H5 Topology Research Articles

Development of Improved Low-leakage Current H6 Single-Phase Full-Bridge Inverter Topology

Objective: To minimize leakage current in non-isolated photovoltaic grid connected inverters. Methods: The circuit design integrates extra switches and modifies the switch drive signals at the midpoint of the DC bus voltage, altering the common-mode current path. Findings: The proposed topology exhibits significant potential for widespread adoption, finding practical applications in diverse industrial settings as well as in residential use. Novelty: The suggested method implies that the topology presents distinctive or beneficial characteristics in contrast to current solutions, rendering it especially promising for a range of industrial and residential applications. This novelty may arise from enhancements in efficiency, cost-effectiveness, scalability, versatility, or other favorable attributes that distinguish it from traditional approaches. Moreover, Simulation outcomes distinctly demonstrate a noteworthy decrease in leakage current within the refined topology when contrasted with both the H5 topology and the High Efficient and Reliable Inverter Concept (HERIC) topology. This compelling evidence affirms the effectiveness of the proposed configuration in proficiently mitigating leakage current. Keywords: Photovoltaic, Common Mode Voltage, Leakage Current, Grid Connected Inverter

Design of H5 Transformerless Inverter for Photovoltaic System

There are two distinct categories of sources for generating electrical power: conventional and non-conventional. At now, traditional sources such as coal, gas, and nuclear power are widely employed for the purpose of electricity generation; nevertheless, they are associated with detrimental environmental consequences. Therefore, it is crucial to utilize renewable energy sources like sun and wind to provide some of the necessary electrical power. The driving force behind this transition is the imperative for clean energy, the mitigation of greenhouse gas emissions, and the capacity to create electricity in geographically isolated regions. A proposed solution for using solar energy in single-phase AC applications involves the implementation of an H5 converter topology. The proposed architecture employs twin input DC-DC boost converters, which incorporate solar panels and batteries, to manage the desired output DC voltage. The H5 topology has notable suitability for single-phase transformerless inverters in AC applications encompassing low and high-power demands, owing to its capacity to effectively mitigate leakage current. In order to evaluate the viability of the suggested methodology, a MATLAB simulation is performed to simulate the complete procedure. Furthermore, the development of a prototype is underway in order to assess and verify the performance and outcomes of the converter. The simulation will be conducted with either the MATLAB.

Analysis and Design of H5 Topology in Grid-Connected Single-Phase Transformerless Photovoltaic Inverter System

Objectives: The transformerless inverters are more efficient, less bulky and cost-effective. But the system faces the problem of leakage current on account of the elimination of isolation transformers. Thus, the problem needs to be mitigated through the inverter topology itself. The objective of this paper is to study and analyze a topology designed for reducing the leakage current. The H5 inverter significantly reduces the leakage current by checking the variation of common mode voltages. The topology uses only one extra switch apart from the conventional full bridge and is simple to design. Method: To reduce the leakage current H5 inverter topology has been designed which works on the basis of decoupling. This work is to be implemented in MATLAB/SIMULINK. The main parameters for analysis are efficiency, leakage current, common mode voltage and their variation with load. H4 and H5 topology will be simulated and results will be compared. Findings: The H5 topology has been found to be effective in suppressing the leakage current to a fairly acceptable magnitude. It has been observed that the H5 topology has a lower leakage current than the conventional H4 topology, i.e. 23mA as opposed to 402mA in H4 topology. But the leakage current increases to up to 5 times if the system is used at load less than the full load. Novelty: The study presents the H5 inverter topology and its SPWM modulation strategy. In order to verify the topology, simulation results are provided. The performance has been tested for different loads connected to grid. The leakage current has been found to be reduced to 23.37 mA but it rises to about 100mA if used at 10% of the full load. Keywords: PV Inverters; H5 Inverters; Leakage Current (Common Mode Current); Common-Mode Voltages; Transformerless Power Converters

Application of Nanotechnology in Waste Water Treatment

In the past few years, there has been a growing concern about the pollution caused by fossil fuels, leading to a significant interest in photovoltaic power generation due to its clean and environmentally friendly features. However, suppressing leakage currents is a major problem for Non-isolated PV inverters. This paper focuses on the leakage current suppression methods, summarises three main leakage current suppression paths and systematically analyses and classifies the DC-bypass topology, the H5 topology and the Neutral Point Clamped (NPC) three-level topology. In order to address the issue mentioned above, several approaches can be taken. Firstly, a suitable sinusoidal pulse width modulation strategy is implemented. Additionally, alterations are made to the common mode impedance Z. Furthermore, efforts are made to ensure a proper match of circuit parameters. The analyses in this paper are all carried out based on bridge-type inverters to provide a reference for the study of leakage current suppression in Non-isolated Inverter. Future studies will be more efficient when similar issues arise.

