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CCS/TMS320F28027: PROBLEM WITH EPWM PULSES

Madhuri Depuru
Intellectual 325 points
Part Number: TMS320F28027


Tool/software: Code Composer Studio

hello sir,

I am currently working over PWM using ADC. I am trying to get the pulses to power full bridge dc/dc converter.

I am able to get the pulses for switches with deadband too. the main problem is that , when I am trying to implement pulse shutdown feature, one channel is getting shutdown and other channel is getting High.

I have found that I used PWM_deadbandpolarity() command, to get out of phase betwwen the two channels and this is causing the other channel not to get shutdown.

Is there any other way I can get out of phase between the two channels without using the above command

please help me

Thankyou

  • 0
    Genius 5885 points

    The dead time module should not be reconfigured during PWM operation.

    I configured EPwm so that I used A and B signals coming from Action Qualifier module into dead-time module.

    For enable/disable I then used continuous software force feature of Action Qualifier to force A and B signals to desired state

    This is an excerpt from my configuration:

    EPwm initialization:

        EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;      // set output on CMPA_UP
        EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;    // clear output on CMPA_DOWN
        EPwm1Regs.AQCTLB.bit.CAU = AQ_SET;      // set output on CMPA_UP
        EPwm1Regs.AQCTLB.bit.CAD = AQ_CLEAR;    // clear output on CMPA_DOWN
        
        EPwm2Regs.AQCTLA.bit.CAU = AQ_SET;      // clear output on CMPA_UP
        EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR;    // set output on CMPA_DOWN
        EPwm2Regs.AQCTLB.bit.CAU = AQ_SET;      // set output on CMPA_UP
        EPwm2Regs.AQCTLB.bit.CAD = AQ_CLEAR;    // clear output on CMPA_DOWN

        // Dead Time
        EPwm1Regs.DBCTL.bit.IN_MODE = 2;    //
        EPwm1Regs.DBCTL.bit.POLSEL = 2;     // active high complementary mode
        EPwm1Regs.DBCTL.bit.OUT_MODE = 3;   // dead band on both outputs

        EPwm2Regs.DBCTL.bit.IN_MODE = 2;    //
        EPwm2Regs.DBCTL.bit.POLSEL = 2;     // active high complementary mode
        EPwm2Regs.DBCTL.bit.OUT_MODE = 3;   // dead band on both outputs

    Software disable:
        EPwm1Regs.AQCSFRC.bit.CSFA = 1;
        EPwm1Regs.AQCSFRC.bit.CSFB = 2;
        EPwm2Regs.AQCSFRC.bit.CSFA = 1;
        EPwm2Regs.AQCSFRC.bit.CSFB = 2;

    Software enable:
        EPwm1Regs.AQCSFRC.bit.CSFA = 0;
        EPwm1Regs.AQCSFRC.bit.CSFB = 0;
        EPwm2Regs.AQCSFRC.bit.CSFA = 0;
        EPwm2Regs.AQCSFRC.bit.CSFB = 0;

    Best regards, Mitja