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

This paper shows several approaches to generate low output voltage (3.3 V and 1.5 V) through on board converters. They all are supplied from a DC voltage ranging between 3 V and 6 V (valid for 5 V or 3.3 V input). With such low input and output voltages, synchronous rectification is mandatory to keep efficiency at reasonable levels. Magnetic components play a key role when Self Driven Synchronous Rectification (SDSR) is used. Several technologies have been used to build them, namely standard multilayer PCB, specific flex foils and thick film on ferrite. Three prototypes have been built using these technologies.

Several alternatives for low output voltage on board converters

Multiple output power converters are widely used in telecommunications equipment when several voltages are needed These power converters are smaller and cheaper than various individual converters However, it is very difficult to obtain multioutput power converters with high efficiency and tight regulation To overcome these difficulties, a new technique has been developed and is presented in this article This technique consists on a forward/flyback topology with active clamp where the forward output is regulated with the duty cycle of the main switch and the flyback output is regulated with the duty cycle of the auxiliary switch Experimental results for a +5 V/20 A, -5 V/125 A power converter show efficiencies at full load higher than 87% and a switching frequency of 175 kHz This solution introduces few additional components, but nevertheless the advantages versus other regulation techniques are not only in efficiency but also in volume and cost

http://ieeexplore.ieee.org/iel3/3585/10697/00498946.pdf

Fixed frequency forward-flyback converter with two fully regulated outputs

Due to complex envelope and phase modulation employed in modern transmitters it is necessary to use power amplifiers that have high linearity. Linear power amplifiers (classes A, B and AB) are commonly used, but they suffer from low efficiency especially if the transmitted signal has high peak to average power ratio (PAPR). Kahn's technique based on envelope elimination and restoration (EER) is based on idea that high efficiency power supply (envelope amplifier) could be used to modulate the envelope of high efficient non linear power amplifiers (classes D or E). This paper presents solutions for power amplifier that performs envelope modulation and class E amplifier that is used as a non linear amplifier. The envelope amplifier is implemented as a multilevel converter in series with linear regulator and can provide up to 100 W of instantaneous power and reproduce 2 MHz sine wave. The implemented Class E amplifier can operate at 120 MHz with efficiency near to 85%. The envelope amplifier and class E amplifier have been integrated and efficiency and linearity of the implemented transmitter has been measured and presented.

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High efficiency power amplifier based on envelope elimination and restoration technique

The magnetic field in a toroidal structure has a three dimensional distribution. Energy and losses calculation in this particular structure makes necessary the use of 3D techniques that accounts for all 3D effects. The calculation of the energy and losses is needed in order to obtain any transformer model. This work presents a procedure that allows the calculation of energy and losses in toroidal structures using 2D approaches. This procedure accounts for 3D effects, solving each toroidal structure by means of two different analyses but using 2D finite element analysis (FEA) solvers. The main advantages of this procedure are the simplicity in the FEA problem definition and the great reduction of the solution time and computer requirements. The methodology can also be used in another 3D structures like EE core shapes.

Study of toroidal transformers by means of 2D approaches

The paper focuses on educational projects developed in the ETSII (Escuela Tecnica Superior de Ingenieros Industriales) of the Polytechnic University of Madrid during the past few years. These projects were developed as new tools for enhancing the active role of students, for improving practical teaching, especially by means of virtual laboratories and different sets of problems and exercises, and for promoting self-learning. The paper analyses the use of ICT in teaching, with the case of a developed e-learning platform as a tracking system for subjects. The paper concludes by discussing the new educational trends in the Centre, devoted to develop an active role of students by activities such as peer mentoring and laboratory monitors programs, and competitions for achieving multidisciplinary engineering challenges.

J.A. Cobos

Papers

Several alternatives for low output voltage on board converters

Fixed frequency forward-flyback converter with two fully regulated outputs

High efficiency power amplifier based on envelope elimination and restoration technique

Study of toroidal transformers by means of 2D approaches

Experiences in education innovation: developing tools in support of active learning