Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

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A review of single-phase improved power quality AC-DC converters

A system and method for variable power transfer in an inductive charging or power system. In accordance with an embodiment the system comprises a pad or similar base unit that contains a primary, which creates an alternating magnetic field. A receiver comprises a means for receiving the energy from the alternating magnetic field from the pad and transferring it to a mobile device, battery, or other device. In accordance with various embodiments, additional features can be incorporated into the system to provide greater power transfer efficiency, and to allow the system to be easily modified for applications that have different power requirements. These include variations in the material used to manufacture the primary and/or the receiver coils; modified circuit designs to be used on the primary and/or receiver side; and additional circuits and components that perform specialized tasks, such as mobile device or battery identification, and automatic voltage or power-setting for different devices or batteries.

System and method for inductive charging of portable devices

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

In this paper, the principle of modularity is used to derive the different multilevel voltage and current source converter topologies. The paper is primarily focused on high-power applications and specifically on high-voltage dc systems. The derived converter cells are treated as building blocks and are contributing to the modularity of the system. By combining the different building blocks, i.e., the converter cells, a variety of voltage and current source modular multilevel converter topologies are derived and thoroughly discussed. Furthermore, by applying the modularity principle at the system level, various types of high-power converters are introduced. The modularity of the multilevel converters is studied in depth, and the challenges as well as the opportunities for high-power applications are illustrated.

Modular Multilevel Converters for HVDC Applications: Review on Converter Cells and Functionalities

This paper reviews the state of the art of field- programmable gate array (FPGA) design methodologies with a focus on industrial control system applications. This paper starts with an overview of FPGA technology development, followed by a presentation of design methodologies, development tools and relevant CAD environments, including the use of portable hardware description languages and system level programming/design tools. They enable a holistic functional approach with the major advantage of setting up a unique modeling and evaluation environment for complete industrial electronics systems. Three main design rules are then presented. These are algorithm refinement, modularity, and systematic search for the best compromise between the control performance and the architectural constraints. An overview of contributions and limits of FPGAs is also given, followed by a short survey of FPGA-based intelligent controllers for modern industrial systems. Finally, two complete and timely case studies are presented to illustrate the benefits of an FPGA implementation when using the proposed system modeling and design methodology. These consist of the direct torque control for induction motor drives and the control of a diesel-driven synchronous stand-alone generator with the help of fuzzy logic.

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FPGA Design Methodology for Industrial Control Systems—A Review

In this paper, a multiphase converter where the phases are coupled by transformers is proposed to implement a minimum energy-storage converter. Advantages and drawbacks of this topology are analyzed and validated by means of three prototypes. The two main advantages of the minimum energy-storage concept are that the converter can be operated at very low frequency since the transient response is not affected by the switching frequency, thus achieving very high efficiency while at the same time, providing a fast energy transfer between the input and the output. Since this topology operates (ideally) with no energy storage, energy flow into the magnetic elements of the topology needs to be adequately controlled. The main application of this topology is a “dc-dc transformer” for two-stage power architectures.

Multiphase Converter Based on Transformer Coupling

This paper presents an analysis of a very high efficiency topology based on a multiphase converter where the coupling among the phases is done by means of transformers. Since energy is not stored in the transformers, it is transferred directly from the input to the output. This topology along with its control strategy, were previously reported in state of the art. Some advantages of the proposed concept are that, thanks to the minimum storage of energy, the transfer rate of the energy is decoupled from switching frequency and can be chosen in order to increase efficiency. The regulation capability of this topology is limited and the topology acts as a dc-dc transformer. In this paper, the proposed topology is analyzed in detail and design guidelines are presented in order to optimize the design of the converter. These guidelines are applied to a specific design in order to build an optimized prototype.

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DC-DC transformer multiphase converter with transformer coupling for two-stage architecture

High switching frequency allows the integration of low power DC/DC converters. Although a high switching frequency would make feasible a voltage mode control with 1MHz bandwidth, parasitic effects and robustness don't allow such a high bandwidth. This paper proposes a fast control to optimize the dynamic response of high frequency DC/DC converters. The proposed control is based on the peak current mode control of the output capacitor current. The output capacitor current loop provides fast dynamic response while the voltage loop provides accurate steady state regulation. Experimental results have validated the fast dynamic response of the proposed control under load steps.

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“Fast control technique for high frequency DC/DC integrated converter based on non-invasive output capacitance current estimation”

Single-stage AC/DC power converters are an advisable solution to meet the regulations for low frequency harmonics (such as EN61000-3-2) at lower cost compared with the two-stage approach. The main challenge is the use of this type of converter in universal line voltage applications. In this paper, a single-stage AC/DC power converter capable of operating with a universal input voltage range is proposed. The main difference with other proposals is that the storage capacitor of this converter holds a voltage equal to the line voltage and it does not penalize the voltage stress on the circuit. An experimental prototype confirms this result.

Universal line voltage single-stage AC/DC converter

The transformer is one of the most important elements in a DC/DC multiple output power supply. The complexity of the winding strategy introduces parasitics that may damage the components of the converter. Also, the manufacturing process is complex and expensive due to the number of insulated windings. A simple and inexpensive way to construct PCB transformers for high frequency multiple output power supplies, reducing parasitics, is proposed in this paper. Experimental results include a comparison between traditional and these PCB transformers.

J.A. Cobos

Papers

Multiphase Converter Based on Transformer Coupling

DC-DC transformer multiphase converter with transformer coupling for two-stage architecture

“Fast control technique for high frequency DC/DC integrated converter based on non-invasive output capacitance current estimation”

Universal line voltage single-stage AC/DC converter

PCB based transformers for multiple output DC/DC converters