• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 1013 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.

CCS: Dead time config

Max Av
Intellectual 470 points

Tool/software: Code Composer Studio

Hi, 

I configured dead time at 18.75ns between PWM1A and PWM1B. Dead time is working. but the problem is that I set the duty of PWM1B to 0, but despite this, it is inverted relative to PWM1A.

I need no inversions.

EALLOW;
    GpioCtrlRegs.GPAPUD.bit.GPIO0 = 1;  // Disable pull-up on GPIO0 (EPWM1A)
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1; // Configure GPIO0 as EPWM1A
    GpioCtrlRegs.GPAPUD.bit.GPIO1 = 1;  // Disable pull-up on GPIO1 (EPWM1B)
    GpioCtrlRegs.GPAMUX1.bit.GPIO1 = 1; // Configure GPIO1 as EPWM1B

    GpioCtrlRegs.GPAPUD.bit.GPIO2 = 1;
    GpioCtrlRegs.GPAMUX1.bit.GPIO2 = 1;
    GpioCtrlRegs.GPAPUD.bit.GPIO3 = 1;
    GpioCtrlRegs.GPAMUX1.bit.GPIO3 = 1;
    EDIS;

    EPwm1Regs.TBCTL.bit.HSPCLKDIV = 0;

    EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW; // set Immediate load
    EPwm1Regs.TBPRD = period - 1;          // PWM frequency = 1 / period
    EPwm1Regs.CMPA.bit.CMPA = period / 2;  // set duty 50% initially
    EPwm1Regs.CMPA.bit.CMPAHR = (1 << 8);  // initialize HRPWM extension
    EPwm1Regs.CMPB.bit.CMPB = period / 2;  // set duty 50% initially
    EPwm1Regs.CMPB.all |= (1 << 8);        // initialize HRPWM extension

    EPwm1Regs.TBPHS.all = 0;
    EPwm1Regs.TBCTR = 0;

    EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
    EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
    EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
    EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
    EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
    EPwm1Regs.TBCTL.bit.FREE_SOFT = 11;

    //dead time
    EPwm1Regs.EPWMXLINK.bit.GLDCTL2LINK = 0;
    EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
    EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
    EPwm1Regs.DBCTL.bit.IN_MODE = DBA_ALL;
    EPwm1Regs.DBCTL.bit.SHDWDBREDMODE = 1;
    EPwm1Regs.DBCTL.bit.SHDWDBFEDMODE = 1;
    EPwm1Regs.DBCTL.bit.LOADREDMODE = 0;    // Load on Counter == 0
    EPwm1Regs.DBCTL.bit.LOADFEDMODE = 0;    // Load on Counter == 0
    EPwm1Regs.DBCTL.bit.HALFCYCLE = 1;
    EPwm1Regs.DBRED.bit.DBRED = 4;
    EPwm1Regs.DBREDHR.bit.DBREDHR = (41.75) * 256;//18.75ns
    EPwm1Regs.DBFED.bit.DBFED = 4;
    EPwm1Regs.DBFEDHR.bit.DBFEDHR = (41.75) * 256;

    EPwm1Regs.HRCNFG2.bit.EDGMODEDB = HR_BEP;    // DBREDHR and DBFEDHR
    EPwm1Regs.HRCNFG2.bit.CTLMODEDBRED = 0; // Load on ZRO
    EPwm1Regs.HRCNFG2.bit.CTLMODEDBFED = 0; // Load on ZRO
    EPwm1Regs.DBREDHR.bit.DBREDHR = (0 << 9);
    ////dead time

    EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
    EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
    EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
    EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;

    EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET; // PWM toggle high/low
    EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;
    EPwm1Regs.AQCTLB.bit.ZRO = AQ_SET;
    EPwm1Regs.AQCTLB.bit.CBU = AQ_CLEAR;

    EALLOW;
    EPwm1Regs.HRCNFG.all = 0x0;
    EPwm1Regs.HRCNFG.bit.EDGMODE = HR_FEP; // MEP control on falling edge
    EPwm1Regs.HRCNFG.bit.CTLMODE = HR_CMP;
    EPwm1Regs.HRCNFG.bit.HRLOAD = HR_CTR_ZERO;
    EPwm1Regs.HRCNFG.bit.EDGMODEB = HR_FEP; // MEP control on falling edge
    EPwm1Regs.HRCNFG.bit.CTLMODEB = HR_CMP;
    EPwm1Regs.HRCNFG.bit.HRLOADB = HR_CTR_ZERO;
#if (AUTOCONVERT)
    EPwm1Regs.HRCNFG.bit.AUTOCONV = 1; // Enable auto-conversion
                                       // logic
#endif
    EPwm1Regs.HRPCTL.bit.HRPE = 0; // Turn off high-resolution period
                                   // control.

  • 0
    TI__Mastermind 42195 points

    Max,

    I have not reviewed you code, however is suspect that you have configured the DB to be in a complementary mode and now are trying to force ePMWxB low using the Action Qualifier(AQ)submodule.

    If this is the case: Please note that the submodules of the PWM take effect sequentially. The AQ takes effect before the DB. Then inside of the DB you had told it to discard the ePWMxB channel generated by the AQ and create a new ePWMxB output which is generated from the ePWMxA input with a known DB.

    If you wish to shutdown the PWM I would suggest looking at the Trip-Zone submodule, which takes effect after the DB.

    Regards,
    Cody 

  • 0 in reply to Cody Watkins
    Intellectual 470 points

    I do not want to completely turn off channel b, I want to turn it on regardless of channel a. In this case, deadtime should be as in the figure:

  • 0 in reply to Max Av
    TI__Mastermind 42195 points

    Max,

    Use the trip-zone submodule to force the PWM output low for each A or B channel when you want that to happen.

    Max Av said:
    I need no inversions.

    Try changing the deadband configuration to active high instead of active high complementary.

    Looking at the last waveform you have drawn it might just make sense to not used the Dead-Band submodule and to add the deadtime in the Action Qualifier. Just a thought, but it un-links ePWMxA and ePWMxB and you could use the AQSFRC or AQCSFRC to force the PWM's output low.

    Regards,
    Cody