http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<<ETX>>

Multi-level conversion : high voltage choppers and voltage-source inverters

This paper presents a comprehensive review of step-up single-phase non-isolated inverters suitable for ac-module applications. In order to compare the most feasible solutions of the reviewed topologies, a benchmark is set. This benchmark is based on a typical ac-module application considering the requirements for the solar panels and the grid. The selected solutions are designed and simulated complying with the benchmark obtaining passive and semiconductor components ratings in order to perform a comparison in terms of size and cost. A discussion of the analyzed topologies regarding the obtained ratings as well as ground currents is presented. Recommendations for topological solutions complying with the application benchmark are provided.

/pdf/review-and-comparison-of-step-up-transformerless-topologies-ubtxng7ots.pdf

Review and Comparison of Step-Up Transformerless Topologies for Photovoltaic AC-Module Application

Wind power is the most reliable and developed renewable energy source over past decades. With the rapid penetration of the wind generators in the power system grid, it is very essential to utilize the maximum available power from the wind and to operate the wind turbine (WT) at its maximal energy conversion output. For this, the wind energy conversion system (WECS) has to track or operate at the maximum power point (MPP). A decent variety of publication report on various maximum power point tracking (MPPT) algorithms for a WECS. However, making a choice on an exact MPPT algorithm for a particular case require sufficient proficiency because each algorithm has its own merits and demerits. For this reason, an appropriate review of those algorithms is essential. However, only a few attempts have been made in this concern. In this paper, different available MPPT algorithms are described for extracting maximum power which are classified according to the power measurement i.e. direct or indirect power controller. Merits, demerits and comprehensive comparison of the different MPPT algorithms also highlighted in the terms of complexity, wind speed requirement, prior training, speed responses, etc. and also the ability to acquire the maximal energy output. This paper serves as a proper reference for future MPPT users in selecting appropriate MPPT algorithm for their requirement.

A review of conventional and advanced MPPT algorithms for wind energy systems

Multilevel inverters (MLIs) are being used in wide range of power electronic applications. These converters have attracted a lot of attention during recent years and exist in different topologies with similar basic concepts. This paper presents five main submodules (SMs) to be used as the basic structures of MLIs. The paper reviews the common MLI topologies from the structural point of view. The topologies are divided into the different SMs to show conventional MLI configurations and future topologies that can be created from the main SMs. A comparative study between different topologies is performed in detail. The MLIs are categorized and investigated with from different perspectives such as the number of components, the ability to create inherent negative voltage, working in regeneration mode and using single dc source.

A General Review of Multilevel Inverters Based on Main Submodules: Structural Point of View

This study proposes a new two-stage high voltage gain boost grid-connected inverter for AC-module photovoltaic (PV) system. The proposed system consists of a high-voltage gain switched inductor boost inverter cascaded with a current shaping (CS) circuit followed by an H
-bridge inverter as a folded circuit and its switches operate at line frequency. The switched inductor boost converter (SIBC) has one switch operates like a continuous conduction mode. The maximum power of the PV module is achieved through the SIBC circuit whereas the grid connection requirements are accomplished using the CS circuit with the H
-bridge inverter. The switch of the CS circuit is controlled with a sine wave modulation control scheme. The main advantages of the new proposed system are high boosting gain, lower switching losses and reduces the ground leakage current as all H
-bridge switches operate at the line frequency. A 120 W prototype has been built and experimentally tested. It has been found that experimental results have a good matching with the proposed analysis and simulation results.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2012.0666

Two-stage micro-grid inverter with high-voltage gain for photovoltaic applications

This study presents a new design and implementation of a three-phase hybrid multilevel inverter (MLI) using space vector modulation. The proposed MLI consists of a reduced number of dc sources and switches to minimise the control complexity. The developed topology consists of two stages: main stage and auxiliary stage. The main stage is a conventional three-phase inverter with one high-voltage input dc source and six switches. The auxiliary stages contain three individual cells. Each cell consists of two switches and one low-voltage input dc source. This topology is a modular type and without changing the previous connection it can be extended for more number of output voltage levels by adding certain number of auxiliary stages. A space vector modulation control technique has been utilised in order to generate different switching sequences. The special feature of the proposed system is its capability to maximise the number of voltage levels using a reduced number of isolated dc voltage sources and electronic switches. A prototype has been developed and tested for various modulation indexes to verify the control technique and performance of the topology. Experimental results validate the simulation results and the experimental results show a good similarity with the simulation results.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2013.0237

Three-phase hybrid multilevel inverter with less power electronic components using space vector modulation

Three-phase hybrid multilevel inverter with less power electronic components using space vector

This paper presents a new design and implementation of a three-phase multilevel inverter $(MLI)$ for distributed power generation system using low frequency modulation and sinusoidal pulse width modulation $(SPWM)$ as well. It is a modular type and it can be extended for extra number of output voltage levels by adding additional modular stages. The impact of the proposed topology is its proficiency to maximize the number of voltage levels using a reduced number of isolated dc voltage sources and electronic switches. Moreover, this paper proposes a significant factor $(F_{C/L})$ , which is developed to define the number of the required components per pole voltage level. A detailed comparison based on $F_{C/L}$ is provided in order to categorize the different topologies of the $MLI$ s addressed in the literature. In addition, a prototype has been developed and tested for various modulation indexes to verify the control technique and performance of the topology. Experimental results show a well-matching and good similarity with the simulation results.

New Three-Phase Symmetrical Multilevel Voltage Source Inverter

This paper proposes and describes the design and operational principles of a three-phase three-level nine switch voltage source inverter. The proposed topology consists of three bi-directional switches inserted between the source and the full-bridge power switches of the classical three-phase inverter. As a result, a three-level output voltage waveform and a significant suppression of load harmonics contents are obtained at the inverter output. The harmonics content of the proposed multilevel inverter can be reduced by half compared with two-level inverters. A Fourier analysis of the output waveform is performed and the design is optimized to obtain the minimum total harmonic distortion. The full-bridge power switches of the classical three-phase inverter operate at the line frequency of 50Hz, while the auxiliary circuit switches operate at twice the line frequency. To validate the proposed topology, both simulation and analysis have been performed. In addition, a prototype has been designed, implemented and tested. Selected simulation and experimental results have been provided.

http://eprints.um.edu.my/4860/1/Design_and_implementation_of_a_multi_level_three%2Dphase_inverter_with_less_switches_and_low_qutput_voltage_distortion.pdf

Mahrous Ahmed

Papers

Two-stage micro-grid inverter with high-voltage gain for photovoltaic applications

Three-phase hybrid multilevel inverter with less power electronic components using space vector modulation

Three-phase hybrid multilevel inverter with less power electronic components using space vector

New Three-Phase Symmetrical Multilevel Voltage Source Inverter

Design and Implementation of a Multi Level Three-Phase Inverter with Less Switches and Low Output Voltage Distortion