• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 626 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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:

TMS320F280049: CMPSS + EPWM Peak Current Mode Control (PCMC) Configuration for Phase-Shift Full-Bridge Converter

TMS320F280039C: How to make Assymmetric and Complemental PWM waveform by only one PWM channel.

Yutaka Kamon
Prodigy 60 points
Part Number: TMS320F280039C

Hello,

I have a question about PWM waveform generation of F280039C.

I want to generate an asymmetric and complementary PWM as shown in the attached image with one PWM channel.
In other words, what we want to achieve is:

　① I want to set the ON timing and OFF timing of pulse A individually.

　②I want to output pulse B, which is complementary to pulse A and has a dead time.

If possible, I would like to know both of the following: how to realize this PWM waveform without using the deadband module, and how to realize this PWM waveform using the deadband module.
Counter mode (UP, Down, Uo-Down) does not matter, but I would like to know as many implementation methods as possible.

Thank you.

  • 0
    TI__Guru 52030 points

    You want to do everything with EPWMA and EPWMB of the same EPWM module?

    And also no deadband module?

    if using UP-DOWN mode:

    1. You dont want it to be symmetric around PRD?

  • 0 in reply to Nima Eskandari
    Prodigy 60 points

    Dear Nima Eskandari,

    Thanks for your quick reply.

    > You want to do everything with EPWMA and EPWMB of the same EPWM module?

    ⇒Yes, exactly. That's right. What I want to achieve is: Use EPWM1 ~ 3 for the U, V, and W phases of the three-phase inverter. And, as I asked, I want to generate asymmetric and complementary PWM on each channel. I want to use other EPWM 4 ~ 8 for another purpose.

    > And also no deadband module?

    ⇒It's OK with or without the deadband module. I would like to know both method if feasible.

    >if using UP-DOWN mode:

    >1. You dont want it to be symmetric around PRD?

    ⇒No, exactly. I want to achieve complementary PWM asymmetric with PRD in the same PWM module.

    Thank you again and I hope replying.

  • 0 in reply to Yutaka Kamon
    TI__Guru 52030 points

    So if you decide to use up-down mode, you have to use the deadband module if your wave is not symmetrical around period. Because you need to use both CMPA AND CMPB to set your channel A duty. So you don’t have any CMPs left for channel B. 

    if you use up count mode, is it okay if you set your EPWM wave high on CTR=0?

  • 0 in reply to Nima Eskandari
    Prodigy 60 points

    Thank you very much for your reply.

    >So if you decide to use up-down mode, you have to use the deadband module if your wave is not symmetrical around period.

    Yes, with up-down mode and deadband module, it can be achieved part of what I want to do,but the starting point of the reference PWM is limited to 0 to the center. Similarly, the end point is limited to the center to PRD.

    >if you use up count mode, is it okay if you set your EPWM wave high on CTR=0?

    I'm afraid but it's not okay. I want to set PWM pulse assymmetry and complementaly.

    Is it possible to use up count mode and with deadband module ? (Please see attached picture.)

  • 0 in reply to Yutaka Kamon
    TI__Guru 52030 points

    I guess even in the up-count mode, you could use CMPA and CMPB to set up the CHANNEL A and then use the deadband module to create CHANNEL B signal.

    Nima

  • 0 in reply to Nima Eskandari
    Prodigy 60 points

    Thank you very much for your opinion. I will try it.

    I think I may ask another question again.

    Thank you again.