Design and Implementation of an AC to DC Matrix Converter with High-Frequency Isolation and Power Factor Correction (for Particle Accelerator Applications)
Design and Implementation of an AC to DC Matrix Converter with High-Frequency Isolation and Power Factor Correction (for Particle Accelerator Applications)

Author: Rafael Garcia Gil

Publisher: Universal-Publishers

Published: 2005-11-05

Total Pages: 282

ISBN-13: 1581122993

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This thesis (written in Spanish) presents the analysis, design and implementation of a four-quadrant power supply with high-frequency isolation, which is expected to be used to feed the low-energy correction magnet of a particle accelerator. In particle accelerator applications the magnetic field during beam acceleration may be either positive or negative, and true bipolar power converters are needed. The selected bipolar topology consists of a bidirectional three-phase to single-phase reduced matrix converter (RMC) with power factor correction and a bidirectional active rectifier. Main features of this power converter are the ability to regenerate energy back to the utility when the magnet acts as generator, unity power factor at the mains and reduction of volume and weight thanks to the inclusion of the isolation transformer at the switching frequency. A space vector modulation (SVM) technique was used to achieve unity power factor at the input and output current regulation simultaneously. This was done while a symmetrical pure AC profile is generated at the primary side of the isolation transformer. The secondary AC signal is then rectified into a positive or negative voltage, according to the desired output current sign, and later filtered to obtain the output DC current in both polarities. The active rectifier used permits reverse current flow to the primary side when driving an inductive load. By synchronising the commutation of both converters and adding a saturable inductor and a blocking capacitor it is possible to achieve soft commutation for most of the semiconductor elements. An all-digital control based on a Digital-Signal-Processor (DSP) and a Field-Programmed-Gate-Array (FPGA) was used to implement space vector modulation and output current regulation. Output current regulation is performed on a powerful 32-bit fixed-point DSP of Motorola, and was implemented by means of an observer based optimum state feedback control (LQR -- Linear Quadratic Regulator). A reduced order observer was implemented to estimate the output filter inductor current, reducing the number of sensors. Experimental results of a 1.5 kW, 20 kHz prototype are presented to illustrate the performance of the proposed topology.

Analysis and Design of Discontinuous Conduction Mode AC-DC Power Factor Correction Converters
Analysis and Design of Discontinuous Conduction Mode AC-DC Power Factor Correction Converters

Author: Sivanagaraju Gangavarapu

Publisher:

Published: 2021

Total Pages: 0

ISBN-13:

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In more electric aircrafts (MEAs), the synchronous generators are connected directly to the turbo-engine to develop constant voltage variable frequency (CVVF) AC supply bus. In addition, the MEA has adopted high voltage DC bus in its power system to cater the various categories of load used by aircraft. Therefore, the MEA requires AC-DC power converters to convert CVVF AC to constant DC. Existing diode-bridge based passive multi-pulse AC-DC converters are suffering from heavy and bulky low frequency 350 Hz transformers, poor input power quality, low efficiency and unregulated output voltage. To overcome these drawbacks, this thesis work proposes and studies several new active switched-mode AC-DC converters (isolated and non-isolated) strictly satisfying the enhanced requirements of the aircraft application. The vital constituent in active AC-DC power conversion is the power factor correction (PFC). Understanding the certain limitations of the continuous conduction mode (CCM) operation for CVVF AC supply, the proposed converters are designed to operate in discontinuous conduction mode (DCM) to make use of its obvious benefits such as inherent PFC, reduced number of sensors, simple control, inherent zero current turn-on of the switches, and inherent zero diode reverse recovery losses. A single sensor based simple voltage control loop is only used to obtain the tightly regulated output voltage, which makes it economical, and improves the system reliability and robustness to high-frequency noise. At first, a three-phase modular single-stage-isolated Cuk converter is proposed on considering Cuk converter merits such as inrush current limitation, no input filter requirement, and easy implementation of high frequency transformer isolation. The phase-modular converters are easy to implement, can be paralleled easily for high power design, operational with two-phase loss, and provide quick repair and maintenance. However, they employ more number of components and suffering from higher conduction losses. To overcome these issues, a new direct three-phase non-isolated Cuk-derived PFC converter with reduced number of components and conduction losses is proposed. With this new topology, the conduction losses are significantly reduced, and efficiency is improved by 4 % compared to the previously analyzed phase-modular converter. However, this converter needs two DC-link capacitors for its operation at DC output that added extra capacitive losses. Further to reduce the capacitive losses, a new direct three-phase non-isolated buck-boost-derived PFC converter with one DC-link capacitor and reduced capacitive losses, along with retention of all the benefits of Cuk-derived PFC converter is proposed. For high power operations, interleaved topology of the three-phase buck-boost-derived PFC converter with reduced filter size, reduced losses, and improved efficiency is proposed. Finally, an isolated topology of the three-phase buck-boost-derived PFC converter with a novel clamping circuit to capture and utilize the transformers leakage inductance energy in order to improve the converter efficiency is proposed. The converters steady-state operation, DCM condition, and design equations are reported in detail. The small-signal models for all the proposed topologies using average current injected equivalent circuit approach are developed, and a detailed closed-loop controller design is illustrated. The simulation results from PSIM 11.1 software and the experimental results from proof-of-concept laboratory hardware prototypes are provided in order to validate the report analysis, design, and performance.

