*2.1. DCM-232 Common Mode Model*

In order to determine the CMV behavior, a CMM for the DCM-232 topology is derived. Considering the directions given in [19], the simplified CMM shown in Figure 2 can be obtained. As it can be observed, there are two separated circuits, the circuit in Figure 2a corresponds to the DC source *VDC*<sup>1</sup> , while the simplified circuit shown in Figure 2b corresponds to the DC source *VDC*<sup>2</sup> . Since the power sources are isolated from each other with a common load, the obtained model is also separated and is essentially the model obtained in [2] for the 3P-FB inverter. Based on that, the common mode voltage in this topology can be calculated in each DC source using (1) and (2). Considering (1) and (2), the CMV can be calculated for each state defined in Table 1, and the results are shown in Table 2. It can be noted that the CMV maintains the same magnitude throughout the switching period when the odd vectors (*V*1, *V*<sup>3</sup> and *V*5) or the even vectors (*V*2, *V*<sup>4</sup> and *V*6) are connected to the load using *VDC*<sup>1</sup> and *VDC*<sup>2</sup> , respectively. On the other hand, when zero vectors are generated (*V*<sup>0</sup> and *V*7), the CMV keeps the previous value because both DC sources are decoupled from the load.

$$V\_{CMV1} = \frac{V\_{aZ1} + V\_{bZ1} + V\_{cZ1}}{3},\tag{1}$$

$$V\_{\rm CMV2} = \frac{V\_{a\rm Z2} + V\_{b\rm Z2} + V\_{c\rm Z2}}{3}.\tag{2}$$

**Figure 1.** DCM-232 three-phase transformerless PV inverter topology.

**Figure 2.** DCM-232 common mode model: (**a**) *VDC*<sup>1</sup> and (**b**) *VDC*<sup>2</sup> .



**Table 2.** Switching configurations of the three-phase DCM-232 transformerless inverter.

