Search

This article presents a two-stage T-type hybrid five-level transformerless inverter (TLI) for grid-connected photovoltaic (PV) applications. The proposed T-type hybrid five-level inverter and its level-shifted pulsewidth modulation scheme offers reduced leakage current by eliminating the high-frequency variations and sudden transitions in the voltage across PV parasitic capacitance CPV and a path for the negative current in all the modes of operation under unity and nonunity power factor conditions of the grid without degrading the waveform quality. Moreover, in this article, the proposed inverter is integrated with a traditional three-level boost converter (3LBC) for boosting the lower PV voltage to higher dc-link voltage and also to extract maximum power from the PV source. The 3LBC provides high efficiency and reduced input inductor size for the same power rating over the conventional boost converter. The simulation results of the proposed system are presented using MATLAB software, and a 500-W experimental prototype is constructed and tested in the laboratory to validate the feasibility of the proposed configuration. Finally, a comparison of the proposed inverter with other five-level TLI topologies is presented to highlight its merits. [ABSTRACT FROM AUTHOR]

Transformerless inverters are getting popular in distributed photovoltaic power generation (PVPG) system due to its light weight, low cost, and higher efficiency in power conversion. However, the production of leakage current leads to severe electromagnetic interference and operational insecurity, which declines the reliability and efficiency of the overall system. Besides that many of the topologies have been addressed with real power injection capabilities in the literature. Therefore, in this paper, an improved hybrid-bridge (IH-B) inverter for transformerless PVPG system is proposed with 1) reduced leakage current by abolishing the fluctuations in common-mode voltage (CMV) due to switch junction capacitances and 2) reactive power capability with a modified sinusoidal pulsewidth modulation technique. This topology is constructed with the combination of bidirectional clamping branch and hybrid-bridge (H-B) inverter topology to maintain CMV at half of the dc-link voltage and ensure better quality of output waveforms at different power factors of the grid. Further, MATLAB simulation results of the IH-B and H-B topologies are presented and compared to prove the potential benefits of the proposed topology. Finally, a 500W prototype model is built and tested to validate the effectiveness of the IH-B topology in reduction of leakage current and reactive power capability. [ABSTRACT FROM AUTHOR]

Summary: Transformerless inverters are becoming popular for grid‐connected photovoltaic applications due to their simplicity, reduced size, weight, cost, and higher efficiency. In this paper, a two‐stage hybrid transformerless multilevel inverter (MLI) for single‐phase grid‐connected photovoltaic power generation system (PVPGS) is presented. The proposed topology comprises a multilevel boost converter (MLBC) and a symmetrical hybrid MLI. MLBC combines the boosting and switched capacitor voltage functions to produce self‐balanced multiple voltage levels. The proposed MLI is derived from a combination of bidirectional switches, a half bridge, and a diode‐clamped branch, which can produce only two variations in the total common mode voltage and is capable of suppressing leakage current as per DIN VDE 0126‐1‐1 grid standards. It offers the advantages of scalability, reactive power capability, reduced total harmonic distortion, and filter size. The proposed hybrid transformerless seven‐level inverter is simulated in MATLAB, and experimental setup is built to validate the effectiveness of the proposed configuration. Finally, a comprehensive comparison is made with other seven‐level inverter topologies. This paper presents a two‐stage hybrid transformerless seven‐level inverter for single‐phase grid‐connected photovoltaic power generation systems. The proposed topology comprises a symmetrical hybrid multilevel inverter (MLI) and multilevel boost converter (MLBC). The MLBC combines the boosting and switched capacitor voltage functions to produce self‐balanced multiple voltage levels. It owns the advantages of modularity, reduced THD, filter size, and minimum leakage current with reactive power capability. The performance of the proposed configuration is validated through MATLAB simulation and experimental setup. [ABSTRACT FROM AUTHOR]

Transformerless inverters have recently gained attention in view of their economic benefits and compactness for photovoltaic (PV) systems. However, the limited voltage regulation and common‐mode (CM) leakage current are major concerns in conventional transformerless PV inverters. This paper presents a single‐phase seven‐level buck‐boost common ground transformerless inverter (SLB2CGTLI) to achieve a wide range of output voltages and zero leakage current without any additional stages, respectively. The proposed converter utilizes switched capacitor (SC) cell to buck‐boost the input DC voltage and generates seven‐level voltage at the output terminals. A simple reconfiguration strategy is adopted in the switched capacitor cell to maintain the charge‐second balance across the capacitors. Moreover, the common ground between the AC grid neutral and the PV panel's negative terminal mitigates the leakage current completely. The theoretical steady state analysis for both buck and boost mode is presented and verified with simulation using MATLAB Simulink. The performance of the proposed inverter is analyzed and validated with experimental results by developing a laboratory prototype. Further, the dynamic response of the proposed converter is carried out using OP4510 real‐time simulator for the grid‐connected PV application. [ABSTRACT FROM AUTHOR]