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.

/pdf/a-review-of-single-phase-improved-power-quality-ac-dc-2pm6h4zjxq.pdf

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

This paper presents a dimmable light-emitting diode (LED) driver with adaptive feedback control for low-power lighting applications. An improved pulsewidth modulation dimming technique is studied for regulating the LED current and brightness. Under universal input voltage operation, high efficiency and high power factor can be achieved by a coupled inductor single-ended primary inductance converter power factor correction (PFC) converter with a simple commercial transition-mode PFC controller. The operation principles and design considerations of the studied LED driver are analyzed and discussed. A laboratory prototype is also designed and tested to verify the feasibility.

/pdf/a-high-efficiency-dimmable-led-driver-for-low-power-lighting-35b376meg0.pdf

A High-Efficiency Dimmable LED Driver for Low-Power Lighting Applications

This paper presents a LED backlight driving system for large-scale of LCD panels. High efficiency, high power factor, circuit simplicity, and low cost can be achieved by using a single-stage charge-pump asymmetrical-half-bridge converter. To regulate the LED current and brightness for the LED backlight system, some current sharing methods are presented and compared. The requirements for the current sharing and luminance balance among paralleled LED arrays can be satisfied while current ripple is eliminated significantly. Because of the addition of bypass diodes, an alternative current path can be offered when a single LED fails. The LED array will not distinguish. A laboratory prototype has been built and tested. The simulation and experimental results are shown to verify the feasibility of the proposed method.

LED backlight driving system for large-scale of LCD panels

This paper presents an LED backlight driving system for large-scale liquid crystal display panels. High efficiency, high power factor, circuit simplicity, and low cost can be achieved by using a single-stage charge-pump asymmetrical half-bridge converter. To regulate the LED current and brightness for the LED backlight system, some current sharing methods are presented and compared. The requirements for the current sharing and luminance balance among paralleled LED arrays can be satisfied while current ripple is eliminated significantly. Because of the addition of bypass diodes, an alternative current path can be offered when a single LED fails. The LED array will not be extinguished. Reliability of the LED backlight system can thus be improved effectively. A laboratory prototype has been built and tested. The simulation and experimental results are shown to verify the feasibility of the proposed method.

LED Backlight Driving System for Large-Scale LCD Panels

Single-phase single-stage power-factor-corrected converter topologies are reviewed in this paper. The topologies discussed in the paper are related to ac-dc and ac-ac converters that are classified on the basis of the frequency of the input ac source, the presence of a dc-link capacitor, and the type of control used (resonant or pulsewidth modulation). The general operating principles and strengths and weaknesses of the converters, which the authors have investigated over the last decade, are discussed in detail, and their suitability in practical applications is stated. Considering practical design constraints, it is possible to effectively employ many single-stage converter topologies in a wide range of applications.

Single-phase single-stage power-factor-corrected converter topologies

A digital controller for a voltage regulator module (VRM) having single phase or multiphase power converters, and an optional dynamic conversion circuit, is disclosed. The digital controller improves the transient response of the VRM during harsh load current transients, and permits a substantial reduction in output capacitance of the VRM. When used with multiphase interleaved power converters, for a given load current requirement, the digital converter permits the number of interleaved phases of the VRM to be minimized. A VRM with the digital controller demonstrates low cost, high power density, high efficiency, and fast transient response.

Digital controller for a voltage regulator module

High-frequency power distribution architecture (HFPDA) has gained more and more attention from both academics and industry in recent years. It is not only applicable in space systems, but also found attractive in power system design for emerging telecommunication and computer systems. As the technology has matured, HFPDA even seems to be attractive for powering the desktop computers employing the latest generation fast microprocessors. This paper presents an ac-ac inverter for HFPDA. The inverter includes a high-frequency resonant inverter and a buck-boost converter for power-factor correction (PFC). A unified controller controls both the resonant inverter and the PFC stage. Unlike other single-stage power-factor-corrected inverter topologies, the proposed inverter system has reduced dc-bus voltage stress for the universal input line voltage. The proposed inverter is found attractive in low-power applications.

A power-factor-corrected AC-AC inverter topology using a unified controller for high-frequency power distribution architecture

Biofilms are complex microbial microcolonies consisting of planktonic and dormant bacteria bound to a surface. The bacterial cells within the biofilm are embedded within the extracellular polymeric substance (EPS) consisting mainly of exopolysaccharides, secreted proteins, lipids, and extracellular DNA. This structural matrix poses a major challenge against common treatment options due to its extensive antibiotic-resistant properties. Because biofilms are so recalcitrant to antibiotics, they pose a unique challenge to patients in a nosocomial setting, mainly linked to lower respiratory, urinary tract, and surgical wound infections as well as the medical devices used during treatment. Another unique property of biofilm is its ability to adhere to both biological and man-made surfaces, allowing growth on human tissues and organs, hospital tools, and medical devices, etc. Based on prior understanding of bacteriophage structure, mechanisms, and its effects on bacteria eradication, leading research has been conducted on the effects of phages and its individual proteins on biofilm and its role in overall biofilm removal while also revealing the obstacles this form of treatment currently have. The expansion in the phage host-species range is one that urges for improvement and is the focus for future studies. This review aims to demonstrate the advantages and challenges of bacteriophage and its components on biofilm removal, as well as potential usage of phage cocktail, combination therapy, and genetically modified phages in a clinical setting.

/pdf/bacteriophage-mediated-control-of-biofilm-a-promising-new-2xcxgff2.pdf

Bacteriophage-Mediated Control of Biofilm: A Promising New Dawn for the Future

Multiphase interleaved buck converter is a widely used topology to power high current microprocessor load in voltage regulator (VR) applications. The current in each phase of the VR is required to be balanced under static and dynamic load conditions without high amplitude beat frequency oscillation. A voltage mode controlled phase current balancing technique is presented in this paper followed by thorough analysis and modeling to address the problems and the corresponding solutions. The presented method can be generally applied to parallel AC-DC and DC-DC converters as well.

Analysis and Modeling of Voltage Mode Controlled Phase Current Balancing Technique for Multiphase Voltage Regulator to Power High Frequency Dynamic Load

This paper presents two approaches for power factor corrected (PFC), low frequency to high frequency power supplies for high frequency power distribution architecture. Boost and buck-boost topologies are applied to the PFC stage respectively. In both approaches, a unified controller controls the PFC stage and the inversion stage. Performance characteristics of the two approaches are presented and a detailed comparison is given. Laboratory prototypes are also built to support the comparison.

Wennan Guo

Papers

Digital controller for a voltage regulator module

A power-factor-corrected AC-AC inverter topology using a unified controller for high-frequency power distribution architecture

Bacteriophage-Mediated Control of Biofilm: A Promising New Dawn for the Future

Analysis and Modeling of Voltage Mode Controlled Phase Current Balancing Technique for Multiphase Voltage Regulator to Power High Frequency Dynamic Load

Comparison between boost and buckboost implemented PFC inverter with build-in soft switching and a unified controller