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Control and Design Aspects of Components and Systems in High-Voltage Converters for Industrial Applications
KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

High-frequency dc-dc converters are widely used in power electronic applications, both in consumer products and industrial products. By operating the converter at higher frequencies both a smaller size and better control characteristics can be obtained.

It is the objective of this work to investigate how high-frequency power converters can be optimized for high-voltage industrial applications. Specifically, power supplies for electrostatic precipitators (ESP) are considered. The work refers to operating frequencies higher than 20 kHz and load voltages reaching 100 kV and above. The power handling capability ranges from 10 to 200 kW.

High-frequency power supplies were originally introduced on the ESP market in 1993. An evaluation of the experiences gained during the first decade of operation is presented. It was found that the dust emissions have been reduced at the majority of the installations.

Efficiency aspects like IGBT losses in soft-switching operation with a sinusoidal collector current and the influence of different control methods have been analyzed. Dynamic properties of the IGBT such as: dynamic conduction losses and dynamic tail charges are presented and experimentally verified. The IGBT losses have been evaluated for LCC-converters operating above the resonance frequency. The losses have been measured and compared for different control methods and for different turn-off strategies, zero-current-switching and zero-voltage-switching, respectively. It is shown experimentally that the LCC-converter is more efficient than the series-loaded resonant converter for a range of values of the parallel capacitance. This is because the LCC-converter allows a lower turns ratio of the transformer.

The high-voltage high-frequency transformer has been analysed with respect to its parasitic elements. A method is presented, integrated rectification, which enables a sub-division of the winding capacitance into an AC-part and a DC-part. It is validated experimentally that they may be utilized as circuit elements and that the ratio of these capacitances may be varied within a wide range. This method is considered to be of importance when optimizing converters utilizing topologies where the output rectifier is followed by a capacitive filter.

Place, publisher, year, edition, pages
Stockholm: KTH , 2010. , xii, 85 p.
Series
Trita-EE, ISSN 1653-5146 ; 2010:038
Keyword [en]
High-voltage converter, resonant converter, high-voltage transformer, transformer parasitics, IGBT, soft-switching, control
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-25280ISBN: 978-91-7415-757-4 (print)OAI: oai:DiVA.org:kth-25280DiVA: diva2:356941
Public defence
2010-10-29, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20101014Available from: 2010-10-14 Created: 2010-10-14 Last updated: 2010-10-14Bibliographically approved
List of papers
1. Three elements resonant converter: The LCC topology by using MATLAB
Open this publication in new window or tab >>Three elements resonant converter: The LCC topology by using MATLAB
2000 (English)In: PESC Record: IEEE Annual Power Electronics Specialists Conference, Galway, UK, 2000, Vol. 2, no Piscataway, NJ, United States, 1077-1083 p.Conference paper, Published paper (Refereed)
Abstract [en]

The behaviour of a series-parallel resonant power converter is analysed by means of MATLAB simulations. PSPICE and experimental results are also presented. Stress parameters are calculated and compared with those of the series-loaded resonant power converter.

Place, publisher, year, edition, pages
Galway, UK: , 2000
Keyword
Capacitance, Computer simulation, DC power transmission, Electric commutation, Electric filters, Electric losses, Electric network topology, Electric potential, Electric windings, Frequency modulation, Natural frequencies, Resonant circuits, Resonant converters, Power converters
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25177 (URN)10.1109/PESC.2000.879962 (DOI)
Conference
2000 IEEE 31st Annual Power Electronics Specialists Conference (PESC); Galway, UK
Note
QC 20101012Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2010-10-14Bibliographically approved
2. High-frequency oscillations in a power transformer: 32ND ANNUAL POWER ELECTRONICS SPECIALISTS CONFERENCE, VOLS 1-4, CONFERENCE PROCEEDINGS
Open this publication in new window or tab >>High-frequency oscillations in a power transformer: 32ND ANNUAL POWER ELECTRONICS SPECIALISTS CONFERENCE, VOLS 1-4, CONFERENCE PROCEEDINGS
2001 (English)In: IEEE POWER ELECTRON SPEC CONF, IEEE , 2001, 612-616 p.Conference paper, Published paper (Refereed)
Abstract [en]

Power transformers are widely used as step-up or step-down devices and they can offer galvanic isolation between the input of the power supply and the output. When the operating frequency is considerably high, transformer parasitics are of importance. Interleaving of the transformer windings causes a reduction of the leakage inductance. However, the winding capacitance and the stray capacitance increases due to the good proximity of the windings achieved by interleaving.

