Hybrid‐bridge transformerless photovoltaic grid‐connected inverter

Abstract

The transformerless inverters with leakage current suppression have become an urgent application tendency in gridconnected photovoltaic systems because of low cost and high efficiency concerns. In this study, the half-bridge module and neutral point clamping (NPC) module are combined to derive an advanced hybrid-bridge transformerless inverter, which not only suppresses leakage current, but also reduces the required bus voltage compared to the conventional half-bridge or NPC inverters. A sinusoidal pulse-width modulation strategy without dead time is presented to enhance both the grid-connected power quality and system reliability. Furthermore, a detailed circuit performance comparison and practical evaluation are presented to show the clear advantages of the hybrid-bridge transformerless inverter. It also provides practical solutions for the leakage current minimisation by considering the contributing factors such as circuit parasitic parameters. Finally, a 3 kW prototype is tested to verify the theoretical analysis and main contributions of the study. 2 Existing topologies with leakage current suppression In transformerless PV grid-connected systems, the leakage current is the common-mode current which flows through www.ietdl.org

A new structure of single‐phase two‐stage hybrid transformerless multilevel PV inverter

“…22 The common emitter bidirectional branch can select capacitor voltages such as V C1 , (V C1 + V C2 ), and (V C1 + V C2 + V C3 ) based on the number of output voltage levels. The hybrid-bridge inverter consists of half-bridge leg with S1 and S2 and an NPC leg with S3, S4, S5, S6, D1, and D2; this enables the polarity generation for the three-level DC voltages.…”

“…The hybrid-bridge inverter consists of half-bridge leg with S1 and S2 and an NPC leg with S3, S4, S5, S6, D1, and D2; this enables the polarity generation for the three-level DC voltages. 22 The common emitter bidirectional branch can select capacitor voltages such as V C1 , (V C1 + V C2 ), and (V C1 + V C2 + V C3 ) based on the number of output voltage levels.…”

Design and control of an LCL-type single-phase grid-connected inverter withinverter current feedback using the phase-delay method

“…Therefore, MPPT efficiency can be high [2]. AC module topologies have been classified as nonisolated [3] and isolated [4][5][6][7][8][9][10][11][12]. Although a grid frequency transformer can provide galvanic isolation between the grid and the PV panel, it is not preferred due to being heavy and bulky [4].…”

A Single-Stage Buck-Boost Three-Level Neutral-Point-Clamped Inverter with Two Input Sources for the Grid-Tied Photovoltaic Power Generation

“…To date, most of the applied PV converter is two-level inverter, whose main shortcomings are the high operational current and in consequence the low operational efficiency [1][2]. For the purpose of increasing power conversion efficiency, the multilevel converters are preferably assumed as the interfacing converter between the PV array and the distribution grid due to its inherent operational characteristics [3][4][5][6][7], such as the reduced voltage stress, low harmonic distortion, low EMI and reduced current rating. Moreover, the mature 1500V PV panel in commercial allows the PV systems integrated into the high voltage grid (e.g.…”