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Wide Range Isolated Power Converters
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.ORCID-id: 0000-0002-7802-0795
2020 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Power electronics technology is rapidly growing in most industrialapplications. There is an increasing demand for efficient and low profilepower converters in the industry like automotive, power grids, renewableenergy systems, electric rail systems, home appliances, and informationtechnology. In some applications, there is an increasing demand for powerconverters showing a stable performance over a wide variation in inputvoltage, whereas in others the demand is for converters showing a stableperformance over a wide variation of output voltage. In this regard, not somuch work has been done to combine both requirements into one solution;this is the primary focus of the dissertation. It presents a unique solution tothe industry, which addresses both requirements. The technique can beapplied in a one size fits all solution which not only extends the range of theline voltage and the output voltage but also provides the flexibility to adjustthe required set of line/output voltage. The variation in line voltage severelydegrades the performance of power converters because of the extendedfreewheeling interval, more circulating current, narrow range of zero voltageswitching and increased EMI. To overcome this, the converter consists of tworeconfigurable modes on the input side that can be configured following thevariation in line voltage to maintain a stable performance. In addition, itproposes three reconfigurable steps for the output voltage, which can be usedto adjust the output voltage from base level X to 2X and 4X in discrete stepsand/or from X - 4X volt while showing stable performance. This makes theproposal a 2x3 reconfigurable modes power converter, which means that thegain of the proposed converter can be raised to 4 or 8. Furthermore, theflexibility in the reconfigurable structure simplifies the implementation of theproposed single solution in a range of applications. Each concept proposed inthe thesis is verified analytically, experimentally and modelling it into aSPICE simulation. Then the whole concept is confined into a single entity,which is applied in an example application of a phase shifted full bridgeconverter. The full converter is characterized for input voltage 100-400Vdc, theoutput voltage 24-96Vdc, and up to the load power of 1kW.

Abstract [sv]

Kraftelektroniktekniken växer snabbt i många industriella tillämpningar. Det finns en ökande efterfrågan på effektiva kraftomvandlare med låg bygghöjd inom fordonsindustrin, elnät, förnybara energisystem, järnvägar, hushållsapparater och informationsteknik. I vissa tillämpningar finns det en ökande efterfrågan på kraftomvandlare som visar en stabil prestanda över mycket varierande inspänning, medan andra omvandlare ska kunna hantera stora variationer i utspänning. Fram tills nu så har inte så mycket arbete gjorts för att kombinera båda kraven till en lösning vilket är den primära målsättningen för denna avhandling. Tekniken kan appliceras i ’one-size-fitsall’ lösning som inte bara utökar området för in- och utspänning utan ger också flexibilitet att justera spänningar inom ett bredare område. Stora variationer i inspänning försämrar kraftigt omvandlarnas verkningsgrad på grund av det utökade cirkulerande ström, och svårigheter att uppnå mjukswitchning och ökad EMI. För att övervinna detta består omvandlaren av två konfigurerbara lägen på ingångssidan som kan justeras efter variationen i inspänning för att upprätthålla en stabil prestanda. Dessutom föreslås tre konfigurerbara steg för utgångsspänningen, som kan användas för att justera utgångsspänningen från en basnivå X till 2X och 4X. Detta resulterar i en omvandlare med 2x3 konfigurerbara lägen, vilket innebär att omvandlarens spänningsomsättning kan varieras med en faktor 8 jämfört med 2 för en traditionell omvandlare. Den konfigurerbara strukturen kan förenkla systemimplementationen då samma omvandlare kan användas för flera olika tillämpningar. De koncept som föreslås i avhandlingen har designats analytiskt, modellerat i en SPICE-simulering samt verifierats experimentellt. Slutligen har hela konceptet kombinerats i en enhet som klarar inspänningar mellan 100-400V DC och utgångsspänningen 24-96Vdc och upp till belastningseffekten på 1kW.