Three-phase AC-AC Power Converters Based on Matrix Converter Topology
Three-phase AC-AC Power Converters Based on Matrix Converter Topology

Author: Paweł Szcześniak

Publisher: Springer Science & Business Media

Published: 2013-02-28

Total Pages: 182

ISBN-13: 1447148967

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AC voltage frequency changes is one of the most important functions of solid state power converters. The most desirable features in frequency converters are the ability to generate load voltages with arbitrary amplitude and frequency, sinusoidal currents and voltages waveforms; the possibility of providing unity power factor for any load; and, finally, a simple and compact power circuit. Over the past decades, a number of different frequency converter topologies have appeared in the literature, but only the converters with either a voltage or current DC link are commonly used in industrial applications. Improvements in power semiconductor switches over recent years have resulted in the development of many structures of AC-AC converters without DC electric energy storage. Such converters are an alternative solution for frequently recommended systems with DC energy storage and are characterized by a lower price, smaller size and longer lifetime. Most of the these topologies are based on the structure of the matrix converter. Three-Phase AC-AC Power Converters Based On Matrix Converter Topology: Matrix-reactance frequency converters concept presents a review of power frequency converters, with special attention paid to converters without DC energy storage. Particular attention is paid to nine new converters named matrix-reactance frequency converters which have been developed by the author and the team of researchers from Institute of Electrical Engineering at the University of Zielona Góra. The topologies of the presented matrix-reactance frequency converters are based on a three-phase unipolar buck-boost matrix-reactance chopper with source or load switches arranged as in a matrix converter. This kind of approach makes it possible to obtain an output voltage greater than the input one (similar to that in a matrix-reactance chopper) and a frequency conversion (similar to that in a matrix converter). Written for researchers and Ph.D. students working in the field of power electronics converters and drive systems, Three-Phase AC-AC Power Converters Based On Matrix Converter Topology: Matrix-reactance frequency converters concept will also be valuable to power electronics converter designers and users; R&D centers; and readers needing industry solutions in variable speed drive systems, such as automation and aviation.

Analysis and Design of Matrix Converters for Adjustable Speed Drives and Distributed Power Sources
Analysis and Design of Matrix Converters for Adjustable Speed Drives and Distributed Power Sources

Author: Han Ju Cha

Publisher:

Published: 2004

Total Pages:

ISBN-13:

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Recently, matrix converter has received considerable interest as a viable alternative to the conventional back-to-back PWM (Pulse Width Modulation) converter in the ac/ac conversion. This direct ac/ac converter provides some attractive characteristics such as: inherent four-quadrant operation; absence of bulky dc-link electrolytic capacitors; clean input power characteristics and increased power density. However, industrial application of the converter is still limited because of some practical issues such as common mode voltage effects, high susceptibility to input power disturbances and low voltage transfer ratio. This dissertation proposes several new matrix converter topologies together with control strategies to provide a solution about the above issues. In this dissertation, a new modulation method which reduces the common mode voltage at the matrix converter is first proposed. The new method utilizes the proper zero vector selection and placement within a sampling period and results in the reduction of the common mode voltage, square rms of ripple components of input current and switching losses. Due to the absence of a dc-link, matrix converter powered ac drivers suffer from input voltage disturbances. This dissertation proposes a new ride-through approach to improve robustness for input voltage disturbances. The conventional matrix converter is modified with the addition of ride-through module and the add-on module provides ride-through capability for matrix converter fed adjustable speed drivers. In order to increase the inherent low voltage transfer ratio of the matrix converter, a new three-phase high-frequency link matrix converter is proposed, where a dual bridge matrix converter is modified by adding a high-frequency transformer into dc-link. The new converter provides flexible voltage transfer ratio and galvanic isolation between input and output ac sources. Finally, the matrix converter concept is extended to dc/ac conversion from ac/ac conversion. The new dc/ac direct converter consists of soft switching full bridge dc/dc converter and three phase voltage source inverter without dc link capacitors. Both converters are synchronized for zero current/voltage switching and result in higher efficiency and lower EMI (Electro Magnetic Interference) throughout the whole load range. Analysis, design example and experimental results are detailed for each proposed topology.

