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Multilayered Coreless Printed Circuit Board (PCB) Step-down Transformers for High Frequency Switch Mode Power Supplies (SMPS)
Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media. (Power Electronics)
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The Power Supply Unit (PSU) plays a vital role in almost all electronic equipment. The continuous efforts applied to the improvement of semiconductor devices such as MOSFETS, diodes, controllers and MOSFET drivers have led to the increased switching speeds of power supplies. By increasing the switching frequency of the converter, the size of passive elements such as inductors, transformers and capacitors can be reduced. Hence, the high frequency transformer has become the backbone in isolated AC/DC and DC/DC converters. The main features of transformers are to provide isolation for safety purpose, multiple outputs such as in telecom applications, to build step down/step up converters and so on. The core based transformers, when operated at higher frequencies, do have limitations such as core losses which are proportional to the operating frequency. Even though the core materials are available in a few MHz frequency regions, because of the copper losses in the windings of the transformers those which are commercially available were limited from a few hundred kHz to 1MHz. The skin and proximity effects because of induced eddy currents act as major drawbacks while operating these transformers at higher frequencies. Therefore, it is necessary to mitigate these core losses, skin and proximity effects while operating the transformers at very high frequencies. This can be achieved by eliminating the magnetic cores of transformers and by introducing a proper winding structure.

A new multi-layered coreless printed circuit board (PCB) step down transformer for power transfer applications has been designed and this maintains the advantages offered by existing core based transformers such as, high voltage gain, high coupling coefficient, sufficient input impedance and high energy efficiency with the assistance of a resonant technique. In addition, different winding structures have been studied and analysed for higher step down ratios in order to reduce copper losses in the windings and to achieve a higher coupling coefficient. The advantage of increasing the layer for the given power transfer application in terms of the coupling coefficient, resistance and energy efficiency has been reported. The maximum energy efficiency of the designed three layered transformers was found to be within the range of 90%-97% for power transfer applications operated in a few MHz frequency regions. The designed multi-layered coreless PCB transformers for given power applications of 8, 15 and 30W show that the volume reduction of approximately 40-90% is possible when compared to its existing core based counterparts. The estimation of EMI emissions from the designed transformers proves that the amount of radiated EMI from a three layered transformer is less than that of the two layered transformer because of the decreased radius for the same amount of inductance.

Multi-layered coreless PCB gate drive transformers were designed for signal transfer applications and have successfully driven the double ended topologies such as the half bridge, the two switch flyback converter and resonant converters with low gate drive power consumption of about half a watt. The performance characteristics of these transformers have also been evaluated using the high frequency magnetic material made up of NiZn and operated in the 2-4MHz frequency region.

These multi-layered coreless PCB power and signal transformers together with the latest semiconductor switching devices such as SiC and GaN MOSFETs and the SiC schottky diode are an excellent choice for the next generation compact SMPS.

Place, publisher, year, edition, pages
Sundsvall, Sweden: Mid Sweden University , 2011. , 88 p.
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 61
Keyword [en]
Multilayered Coreless PCB transformers, High frequency converters
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:miun:diva-13967Local ID: STCISBN: 978-91-86694-40-1OAI: oai:DiVA.org:miun-13967DiVA: diva2:422609
Presentation
2011-05-20, O102, Mid Sweden University, Holmgatan 10, Sundsvall, 13:15 (English)
Opponent
Supervisors
Funder
EU, European Research Council
Available from: 2011-06-13 Created: 2011-06-13 Last updated: 2016-10-19Bibliographically approved
List of papers
1. Radiated Emissions of Multilayered Coreless Printed Circuit Board Step-Down Power Transformers in Switch Mode Power Supplies
Open this publication in new window or tab >>Radiated Emissions of Multilayered Coreless Printed Circuit Board Step-Down Power Transformers in Switch Mode Power Supplies
2011 (English)In: 8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia 2011, IEEE conference proceedings, 2011, 960-965 p.Conference paper (Refereed)
Abstract [en]

This paper addressesradiatedEMI issues in Coreless PCB step-down transformers used for power transfer applications. In case of SMPS circuits, since the waveforms are not sinusoidal in nature, most of theradiatedemissionsare not only from fundamental frequency component but also from harmonic contents. According to antenna theory,radiatedEMI for three different power transformers of different radii were estimated for fundamental frequency of 2MHz to 300MHz. The computations were made for both sinusoidal and square wave excitations and at a load power of 20W. The calculatedradiatedpower obtained for simulated waveforms and for practical measured current waveforms are in good agreement with each other up to certain bandwidth. These computational results confirm thatradiatedpower can be reduced in three layered 2:1 transformer compared to two layered 2:1 transformer. Also theradiatedemissionsare negligible in case of sinusoidal excitations compared to square wave excitations. © 2011 IEEE.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2011
Keyword
Harmonics; MHz frequency of operation; Multilayered Coreless PCB step down power transformers; Radiated EMI
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-13247 (URN)10.1109/ICPE.2011.5944654 (DOI)2-s2.0-80052087677 (ScopusID)STC (Local ID)978-1-61284-956-0 (ISBN)978-1-61284-958-4 (ISBN)STC (Archive number)STC (OAI)
Conference
8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia;Jeju;30 May 2011through3 June 2011;Category numberCFP11CPB-USB;Code86200
Available from: 2011-02-11 Created: 2011-02-11 Last updated: 2016-10-19Bibliographically approved
2. Coreless Printed Circuit Board (PCB) StepdownTransformers for DC-DC ConverterApplications
Open this publication in new window or tab >>Coreless Printed Circuit Board (PCB) StepdownTransformers for DC-DC ConverterApplications
2010 (English)In: PROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, ISSUE 70, OCTOBER 2010, ISSN:1307-6892, France: World Academy of Science Engineering and Technology , 2010, 380-389 p.Conference paper (Refereed)
Abstract [en]

