DOCSLIB.ORG

Antenna Design & Coupling Studies at Medium Frequency for Lmproved

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Antenna Design & Coupling Studies at Medium Frequency for Lmproved ANTENNA DESIGN{ COUPLING STUDIES AT MEDIUM FR EQUE NCY FOR IMPROVED COAL MINE COMMUNICATION5 PREPARED FOR UN l TED STATES DEPARTMENT 0 F THE I NTEF?I OR BUREAU OF MlflES TERRYS. CORY, P.E. ENGl NEERl NG CONSULTANT CEDAR RAPIDS, IOWA FINAL REPORT PURCHASE ORDER NO. PO382223 15 DECEMEER 1978 The views and conclusions contained in this document are those of the author and should not be interpreted as necessarily representing the official policies or recommendations of the Interior Department's Bureau of Mines or of the U,S, Government Zct'u~~UL-U,,,~.~,),, ,- . : I. Kepnrc No. j ?# 3. Xecip~enr's Accession No. i +, Title ..nd Subtitle 5. Report Dare 15 December, 1978 Antenna Desi gn 8 Coup 1 ing Stud Ies at Med Iurn Frequency for l mproved Coa l MI ne Commun i cat1ons I 1 7. Aurh~r(s) 8. Performing Or~onizarionReport No. I ! Terry S. Cory i ! I I I i f 9. Performing Organization Name and Address f 10. Project/Tasic/Work tinir No. i j Terry S. Cory, P.E. I 2857 West, Mount Vernon Road S.E. 11. Contract or Grant No. Cedar Rapids, Iowa 52403 , Purchase Order P3332223 I1 13. Type of Xeport 12. Sponsoring Organization Name dud Acidrcss Office of the Assistant Director -,Mining Find Report I Bureau of lines Department of the Interior ! ! 1 Washinqton. D.C. 7W41 14. 1 15. Supplementary Nores i f I Prior related work - Wlre less Communications for Trackl ess Hau l a~eVnh i c lss i USBM contract ~0377013 This report covers antenna design, analysis, and development work suited for use with a wlreless radio communication system operating at rnsdlun frequency. The work includes the test and evaluation of pro+ot'/pe vehicular antennas deve loped dur i ng the program. 17. Orlglnator's Key Words - 18. Availability Statement MF wireless radio communication; vehicular antennas; portable antennas I 19. U.S. Security Classif. of the Repon ; 20. U.S. Security Classif. of This Page 21, No. of Pages 22. Price f Unclassified Unclassified I 55 f FOREWARD This report was prepared by Terry S. Cory, P.E. for the U.S. Bureau of Mines under purchase order P038223. The work was initiated via an unso l icited proposa l under Coal Mine Health and Safety Program. It was admi ni stered under the techn i ca I d i rect i on of the 8ruceton Research Center with Mr. Robert Chufo acting as the Technical Project Officer. The BuMines Contracting Officer was klrs. Chalene Wolper. Thi s report i s a summary of the work recently cornp leted; performed during the period 15 July 1978 through I Oecomber 1978. The report w3s submitted by the author on 15 Decomber 1978. Any reference to specific brands, equipmen?, or trade names eithsr specifically written or implied does not imply endorsement by the Bureau of Mines. No patentable techniques have been developed or otherwise used during the course of thf s program, The vehicular an+:~nne design may be patentable. Tabls of Contents Page Report Documentation Page---------------- Foreward--------------------------------- 1.0 Introduction----------------------- 2.0 SUm~ryIIII--I-I-I-~--------------- 2.1 Antenna Design 8 Performance------- 2.1.1 Performance bnslderations--------- 2.1.2 Prototype Antenna DescrlptIon &---- Performance 3.0 Technical Approach---------------- 3.1 General Description---------------- 3.2 Theoretical Baseline------------- 3.2.1 Antenna Design Algorithm----------- 3.2.2 Litz vs Sol id Wire Comparisons----- 3.2.3 Intrinsic Safety Parameters-------- 3.2.4 Antenna Winding Conficuratlon------ Considerations 3.3 Selection of Design Parameters----- 4.0 Veh icu l ar Antennz Performance------ 5.0 Antenna Coupl ing to PJine Wlring---- 5.1 General Considerations------------- 5.2 Description