**2. Topology Description and Proposed Space Vector PWM Techniques**

A simplified circuit of the DCM-232 topology considered for the design of the SVPWM techniques is shown in Figure 1. One of the main considerations for the simplified circuit is that the DC sources are assumed constant. However, in a real PV transformerless system, the voltage magnitude is slightly variable and, in that case, it is necessary to implement a solution, for example, modifying the modulation strategy or implementing a balance control loop; nevertheless, this topic is out of the scope of this paper and is left for a future research. Three additional important considerations of the simplified diagram are that only the stray capacitance generated by the PV panel are considered; the drive circuits for the semiconductors and control system are not included because these elements do not affect the common mode behavior. Finally, in the case of the ground impedance, the capacitive and inductive effects are disregarded in the system. Therefore, the impedance is considered mainly resistive [18]. The different states that can be proposed to control the DCM-232 inverter in which the structure consists of ten switches are summarized in Table 1. As it can be observed, there are eight possible states. These states produce the following voltage levels between phases and the neutral connection: *VDC*<sup>1</sup> = *VDC*<sup>2</sup> , 2*VDC*/3, *VDC*/3, 0*V*, −*VDC*/3, and −2*VDC*/3. It is important to note that all of the states considered here are exactly the same as in the conventional 3P-FB inverter. However, the main difference is that the switches on the DC side, *S*7*<sup>a</sup>* ,*S*7*<sup>b</sup>* , *S*8*<sup>a</sup>* , and *S*8*<sup>b</sup>* , are used to make a decoupling action when certain active or null vectors supply the load.
