DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

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Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

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

Photovoltaic (PV) energy has grown at an average annual rate of 60% in the last five years, surpassing one third of the cumulative wind energy installed capacity, and is quickly becoming an important part of the energy mix in some regions and power systems. This has been driven by a reduction in the cost of PV modules. This growth has also triggered the evolution of classic PV power converters from conventional singlephase grid-tied inverters to more complex topologies to increase efficiency, power extraction from the modules, and reliability without impacting the cost. This article presents an overview of the existing PV energy conversion systems, addressing the system configuration of different PV plants and the PV converter topologies that have found practical applications for grid-connected systems. In addition, the recent research and emerging PV converter technology are discussed, highlighting their possible advantages compared with the present technology. Solar PV energy conversion systems have had a huge growth from an accumulative total power equal to approximately 1.2 GW in 1992 to 136 GW in 2013 (36 GW during 2013) [1]. This phenomenon has been possible because of several factors all working together to push the PV energy to cope with one important position today (and potentially a fundamental position in the near future). Among these factors are the cost reduction and increase in efficiency of the PV modules, the search for alternative clean energy sources (not based on fossil fuels), increased environmental awareness, and favorable political regulations from local governments (establishing feed-in tariffs designed to accelerate investment in renewable energy technologies). It has become usual to see PV systems installed on the roofs of houses or PV farms next to the roads in the countryside. Grid-connected PV systems account for more than 99% of the PV installed capacity compared to

An Overview of Recent Research and Emerging PV Converter Technology

Photovoltaic (PV) energy has grown at an average annual rate of 60% in the last five years, surpassing one third of the cumulative wind energy installed capacity, and is quickly becoming an important part of the energy mix in some regions and power systems. This has been driven by a reduction in the cost of PV modules. This growth has also triggered the evolution of classic PV power converters from conventional single-phase grid-tied inverters to more complex topologies to increase efficiency, power extraction from the modules, and reliability without impacting the cost. This article presents an overview of the existing PV energy conversion systems, addressing the system configuration of different PV plants and the PV converter topologies that have found practical applications for grid-connected systems. In addition, the recent research and emerging PV converter technology are discussed, highlighting their possible advantages compared with the present technology.

Grid-Connected Photovoltaic Systems: An Overview of Recent Research and Emerging PV Converter Technology

Impedance networks cover the entire of electric power conversion from dc (converter, rectifier), ac (inverter), to phase and frequency conversion (ac-ac) in a wide range of applications. Various converter topologies have been reported in the literature to overcome the limitations and problems of the traditional voltage source, current source as well as various classical buck-boost, unidirectional, and bidirectional converter topologies. Proper implementation of the impedance-source network with appropriate switching configurations and topologies reduces the number of power conversion stages in the system power chain, which may improve the reliability and performance of the power system. The first part of this paper provides a comprehensive review of the various impedance-source-networks-based power converters and discusses the main topologies from an application point of view. This review paper is the first of its kind with the aim of providing a “one-stop” information source and a selection guide on impedance-source networks for power conversion for researchers, designers, and application engineers. A comprehensive review of various modeling, control, and modulation techniques for the impedance-source converters/inverters will be presented in Part II.

Impedance-Source Networks for Electric Power Conversion Part I: A Topological Review

Experimental Verification of Novel Bi-Directional qZSI Based DC/DC Converter for Short Term Energy Storage Systems

Investigation of Radiated Emissions of a Galvanically Isolated qZS DC-DC Converter

This work proposes an intelligent control method for ensuring the Direct Current (DC) link voltage stability and for improving the DC-link voltage transient response in a residential Energy Router (ER) This ER is an interface among the main grid, local AC or DC loads and sources When connecting different loads to the DC-link, the classic Proportional Integrator Derivative (PID) controller has been unable to provide a stable DC-link voltage In this study, the PID controller will be compared with the proposed fuzzy logic controller in different DC load levels The results prove the enhanced functionality of the proposed control method

Improved DC-Link Voltage Transient Response and Stability Issues in Energy Router with Fuzzy Logic Control Method

This paper presents a new bi-directional isolated DC/DC converter for supercapacitor (SC) interfacing. During the SC charging mode, the converter operates as a VSI-based step-down DC/DC converter and during the energy recovery mode, as a qZSI-based step-up DC/DC converter. For galvanic isolation and voltage matching a medium frequency transformer was implemented. To achieve higher SC voltage boost the qZSI with the two-stage quasi-Z-source (qZS) network was introduced. The paper discusses the PSIM simulation and experimental results of proposed converter operating with a 14.4 V 142 F supercapacitor.

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Experimental verification of novel bi-directional qZSI based DC/DC converter for short term energy storage systems

A conventional nearly zero energy building (NZEB) is a grid connected system that cannot operate off-grid. By adding a special power electronic interface (PEI) to the point of common coupling, the conventional NZEB could be transformed into a hybrid nanogrid with a wider variety of functions, incl. off-grid operation and bidirectional energy flow control. However, most of the sources in the NZEB are grid followers and require a single grid-forming unit. Thus, typical decentralized control methods (e.g. droop control, virtual generator) cannot be implemented in such systems. This paper analyzes the bidirectional operation of the grid-forming inverter for the NZEB. The main focus is on the light or no load operation that corresponds to a mode when the PEI is naturally unable to control the voltage inside the building. Four control methods are proposed, analyzed and compared. The best method was determined and verified by the help of computer simulations.

Indrek Roasto

Papers

Experimental Verification of Novel Bi-Directional qZSI Based DC/DC Converter for Short Term Energy Storage Systems

Investigation of Radiated Emissions of a Galvanically Isolated qZS DC-DC Converter

Improved DC-Link Voltage Transient Response and Stability Issues in Energy Router with Fuzzy Logic Control Method

Experimental verification of novel bi-directional qZSI based DC/DC converter for short term energy storage systems

Control of Bidirectional Grid-Forming Inverter for Nearly Zero Energy Buildings