of the Technique------- 5.3 Entry Crossectional Geometry------- 5.4 Presentation of Results------------ List of l l l ustrat ions Fi gure I Vehicular Antenna Prototype------------------------ 2 Portable Antenna Test Configuration---------------- 3 Resistance of Litz Wire Compared to Sol id \dire----- for Fi xed Overa l l Diameter and Strand Diameter vs Wire-Wire Spacing 4 Res i stance of Litz W 1 re Compared to Sol i d W i re----- for Fixed Strand Diameter and Wire-Wire Spacing vs Overal l Wire Diameter 5 Resistance of Litz Wire Compared to Sol id Wi re----- for Fi xed Overa l I Dl amterand W i re-W i re Spacl ng vs Strand Size 6 Possible AC Intrinsic Safety Criteria Using ------- Bandwidth of Antenna as a Measure Showing Vinimum Bandwidth as a Function of Input Power 7 Winding and Wiring Configuration for the Vehicular- Antenna Prototype Showi ng the Connection Arrangement of Turns to Mi n i mi ze Dl stributed Ca~acitance 8 NIA & Bandwidth Comparisons for 6-1 nch by 3-Foot--- Vehicular Antenna 8 1000 KHz vs Solid Wire a~d Litz Wire 9 NIA for Vehicular Antennas 6-Inches Htgh vs-------- Length and Number of Turns for 1790/44 Litz Wi re for 3 KHz Minimum Bandwidth @ 1000 KHz and Below - Optimum for If-Inch Electrostatic Shield 10 NIA Comparison for 6-1 nch by 3-Foot Vehicular------ Antenna Designs for 1700/44 Litz Wire for 12 KHz Minimum Bandwidth @ 1000 KHz and Below - Optimized for I+-Inch Electrostatlc Shield I I NIA vs Frequency for 6-Inch by 3-Foot Vehicular---- Antenna of 12 Turns in a I$-Inch Electrostatic Shield with 1700/44 Litz Wire 12 Unpadded Bandwidth vs Frequency for 6-Inch by------ 3-Foot Veh icul at Antenna of 12 Turns in It- I nch Electrostatic Shield - With and Without Litz Wire 13 Cornpari son of Measured and Computed Reactance for-- Vehicular Antenna Prototypes Illustrating the Effect of Windi ng Reversal 14 Balanced Tuning Circuits used In Vehicular--------- Antenna Prototype Match i ng to a Matched l mpedance Level of 200 Ohms 15 4:l Balanced ( 200 Ohm 1 to Unbanlanced ( 50 Ohm)-- Transformer 16 Tuning Curve for Prototype Vehicular Antenna Tuned- to Nominally 520 KHz Showing Frequency Shift Due toMeasurement over Dielectric and Steel Mounting surfaces 17 Tuni ng Curve for Prototype Vehicular Antenna Tuned- to Nominally 920 KHz Showin9 Frequency Shift Due to Measurement over Dielectric and Steel Mounting Surfaces List of lilustrations (cont,) Fi gure Page 18 Magnetic Field Mapping of a Conducting Line--------------- Source in Free Space 19 Graphical Field Mapping from Conductor Near--------------- Roof & Rib Corner Without a Vehicle Present 20 Graphical Field Mapping from Conductor Near--------------- Roof & Rib Corner With a Veh icI e Present 21 Graph i ca I Fie1d Mapp i ng from Conductor Near--------------- Fioor & Rib Corner With a Vehicle Present 21 Graphical Field Pkpping from Conductor on----------------- Floor Close to Vehicle 1.0 INTRODUCTION This report covers antenna deslgn, analysis, and development work performed for the U.S, Bureau of Mines under Purchase Order PO382223 by Terry S. Cory, P.E. The anticipated usage of the antennas and accompanying analysis is for medium frequency wireless communications in coal mines. The work has l nc l uded a comp l ete veh icul ar antenna des i gn experience through the prototype development stage, design analysis and comparative tests to be useful in eventual development of optimized portable PAIant~nna systems, and analysis of the coupling between vehicular antennas and existing mine wiring. The vehicular antenna work was an extension of earl ier configuration stud! es and pre l i mi nary des i gn ana I ys i s performd under USBM Contract H0377013 ( Collins/Rockwell on Wireless Communications for Trackless Haulage Vehicles, Medium frequency technology In coal nines Is rapidly aporoaching th: point where systems can be configured