Analysis and classification of Non-isolated inverter leakage currents for photovoltaic systems

In the past few years, there has been a growing concern about the pollution caused by fossil fuels, leading to a significant interest in photovoltaic power generation due to its clean and environmentally friendly features. However, suppressing leakage currents is a major problem for Non-isolated PV inverters. This paper focuses on the leakage current suppression methods, summarises three main leakage current suppression paths and systematically analyses and classifies the DC-bypass topology, the H5 topology and the Neutral Point Clamped (NPC) three-level topology. In order to address the issue mentioned above, several approaches can be taken. Firstly, a suitable sinusoidal pulse width modulation strategy is implemented. Additionally, alterations are made to the common mode impedance Z. Furthermore, efforts are made to ensure a proper match of circuit parameters. The analyses in this paper are all carried out based on bridge-type inverters to provide a reference for the study of leakage current suppression in Non-isolated Inverter. Future studies will be more efficient when similar issues arise.

Bidirectional Synchronous H6 Inverter for Hybrid AC/DC Distribution System With Improved Light Load Efficiency

The overall efficiency of DC distribution systems may be impacted by the operation of the bidirectional inverter connected to the grid; one of its most critical components. When compared to high-demand industries, the typical load profile of such system in residential buildings is highly variable, including several periods of light-load. Therefore, this paper presents a method to overcome the reduced efficiency at light-load of bidirectional inverters integrated into a DC distribution system powered by renewable energy. Existing topologies are evaluated for obtaining optimal efficiency as well as an investigation of loss breakdown at light-load using analytic models and PSIM simulation. A novel synchronous H6 transformer-less topology is proposed. Simulation results show that the proposed topology can achieve an efficiency of 96.5% under full load and 98.3% under light-load. Efficiency improvements over a standard H6 topology are 4.5% under light-load and 1.5 % at full load. This is mostly due to reduced conduction and switching ON loss of MOSFETs used to replace diodes. When using the rectifier mode, similar levels of improvement are observed, with a 4% increase under light-load and a 1.2% improvement under full load conditions, respectively. Experimental results confirm the effectiveness of the proposed topology, showing nearly the same trend in improvement vs. the standard H6.

Comparative Analysis Different Topologies of Grid-tied Transformer Less Inverters for Photovoltaic system.

Transformer less inverters are widely used in grid-tied photovoltaic (PV) generation systems, due to the benefits of achieving high efficiency and low cost. Various transformer less inverter topologies have been proposed to meet the safety requirement of leakage currents. In this paper, a family of H6 transformer less inverter topologies with low leakage currents is proposed, and the intrinsic relationship between H5 topology, highly efficient and reliable inverter concept (HERIC) topology, and the proposed H6 topology has been discussed as well. One of the proposed H6 inverter topologies is taken as an example for detail analysis with operation modes and modulation strategy. The power losses and power device costs are compared among the H5, the HERIC, and the proposed H6 topologies. A universal prototype is built for these three topologies mentioned for evaluating their performances in terms of power efficiency and leakage currents characteristics. Experimental results show that the proposed H6 topology and the HERIC achieve similar performance in leakage currents, which is slightly worse than that of the H5 topology, but it features higher efficiency than that of H5 topology.

