Leakage Current Suppression of Single-Phase Five-Level Inverter for Transformerless Photovoltaic System

Zhu, Xiaonan; Wang, Hongliang; Sun, Rong; Wang, Hanzhe; Zhang, Wenyuan; Deng, Xiaojun; Yue, Xiumei

doi:10.1109/tie.2020.3029480

Cited by 27 publications

(11 citation statements)

References 34 publications

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“…The overall efficiency of [26] is quite balanced but it doesn't feature voltage boosting capabilities instead of having an SC based architecture. The topology of [9] achieves excellent efficiency, but it suffers from an increasing number of semiconductor switches (12 MOSFETs) for a five-level output voltage, and it also requires three SCs, two of which are connected in series, causing voltage balancing issues. The rated efficiency is found to be 98.3% at 1200W output power for the proposed transformerless inverter.…”

Section: Comparative Analysismentioning

confidence: 99%

“…So, it is crucial to stop or suppress this leakage current since it can affect personal safety and result in worsened power quality. In order to combat the issue, several research works have been conducted which are not only suppressing the leakage current [6], [7], but also reducing the number of devices (power switches, capacitors, inductors, and diodes) [8], [9], [10], [11], [12], [13] in their proposed inverter topology for improved electrical and thermal efficiency. Most of these literatures reduce the leakage current via:…”

Section: Introductionmentioning

confidence: 99%

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A Five-Level Switched-Capacitor Based Transformerless Inverter With Boosting Capability for Grid-Tied PV Applications

et al. 2023

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Transformerless grid-connected inverters have attained a lot of research interest in renewable energy interface applications, due to certain promising properties like greater efficiency, light weight, affordable price, and tolerable power density. Among various types of transformerless grid-tied photovoltaic (PV) inverters, multilevel inverters (MLIs) are mostly popular due to their ability to transmit reactive power, small filter size for reducing total harmonic distortion (THD) and their common-ground (CG) configuration to mitigate the detrimental leakage current due to the parasitic capacitances of the PV array. Again, among different types of MLIs for PV systems, switched-capacitor (SC) based multilevel inverter topologies are the burning topic in current decades due to their single source requirements for producing multilevel output voltage. However, for mostly used single-phase five-level inverters, most of the existing SC based topology requires at least two SCs for power conversion. In this paper, a five-level transformerless inverter based on a single SC is proposed, requiring only seven switches, no diode, a single capacitor, and one dc voltage source. The proposed transformerless MLI also has auto-boosting capability. Notably, the number of power switches operating at high frequency is limited to three, which lowers down the switching losses of the inverter. Rather than a new single SC based five-level transformerless inverter topology, a control scheme is also presented to inject a precisely regulated current into the grid that can govern both the active and reactive power support modes. In-depth comparisons between the proposed and cutting-edge MLIs are also provided. All these claims are validated through MATLAB/Simulink and PLECS computer simulation environments. A laboratory-scaled prototype is also built and tested to support the simulated claims further and validate the effectiveness and feasibility of the proposed five-level transformerless inverter topology.

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Section: Comparative Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Five-Level Switched-Capacitor Based Transformerless Inverter With Boosting Capability for Grid-Tied PV Applications

et al. 2023

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“…The absence of a transformer leads to leakage current due to the non-existence of galvanic isolation. Here, the leakage current reduction can be achieved by adding additional power components to the inverter 5 , 6 . Several approaches like ac decoupling, dc decoupling, H-Bridge zero voltage rectifier (HB-ZVR), and midpoint clamped methods are available 7 for addressing the leakage current issue.…”

Section: Introductionmentioning

confidence: 99%

“…This issue is effectively addressed by the common ground (CG) type topologies introduced in 8 by directly connecting the negative terminal of PV and the grid's neutral terminal, leading to zero leakage current. The CG type inverters often use a virtual dc source which can be either a floating capacitor (FC) or a switched capacitor (SC) 6 . In 9 , 10 , the topology uses a floating capacitor which requires high capacitance values to maintain the voltage across the FC 11 .…”

Section: Introductionmentioning

confidence: 99%

Common ground type five level inverter with voltage boosting for PV applications

Ali

Almakhles

2022

Sci Rep

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The boost-switched capacitor inverter topology with reduced leakage current is highly suitable for distributed photovoltaic power generation with a transformerless structure. This paper presents a single-stage 5-level (5L) transformerless inverter with common ground (CG) topology for single-phase grid-connected photovoltaic application. A generalized version of the proposed topology is also presented. The proposed topologies are derived by combining the dc/dc boost converter and switched capacitor cell. The primary focus has been given to the 5L version of the proposed topology. The number of switch counts is reduced, the maximum voltage gain is four times, and the inrush current is suppressed due to the input inductor configuration. Also, the voltages across the switched capacitors (SCs) are self-balanced. The negative source terminal and the load are connected directly to suppress the leakage current. It is thoroughly compared with other recent CG-Type topologies to attest to the advantages of the proposed topology. The laboratory prototype is developed for 600 W with the maximum efficiency is 94.21%, and the maximum source current is not more than 25A. Further, the operation of the proposed topology is verified under dynamic loading conditions, and the results are presented.

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“…Variants with the use of two-level inverters with low efficiency are proposed [21]. In addition, other works have proposed new topologies of converters [22].…”

Section: Introductionmentioning

confidence: 99%

A Five-Level Converter in a Three-Level Mode for Common-Mode Leakage Current Suppression in PV-Generation Systems

et al. 2021

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Power generation systems (PGSs) based on renewable energy sources are finding ever-widening applications, and many researchers work on this problem. Many papers address the problem of transformerless PGSs, but few of them aimed at conducting research on structures with multilevel converter topologies as part of a PGS. In this paper a grid-tied transformerless PV-generation system based on a multilevel converter is discussed. There are common-mode leakage currents (CMLCs), which act as a parasitic factor. It is also known that common-mode voltage is the main cause of the common-mode leakage current in grid-tied PV-generation systems. This paper considers the space vector pulse-width modulation (PWM) technique, which is used to suppress or reduce common-mode leakage current. The proposed PWM technique with the reduction of common-mode leakage current for a generation system based on the multilevel converter controlled with a PWM technique was verified experimentally. The experimental results accurately confirmed the mathematical model and the compensation achieved without errors. In the experiment, there was an approximately six-fold decrease in the common-mode leakage current (10.3 mA in rejection mode and 61 mA in non-rejection current). This can lead to the elimination of CMLC in a multilevel semiconductor converter only by changing the modulation mode. This suggests the possibility of using these devices as part of transformerless generation systems. Suppression of CMLC can only be carried out by changing the PWM algorithm. Both considered topologies can implement this mode of operation. The proposed converter has a higher efficiency up to a frequency multiplicity of 2000.

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Leakage Current Suppression of Single-Phase Five-Level Inverter for Transformerless Photovoltaic System

Cited by 27 publications

References 34 publications

A Five-Level Switched-Capacitor Based Transformerless Inverter With Boosting Capability for Grid-Tied PV Applications

A Five-Level Switched-Capacitor Based Transformerless Inverter With Boosting Capability for Grid-Tied PV Applications

Common ground type five level inverter with voltage boosting for PV applications

A Five-Level Converter in a Three-Level Mode for Common-Mode Leakage Current Suppression in PV-Generation Systems

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