for use in particular minss, A key portion of the R&D invloves establishing a viable set of vehicular antcnna parameters so that coupling loss into or out of existing mine siring can be estimated for the case where the vehicle is in the same entry as the wiring, Such a set of parameters has been established and coupling estimates have been made as part of this work. Coup l i ng for remotel y located transmitters ( and receivers 1 has besn estimated as part of propagation rmasuremnt Contracts I40366028 and H0377053. The only part of the vehicular antenna problem for which there is no data is that where the antenna is simu1 taneous I y matched to two freauenciss, The eventua l mi ne wi rel ess radio systems are expected to be two frequency systems to permit the use of repeaters, Portable radio systems including antennas at medium frequency have heen desianed and have undergone lirclted testing In coal mines. An optirlzed portable system probably has not yet been designed; particularly whm operation is expected in close proxi mity to ex1 st1ng mine wf ring conductors, The integral design of the radio transrnltter PA and the antenna matchins/ phasl ng network as a system Is necessary for opt1mum design. Tests of the portable equipment available have, however, provided a starting point for the general inclusion of portables into a complete system design, The analysis performed as part of this work will help to bound the physical characteristics of portable antennas and data is given on ths rzw ( untuned character of flat-strip winding conflguratlons. 2.0 SUMMARY This program has provided antenna design analysis which has led to the design, building, and testing of a prototype mine wireless vehicular antenna prototype. The analysis also enabled the building of a portabls antenna wiring configuration which was tssted against the RACAL antenna and agai nst another portab l e antenna w i ring a l ternati ve provi ded by the Bureau. The antenna design activity also provided the basis for the prediction of antenna coupling into existing mine wiring which was performed using graphical field mapping.
Load more

Recommended publications
  • Crystal Radio Set Systems: Design, Measurement, and Improvement Volume II a Web Book by Ben Tongue
    Crystal Radio Set Systems: Design, Measurement, and Improvement Volume II A web book by Ben Tongue First published: 10 Jul 1999; Revised: 01/06/10 i NOTES: ii 185 PREFACE Note: An easy way to use a DVM ohmmeter to check if a ferrite is made of MnZn of NiZn material is to place the leads of the ohmmeter on a bare part of the test ferrite and read the The main purpose of these Articles is to show how resistance. The resistance of NiZn will be so high that the Engineering Principles may be applied to the design of crystal ohmmeter will show an open circuit. If the ferrite is of the radios. Measurement techniques and actual measurements are MnZn type, the ohmmeter will show a reading. The reading described. They relate to selectivity, sensitivity, inductor (coil) was about 100k ohms on the ferrite rods used here. and capacitor Q (quality factor), impedance matching, the diode SPICE parameters saturation current and ideality factor, #29 Published: 10/07/2006; Revised: 01/07/08 audio transformer characteristics, earphone and antenna to ground system parameters. The design of some crystal radios that embody these principles are shown, along with performance measurements. Some original technical concepts such as the linear-to-square-law crossover point of a diode detector, contra-wound inductors and the 'benny' are presented. Please note: If any terms or concepts used here are unclear or obscure, please check out Article # 00 for possible explanations. If there still is a problem, e-mail me and I'll try to assist (Use the link below to the Front Page for my Email address).