Novel H6 Transformerless Inverter for Grid Connected Photovoltaic System to Reduce the Conduction Loss and Enhance Efficiency

Presence of a transformer in a grid connected photovoltaic system provides galvanic isolation between the photovoltaic panels and the grid. However, it increases the overall cost, makes the circuit bulky and reduces the efficiency of the system. Hence, transformerless inverters have gained significant importance owing to its low cost, light weight and increased efficiency. However, due to the absence of the transformer, there is no galvanic isolation between photovoltaic panels and the grid and there is always a threat of flow of leakage current. In this research paper, an elaborate analysis of H4, H5 and H6 transformerless inverter is carried out. DC side decoupled circuits are studied to eliminate the leakage current. Their performances are compared based on the simulations carried out in MATLAB/SIMULINK software. A novel H6 inverter is proposed by introducing an additional switch in H5 topology. A direct current path is provided in H5 topology during one of the active modes, so that current flows through few switches thereby reducing the conduction losses. Common mode voltage remains constant in the proposed H6 inverter and hence the leakage current is eliminated. The proposed H6 inverter can thus be a promising topology to eliminate leakage current and reduce conduction loss in the transformerless grid connected photovoltaic system.

Transformerless Six-Switch (H6)-Based Single-Phase Inverter for Grid-Connected Photovoltaic System With Reduced Leakage Current

Due to the advancements of power electronic devices and photovoltaic (PV) power systems, there has been an increasing interest in transformerless grid-connected PV inverters, which offer lower cost, smaller volume, and higher efficiency than the one with the transformer. However, transformerless inverters with conventional topologies suffer from leakage current problem, which needs to be handled carefully. To overcome the conduction loss and leakage current problem associated with conventional transformerless inverters, a new transformerless H6 (six-switch-based) inverter topology is proposed in this article that can maintain constant common-mode (CM) voltage. At the same time, reduce or eliminate the leakage current problem. The proposed inverter topology is simulated using MATLAB/Simulink software to validate the proposed system's accuracy. The proposed topology's effectiveness is verified through the comparative results of CM voltage, CM leakage current, and conduction loss of the proposed topology with the conventional H6-I, H6-II, and H5 topologies. Finally, to validate the proposed topology, a laboratory prototype is also built and tested. The experimental results validate the theoretical analysis and simulation results.

Minimization of leakage current in a maximum boost control impedance source transformer-less inverter

The solar energy is utilized the most for a decade and the grid connected inverter is necessary for the distribution systems as the grid connected inverter will performances as in interface between the renewable solar energy source and the distribution end. However, due to the existence of magnetizing current in the transformer, the lower order harmonics in the grid current is high in PV systems. In addition, the efficiency of the system and inverter lifetime is reduced due to the usage of high volume capacitance. To overcome this issue, the transformer-less inverter is used in grid-tied PV system where the size and weight is reduced which results in reduction of cost and improve the efficiency of system. However, the leakage current is a major issue needs to be addressed which is minimized by Galvanic isolation methods in the transformer less photovoltaic (PV) inverters. In this project, the performance of the boosting H5 topology is proposed theoretically and analysed with validated simulation and experimental results. It helps in choosing and providing the best design principles.

Comparative Analysis Deferent Topologies for Photovoltaic Based Grid-Tied Transformerless Inverters

Transformerless inverters are widely used in grid-tied photovoltaic (PV) generation systems, due to the benefits of achieving high efficiency and low cost. Various transformer less inverter topologies have been proposed to meet the safety requirement of leakage currents. In this paper, a family of H6 transformer less inverter topologies with low leakage currents is proposed, and the intrinsic relationship between H5 topology, highly efficient and reliable inverter concept (HERIC) topology, and the proposed H6 topology has been discussed as well. One of the proposed H6 inverter topologies is taken as an example for detail analysis with operation modes and modulation strategy. The power losses and power device costs are compared among the H5, the HERIC, and the proposed H6 topologies. A universal prototype is built for these three topologies mentioned for evaluating their performances in terms of power efficiency and leakage currents characteristics. Experimental results show that the proposed H6 topology and the HERIC achieve similar performance in leakage currents, which is slightly worse than that of the H5 topology, but it features higher efficiency than that of H5 topology.

