scholarly journals Current Source AC-Side Clamped Inverter for Leakage Current Reduction in Grid-Connected PV System

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1296 ◽  
Author(s):  
Li ◽  
Wang ◽  
San ◽  
Guo
Keyword(s):  
Leakage Current ◽  
Single Phase ◽  
Current Source ◽  
Electrolytic Capacitor ◽  
Modulation Method ◽  
Switching Frequency ◽  
Pv System ◽  
Common Mode ◽  
Common Mode Voltage ◽  
Single Phase Inverter

For the grid-connected photovoltaic inverters, the switching-frequency common-mode voltage brings the leakage current, which should be eliminated. So far, many kinds of single-phase inverters have been published for this purpose, but most of them are the conventional voltage-type ones, which have the disadvantages of poor reliability due to the DC-link electrolytic capacitor and the risk of short-through of the bridge switches. To solve this technical issue, a novel current source inverter with AC-side clamping is proposed to mitigate the switching-frequency common-mode voltage. Meanwhile, a novel modulation method is proposed for the new single-phase inverter to achieve low-frequency operation of the main switches, which reduces the switching losses. Finally, the proposed method is implemented on the TMS320F28335DSP + XC6SLX9FPGA digital hardware platform. Also, the performance comparisons are done with the traditional solution. The results prove the proposed solution.

scholarly journals A Multi-Functional De-Icing Equipment Using Modular Parallel PWM Current Source Converters

2021 ◽  
Vol 256 ◽  
pp. 01033
Author(s):  
Yang Hu ◽  
Heng Zhang ◽  
Jing Chen ◽  
Huan Zhang ◽  
Xinmeng Liu ◽  
...  
Keyword(s):  
Reactive Power ◽  
Low Voltage ◽  
Current Source ◽  
Modulation Method ◽  
Switching Frequency ◽  
Common Mode ◽  
Common Mode Voltage ◽  
Current Sharing ◽  
Harmonic Elimination ◽  
Switching State

For transmission line de-icing, a five level specific harmonic elimination (5l-she) modulation method for high-power parallel current source is proposed, which realizes the current balance of DC bridge arm and the suppression of common mode voltage, and ensures the power quality of grid connected current at low switching frequency. In addition the reactive power of the low voltage load can be compensated at the same time. Firstly, the switching states are classified according to the different mode lengths of PWM current, and the common mode voltage corresponding to each switching state is calculated. Secondly, the current sharing control strategy is established based on the analysis of the influence of redundant switching state on the current sharing of DC bridge arm. Then, the 5l-she waveform is constructed based on the switching state with lower common mode voltage, and the redundant switching states is optimized according to the current sharing strategy. Finally, the effectiveness of the proposed method is verified by simulation.

scholarly journals A Novel Inverter Topology for Single-Phase Transformerless PV System

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Haiyan Cao
Keyword(s):  
Leakage Current ◽  
Single Phase ◽  
High Efficiency ◽  
Low Cost ◽  
Experimental Tests ◽  
Pv System ◽  
Common Mode ◽  
Common Mode Voltage ◽  
The Common ◽  
Inverter Topology

Transformerless photovoltaic (PV) power system is very promising due to its low cost, small size, and high efficiency. One of its most important issues is how to prevent the common mode leakage current. In order to solve the problem, a new inverter is proposed in this paper. The system common mode model is established, and the four operation modes of the inverter are analyzed. It reveals that the common mode voltage can be kept constant, and consequently the leakage current can be suppressed. Finally, the experimental tests are conducted. The experimental results verify the effectiveness of the proposed solution.

scholarly journals An Efficient H7 Single-Phase Photovoltaic Grid Connected Inverter for CMC Conceptualization and Mitigation Method

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1440 ◽  
Author(s):  
Mehrdad Mahmoudian ◽  
Eduardo M. G. Rodrigues ◽  
Edris Pouresmaeil
Keyword(s):  
Leakage Current ◽  
Single Phase ◽  
Pulse Width Modulation ◽  
Reactive Power ◽  
Negative Impact ◽  
Harmonic Distortion ◽  
Common Mode ◽  
Safety Issues ◽  
Common Mode Voltage ◽  
Circuit Components