In this paper, multilayered coreless printed circuit board (PCB) step-down power transformers for DC-DC converter applications have been designed, manufactured and evaluated. A set of two different circular spiral step-down transformers were fabricated in the four layered PCB. These transformers have been modelled with the assistance of high frequency equivalent circuit and characterized with both sinusoidal and square wave excitation. This paper provides the comparative results of these two different transformers in te rms of their resistances, self, leakage, mutual inductances, coupling coefficient and also their energy efficiencies. The operating regions for optimal performance of these transformers for power transfer applications are determined. These transformers were tested for the output power levels of about 30 Watts within the input voltage range of 12-50 Vrms. The energy efficiency for these step down transformers is observed to be in the range of 90%-97% in MHz frequency region.

Place, publisher, year, edition, pages
France: World Academy of Science Engineering and Technology, 2010
Series
, WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, ISSN 1307-6892 ; 70
Keyword
Coreless Step down Transformer, DC-DC Converter applications, High frequency transformer, MHz operating frequency, Multilayered PCB transformers, Power Transfer Applications
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-12242 (URN)2-s2.0-84871422637 (ScopusID)
Conference
International Conference on Electrical Machines and Power Electronics
Available from: 2010-11-17 Created: 2010-11-17 Last updated: 2016-09-22Bibliographically approved
3. Comparison of Two Layered and Three Layered Coreless Printed Circuit Board Step-Down Power Transformers
Open this publication in new window or tab >>Comparison of Two Layered and Three Layered Coreless Printed Circuit Board Step-Down Power Transformers
2011 (English)In: 2011 INTERNATIONAL CONFERENCE ON INSTRUMENTATION, MEASUREMENT, CIRCUITS AND SYSTEMS (ICIMCS 2011), VOL 2: FUTURE COMMUNICATION AND NETWORKING, Shenzhen: IEEE conference proceedings, 2011, 59-62 p.Conference paper (Refereed)
Abstract [en]

In this paper the comparative results of two layered and three layered coreless Printed Circuit Board (PCB) step down 2:1 power transformers operating in MHz frequency were addressed. The  two different step down transformers approximately having same self inductances, one in two layer and the other in three layer were designed and evaluated for the given power transfer application. The performance characteristics of these transformers under similar conditions were measured and the comparative parameters of these transformers in terms of their resistances, self, leakage, mutual inductances, and coupling coefficient are analyzed. For the given output power, the measured energy efficiency of the three layered transformer is improved by 3% and the area is reduced by 32% compared to two layered transformer. The efficiency of the three layered transformer is 94.5% approximately for an output power level of 25W at an operating frequency of 2.5MHz

Place, publisher, year, edition, pages
Shenzhen: IEEE conference proceedings, 2011
Keyword
Coreless Printed Circuit Board (PCB) transformer, MHz frequency region, Multilayered coreless PCB transformer, Step-down transformer, Power density.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-14643 (URN)000306295600013 ()978-0-7918-5990-2 (ISBN)
Conference
International Conference on Instrumentation, Measurement, Circuits and Systems (ICIMCS 2011)
Available from: 2011-10-27 Created: 2011-10-27 Last updated: 2014-08-31Bibliographically approved
4. A ZVS Flyback DC-DC Converter using Multilayered Coreless Printed Circuit Board (PCB) Step Down Power Transformer
Open this publication in new window or tab >>A ZVS Flyback DC-DC Converter using Multilayered Coreless Printed Circuit Board (PCB) Step Down Power Transformer
2010 (English)In: World Academy of Science, Engineering and technology, Paris: World Academy of Science,Engineering and Technology , 2010, 148-155 p.Conference paper (Refereed)
Abstract [en]

The experimental and theoretical results of a ZVS (Zero Voltage Switching) isolated flyback DC-DC converter using multilayered coreless PCB step down 2:1 transformer are presented.The performance characteristics of the transformer are shown which are useful for the parameters extraction. The measured energy efficiency of the transformer is found to be more than 94% with the sinusoidal input voltage xcitation. The designed flyback converter has been tested successfully upto the output power level of 10W,with a switching frequency in the range of 2.7MHz-4.3MHz. The input voltage of the converter is varied from 25V-40V DC.Frequency modulation technique is employed by maintaining constant off time to regulate the output voltage of the converter. The energy efficiency of the isolated flyback Converter circuit under ZVS condition in the MHz frequency region is found to be approximately in the range of 72-84%. This paper gives the comparative results in terms of the energy efficiency of the hard switched and soft switched flyback Converter in the MHz frequency region.

Place, publisher, year, edition, pages
Paris: World Academy of Science,Engineering and Technology, 2010
Series
, World Academy of Science ,Engineering and Technology,ISSUE 70,OCTOBER 2010, ISSN 1307-6892 ; 70
Keyword
Coreless PCB step down transformer, DC-DC Converter, Flyback, Hard Switched Converter, MHz Frequency region, Multilayered PCB transformer, Zero Voltage Switching
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-12278 (URN)2-s2.0-80052088161 (ScopusID)
Conference
International Conference on Electrical Machines and Power Electronics (ICEMPE),2010
Available from: 2010-11-24 Created: 2010-11-24 Last updated: 2016-09-26Bibliographically approved

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