Compile the project by selecting Lab 1: Open Loop PWM in the drop-down menu of Project Options from PowerSUITE GUI. This lab is intended to validate the PWM outputs and can be checked directly using the TIDA-010054 hardware (HW) or using the F2804X control card with a docking station.

Run the project by clicking the green run button in CCS.

Figure 4-10 Run CCS

Populate the required variables in the watch window by loading JavaScript® setupdebugenv_lab1.js in the scripting console.

Figure 4-11 Loading Labs

Figure 4-12 Select a Lab

1. After running the script, the watch window is populated with the variables in Figure 4-13.
   Figure 4-13 Watch Window
2. Enable Continuous refresh on the top right of the expression window.
3. Enable PWM by writing “1” to the DAB_clearTrip variable. (This variable resets to zero post writing and the normal.)

• Pass criteria for Lab1

  Connect probes on PWM1A (Q1), PWM1B (Q2), PWM3A(Q5), and PWM3B (Q6).

  1A and 1B are a complimentary pair, 3A is in sync with 1A with the specified phase shift, and the phase shift is controlled by the variable, DAB_pwmPhaseShiftPrimSecRef_pu.

  Check the following:

  1. Frequency is 100 kHz
     

     PWM1A (yellow), PWM1B (red), PWM3A (blue), PWM3B (green)

     Figure 4-14 100 kHz PWM
  2. Now change the phase shift to 0.05 → 500 ns, to see more observable phase shift.
     Figure 4-15 Phase Shift 500 ns
  3. Verify on the oscilloscope, that the phase shift matches the specified value. To verify high-resolution operation select values which do not align with the system-clock, which means are not divisible by 10 ns. In Figure 4-16 and Figure 4-17, the phase shift is measured using the oscilloscope to be approximately 500 ns for 500-ns setpoint and approximately 502 ns for a 502-ns setpoint, a small jitter of approximately 1–2 ns can be the measurement error.
     CAUTION: Phase shift is not recommended to be operated beyond 0.45 pu.
     

     Phase shift is measured by using the math channel of the oscilloscope. The orange waveform is PWM3B – PWM1B. The width is equal to phase shift. The measured phase shift = 499.8 ns.

     Figure 4-16 High-Resolution Phase Shift 500 ns
     

     Phase shift is measured by using the math channel of the oscilloscope. The orange waveform is PWM3B – PWM1B. The width is equal to phase shift. The measured phase shift = 501.6 ns.

     Figure 4-17 High Resolution Phase Shift 502 ns
  4. Change the PWM probes to PWM1A, PWM1B, PWM2A, and PWM2B.
     • Verify PWM1A and 2B are in sync and in phase
     • Verify PWM1B and 2A are in sync and in phase
     

     PWM1A (yellow), PWM1B (red), PWM2A (green), PWM2B (blue)

     Figure 4-18 PWM in Sync
  5. Verify that they remain in sync and in phase as the phase shift for the secondary side PWM is changed.
     

     PWM1A (yellow), PWM1B (red), PWM2A (green), PWM2B (blue)

     Figure 4-19 PWM in Sync With Phase Shift