Transformerless inverters are the economic choice as power interfaces between photovoltaic (PV) renewable sources and the power grid. Without galvanic isolation and adequate power convert design, single-phase grid connected inverters may have limited performance due to the presence of a significant common mode ground current by creating safety issues and enhancing the negative impact of harmonics in the grid current. This paper proposes an extended H6 transformerless inverter that uses an additional power switch (H7) to improve common mode leakage current mitigation in a single-phase utility grid. The switch with a diode in series connection aims to make an effective clamp of common mode voltage at the DC link midpoint. The principles of operation of the proposed structure with bipolar sinusoidal pulse width modulation (SPWM) is presented and formulated. Laboratory tests’ performance is detailed and evaluated in comparison with well-known single-phase transformer-less topologies in terms of power conversion efficiency, total harmonic distortion (THD) level, and circuit components number. The studied topology performance evaluation is completed with the inclusion of reactive power compensation functionality verified by a low-power laboratory implementation with 98.02% efficiency and 30.3 mA for the leakage current.

scholarly journals A Transformerless Single-Phase Current Source Inverter Topology and Control for Photovoltaic Applications

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2011 ◽  
Author(s):  
Jorge Cardoso ◽  
Nimrod Vazquez ◽  
Claudia Hernandez ◽  
Joaquin Vaquero
Keyword(s):  
Low Power ◽  
Leakage Current ◽  
Single Phase ◽  
Low Voltage ◽  
Neutral Line ◽  
Current Source ◽  
Total Efficiency ◽  
Pv System ◽  
Phase Current ◽  
Current Source Inverter

Low power grid-tied photovoltaic (PV) generation systems increasingly use transformerless inverters. The elimination of the transformer allows smaller, lighter and cheaper systems, and improves the total efficiency. However, a leakage current may appear, flowing from the grid to the PV panels through the existing parasitic capacitance between them, since there is no galvanic isolation. As a result, electromagnetic interferences and security issues arise. This paper presents a novel transformerless single-phase Current Source Inverter (CSI) topology with a reduced inductor, compared to conventional CSIs. This topology directly connects the neutral line of the grid to the negative terminal of the PV system, referred as common mode configuration, eliminating this way, theoretically, the possibility of any leakage current through this terminal. The switches control is based on a hysteresis current controller together with a combinational logic circuitry and it is implemented in a digital platform based on National Instruments Technology. Results that validate the proposal, based on both simulations and tests of a low voltage low power prototype, are presented.

scholarly journals Highly Efficient Transformerless Inverter with Flying-Capacitor Buck–Boost for Single-Phase Grid-Connected PV Systems

2021 ◽  
Vol 11 (22) ◽  
pp. 10841
Author(s):  
Ali Salem ◽  
Khaled Sedraoui
Keyword(s):  
Leakage Current ◽  
Single Phase ◽  
Common Ground ◽  
Pulse Width Modulation ◽  
Theoretical Calculations ◽  
Pv System ◽  
Negative Power ◽  
Power Cycle ◽  
Common Mode Voltage ◽  
Dc Bus

Grid-connected inverters (GCI) are commonly used in PV system applications to generate a regulated AC current to feed into the grid. Transformerless inverters are the most advanced inverters that are used in industry, which provide efficiency with smaller size and lower cost. This paper proposes a grid-connected single-phase transformerless inverter with the technology of common ground and the virtual DC bus concept. In this topology, the grid neutral is connected directly to the PV ground, which generates a constant common mode voltage (CMV), thus leading to the elimination of the leakage current caused by the PV array’s parasitic capacitance. The proposed inverter has a buck–boost circuit with a flying capacitor to generate the DC bus for a negative power cycle, four switches, and two diodes. A unipolar sinusoidal pulse width modulation (SPWM) technique is used which reduces the output filter requirements. In addition, only one switch carries the load current during the active states of both the negative and positive power cycle, thus minimizing the conduction losses. One more advantage presented in the proposed inverter is its ability to charge the flying capacitor during all operation states due to the existence of the buck–boost circuit. Design and theoretical calculations were conducted in this paper to optimize the losses. Moreover, the PSIM simulation was used to validate the proposed topology inverter, verify the performance by showing leakage current elimination, and achieve unipolar voltage in the output bus. The simulation results show a peak efficiency of 98.57% for a 2 kW inverter, which agrees with the theoretical calculations.

