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An Improved Proposed Single Phase Transformerless Inverter with Leakage Current Elimination and Reactive Power Capability for PV Systems Application
摘要： Single-phase transformerless inverters are broadly studied in literature for residential-scale PV applications due to their great advantages in reducing system weight, cost and elevating system efficiency. The design of transformerless inverters is based on the galvanic isolation method to eliminate the generation of leakage current. Unfortunately, the use of the galvanic isolation method alone cannot achieve constant common mode voltage (CMV). Therefore, a complete elimination of leakage current cannot be achieved. In addition, modulation techniques of single-phase transformerless inverters are designed for the application of the unity power factor. Indeed, next-generation PV systems are required to support reactive power to enable connectivity to the utility grid. In this paper, a proposed single-phase transformerless inverter is modified with the clamping method to achieve constant CMV during all inverter operating modes. Furthermore, the modulation technique is modified by creating a new current path in the negative power region. As a result, a bidirectional current path is created in the negative power region to achieve reactive power generation. The simulation results show that the CMV is completely clamped at half the DC link voltage and the leakage current is almost completely eliminated. Furthermore, a reactive power generation is achieved with the modified modulation techniques. Additionally, the total harmonic distortion (THD) of the grid current with the conventional and a modified modulation technique is analyzed. The efficiency of the system is enhanced by using wide-bandgap (WBG) switching devices such as SiC MOSFET. It is observed that the efficiency of the system decreased with reactive power generation due to the bidirectional current path, which leads to increasing conduction losses.
关键词： leakage current,transformerless inverter,reactive power,wide-bandgap (WBG),silicon carbide (SiC),photovoltaic (PV) power system
更新于2025-09-23 15:23:52
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A novel photovoltaic inverter topology based on common mode current suppression
摘要： Aiming at the problems of large leakage current and low efficiency of existing transformerless single-phase grid-connected photovoltaic inverters, a novel transformerless single-phase grid-connected photovoltaic inverter topology is proposed. In this topology, two freewheeling diodes are added to the single-phase full-bridge inverter, and the filter inductors are moved between the upper and lower bridge arms, so that the common mode voltage remains constant during the switching period and the common mode current is effectively suppressed. Meanwhile the high frequency switch uses MOSFET to reduce the switching loss, and the power frequency switch uses IGBT to reduce the conduction loss, and additional switches are avoided, thus the overall system losses are reduced. Finally, through simulation and the experimental platform of 3kW single-phase grid-connected photovoltaic inverter, it is verified that compared with the traditional full-bridge topology, the novel topology can effectively suppress the common mode current, while compared with the H5 and H6 topology, the novel topology reduces the system loss and improves the system efficiency.
关键词： efficiency,loss,single-phase grid-connected photovoltaic inverter,transformerless,common mode current
更新于2025-09-19 17:13:59
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A Zero-Voltage-Transition H5-Type Transformerless Photovoltaic Grid-Connected Inverter
摘要： Efficiency and leakage current are two major issues for transformerless grid-connected inverters (TLI). Soft-switching technologies can reduce switching losses and be applied in TLIs. Herein, a zero-voltage-transition H5 type (ZVT-H5) inverter with soft turn-on and turn-off transitions of high-frequency main switches is derived from basic resonant tanks. Compared with the hard-switching H5 (HS-H5) inverter, the conversion efficiency of ZVT-H5 is significantly improved. Moreover, the reverse recovery problem of freewheeling diodes is alleviated under the operation of the auxiliary resonant network. Meanwhile, a diode clamping branch is employed to achieve constant common-mode characteristic for the ZVT-H5. The construction process of the proposed topology is described, and the operation principle of the auxiliary resonant network is analyzed. Moreover, the resonant parameter design of ZVT-H5 and its circuit performance are discussed in detail. Finally, the experimental results of a 3-kW prototype at 100 kHz switching frequency are provided to verify the effectiveness of the ZVT-H5.
关键词： Grid-connected inverter,Resonant tank,Transformerless,Zero-voltage-transition (ZVT)
更新于2025-09-16 10:30:52
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Integrated step-up non-isolated inverter with leakage current elimination for grid-tied photovoltaic system
摘要： This study presents a non-isolated step-up inverter without leakage current for low-voltage renewable energy generation such as photovoltaic (PV) cells grid connection. From the structure of the proposed inverter, the negative terminal of the PV array is directly linked with the grid neutral, so the common mode voltage of the parasitic capacitance can be kept constant and the leakage current will not be generated in theory. Moreover, this transformerless inverter can produce an AC output voltage higher than the input DC voltage, which will reduce the sizes of the generation system. A switching modulation strategy carrier-based is analysed in detail when the input inductor current is operated in discontinuous conduction mode. The operation modes of the proposed inverter are also discussed, respectively, in positive and negative half line cycles. Finally, a digital experimental prototype is tested in the laboratory, and the experimental results are consistent with the theoretical analysis.
关键词： leakage current elimination,non-isolated inverter,transformerless inverter,step-up inverter,grid-tied photovoltaic system
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe) - Bucharest, Romania (2019.9.29-2019.10.2)] 2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe) - A New Transformerless Configuration for Grid-Connected Photovoltaic Inverters
摘要： Due to high efficiency, low cost and weight, inverters are widely used to deliver the transformerless photovoltaic (PV) energy to the grid. On the other hand, due to VDE standards, the leakage current between the stray capacitance of the PV array and the ground should be limited for the grid connected PV systems. In this case, some transformerless structures have been presented to restrict the leakage current. This paper presents a new transformerless structure for the PV inverters. The proposed structure keeps the common mode voltage constant in all switching periods and will suppress the leakage current. The performance of the proposed structure is verified by both mathematical and simulation (MATLAB/Simulink and PLECS Blockset) results.
关键词： Common mode (CM) voltage,Photovoltaic (PV),Leakage current,Transformerless inverter
更新于2025-09-12 10:27:22
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Five-Level Transformerless Inverter for Single-Phase Solar Photovoltaic Applications
摘要： Transformerless inverters are extensively employed in grid connected photovoltaic (PV) generation systems due to its advantages of achieving low cost and high efficiency. However, the common mode voltage issues have been motivated the proposition of new topologies, control and modulation schemes. In common-ground PV inverters the grid neutral line is directly connected to the negative pole of the dc bus. Therefore, the parasitic capacitances are bypassed and the leakage current can be eliminated. In this paper a five-level common ground transformerless inverter with reduced output harmonic content for PV systems is proposed. In addition, the proposed inverter can process reactive power and it presents a maximum dc-voltage utilization in opposition to half-bridge based topologies. The operation modes of the proposed inverter, a simple modulation strategy, as well as the design guidelines are analyzed in detail. Finally, experimental results demonstrate the feasibility and good performance of the proposed inverter.
关键词： Photovoltaic systems,transformerless inverters,common ground voltage,multilevel inverters
更新于2025-09-11 14:15:04