AC to AC Converters
AC to AC Converters

Author: Narayanaswamy P R Iyer

Publisher: CRC Press

Published: 2019-06-03

Total Pages: 309

ISBN-13: 0429516223

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Power electronic converters can be broadly classified as AC to DC, DC to AC, DC to DC and AC to AC converters. AC to AC converters can be further classified as AC Controllers or AC regulators, Cycloconverters and Matrix converters. AC controllers and cycloconverters are fabricated using Silicon Controlled Rectifiers (SCR) whereas matrix converters are built using semiconductor bidirectional switches. This text book provides a summary of AC to AC Converter modelling excluding AC controllers. The software Simulink® by Mathworks Inc., USA is used to develop the models of AC to AC Converters presented in this text book. The term model in this text book refers to SIMULINK model. This text book is mostly suitable for researchers and practising professional engineers in the industry working in the area of AC to AC converters. Features Provides a summary of AC to AC Converter modelling excluding AC controllers Includes models for three phase AC to three phase AC matrix converters using direct and indirect space vector modulation algorithm Presents new applications such as single and dual programmable AC to DC rectifier with derivations for output voltage Displays Hardware-in-the Loop simulation of a three phase AC to single phase AC matrix converter Provides models for three phase multilevel matrix converters, Z-source Direct and Quasi Z-source Indirect matrix converters; a model for speed control and brake by plugging of three phase induction motor and separately excited DC motors using matrix converter; a model for a new single phase and three phase sine wave direct AC to AC Converter without a DC link using three winding transformers and that for a square wave AC to square wave AC converter using a DC link; models for variable frequency, variable voltage AC to AC power supply; models for Solid State Transformers using Dual Active Bridge topology and a new direct AC to AC Converter topology; and models for cycloconverters and indirect matrix converters

Power Factor Correction in a Single Phase AC to DC Converter
Power Factor Correction in a Single Phase AC to DC Converter

Author:

Publisher:

Published:

Total Pages:

ISBN-13:

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Electronic equipments recently in use (PCs, TVs, and Telecommunication Equipments etc.) require power conditioning of some form, typically rectification, for their proper working. But since they have non-linear input characteristics and they are connected the electricity distribution network they produce a non-sinusoidal line current. Current of frequency components which are multiples of the natural frequency are produced that are otherwise called the line harmonics. With constantly increasing demand of these kind of equipments at a high rate, line current harmonics have become a significant problem. There has been an introduction of a lot of international standards which pose limitations on the harmonic content in the line currents of equipments connected to electricity distribution networks. This calls for measures to reduce the line current harmonics which is also otherwise known as Power Factor Correction - PFC. There exist two kinds of power factor correction techniques - passive power factor correction and active power factor correction. In this thesis we tried to devise an active power factor correction method for improvement of the power factor. In this work the advantages of a boost converter is combined with that of the average current mode control to implement the technique. UC3854 was used to design the power factor corrector. This integrated circuit had all the circuits necessary to control a power factor corrector and was designed to implement the average current mode control.

Novel Bidirectional Single-phase Single-stage Isolated AC-DC Converter with PFC for Charging of Electric Vehicles
Novel Bidirectional Single-phase Single-stage Isolated AC-DC Converter with PFC for Charging of Electric Vehicles

Author: Anant Kumar Singh

Publisher:

Published: 2016

Total Pages:

ISBN-13:

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This thesis proposes a novel bidirectional single-phase single-stage AC-DC converter for Electric Vehicle (EV) charging application. AC side of the proposed converter consists of a current-fed half bridge converter. This is connected to the full-bridge converter on secondary side of a high-frequency (HF) transformer. Power Factor Correction (PFC) can be attained by regulating the current at the input of the ac side. In addition to that, the proposed converter achieves Zero Current Switching (ZCS) of primary side switches and zero current turn-on for secondary side devices throughout the operation without any additional components. Furthermore, a novel modulation technique and control algorithm is implemented. This ensures soft-switching throughout the operation range of the converter during bidirectional power flow. Design equations are derived to help suitable selection of components for a given specification. The proposed converter is designed for 1.5KW capacity for EV charging application. The simulation and experimental results are presented.

Investigation of Power Factor Correction in Single Phase AC-DC Converters
Investigation of Power Factor Correction in Single Phase AC-DC Converters

Author:

Publisher:

Published:

Total Pages:

ISBN-13:

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An ac to dc converter is an integral part of any power supply unit used in the all electronic equipments. These electronic equipments form a major part of load on the utility. Generally, to convert line frequency ac to dc, a line frequency diode bridge rectifier is used. To reduce the ripple in the dc output voltage, a large capacitor is used at the rectifier output. But due to this large capacitor, the current drawn by this converter is peaky in nature. This input current is rich in low order harmonics. Also, as power electronics equipments are increasingly being used in power conversion, they inject low order harmonics into the utility. Due to the presence of these harmonics, the total harmonic distortion is high and the input power factor is poor. Because of the problems associated with low power factor and harmonics, utilities will enforce harmonic standards and guidelines, which will limit the amount of current distortion allowed into the utility, and thus the simple diode rectifier may not be in use. So, there is a need to achieve rectification at close to unity power factor and low input current distortion. Initially, power factor correction schemes have been implemented mainly for heavy industrial loads like induction motors, induction heating furnaces etc., which forms a major part of lagging power factor load. Hence, PFC is becoming an important aspect even for low power application electronic equipments. There are two types of PFC"s. 1) Passive PFC, 2) Active PFC. The active PFC is further classified into low-frequency and high-frequency active PFC depending on the switching frequency. Different techniques in passive PFC and active PFC are presented here. Among these PFC"s, we will get better power factor by using high-frequency active PFC circuit. Any DC-DC converters can be used for this purpose, if a suitable control method is used to shape its input current or if it has inherent PFC properties. The DC-DC converters can operate in Continuous Inductor C