scholarly journals Cascaded H-Bridge Converter Based on Current-Source Inverter with DC Links Magnetically Coupled to Reduce the DC Inductors Value

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 324
Author(s):  
Pedro E. Melín ◽  
Carlos R. Baier ◽  
Eduardo E. Espinosa ◽  
José R. Espinoza
Keyword(s):  
Single Phase ◽  
Magnetic Energy ◽  
Computational Simulation ◽  
Current Source ◽  
Experimental Tests ◽  
Magnetic Core ◽  
Switching Frequency ◽  
Three Phase ◽  
Single Phase Inverter ◽  
Current Source Inverters

The main drawback of the Cascaded-H Bridge converter based on three-phase/single-phase current-source inverters is the large DC inductors needed to limit the variation of the DC current caused by the single-phase inverter oscillating power. If the oscillating power is somehow compensated, then the DC inductor can be designed just as a function of the semiconductors’ switching frequency, reducing its value. This work explores the use of three-phase/single-phase cells magnetically coupled through their DC links to compensate for the oscillating power among them and, therefore, reduce the DC inductor value. At the same time, front ends controlled by a non-linear control strategy equalize the DC currents among coupled cells to avoid saturating the magnetic core. The effectiveness of the proposal is demonstrated using mathematical analysis and corroborated by computational simulation for a 110 kVA load per phase and experimental tests in a 2 kVA laboratory prototype. The outcomes show that for the tested cases, coupling the DC links by a 1:1 ratio transformer allows reducing the DC inductor value below 20% of the original DC inductor required. The above leads to reducing by 50% the amount of magnetic energy required in the DC link compared to the original topology without oscillating power compensation, keeping the quality of the cell input currents and the load voltage.

scholarly journals Design Considerations for Gan-Based Microinverter for Energy Storage Integration Into Ac Grid

2017 ◽  
Vol 54 (5) ◽  
pp. 14-25 ◽  
Author(s):  
K. Kroics ◽  
J. Zakis ◽  
A. Suzdalenko ◽  
O. Husev
Keyword(s):  
Energy Storage ◽  
Single Phase ◽  
Phase Interface ◽  
Wide Bandgap ◽  
Electrolytic Capacitor ◽  
Switching Frequency ◽  
Higher Power ◽  
Driver Circuit ◽  
Single Phase Inverter ◽  
Commercial Applications

Abstract A full bridge converter with electrolytic capacitor on the dc bus is a widely used approach for a single phase interface for renewable energy source generation or energy storage integration in the utility grid. New wide bandgap devices enable higher switching frequency, higher efficiency and higher power density. In the paper, the authors introduce the challenges associated with an increase in switching frequency of a single phase inverter and implementation of wide bandgap GaN-based transistors instead of traditional Si-based transistors. The low gate threshold voltage of GaN transistor and unique reverse conduction behaviour require different driving circuit. The design of the driver circuit and other practical issues are analysed in the paper. The paper also presents some practical results. The research results can be useful to avoid mistakes by designing GaN-based power converters as these devices become increasingly interesting for commercial applications.

scholarly journals Research on an Improved Single-Phase Unisolated Grid-Connected Photovoltaic Inverter

2021 ◽  
Vol 23 (2) ◽  
pp. 123-130
Author(s):  
Baoge Zhang ◽  
Deyu Hong
Keyword(s):  
Leakage Current ◽  
Single Phase ◽  
Current Problem ◽  
Input Voltage ◽  
Common Mode ◽  
Common Mode Voltage ◽  
Voltage Clamping ◽  
The Common ◽  
Simulation Results ◽  
Inverter Topology

An improved single-phase unisolated grid-connected photovoltaic inverter topology is proposed to solve the common mode leakage current problem of unisolated grid-connected photovoltaic inverters. By analyzing the topology structure and voltage clamping principle of the improved inverter, the topology can maintain the same low input voltage as the full-bridge inverter, and ensure that the common-mode voltage in the continuation mode is clamped to the midpoint voltage of the bus, so as to effectively reduce the common-mode leakage current caused by the common-mode voltage suspension in the continuation mode. Moreover, the common-mode leakage current of the improved topology is smaller than that of the traditional H6-2D topology at similar conversion efficiency. The simulation results on MATLAB /Simulink platform show that the topology is feasible and effective.

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