Review on Photovoltaic Based Grid-Tied System using H6 Transformer Less Full-Bridge Inverters

Transformer less inverters are widely used in grid-tied photovoltaic (PV) generation systems, due to the benefits of achieving high efficiency and low cost. Various transformer less inverter topologies have been proposed to meet the safety requirement of leakage currents, such as specified in the VDE-4105 standard. In this thesis, a family of H6 transformer less inverter topologies with low leakage currents is proposed, and the intrinsic relationship between H5 topology, highly efficient and reliable inverter concept (HERIC) topology, and the proposed H6 topology has been discussed as well. One of the proposed H6 inverter topologies is taken as an example for detail analysis with operation modes and modulation strategy. The power losses and power device costs are compared among the H5, the HERIC, and the proposed H6 topologies. A universal prototype is built for these three topologies mentioned for evaluating their performances in terms of power efficiency and leakage currents characteristics. Experimental results show that the proposed H6 topology and the HERIC achieve similar performance in leakage currents, which is slightly worse than that of the H5 topology, but it features higher efficiency than that of H5 topology.

Simulation Analysis of Single-Phase Transformerless H6 Inverter based Dual Input buck-boost Converter

To use the multiple renewable energy sources for single-phase AC applications with an H6 converter topology. Dual input DC-DC buck-boost converters that integrate the solar panel and a battery will regulate the required output DC voltage. Furthermore, for the AC applications of having small power and High power, the H6 topology of single-phase transformerless inverter is preferred because of less leakage current. To validate the proposed technique's feasibility, the MATLAB simulation is performed for the whole process that validates the converter's results and performance.

Multilevel common‐ground inverter with voltage boosting for PV applications

Nowadays, transformer-less Photovoltaic-based grid-connected inverters are more popular in renewable energy application due to their reduced size, cost, and high efficiency. However, the absence of galvanic isolation leads to the flow of leakage current in such system hindering personal safety, and deteriorating power quality. Therefore, this paper presents a five-level transformer-less inverter topology for PV applications with less component count and reduced complexity. The proposed inverter topology completely eliminates the common mode leakage current. Besides, the proposed topology has an inherent capability to boost the voltage without using any magnetic component or boosting circuit, and is based on the principle of switched/auxiliary capacitor. The proposed topology do not have any limitation of modulation index since the auxiliary capacitors are naturally balanced, hence less complex or no dedicated control scheme is required for balancing/regulating the auxiliary capacitor voltages. In order to verify the performance of the proposed inverter topology, a laboratory prototype is developed which confirms the operation, and feasibility of the proposed inverter. Results depicting the output voltage, load current, and voltage across the auxiliary capacitor are presented for various operating conditions. Further, simulation results depicting the leakage current in the proposed, H5, and H6 topologies are included. Finally, a quantitative comparison study is done, highlighting the benefits of the proposed inverter topology regarding boosted voltage, elimination of leakage current, and reduced component count.

Improvements to the H5 inverter topology for transformer‐less grid‐photovoltaic interface applications

Incorporation of transformer in grid-photovoltaic (PV) interfaces makes the systems bulky and expensive, and reduces the system efficiency. Consequently, in recent years, researchers have proposed many transformers-less inverter topologies for grid-PV interface applications. Among them, the H5 topology is one with the simplest structure, least switches, and higher efficiency. However, its ground-leakage current repression property is unsatisfactory due to its asymmetry structure and switch-junction capacitance effects. From the aspect of single-phase transformer-less grid-PV interface applications, this study proposes an improved H5 topology, namely 2D-H5 topology, by incorporating a capacitor divider with a clamp branch consisting of two blocking diodes in the basic H5 structure in order to maintain constant common-mode (CM) voltage. The constant CM voltage will cause no CM (i.e. ground-leakage) current through the stray capacitance between the PV array and the ground. Besides, the proposed topology provides the same differential-mode characteristic as good as in a unipolar modulation full-bridge (H4) inverter for ensuring quality of grid injected power. The proposed topology has been analysed in detail, and verified with satisfactory simulation and experimental results in comparison to the existing transformer-less H5 topology. The proposed improvement enables a reduction in the ground-leakage current in conformity with PV interface standards.