Place, publisher, year, edition, pages
IEEE, 2001
Series
IEEE POWER ELECTRONICS SPECIALISTS CONFERENCE RECORDS, ISSN 0275-9306
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25169 (URN)10.1109/PESC.2001.954183 (DOI)000173448300101 ()0-7803-7067-8 (ISBN)
Conference
32nd Annual Power Electronics Specialist Conference (PESC 2001) VANCOUVER, CANADA, JUN 17-21, 2001
Note
QC 20101012Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2010-10-14Bibliographically approved
3. On conversion losses in SLR and LCC-topologies
Open this publication in new window or tab >>On conversion losses in SLR and LCC-topologies
2002 (English)Conference paper, Published paper (Other academic)
Abstract [en]

A methodto improve the efficiency of the SLR-converter is presented. By adding a capacitor the overall component stresses can be lowered. Simulation and experimental results are presented. A 60kW converter is tested in order to verify the theoretical results. Substantial improvements can be obtained by the proposed method.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25277 (URN)
Conference
3rd Mediterranean Conference and Exhibition on Power Generation, Transmission, Distribution and Energy Conversion, 4 – 6 November 2002, Glyfada, Athens, Greece
Note
QC 20101014Available from: 2010-10-14 Created: 2010-10-14 Last updated: 2010-10-14Bibliographically approved
4. On experiences of the application of high-frequency power converters for ESP energisation
Open this publication in new window or tab >>On experiences of the application of high-frequency power converters for ESP energisation
2004 (English)In: ICESP IX CONFERENCE, 2004Conference paper, Published paper (Other academic)
Abstract [en]

In order to improve Electrostatic Precipitator (ESP) efficiency and system cost a new technology for ESP power supplies, high-frequency power conversion, has been introduced.The first paper on commercial installations was presented about ten years ago (EPRI 1995, Toronto). Products based on this technology have been available on the market since 1993. With the first generation of products the applications were limited to small size ESPs. Through the years the scope has widened and today covers many processes. Still, the available power level limits the use on larger ESP bus sections.

The estimated number, world wide, of installed ESP power supplies based on high-frequency power conversion is close to 1000. This paper aims to evaluate the experiences, which have been gained  through these installations. Aspects such as ESP efficiency, cost and reliability are discussed.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25279 (URN)
Conference
The International Conference on Electrostatic Precipitation, Held in Kruger Gate, Mpumalanga, South Africa May May 17 - 21, 2004
Note
QC 20101014Available from: 2010-10-14 Created: 2010-10-14 Last updated: 2010-10-14Bibliographically approved
5. A novel control strategy applied to the series loaded resonant converter
Open this publication in new window or tab >>A novel control strategy applied to the series loaded resonant converter
2005 (English)In: 2005 European Conference on Power Electronics and Applications, Dresden, 2005, Vol. 2005, 1665918- p.Conference paper, Published paper (Refereed)
Abstract [en]

An novel control strategy of the series loaded resonant converter is presented. The main objective of the control strategy is to minimize the switching losses in the main switching elements (IGBT). The results are experimentally verified on a 60kW/25kHz prototype converter. The IGBT losses obtained with the proposed control strategy are compared with those of the commonly used frequency control and phase-shift control strategies. With the proposed control strategy it is found that the losses are reduced in the entire operating range compared to phase-shift control. The same statement is valid also for frequency control, except for the highest output voltage.

Place, publisher, year, edition, pages
Dresden: , 2005
Keyword
Converter control, IGBT, Resonant converter, Soft switching, Control theory, Electric frequency control, Electric losses, Insulated gate bipolar transistors (IGBT), Phase shift, Switching, Resonant converters, Switching losses, Power converters
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25176 (URN)2-s2.0-33947640104 (Scopus ID)978-907581508-5 (ISBN)
Conference
2005 European Conference on Power Electronics and Applications; Dresden; 11 September 2005 through 14 September 2005
Note
QC 20101012Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2010-10-14Bibliographically approved
6. On Cascading of the Series Loaded Resonant Converter
Open this publication in new window or tab >>On Cascading of the Series Loaded Resonant Converter
2008 (English)In: 2008 IEEE POWER ELECTRONICS SPECIALISTS CONFERENCE, IEEE , 2008, 3857-3860 p.Conference paper, Published paper (Refereed)
Abstract [en]

In this paper a novel method for cascading H-bridge and resonant tanks in a SLR, series loaded resonant, converter is presented. The main focus is on load sharing. Different methods are discussed. Their robustness regarding variations in operating frequency, values of the components and parasitic elements are evaluated. The results are validated both by simulations and by experiments. For the experimental part a 120kW/70kV system has been designed and tested. The measurements confirm the simulations, where the proposed method shows an equal sharing of the load (current) even when operating the system close to resonance with a +/- 10% worst-case variation of the resonant tank components. The method is derived for two subsystems, but can be generalised to any number of subsystems. Thus, enabling the use of compact, standardised modules connected together forming very powerful systems.