Ort, förlag, år, upplaga, sidor
Sundsvall: Mid Sweden University , 2020. , s. 43
Serie
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 328
Nyckelord [en]
Power converters, Resonant converters, wide range converter, stable performance
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
URN: urn:nbn:se:miun:diva-39071ISBN: 978-91-88947-59-8 (tryckt)OAI: oai:DiVA.org:miun-39071DiVA, id: diva2:1432848
Disputation
2020-06-09, C312, Holmgatan 10, Sundsvall, 09:30 (Engelska)
Opponent
Handledare
Anmärkning

Vid tidpunkten för disputationen var följande delarbeten opublicerade: delarbete 2 (accepterat), delarbete 3 och 6 (inskickat), delarbete 9 (under utgivning).

At the time of the doctoral defence the following papers ware unpublished: paper 2 (accepted), paper 3 och 6 (submitted), paper 9 (in press).

Tillgänglig från: 2020-05-29 Skapad: 2020-05-28 Senast uppdaterad: 2020-06-22Bibliografiskt granskad
Delarbeten
1. Modeling and Characterization of Series Connected Hybrid Transformers for Low-Profile Power Converters
Öppna denna publikation i ny flik eller fönster >>Modeling and Characterization of Series Connected Hybrid Transformers for Low-Profile Power Converters
2020 (Engelska)Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 8, s. 53293-53306Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Compact and low profile power converters are the main business of today's power industry. A significant volume of a power converter is occupied by the power transformer. This article proposes a unique solution that would make the power converters low profile. Instead of designing a power converter by using a single bulky transformer, the solution proposed is to split the main bulky transformer into a number of low profile transformers. This not only reduces the total weight and volume of the converter but also the total transformer losses. The use of more than one transformer in series reduces the applied voltage on the transformers, which minimizes the required turns ratio and decreases the stress on the secondary rectifiers and filter elements. Moreover, the decrease in the applied voltage reduces the proportional loss per transformer and makes it possible to design a hybrid transformer by combining Litz wire and traces of a printed circuit board. The reduced copper loss and lower heat dissipation per transformer simplify thermal management. An analytical comparison is made between the utilization of a single transformer or a number of transformers. The procedure of splitting a volume of a single transformer into a number of small transformers has been comprehensively discussed. The idea is investigated both experimentally and in computer simulation for an example application of a phase shifted full bridge dc-dc converter. The converter is characterized up to a load power of 2.2 kW at Vin = 400 Vdc and Vout = 48 Vdc. To make the approach more practical, the transformers are modeled using the traditional analytical method. The design of the example application using the split transformer approach reduces the total transformer weight by 45%, compared to the traditional approachwith a single transformer. The converter also shows good performance with a maximum efficiency of 96%.

Ort, förlag, år, upplaga, sidor
IEEE, 2020
Nyckelord
Series transformers, modeling of transformers, transformer design, isolated converter, medium power converter, low profile converters, ZVS converter, PSFB converter, lightweight converter
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:miun:diva-38693 (URN)10.1109/ACCESS.2020.2981342 (DOI)000524749000031 ()2-s2.0-85082629619 (Scopus ID)
Tillgänglig från: 2020-03-20 Skapad: 2020-03-20 Senast uppdaterad: 2020-05-29Bibliografiskt granskad
2. Characterization of phase shifted full bridge converter along with GaN devices and series-connected hybrid transformers for medium power applications
Öppna denna publikation i ny flik eller fönster >>Characterization of phase shifted full bridge converter along with GaN devices and series-connected hybrid transformers for medium power applications
2020 (Engelska)Ingår i: / [ed] IEEE, 2020, s. 1058-1064Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Compact power converters are the major concern of today’s power industry. This article proposes GaN devices based isolated dc-dc phase shifted full bridge converter along with the configuration of four series-connected hybrid transformers. The series connection of transformers reduces the applied volt-second on each transformer which reduces the proportional losses and simplify thermal management. This configuration also reduces the required turn’s ratio as well as bringing down the stress on the secondary devices and filters. The converter is characterized in a compact prototype up to the load power of 2.2 kW for Vout=48 Vdc at Vin=400 Vdc. The converter reports satisfactory performance with a maximum efficiency of 96%.

