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TMS320F2800157: Average current sense in peak current control

Suiyang Hu
Prodigy 195 points

Part Number: TMS320F2800157
Other Parts Discussed in Thread: TIDM-DC-DC-BUCK

Dear c2000 experts,

Rencently, i am developing a peak current control buck converter, using c2000 mcu cmpss to monitor current and disable driver though Cmpss->ePWM DC->T1 event->ePWM AQ.

In average current mode, we usually begin ADC in Ton/2 to get average current information, but in peak current control, the Ton time is determined by T1 event, we can not know the actual CTR value, i hope ti c2000 experts could provide a effective method to get accurate average current information. or can i know the epwm.ctr value when T1 event come?

Thanks,

Best Regards,

Suiyang

  • 0 in reply to Suiyang Hu
    TI__Mastermind 20421 points

    Hi Suiyang,

    Thank you for your patience over the holiday season and happy new year.

    I think it will be very helpful to refer to TIDM-DC-DC-BUCK which employs PCMC on a buck converter design, you can view the design guide which has very detailed guidance.

    For your purposes, it is possible to route the CMPSS signal to the ePWM Event Trigger module. Event Trigger can generate SOCA signal event based on DCxEVT1 signal. You should be able to use this SOCA to sample the current sensing ADC. 

    You won't be able to use this CMPSS to generate an ISR interrupt, but you can use an ADC interrupt for this purpose to read the current sensing information 

    Regards,

    Peter

  • 0 in reply to Peter Luong
    Prodigy 195 points

    Hi Peter,

    Thanks for your advise, I will check the TIDM-DC-DC-BUCK design.

    As your advise, using DCxEVT1 to generate SOCA signal, I was concerned about this signal aslo disable PWM driver, which will cause current decrease fastly, do you think these is a risk that we would get a not so accurate current information based DCxEVT1 SOCA signal?

    Happy new year！

    Best Regards,

    Suiyang

  • +1 in reply to Suiyang Hu
    TI__Mastermind 20421 points

    Hi Suiyang,

    How long have you configured your ADC sampling and hold time for? Additionally, the T1 AQ signal has a 3 CLK cycle qualification period before it shuts off the PWM signal. I believe you can try tuning your ACQPS values and checking your current sensing readings if you have access to your hardware. We should be following a similar approach in the TIDM-DC-DC-BUCK (refer to EPWM6/EPWM1: the DRV PWM signal)

    Regards,

    Peter