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

Piezoelectric transformers (PTs) provide several advantages compared to magnetic components, which are higher power density, lower radiated noise, and higher voltage isolation capability. PT must be properly designed to benefit the power converter with the aforementioned advantages. Analytical models are widely used for PT design in order to validate it before constructing the prototype. In this paper, the additional usefulness of finite element analysis (FEA) for PT design is shown. With FEA, it is possible to optimize the PT design not only by maximizing the energy transference but also by cleaning the working frequency range of spurious modes (geometrical 2D/3D effects). Moreover, FEA tools allow the study of other main aspects of the PT design such as manufacturing tolerances or the influence of the fixing layer on PT performance (which is a critical design point). A method for modeling and designing PTs is proposed, combining analytical 1D models and FEA results. The proposed method is validated with measurements of a PT design for a 10-W ac/dc converter prototype for mobile phone battery charger.

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Design of Piezoelectric Transformers for Power Converters by Means of Analytical and Numerical Methods

The selection of the right power distribution architecture for a given application has a tremendous impact on the overall system in terms of efficiency, cost, reliability, fault tolerance and size. Moreover, with the increasing number of power sources, storage elements, different supply voltages and strong requirements imposed at system level, the selection of the appropriate architecture becomes a nightmare for the system designer. The purpose of this paper is to describe a methodology for the selection of the most suitable architecture for a fuel cell based power distribution application. The methodology is based on the assessment of metric functions for all the components that can configure the architecture as a function of the electrical boundary conditions of each component.

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High level decision methodology for the selection of a fuel cell based power distribution architecture for an aircraft application

The boost topology with ripple cancellation network allows input and output current ripples attenuation, which means the suppression of the input filter and a high reduction of the output filter. However, to achieve the ripple cancellation, the complexity and the number of components of the converter need to be increased as compared with the conventional boost. A detailed analysis is developed to specify the advantages and disadvantages of this topology. This paper presents the averaged model that derives the complex transfer function of the topology. The theoretical transfer function is obtained. Due to the complexity of the seventh-order transfer function that is obtained, a simplified second-order transfer function is calculated to simplify control design calculations. A comparison between the analyzed topology and a conventional boost in terms of weight and losses is carried out. To estimate the current ripple calculation, it is proposed to use the ripple theorem, which allows an estimation of the efficiency of the cancellation network using the averaged model. A prototype to validate ripple cancellation and the dynamic analysis is developed. Measured waveforms and Bode plots are enclosed. Current ripple cancellation at the input and output in both conduction modes of the converter is also validated.

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Dynamic Analysis of a Boost Converter With Ripple Cancellation Network by Model-Reduction Techniques

This paper analyzes the conduction boundary of boost power factor preregulators fed by universal input (84 to 264 V rms). Former publications do not discuss the possible and undesirable continuous-discontinuous conduction traverse (or vice versa) when the conduction-boundary curve is not correctly considered. Therefore, we extend the results of the critical conduction parameter of a boost power factor preregulator (PFP) with constant rms input voltage to encompass universal input operation. It is shown that the CCM operation is always guaranteed by designing for the greatest rms input voltage. But for a DCM boost PFP it is necessary to find which input voltage (maximum M or minimum M, M being the output voltage/input voltage ratio) gives the more restrictive condition to the design. On other hand, the converter can traverse the discontinuous-continuous boundary unexpectedly. Some design examples and simulations complete the analysis.

Analysis of the conduction boundary of a boost PFP fed by universal input

Multiphase technique is being used in several DC-DC applications such as VRM and automotive. The use of a high number of phases provides several advantages being the reduction of input and output filters one of the most important. However, due to the tolerances of the components (semiconductors and inductors) these advantages are limited. The purpose of this paper is to evaluate the effect of tolerances in the inductance on the output current and voltage ripple. Also, it is shown how the digital control may help to reduce drastically this problem. Experiments are included in the paper

J.A. Cobos

Papers

Design of Piezoelectric Transformers for Power Converters by Means of Analytical and Numerical Methods

High level decision methodology for the selection of a fuel cell based power distribution architecture for an aircraft application

Dynamic Analysis of a Boost Converter With Ripple Cancellation Network by Model-Reduction Techniques

Analysis of the conduction boundary of a boost PFP fed by universal input

Effect of the Tolerances in Multi-Phase DC-DC Converters