Nyckelord
GaN devices, hybrid transformers, phase shifted full bridge converter, medium power applications
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:miun:diva-39022 (URN)2-s2.0-85089661102 (Scopus ID)9783800752454 (ISBN)
Konferens
IEEE PCIM Europe digital days 2020, Nuremberg, Germany, 7–8 July, 2020
Anmärkning

As a response to the spread of Covid-19, the PCIM Europe community will be meeting virtually. For the first time ever, the “PCIM Europe digital days” will be held from 7 – 8 July 2020 on a virtual platform.

Tillgänglig från: 2020-05-13 Skapad: 2020-05-13 Senast uppdaterad: 2022-11-23Bibliografiskt granskad
3. Dual-mode stable performance Phase-Shifted Full-Bridge converter for wide-input and medium power applications
Öppna denna publikation i ny flik eller fönster >>Dual-mode stable performance Phase-Shifted Full-Bridge converter for wide-input and medium power applications
2021 (Engelska)Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 36, nr 6, s. 6375-6388Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Power converters with an extended range of line voltage are the main requirement in today's industrial applications like photovoltaic and supercapacitors based energy systems. The variation in the line voltage severely degrades the performance of power converters, because of the extended freewheeling interval, more circulation current, narrow range of zero voltage switching and increased EMI. This work suggests a modified Phase-Shifted Full-Bridge converter that cuts the freewheeling interval and minimizes these problems. It extends the input voltage range by keeping the operational duty cycle of the converter high over the wide range of input voltage while maintaining the performance stable. The proposed converter consists of four low profile transformers having reconfigurable interconnection structure. There are two distinct reconfigurable modes, a series mode and a parallel mode, which can be configured with changes in the operational conditions. The operation of the proposed converter with high switching frequency improves power density. Additionally, the use of multiple transformers minimizes heat management efforts and reduces the overall volume of the converter. The proposed work is validated in hardware characterization for a wide range of input voltage 100-400Vdc and up to the load power of 1kW. The measured energy efficiency of the proposed converter remains stable over the complete range input voltage 100-400Vdc.

Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:miun:diva-39076 (URN)10.1109/TPEL.2020.3033386 (DOI)000655512500031 ()2-s2.0-85100753047 (Scopus ID)
Tillgänglig från: 2020-05-29 Skapad: 2020-05-29 Senast uppdaterad: 2021-06-24Bibliografiskt granskad
4. A Modified Higher Operational Duty Phase Shifted Full Bridge Converter for Reduced Circulation Current
Öppna denna publikation i ny flik eller fönster >>A Modified Higher Operational Duty Phase Shifted Full Bridge Converter for Reduced Circulation Current
2020 (Engelska)Ingår i: IEEE Open Journal of the Industrial Electronics Society, ISSN 2644-1284, Vol. 1, s. 82-96Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Besides many advantages, the reduction in the operational duty of traditional phase shifted full converter limits its scope in applications where a wide range of input voltage is the main requirement. Operation with low duty cycle extends freewheeling interval, which results in degraded performance such as more circulation current, increased conduction loss in power devices, narrow range of zero voltage switching and increased EMI. To overcome these drawbacks, this work suggests a modified phase shifted full bridge converter that keeps the operational duty of the converter high for a wide range of input voltage. This cuts the freewheeling interval and improves performance. The proposed converter consists of four low profile transformers having reconfigurable interconnection structure. There are two distinct reconfigurable modes, a low gain mode and a high gain mode, which can be adopted in accordance with the variation in line voltage. The proposed work is validated in LTspice simulation and hardware characterization for a wide range of input voltage 100-400Vdc/12Vout and up to the load power of 1.2kW.

