**A. Grid-Connected PV Application Case**

A 4.2 mH interface inductor was used to establish the connection between the proposed topology and the grid during experimental testing. The parameters used for the experiment can be seen in Table 1. The entire closed-loop control scheme depicted in Figures 3 and 4 was used to execute the constructed inverter. In this case, the nonlinear load was disconnected from the constructed inverter; therefore, the harmonic current extraction term from (2) was zero. In addition, the reactive current reference of the constructed inverter was set to zero to guarantee unity-power factor. The proposed topology was used only to connect the PV modules to the grid. Twelve PV modules were used in the experimental setup; six of them are connected to the upper part such that one PV module was assigned for each H-bridge cell and the other six PV modules were connected to the lower part such that two parallel PV modules were assigned to each VSI unit. The P&O MPPT algorithm was used to track the maximum power of the PV modules by using a DC–DC Cuk converter. ´

Figure 17 shows the experimental DC-link voltages of the proposed topology. This figure demonstrates that the control scheme was successful in maintaining the DC-link voltages at the reference voltages. On the other hand, the three-phase grid voltages were measured using voltage sensor model LV 25-P to be used for the phase-locked loop. A snapshot of the generated voltages (*va*<sup>1</sup>*a*2, *vb*<sup>1</sup>*b*2, *vc*<sup>1</sup>*c*<sup>2</sup> across the primary windings of the *T*1, *T*2, and *T*<sup>3</sup> transformers) measured via an oscilloscope is shown in Figure 18. Figure 19 reveals the harmonic spectrum of the generated voltage *va*<sup>1</sup>*a*2. As displayed in this figure, the THD was 8.57%. Figure 20 shows the grid currents measured by the Hall-effect current sensor model LTS 25-NP.

**Figure 17.** Experimental DC-link voltages.

**Figure 18.** The snapshot of the three-phase generated voltages.

**Figure 19.** Experimental harmonic spectrum of the generated voltage *va*<sup>1</sup>*a*2.

**Figure 20.** Experimental three-phase grid currents.

The proposed control scheme succeeded in keeping the grid currents in phase with the grid voltages so that the power factor was unified, as demonstrated in Figure 21. From another point of view, the THD of the grid current, *ia*, was 4.41%, which is within the IEEE-519 standard limit. The harmonic spectrum of the grid current in the proposed MLI can be seen in Figure 22.

**Figure 21.** Experimental grid voltage and grid currents.

**Figure 22.** Experimental harmonic spectrum of the grid current *ia*.
