A and output to OutA
  2. Add both rise and fall to input A and output to OutB

From Figure 15-33 in the Technical reference, it seems like S8 won't let me do goal #2 while fulling goal #1. Is that correct? Do you have any suggestions on overcoming this issue?

My alternative solution is just implement  ePWMxB as a replication of ePWMxA and just mannual add an offset to CMPA and CMPB for each ePWM. Do you think this is a workable solution? 

For example:

  • ePWMxB(CMPA+offset1, CMPB+offset2)
  • ePWMxA(CMPA+offset2, CMPB)

Thank you!

Regards

Jin

  • 0
    TI__Mastermind 23410 points

    Hi Jin,

    Jin Gao1 said:

    it seems like S8 won't let me do goal #2 while fulling goal #1. Is that correct? Do you have any suggestions on overcoming this issue?

    Yes, this is correct, you will have to do either option 1 or option 2. 

    Adding an offset to CMPA/CMPB could work. Do you plan to keep a fixed delay value for rising and falling edge?

    Best Regards,

    Marlyn

  • 0 in reply to Marlyn Rosales Castaneda20
    Prodigy 90 points

    Yes it will be fixed delay. But I just realized it won't work with offset either.

    Because CMPA and CMPB are shared between Channel A and Channel B, I can't apply the different offsets to each channel. 

    Do you have a suggestion for a different workaround, other than using two different EPWM-A channels 

    Thank you

  • 0 in reply to Jin Gao1
    TI__Mastermind 23410 points

    Hi Jin,

    What are your action qualifier settings? Could you get away with only using CMPA for outputA and CMPB for outputB?

    Best Regards,

    Marlyn