Nyckelord
Wide range power converters, PSFB, Series transformers, Stable performace
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:miun:diva-39014 (URN)10.1109/OJIES.2020.2994142 (DOI)000669551100008 ()2-s2.0-85103404484 (Scopus ID)
Tillgänglig från: 2020-05-13 Skapad: 2020-05-13 Senast uppdaterad: 2022-06-01Bibliografiskt granskad
5. Reconfigurable three state dc-dc power converter for the wide output range applications
Öppna denna publikation i ny flik eller fönster >>Reconfigurable three state dc-dc power converter for the wide output range applications
Visa övriga...
2019 (Engelska)Ingår i: IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society, Lisbon: IEEE, 2019, s. 4911-4916Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Improving the dc voltage gain of power converters has been the primary focus of the current and past research in the area of power electronics. This work presents another solution to widen the range of the output voltage. It proposes three reconfigurable steps for the output voltage. The range of theoutput voltage varies up to four times the base level. These configurations together vary the output voltage from 15 to 96 volts. A soft switched dc-dc power converter is built with the traditional topology of phase shifted full bridge converter along with improved characteristics. For better management of thetransformer loss, a configuration of four transformers has been employed. The proportional gate drive approach is implemented to obtain four similar isolated blocks of the output voltage. This makes it possible to either configure these blocks all in series,parallel or in series/ parallel combination of two. The concept is verified in a low-profile prototype. The hardware is characterized up to the load power of 1kW for the input voltage of 400Vdc. The converter reports better efficiency over the complete range of output voltage.

Ort, förlag, år, upplaga, sidor
Lisbon: IEEE, 2019
Nationell ämneskategori
Elektroteknik och elektronik
Identifikatorer
urn:nbn:se:miun:diva-37646 (URN)10.1109/IECON.2019.8927652 (DOI)000522050604145 ()2-s2.0-85084144277 (Scopus ID)978-1-7281-4878-6 (ISBN)
Konferens
45th Proceedings of inductrial electronics, Lisbon, Portugal
Tillgänglig från: 2019-11-08 Skapad: 2019-11-08 Senast uppdaterad: 2020-05-29
6. A 2x3 Reconfigurable Modes Wide Input Wide Output Range dcdc Power Converter
Öppna denna publikation i ny flik eller fönster >>A 2x3 Reconfigurable Modes Wide Input Wide Output Range dcdc Power Converter
(Engelska)Ingår i: IEEE Access, E-ISSN 2169-3536Artikel i tidskrift (Refereegranskat) Submitted
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:miun:diva-39077 (URN)
Tillgänglig från: 2020-10-01 Skapad: 2020-05-29 Senast uppdaterad: 2020-05-29Bibliografiskt granskad
7. An improved modelling and construction of power transformer for controlled leakage inductance
Öppna denna publikation i ny flik eller fönster >>An improved modelling and construction of power transformer for controlled leakage inductance
2016 (Engelska)Ingår i: Environment and Electrical Engineering (EEEIC), 2016 IEEE 16th International Conference on, IEEE, 2016Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

In this work, a transformer with increased leakage inductance for the soft switched power applications is presented as a practical solution by constructing a transformer with good control over the leakage inductance. An analytical reluctance based model is presented, which accurately predicts the leakage inductance. With the presented approach, a transformer is designed with a leakage inductance varying between 3-7μH. Increasing the efficiency and improving the power density has been the main focus of power electronics researchers in the recent years. In this regards, transformers with increased leakage inductance are becoming more popular in order to accomplish different soft switching concepts and for improving the power density.

Ort, förlag, år, upplaga, sidor
IEEE, 2016
Nyckelord
ZVS, Integrated transformer, Leakage inductance, Power density, Resonant Converters, Inductance, Windings, Ferrites, Mathematical model, Permeability
Nationell ämneskategori
Elektroteknik och elektronik
Identifikatorer
urn:nbn:se:miun:diva-29006 (URN)10.1109/EEEIC.2016.7555605 (DOI)000387085800179 ()2-s2.0-84988409826 (Scopus ID)STC (Lokalt ID)978-1-5090-2320-2 (ISBN)978-1-5090-2319-6 (ISBN)STC (Arkivnummer)STC (OAI)
Konferens
IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC), 7-10 June 2016 Florence, Italy
Tillgänglig från: 2016-10-01 Skapad: 2016-10-01 Senast uppdaterad: 2020-05-29Bibliografiskt granskad
8. A phase shifted full bridge converter with novel control over the leakage inductance
Öppna denna publikation i ny flik eller fönster >>A phase shifted full bridge converter with novel control over the leakage inductance
2016 (Engelska)Ingår i: 2016 18TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'16 ECCE EUROPE), Institute of Electrical and Electronics Engineers (IEEE), 2016, artikel-id 7695545Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

