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

An EMI filter for a three-phase buck-type medium power pulse-width modulation rectifier is designed. This filter considers differential mode noise and complies with MIL-STD-461E for the frequency range of 10kHz to 10MHz. In industrial applications, the frequency range of the standard starts at 150kHz and the designer typically uses a switching frequency of 28kHz because the fifth harmonic is out of the range. This approach is not valid for aircraft applications. In order to design the switching frequency in aircraft applications, the power losses in the semiconductors and the weight of the reactive components should be considered. The proposed design is based on a harmonic analysis of the rectifier input current and an analytical study of the input filter. The classical industrial design does not consider the inductive effect in the filter design because the grid frequency is 50/60Hz. However, in the aircraft applications, the grid frequency is 400Hz and the inductance cannot be neglected. The proposed design considers the inductance and the capacitance effect of the filter in order to obtain unitary power factor at full power. In the optimization process, several filters are designed for different switching frequencies of the converter. In addition, designs from single to five stages are considered. The power losses of the converter plus the EMI filter are estimated at these switching frequencies. Considering overall losses and minimal filter volume, the optimal switching frequency is selected.

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New considerations in the input filter design of a three-phase buck-type PWM rectifier for aircraft applications

Several magnetic components (transformers and inductors) have been designed with very low profile (4 mm height) cores. To achieve such a low height, full custom cores have been used, together with an advanced technology (flex foils) for the windings. This freedom in the selection of dimensions and materials makes the design procedure completely different to the traditional schemes with commercial cores. The process used to obtain an optimum design is described in this paper. It is based on the use of models based on finite element analysis (FEA) tools, and spreadsheets. This procedure has been applied to the design of a transformer and an inductor, with a size of 10/spl times/10/spl times/4 mm/sup 3/ for each, to be used in an onboard power converter in telecommunication systems. Experimental results of a 5 W, low output voltage (3.3 V/spl times/1.5 A) prototype with these magnetic components are included in the paper.

Design of very low profile magnetic components using flex foils

This paper presents a very simple step-down DC/DC low power converter based on piezoelectric transformers (PTs) without any magnetic component. PTs become very interesting in this kind of applications comparing with magnetic transformers due to the higher power density. It is important to highlight that the PT has been specifically designed to avoid the use of magnetic components. Dynamic response of the power stage with the PT is analyzed, achieving a 2.5 kHz bandwidth. The use of a PT allows a wide input voltage range (20 V-75 V), 3 V, 1 W DC/DC converter.

Magnetic-less converter based on piezoelectric transformers for step-down DC/DC and low power application

The energy consumption in notebooks and multimedia terminals limits autonomy, high performance and further reduction of size The DVS represents an alternative solution to current techniques that dramatically reduces energy consumption in digital systems The power supply becomes a very important part of the system as it enables the voltage scaling This paper analyzes the requirements and challenges for these power supplies, highlighting the interesting solutions and the research trends

http://ieeexplore.ieee.org/iel5/8430/26552/01182918.pdf

The future DC-DC converter as an enabler of low energy consumption systems with dynamic voltage scaling

This work is focused on the analysis of an analytical thermal model for magnetic components. This model can be used to predict the average temperature rise in the outer surface of the device using a very simple expression. The application scope of the model is shown from a practical point of view. An analytical procedure to calculate its parameters is proposed. Finally, the model has been validated using finite element analysis and measurements.

J.A. Cobos

Papers

New considerations in the input filter design of a three-phase buck-type PWM rectifier for aircraft applications

Design of very low profile magnetic components using flex foils

Magnetic-less converter based on piezoelectric transformers for step-down DC/DC and low power application

The future DC-DC converter as an enabler of low energy consumption systems with dynamic voltage scaling

A very simple analytical approach of thermal modeling for magnetic components