Single‐phase common ground type 5L inverter with reduced capacitor voltage stress for photovoltaic applications

Abstract

In recent years, common ground (CG)-type transformerless (TL) inverters have been paid more attention. However, the existing topologies have more voltage stress on either switch or on capacitor voltage or in both. This article proposes a novel five-level TL inverter topology with a CG type and a voltage stress reduction on power components. The proposed topology offers less component count and a simple structure. Here, the quasi-soft charging (QSC) technique is proposed to minimize the high charging current during the capacitor charge. Since the proposed topology is the family of switched capacitors (SC), the determination of SC and QSC is presented. A detailed comparison of the proposed topology with other recent five-level topologies is presented, and the proposed topology's advantage is highlighted. Further, the performance of the proposed topology is verified in simulation software and verified in a scale-down hardware setup developed for 400 W. The various experimental results are presented to ensure the feasibility of the proposed topology.

New boost type single phase inverters for photovoltaic applications with reduced device count

“…In modes (freewheeling) and (+0 v in ), shown in Fig 3(D)-3(E), the switch S 1 is open, and the inductor current charges the capacitors C 1 and C 2 , and the switch S 2 will be conducted to provide the freewheeling path for the load. The load output equation is v o = 0, and the inductor is charging, as given in (4).…”

“…The proposed scheme is compared with more modern transformer-less three-level inverter topologies in Table 2. Reactive power control becomes harder with the topology presented in [4] due to the increasing number of components. Buck and boost are constructed utilizing more components in [5].…”

“…For singlephase applications, the conventionally available two-level full-bridge inverter is the most common type of photovoltaic inverter employed. Common mode voltage and leakage current, on the other hand, provide substantial challenges [2][3][4].…”

A five‐level common‐ground inverter with step‐up/step‐down dual‐mode operation for transformerless grid‐connected PV application

“…On the other hand, multilevel CG topologies have been developed to improve the quality of the output voltage 28–43 . Five‐level topologies are proposed in Kadam and Shukla 28 and Grigoletto 35 ; although the circuits eliminate switched‐capacitors, that can improve the efficiency and reliability, they require a voltage balance mechanism.…”

“…On the other hand, multilevel CG topologies have been developed to improve the quality of the output voltage. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] Five-level topologies are proposed in Kadam and Shukla 28 and Grigoletto 35 ; although the circuits eliminate switched-capacitors, that can improve the efficiency and reliability, they require a voltage balance mechanism. Furthermore, these topologies present only buck characteristics demanding elevated dc bus voltage.…”