The electronics industry is progressing towards the high density board solutions due to the requirement of compact and intelligent electronic systems. In order to meet the industry demands, the power system is required to be of high power density. This article proposes one of the solution to improve the power density for the medium power applications. In phase shifted full bridge converter, the intrinsic leakage inductance of the main transformer is not high enough to obtain the zero voltage switching of the power switches for the entire operating conditions. An additional shim inductor is usually connected in series with the primary winding of the main transformer to increase the collective leakage inductance. This additional shim inductor degrades the power density of the converter. This paper proposes a method to embed and control the resonance inductance inside the main transformer. In addition to the increased inter-winding spacing, this paper proposes a practical approach to integrate the ferrite rods inside the main transformer for further increase in the leakage inductance. A power transformer is constructed and investigated by using the modelled equations to estimate the leakage inductance. A prototype phase shifted full bridge converter is also developed to investigate the performance of the proposed transformer. The converter is designed for the switching frequency of 400kHz, and tested up to 600watts output power at the input voltage of 200Vdc. The performance of the proposed converter is also compared with the converter of using an external inductor. The investigations show that, in addition to the improved power density, the converter with the proposed transformer is more efficient than the converter with the traditional transformer.

Ort, förlag, år, upplaga, sidor
Institute of Electrical and Electronics Engineers (IEEE), 2016
Serie
European Conference on Power Electronics and Applications, ISSN 2325-0313
Nyckelord
ZVS converter, Transformer, Device modelling, High power density systems, Efficiency
Nationell ämneskategori
Elektroteknik och elektronik
Identifikatorer
urn:nbn:se:miun:diva-29392 (URN)10.1109/EPE.2016.7695545 (DOI)000386637300294 ()2-s2.0-84996605370 (Scopus ID)STC (Lokalt ID)STC (Arkivnummer)STC (OAI)
Konferens
18th European Conference on Power Electronics and Applications (EPE), SEP 05-09, 2016, GERMANY
Tillgänglig från: 2016-12-02 Skapad: 2016-12-02 Senast uppdaterad: 2020-05-29Bibliografiskt granskad
9. Contribution of Leakage Flux to the total Losses in Transformers with Magnetic Shunt
Öppna denna publikation i ny flik eller fönster >>Contribution of Leakage Flux to the total Losses in Transformers with Magnetic Shunt
2021 (Engelska)Ingår i: International journal of electronics (Print), ISSN 0020-7217, E-ISSN 1362-3060, Vol. 108, nr 4, s. 558-573Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

To execute soft switching methods in resonant power converters, transformers with larger leakage inductance are getting more attention. Many papers have constructed various concepts in this regard. However, a discussion about, how the transformer efficiency is affected is lacking in the literature. This paper analyses the effects of the increased leakage inductance on the performance of the transformer. A transformer for increased leakage inductance is modelled and constructed to investigate the losses. The model discusses the effects of increased leakage inductance either by increasing the inter-winding spacing or by integrating the magnetic shunt within the transformer. The investigations show that increasing the leakage inductance by inserting a magnetic shunt can have severe degrading effects on the performance of the transformer, if not designed adequately. Additional losses are also calculated and the effects are verified by the experiments.

Ort, förlag, år, upplaga, sidor
London: Taylor & Francis Group, 2021
Nyckelord
Integrated Leakage inductance, leakage loss, resonant converters
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:miun:diva-39021 (URN)10.1080/00207217.2020.1793404 (DOI)000553389600001 ()2-s2.0-85087874033 (Scopus ID)
Tillgänglig från: 2020-05-13 Skapad: 2020-05-13 Senast uppdaterad: 2021-05-11Bibliografiskt granskad

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