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dead time in trip zone module

Valdis Ivanov
Prodigy 140 points

Other Parts Discussed in Thread: TMS320F28027

Hi all.

I use tms320F28027 Piccolo MCU.  I design converter with current mode control. On current limit event I need to go ePWM2A to low, and ePWM2B to high. Dead time must

be inserted between  ePWM1A going to low and ePWM1B going to high. But ePWM1A going to low and ePWM1B going to high occurs simultaneously. It is crush for my converter. Snip of my code:

EPwm2Regs.TZSEL.bit.DCAEVT2 = 1;                              // Enable DCAEVT2 as CBC trip source for ePWM2 module.
EPwm2Regs.DCTRIPSEL.bit.DCAHCOMPSEL = 9;       // COMP2OUT is input of Event Qualification A
EPwm2Regs.TZDCSEL.bit.DCAEVT2 = 2;                        // DCAEVT2 = DCAH high(will become active)

EPwm2Regs.DCFCTL.bit.PULSESEL = 1;                       // Time-base counter equal to zero (TBCTR = 0x0000) - start blank timer
EPwm2Regs.DCFCTL.bit.BLANKINV = 0;                        // Blanking window is not inverted
EPwm2Regs.DCFCTL.bit.BLANKE = 1;                            // Blanking window is enabled
EPwm2Regs.DCFCTL.bit.SRCSEL = 1;                           // Source Is DCAEVT2 Signal
EPwm2Regs.DCFOFFSET = 0;                                          // no offset
EPwm2Regs.DCFWINDOW = 30;                                      // Blanking window is 0.5 us


EPwm2Regs.TZCTL.bit.TZA = 2;                                         // Force EPWM2A to a low state
EPwm2Regs.TZCTL.bit.TZB = 1;                                        // Force EPWM2B to a high state

How solve this problem? Thanks in advance!

  • 0
    Genius 5170 points

    Hello As far as I know dead time will not be inserted when PWM outputs respond to trip zone function. The ePWM module block diagram shows tip zone block is placed after dead band module indicating trip zone will change PWM output based on the setting without any delay and I beleive that is the goal of trip zone...turnin goff PWM outputs as soon as possible in the vent of a fault.