9.2.1 Changing DC Voltage Source

This exercise is intended to change the value of the DC Voltage source and observe its impact on the levels and waveforms, essentially, the inverter voltages.

For that, keep all the parameters unchanged except for the slider: Vdc (V).

Figure 25: Changing DC Voltage Source

Apply the changes, as shown in the first column of table 18 below, observe the waveforms and fill out the rest:

Table 18: Output Voltage Levels

Verify that the voltage value of Display₄ follows Vdc/2*Reference Amplitude*sqrt (3/2) for each Vdc value in table 18.

9.2.2 Changing AC-source Frequency - Synchronization On/Off

This exercise is intended to highlight the pulsations phenomenon obtained during the loss of synchronization between the AC-source and the inverter output, a phenomenon like the loss of synchronization between a power grid and a synchronous generator.

Change the slider Frequency (Hz) and observe the pulsations in the inverter currents as shown in figure 26.

Figure 26: Changing AC-source Frequency

Click the SYNCHRONIZE button that forces the PWM reference frequency to stick to the BEMF frequency and observe the waveforms of figure 27:

Figure 27: Synchronize Button Activated

9.2.3 Changing AC-source Phase-shift

This exercise is intended to show the impact of changing the phase-shift of the AC Source with respect to the reference signal.
Using the slider PhaseShift (Deg) do the following:

Choose positive values, thus rendering the load more inductive, and observe the waveforms of the voltages and currents as shown in figure 28.

Figure 28: Changing AC-source Phase-Shift; Load More Inductive

Repeat the exercise with negative values (capacitive load) as seen in figure 29.

Figure 29: Changing AC-source Phase-Shift; Load More Capacitive

9.2.4 Effect of Neutral Connection

This exercise is intended to show the impact of the neutral connection.

Set Vdc to 140 V.

Figure 30: Neutral Connection Activated and Vdc set to 140 V

Fill out table 19 when the Neutral Button is pressed or not.

Table 19: Impact of Neutral Connection

How does the neutral connection impact the power flow?

How does the neutral connection impact the THD of load and inverter currents?