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

New regulations impose more stringent limits on current harmonics injected by power converters that are achieved with pulsewidth-modulated (PWM) rectifiers. In addition, several applications demand the capability of power regeneration to the power supply. This work presents the state of the art in the field of regenerative rectifiers with reduced input harmonics and improved power factor. Regenerative rectifiers are able to deliver energy back from the dc side to the ac power supply. Topologies for single- and three-phase power supplies are considered with their corresponding control strategies. Special attention is given to the application of voltage- and current-source PWM rectifiers in different processes with a power range from a few kilowatts up to several megawatts. This paper shows that PWM regenerative rectifiers are a highly developed and mature technology with a wide industrial acceptance.

http://www.lcda.cl/descargas/rodriguez_dixon_pont_espinoza_lezana05.pdf

PWM regenerative rectifiers: state of the art

This paper presents a comprehensive study on the state-of-the-art and emerging wind energy technologies from the electrical engineering perspective. In an attempt to decrease cost of energy, increase the wind energy conversion efficiency, reliability, power density, and comply with the stringent grid codes, the electric generators and power electronic converters have emerged in a rigorous manner. From the market based survey, the most successful generator-converter configurations are addressed along with few promising topologies available in the literature. The back-to-back connected converters, passive generator-side converters, converters for multiphase generators, and converters without intermediate dc-link are investigated for high-power wind energy conversion systems (WECS), and presented in low and medium voltage category. The onshore and offshore wind farm configurations are analyzed with respect to the series/parallel connection of wind turbine ac/dc output terminals, and high voltage ac/dc transmission. The fault-ride through compliance methods used in the induction and synchronous generator based WECS are also discussed. The past, present and future trends in megawatt WECS are reviewed in terms of mechanical and electrical technologies, integration to power systems, and control theory. The important survey results, and technical merits and demerits of various WECS electrical systems are summarized by tables. The list of current and future wind turbines are also provided along with technical details.

High-Power Wind Energy Conversion Systems: State-of-the-Art and Emerging Technologies

Based on the combination of a three-phase diode bridge and a DC/DC boost converter, a new three-phase three-switch three-level pulsewidth modulated (PWM) rectifier system is developed. It can be characterized by sinusoidal mains current consumption, controlled output voltage, and low-blocking voltage stress on the power transistors. The application could be, e.g., for feeding the DC link of a telecommunications power supply module. The stationary operational behavior, the control of the mains currents, and the control of the output voltage are analyzed. Finally, the stresses on the system components are determined by digital simulation and compared to the stresses in a conventional six-switch two-level PWM rectifier system.

A novel three-phase utility interface minimizing line current harmonics of high-power telecommunications rectifier modules

Solid-state switch mode AC-DC converters having high-frequency transformer isolation are developed in buck, boost, and buck-boost configurations with improved power quality in terms of reduced total harmonic distortion (THD) of input current, power-factor correction (PFC) at AC mains and precisely regulated and isolated DC output voltage feeding to loads from few Watts to several kW. This paper presents a comprehensive study on state of art of power factor corrected single-phase AC-DC converters configurations, control strategies, selection of components and design considerations, performance evaluation, power quality considerations, selection criteria and potential applications, latest trends, and future developments. Simulation results as well as comparative performance are presented and discussed for most of the proposed topologies.

Comprehensive Study of Single-Phase AC-DC Power Factor Corrected Converters With High-Frequency Isolation

A novel active power factor correction method for power supplies with three-phase front-end diode rectifiers is proposed and analyzed. The implementation of this method requires the use of an additional single switch boost chopper. The combined front-end converter draws sinusoidal AC currents from the AC source with nearly unity input power factor while operating at a fixed switching frequency. It is shown that when the active input power factor correction stage is also used to regulate the converter DC bus voltage, the converter performance can improve substantially in comparison with the conventional three-phase AC-to-DC converters. These improvements include component count reduction, simplified input synchronization logic requirements, and smaller filter refractive components. Theoretical results are verified experimentally. The proposed method has the disadvantage of substantially increasing the current stresses of the switching devices and the high-frequency ripple content of the prefiltered AC input currents. >

An active power factor correction technique for three-phase diode rectifiers

Single-phase offline switch mode rectifiers (or offline DC-DC converters) face severe component stresses in higher than 10kW applications. The authors show that in three-phase, switch-mode rectifier (SMR) topologies' component stresses are reduced, and performance is improved substantially. These improvements include faster response times, reduced switching stresses of the power semiconductor devices, and reduced size and ratings of associated reactive components. The authors also present an analysis and design approach for three-phase SMR converters under large-input voltage and load variations. Output voltage control is achieved by varying the duty cycle of the inverter power semiconductor switches. Theoretical results are verified experimentally. >

Analysis and design of a three-phase offline DC-DC converter with high-frequency isolation

A comparative evaluation is presented of high-frequency voltage-source fed (VSF) and current-source fed (CSF) switch-mode rectifier (SMR) converters supplied from single-phase AC mains and operating under large input voltage and load fluctuations. For medium power applications (i.e. 3 kW), VSF SMR converters use passive waveshaping techniques. CSF SMR converters, on the other hand, use active waveshaping techniques. Use of active waveshaping techniques increases the input power factor from approximately 0.5 to 0.9-1.0. It is shown that when the active input current waveshaping stage is also used to regulate the SMR DC bus voltage, the converter performance can improve substantially. These improvements include reduction in switching stresses of the power semiconductor switches and reduction in the size and ratings of associated reactive components. Key theoretical results are verified experimentally. >

A comparative evaluation of SMR converters with and without active input current waveshaping

In this paper a passive waveshaping method for a three-phase diode rectifier is presented. It is shown that application of the proposed passive method yields a significantly higher input power factor, a lower input current distortion factor, a lower input RMS current and a lower total volt-ampere (VA) rating of the reactive components than the conventional three-phase diode rectifier. Relevant input and output current waveforms, component ratings, and power factor values are derived. Different modes of operation are investigated as a means of improving performance. Finally, predicted results are verified experimentally on a laboratory prototype unit.

Passive input current waveshaping method for three-phase diode rectifiers

A novel offline high-frequency switch-mode rectifier (SMR) converter topology is presented. This topology allows the safe use of lossless single-capacitor switch snubbers from zero to rated load power variation. To ensure the safe and lossless operation of the high-frequency stage under all operating conditions, the inverter stage is analyzed in detail and expressions are derived for the snubber capacitor voltage as a function of the high-frequency transformer leakage and magnetizing inductances, operating frequency, and the charging time of the snubber capacitors. The effect of AC source voltage fluctuations on the input power factor is also analyzed for the front-end half-controlled bridge rectifier. The theoretical results have been verified experimentally. >

A.R. Prasad

Papers

An active power factor correction technique for three-phase diode rectifiers

Analysis and design of a three-phase offline DC-DC converter with high-frequency isolation

A comparative evaluation of SMR converters with and without active input current waveshaping

Passive input current waveshaping method for three-phase diode rectifiers

A high-frequency off-line SMR converter with improved performance characteristics