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

Power electronics

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

This paper examines the practical design issues of sliding-mode (SM) controllers as applied to the control of dc-dc converters. A comprehensive review of the relevant literature is first provided. Major problems that prevent the use of SM control in dc-dc converters for industrial and commercial applications are investigated. Possible solutions are derived, and practical design procedures are outlined. The performance of SM control is compared with that of conventional linear control in terms of transient characteristics. It has been shown that the use of SM control can lead to an improved robustness in providing consistent transient responses over a wide range of operating conditions.

/pdf/general-design-issues-of-sliding-mode-controllers-in-dc-dc-2a89149gfx.pdf

General Design Issues of Sliding-Mode Controllers in DC–DC Converters

Converting solar energy into valuable hydrogen and hydrocarbon fuels through photocatalytic water splitting and CO2 photo-reduction is highly promising in addressing the growing demand for renewable and clean energy resources. Developing efficient photocatalysts for solar-driven H2 production and CO2 reduction is the most essential part in achieving this goal. For the purpose of attaining high photocatalytic efficiency, hetero-nanostructures formed by multiple material components have been demonstrated as an effective strategy. Within this heterostructure, its interface is a critical consideration, whereby it determines the principle of charge transfer across the heterojunctions and consequent surface reactions. This article reviews the recent developments of hetero-nanostructures for photocatalytic H2 production and CO2 reduction based on material compositions that form heterojunctions.

Hetero-nanostructured suspended photocatalysts for solar-to-fuel conversion

Active power decoupling methods are developed to deal with the inherent ripple power at twice the grid frequency in single-phase systems generally by adding active switches and energy storage units. They have obtained a wide range of applications, such as photovoltaic (PV) systems, light-emitting diodes (LEDs) drivers, fuel cell (FC) power systems, and electric vehicle (EV) battery chargers, etc. This paper provides a comprehensive review of active power decoupling circuit topologies. They are categorized into two groups in terms of the structure characteristics: independent and dependent decoupling circuit topologies. The former operates independently with the original converter, and the latter, however, shares the power semiconductor devices with the original converter partially and even completely. The development laws for the active power decoupling topologies are revealed from the view of “duality principle,” “switches sharing,” and “differential connection.” In addition, the exceptions and special cases are also briefly introduced. This paper is targeted to help researchers, engineers, and designers to construct some new decoupling circuit topologies and properly select existing ones according to the specific application.

Review of Active Power Decoupling Topologies in Single-Phase Systems

In many emerging applications it is required a high boosting gain; in the literature has been proposed many topologies to make this possible, since the traditional dc-dc boost converter can not make the very high boosting function by itself. In this paper a different approach to obtain the high boosting gain is proposed: the tapped-inductor boost converter. This converter has few components and high efficiency, and also operates in a simple way. Analysis and experimental results are presented.

The Tapped-Inductor Boost Converter

Transformerless inverters are being widely used in grid-connected photovoltaic (PV) generation systems. Transformer elimination, in grid-connected PV systems, has many advantages. This not only reduces cost, size, and weight, but also increases the whole system efficiency. However, once the transformer is removed, there is no galvanic isolation between grid and PV array; as a consequence, leakage current appears due to parasitic capacitance to the ground, resulting in prohibitive electromagnetic interference and security issues.

A New Common-Mode Transformerless Photovoltaic Inverter

A single-phase common-mode transformerless grid-connected photovoltaic (PV) converter, which is based on the integration of two stages, is proposed in this paper. Transformer elimination in grid-connected PV systems has many advantages. It not only reduces cost, size, and weight but also increases the complete system efficiency. Since there is no galvanic isolation between grid and PV array, a leakage current may appear due to the PV parasitic capacitance to the ground, if this is not taken into account in the converter design. This paper presents a dc/dc boost converter integrated with a full-bridge inverter. The integration of these two stages reduces the ground leakage current. The neutral line of the grid is directly connected to the negative terminal of the PV array, eliminating any possibility of leakage current in this terminal. The principle of operation of the transformerless converter is analyzed, and a 200-W topology is experimentally tested.

Integrating Two Stages as a Common-Mode Transformerless Photovoltaic Converter

DC/AC converters are widely used in several applications; traditionally, they can be classified in two types: the voltage-source inverters (VSIs) and the current-source inverters (CSIs). Their use depends on their application; however, some of them are common for both types of converters. Another possibility for the dc/ac conversion is the multilevel configuration, and the most analyzed is the VSI. In this paper, a different multilevel CSI is proposed: the paralleled configuration. To control the converter, a different sinusoidal pulse with modulation is employed; it consists of modifying the reference signal instead of using multiple carriers. Additionally, a balancing method for the inductor currents is given. The operation, analysis, and implementation are presented; moreover, simulation and experimental results are shown.

A Different Multilevel Current-Source Inverter

An active current injection network for a three-phase rectifier is proposed. The proposed circuit uses three bidirectional switches operating at low frequency and a half-bridge inverter operating at high frequency. It also uses an inductor in order to make the current modulation. Because only 3.7% of the total power delivered to the load is processed by the injection network, the proposed converter offers high efficiency, and not only a high power factor is obtained but also the total harmonic distortion is reduced. Operation, analysis, simulation, and experimental results are shown in this paper.

Nimrod Vazquez

Papers

The Tapped-Inductor Boost Converter

A New Common-Mode Transformerless Photovoltaic Inverter

Integrating Two Stages as a Common-Mode Transformerless Photovoltaic Converter

A Different Multilevel Current-Source Inverter

Three-Phase Rectifier With Active Current Injection and High Efficiency