Bidirectional Clamping-Based H5, HERIC, and H6 Transformerless Inverter Topologies With Reactive Power Capability

Transformerless inverters (TLIs) are competently accepted for photovoltaic (PV) applications because of their high efficiency, reduced size, and lower cost. But in the absence of a transformer, there exists a galvanic connection between the PV array to ground and it results in the flow of hazardous leakage current. Several TLI topologies have been proposed in the literature with decoupling circuits to reduce the leakage current. Among those H5, Heric, and H6 topologies are the most popular and widely accepted TLIs. Nevertheless, the effect of switch junction capacitances was not considered in the common-mode voltage analysis, which inevitably causes excess leakage current. Also, reactive power capability cannot be accomplished with traditional pulsewidth modulation (PWM) schemes due to the absence of a bidirectional current path during the freewheeling period. Therefore, in this article, a bidirectional clamping (BDC) based H5, Heric, and H6 TLI topologies are proposed with improved PWM schemes. BDC branch reduces the leakage current by clamping the inverter terminal voltages to half of the dc-link voltage during the freewheeling period and the improved PWM schemes ensure the bidirectional current path while operating in negative power region. The performance of both traditional and proposed topologies is tested with MATLAB simulations and further justified with experimental results.

A novel photovoltaic inverter topology based on common mode current suppression

ABSTRACT 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. 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.

A Blended Improved H5 Topology With ILQG Controller to Augment the Performance of Microgrid System for Grid-Connected Operations

The development of the world demands on the progress of electricity operation and quality enhancement. Microgrid (MG) is a solution that manages the additional need of electricity. The MG generates electricity mostly from renewable energy sources, e.g. solar, wind and hydro. Most renewable energy sources require energy storage system as they are highly unpredictable in nature. An inverter is needed to convert that stored DC power to AC. The presence of a capacitor within the grid provides a galvanic connection that varies the common mode (CM) voltage of the inverter. Thus, the leakage current as well as the total harmonic distortion (THD) of the grid voltage and current increases. The increase of the leakage current hampers the safe operation of the MG. Now-a-days transformerless inverter is gaining more attention because of high efficiency, low cost, less weight and the capability of eliminating the high frequency component from the inverter CM voltage. In addition, a controller inclusion with a transformerless inverter can maintain a near-seamless performance. This paper proposes a blended technique of an improved H5 topology with an Integral Linear Quadratic Gaussian (ILQG) controller for grid-connected MG operations, that reduces the inverter leakage current by keeping the CM voltage constant. Thus it has the capability to reduce the THD of voltage and current. A comparative analysis has been carried out between this technique and existing topologies with different modulation techniques that helps to find out the most optimum inverter package to eliminate the leakage current and reduce the THD of grid voltage and grid current to almost zero.

The Study on the Key Hardware Development of Single-Phase Photovoltaic Grid-Connected Inverters

High-efficiency inverter topology design on single-phase photovoltaic grid-connected equipment is the core of bringing considerable benefits to the society and the investors. In order to study the key hardware design of the inverter that meets the leakage current requirement and achieve the maximum efficiency, this paper analyses the H-bridge based topology (H5 and H6) and DPB topology. Firstly, this paper discusses the working principle of these topologies and concludes that the DPB topology involves fewer MOSFETs than the H-bridge based topology. Additional studies of power device analysis and other component losses in these topologies have concluded that DPB topology typically has lower power device losses at different load ratios. For instance, when the load ratio (Po / Pe) is 100, the power device loss of the H5 topology is 77 W, and the loss of the H6 topology is 68.7 W. Under the same conditions, the loss of the power device in the DPB topology is only 53.6 W.

An Improved H5 Topology With Low Common-Mode Current for Transformerless PV Grid-Connected Inverter

Transformerless photovoltaic (PV) grid-connected inverters have become more and more popular in distributed PV power generation systems due to the advantages on high efficiency, low cost, and small size. However, common-mode (CM) current in the transformerless PV inverters can result in serious electromagnetic interference and insecurity, which will further reduce the reliability of the PV inverter systems. In this paper, an improved H5 topology, namely H5-D topology, is proposed, in which a clamping diode is added on the basis of H5 topology to eliminate the CM voltage fluctuation in H5 topology. Further, the PSIM simulation results of the H5-D topology and H5 topology are given and compared, especially, the performance of H5-D topology for CM current suppression is presented and analyzed concretely. Finally, the experimental prototypes of the H5-D topology and H5 topology are built and tested, and the experimental results validate the advantages of the H5-D topology. The proposed H5-D topology provides a new practical topology for distributed PV grid-connected power generation systems.