Place, publisher, year, edition, pages
IEEE, 2008
Series
IEEE POWER ELECTRONICS SPECIALISTS CONFERENCE RECORDS, ISSN 0275-9306
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25168 (URN)000260398502157 ()978-1-4244-1667-7 (ISBN)
Conference
39th IEEE Power Electronic Specialists Conference (PESC 08) Rhodes, GREECE, JUN 15-19, 2008
Note
QC 20101012Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2010-10-14Bibliographically approved
7. On the distribution of AC and DC winding capacitances in high-frequency power transformers with rectifier loads
Open this publication in new window or tab >>On the distribution of AC and DC winding capacitances in high-frequency power transformers with rectifier loads
2011 (English)In: IEEE Transactions on Industrial Electronics, ISSN 0278-0046Article in journal (Refereed) Published
Abstract [en]

In this paper a method to adjust the AC winding capacitance of high-voltage high-frequency transformers by means of a winding-rectifier integration is described. First a theoretical background to the method is given. From the theory, an equivalent circuit describing the characteristics of the combination of the transformer and the rectifier is derived. The derived circuit introduces the concept of a DC-capacitance. Finally, the equivalent circuit and the method itself are verified by means of experiments on a transformer-rectifier system from an industrial application with the ratings 70 kV, 30 kW, 25 kHz. The results from the experiments show that it is possible to vary the AC component of the winding capacitance from a few percent up to 95 percent of the total winding capacitance. This means that it is virtually free to choose between AC or DC capacitance during the design stage. This is very important in applications such as resonant converters with transformers having secondary windings connected to rectifiers with capacitive output filters.

Keyword
Capacitance, Converters, Equivalent circuits, Integrated circuit modeling, Power transformers, Rectifiers, Windings, high-voltage conversion, resonant converters, transformer parasitics, winding capacitance
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25218 (URN)10.1109/TIE.2010.2055773 (DOI)000289478000030 ()2-s2.0-79954464727 (Scopus ID)
Note
QC 20101013Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2011-05-02Bibliographically approved
8. On dynamic effects influencing IGBT losses in soft switching converters
Open this publication in new window or tab >>On dynamic effects influencing IGBT losses in soft switching converters
2011 (English)In: IEEE Transactions on Power Electronics, ISSN 0885-8993, Vol. 26, no 1, 260-271 p.Article in journal (Refereed) Published
Abstract [en]

Two different dynamic effects influencing the IGBT losses in soft switching converters are demonstrated. The first one, The Dynamic tail-charge effect shows that the tail-charge is dependent not only on the absolute value of the current at turn-off but also on the dynamics of the current. This effect may have a significant impact on the optimization of zero-current-switching converters. The Dynamic conduction losses originate from the conductivity modulation lag of the IGBT. It is shown by experiments that the on-state losses depend on the operating frequency. Different methods to accurately determine the on-state losses are evaluated. It was found that the best method is an indirect measurement where the stray inductance is identified by the use of an oscillating circuit. The experiments are performed under a sinusoidal current excitation at a fixed amplitude (150 A) for different frequencies (up to 104 kHz). The switching devices used are IGBT-modules rated 300-400 A/1200 V in a bridge-leg configuration. From the experiments performed it is found that IGBTs of a modern PT design have the lowest losses in the series-loaded resonant converters studied in the present paper.

Place, publisher, year, edition, pages
IEEE, 2011
Keyword
IGBT, conductivity modulation, resonant converters, soft switching, tail-current
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25216 (URN)10.1109/TPEL.2010.2055581 (DOI)000285843000025 ()2-s2.0-78650984362 (Scopus ID)
Note
QC 20101013Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2012-01-04Bibliographically approved

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Citation style
  • apa
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  • ieee
  • modern-language-association-8th-edition
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  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
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  • Other locale
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Output format
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