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Original question:

CCS/TMS320F28069M: Selection of TBPHS for a three phase system in UPDOWN mode.

CCS/TMS320F28377S: Phase shift operation

D MISHRA
Intellectual 470 points

Part Number: TMS320F28377S

Tool/software: Code Composer Studio

Hi,

I am operating the adjacent legs of an inverter with some phase shift let it be 30 deg in 28377S launchpad.I have set up the TBPRD for 25kHz frequency with PWM2 as master and PWM 6,7 as slaves. I have used the below command lines to set the master and then changed the phase by 100-200 to get some phase shift in PWM6, but i am not getting any phase-shift. What may be the possible reasons for this.

EPwm2Regs.TBCTL.bit.PHSEN = 0; 

EEPwm2Regs.TBCTL.bit.SYNCOSEL =0;

.

.

EPwm6Regs.TBCTL.bit.PHSEN = 100; 

EEPwm6Regs.TBCTL.bit.SYNCOSEL =1

Thank you for your time.

  • 0
    TI__Mastermind 27200 points

    Your register settings are correct, however this master/slave combination is not possible on F28377S.  Please refer to the time-base counter sync. chains diagram on p.1597 of the TRM:

    http://www.ti.com/lit/ug/spruhx5f/spruhx5f.pdf

    You could use PWM1 as the master, then configure the sync. muxes to offset PWMs 6 & 7, but PWM2 can only sync. PWM3.  Unfortunately you'll need to make another choice of PWM modules.

    Regards,

    Richard

  • 0 in reply to Richard Poley
    Intellectual 470 points

    Hi Richard,

    Thanks for your reply. As I am using the 28377S launchpad, it has limited PWM options like EPWM2,6 and EPWM7-11. But i need four pairs of EPWM, where leg 1 should work as the master for leg2&3 and leg 3 also work as the master for leg4. So what may be the combination for EPWMs. If it's not possible that leg3 can act as the master for one combination and slave for other, then it would be fine with one master and three slaves. 

    Thank you for your kind consideration to reply.

  • 0 in reply to D MISHRA
    TI__Mastermind 27200 points
    You're welcome!

    I think the "one master, three slave" combination is achievable. If you take ePWM7 - 10, all of which emerge at the board headers, then module 7 could be the master for modules 8 & 9 in the same chain, and also the master for module 10 which is in a separate chain. I don't see a way to get the first combination you mentioned with this device & board.

    Regards,

    Richard
  • 0 in reply to Richard Poley
    Intellectual 470 points

    Thanks a lot for your reply.