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TMS320F280025C: TMS320F280025C

Hely Zhang
Intellectual 1160 points
Part Number: TMS320F280025C
Other Parts Discussed in Thread: C2000WARE

Hi,

I am debugging a digital buck board for customer based on TIDM_DC_DC_BUCK, I already ported software to F280025C.
These days, I found there is a surge current with load transient, since duty cycle of buck MOSFET was increased very
quickly due to Vout is dropping, so i want to either control loop speed, or change PID controller
Regarding control loop speed, are below defines correct?
#define BUCK_ISR_CTRL_LOOP_RATIO 1

Regarding PID controller parameters, I found below sentences inside BUCK_runIsr(), but not sure which parameters
I should change inside BUCK_ctrl, could you tell me which is K parameters, which is I parameters of the ?
BUCK_ek_pu = BUCK_vOutSet_pu -BUCK_vOutSensed_pu;
//
// Calculate the required control effort (duty cycle)
//
BUCK_uk_pu = BUCK_DCL_RUN_IMMEDIATE(&BUCK_ctrl,
BUCK_ek_pu); 

Or if you can give any other suggestions to suppress the surge current?

Regards

Hely

  • 0
    TI__Mastermind 19171 points

    Hi Hely,

    Would you be able to provide the scope waveforms showcasing this behavior? 

    Hely Zhang said:
    Regarding control loop speed, are below defines correct?
    #define BUCK_ISR_CTRL_LOOP_RATIO 1

    This variable determines the number of ADC SOC events which must occur before the ISR is triggered. If you increase this number, your control loop would happen less frequently.

    You can check the coefficients in the buck.c file which gets returned into the DCL PID function responsible for the control loop.

    Regards,

    Peter

  • 0 in reply to Peter Luong1
    TI__Intellectual 1160 points

    Hi, Peter

    Thanks.

    Can I have EPWM_TZ_SIGNAL_DCAEVT1 to trigger a OST protection for over voltage by a CMPSS, and have EPWM_TZ_SIGNAL_DCAEVT2 to trigger a CBC protection for over current by another CMPSS?

    Are OST and CBC independent?  will CBC event also create a OST flag?  seems if I do not setup OVP CMPSS, CBC over current protection works well, but a OST flag will be set even I have only over current signal after I setup OVP CMPSS.

    Could you give some suggestions?

    Thanks

    Hely

  • 0 in reply to Hely Zhang
    TI__Mastermind 19171 points

    Hi Hely,

    You are correct, the OST and CBC are independent of each other. The CBC restores the output whenever the fault condition is lifted but you do not have to clear a flag for the output to restore. Whereas with the OST, you must clear the flag manually. You should be able to refer to the digital compare event example in our C2000Ware examples folder for this support

    Regards,

    Peter