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

This paper analyzes the PWM control method for a new type of step-up DC/DC converters with galvanic isolation - the quasi-Z-source inverter (qZSI) based DC/DC converter. The PWM control method for qZSI with soft-switching capability is proposed and experimentally proved. The operation principles of discussed converter are explained. The experimental verification and analysis of top and bottom IGBTs of inverter bridge has been made. A prototype has been built in the laboratory and experiments are presented to analyse the soft-switching capability in loss reduction.

Soft-switching capability analysis of a qZSI-based DC/DC converter

This paper describes a novel power conditioning system for residential fuel cell power plants, consisting of a step-up DC/DC converter and a single or a multiphase inverter. To increase the efficiency of the whole system a quasi Z-source inverter along with a step-up isolation transformer and a voltage doubler rectifier can be used. Due the continuous input current and low current ripple, the service life of a fuel cell is significantly increased. Further reduction in the output current ripple of a fuel cell is achieved by implementing an interleaved converter design with shifted switching and active ripple cancellation. Interleaved converter design also enables variations in the operating cell count to increase the overall efficiency of a power conditioning system.

Novel power conditioning system for residential fuel cell power plants

This paper presents a new integrated (multiport) DC/DC converter for hydrogen-based energy storages. In comparison with traditional solutions based on individual converters for interfacing of an electrolyser and a fuel cell the proposed topology features reduced energy conversion stages. The paper analyzes and discusses the operating principle of the new converter. Several guidelines are presented for the new converter design. Finally, theoretical background was experimentally verified.

Experimental study of new integrated DC/DC converter for hydrogen-based energy storage

This article focuses on fast chargers of electric vehicles. One of the crucial parts of a fast charger is the secondary charging converter that must be able to regulate efficiently battery charge voltage and current. To be able to use the electric vehicle battery as a temporary energy storage in the electric grid, the topology of a charging converter must enable a bidirectional energy flow. Bidirectional converters need an additional boost circuit to stabilize the battery voltage while draining energy from it. Class 3 unidirectional charging converters could be realized with a current doubler rectifier topology and bidirectional ones with a controllable full-bridge rectifier/inverter, resulting from its advantage over the current doubler in this operational mode. A quasi Z source could be used as a filter/boost circuit.

Analysis of battery charger topologies for an electric vehicle

This paper describes a novel topology for a multiport electric vehicle battery charging converter. Due to high energy demand and high input currents, a fast-charging station is placed close to the substation that contains a low frequency transformer. Inside the fast-charging station, an intermediate DC-bus connects energy storages, a supply grid rectifier and charging converters. Low voltage (570 V) causes high currents and results in high losses at busbars, magnetic components and semiconductor devices. We propose a high voltage input multiport converter topology with a high frequency isolation transformer for a fast charger of an electric vehicle. High input voltage enables currents and conduction losses to be kept low in the charging converter until the very last conversion stage that is connected to the electric vehicle battery. Also, the dimensions of magnetic components are reduced due to high frequency. Grid-side converter is realized using the back to back cascaded converter topology. Charging converters can be realized with the current doubler rectifier topology and bidirectional with a controllable full bridge rectifier/inverter as in this operational mode it has an advantage over a current doubler. The quasi Z source could be used as a filter/boost circuit. The proposed charging station topology was verified by computer simulations.

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Papers

Soft-switching capability analysis of a qZSI-based DC/DC converter

Novel power conditioning system for residential fuel cell power plants

Experimental study of new integrated DC/DC converter for hydrogen-based energy storage

Analysis of battery charger topologies for an electric vehicle

Electric vehicle fast charger high voltage input multiport converter topology analysis