    [Show full text]
  • Optimization of Low Frequency Litz-Wire RF Coils
    Optimization of Low Frequency Litz-wire RF Coils J.A. Croon, II. M. fkJrSbooll1, A. F. Mehlkopf Fi7culty of Applied Physics, DeFt IJniversity of Technology, P.O. Box 5046, 2600 GA Delft, 77zeNetherlands INTRODUCTION Equations ]4] and [5] show that the skin losses are proportional to the In MRI the patient or sample losses increase with the square of the resistivity while the proximity losses are proportional to the conductiv- resonance frequency. This makes coil losses significant at low field ity. The rota1 losses are minimized if the derivative of P,,,, to p is zero. strengths. dP,oss %kin Rprox_ It is well known (1) that for frequencies of several hundreds of l&z - =--- - 0 or Rski,, = R WI stranded or litz wires can have lower losses than conventional wires, do P P PYqX Here we will investigate and present the optimization of copper solenoid coils for room temperature and for liquid nitrogen temperature. Thus the maximum coil quality is achieved if the skin losses equal the For litz wire coils we distinguish three types of losses: proximity losses. 1. losses within each considered strand, 2. proximity losses in the surrounding strands and RESULTS 3. eddy losses the environment of the coil (mainly determined by the The results of table 1 concern solenoids with a single litz wire and with sample losses). The losses within the considered strands are called skin six parallel litz wires. The six parallel wires are placed above each losses. We will show that the maximum coil quality is achieved if the other and twisted such that the losses in each parallel wire are the skin losses are equal to the proximity losses.
    [Show full text]
  • Figure 1 Old Huge Magnetic Receiving Loop Antennas
    ANTENTOP- 02- 2004, # 006 Old Receiving Magnetic Loop Antennas Igor Grigorov, RK3ZK [email protected] Receiving magnetic loop antennas were widely used in the professional radio communication from the beginning of the 20 Century. Since 1906 magnetic loop antennas were used for direction finding purposes needed for navigation of ships and planes. Later, from 20s, magnetic loop antennas were used for broadcasting reception. In the USSR in 20- 40 years of the 20 Century when broadcasting was gone on LW and MW, huge loop antennas were used on Reception Broadcasting Centers (see pages 93- 94 about USSRs RBC). Magnetic loop antennas worldwide were used for reception service radio stations working in VLW, LW and MW. The article writes up several designs of such old receiving loop antennas. LW- MW Huge Receiving Loop Fig. 2 shows a typical connection of the above mention Antennas for Broadcasting and huge magnetic receiving loop antennas designed for Direction Finding working on one fixing frequency to the receiver. To a resonance the loop A1 is tuned by lengthening coil L1 In old radio textbooks you can find description of old (sometimes two lengthening coils switched symmetrically magnetic receiving loop antennas. As a rule, old to both side of the loop were used) and variable air- magnetic receiving loop antennas had a triangle or dielectric capacitor C1. T1 did connection with antenna square shape, a side of the triangle or square had feedline. L1, C1 and T1, as a rule, are placed directly length in 10-20 meters. The huge square was put near the antenna keeping minimum length for wires from on to a corner.
    [Show full text]
  • Wireless Energy Transfer by Resonant Inductive Coupling
    Wireless Energy Transfer by Resonant Inductive Coupling Master of Science Thesis Rikard Vinge Department of Signals and systems CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2015 Master’s thesis EX019/2015 Wireless Energy Transfer by Resonant Inductive Coupling Rikard Vinge Department of Signals and systems Division of Signal processing and biomedical engineering Signal processing research group Chalmers University of Technology Göteborg, Sweden 2015 Wireless Energy Transfer by Resonant Inductive Coupling Rikard Vinge © Rikard Vinge, 2015. Main supervisor: Thomas Rylander, Department of Signals and systems Additional supervisor: Johan Winges, Department of Signals and systems Examiner: Thomas Rylander, Department of Signals and systems Master’s Thesis EX019/2015 Department of Signals and systems Division of Signal processing and biomedical engineering Signal processing research group Chalmers University of Technology SE-412 96 Göteborg Telephone +46 (0)31 772 1000 Cover: Magnetic field lines between the primary and secondary coil in a wireless energy transfer system simulated in COMSOL. Typeset in LATEX Göteborg, Sweden 2015 iv Wireless Energy Transfer by Resonant Inductive Coupling Rikard Vinge Department of Signals and systems Chalmers University of Technology Abstract This thesis investigates wireless energy transfer systems based on resonant inductive coupling with applications such as charging electric vehicles. Wireless energy trans- fer can be used to power or charge stationary and moving objects and vehicles, and the interest in energy transfer over the air has grown considerably in recent years. We study wireless energy transfer systems consisting of two resonant circuits that are magnetically coupled via coils. Further, we explore the use of magnetic materials and shielding metal plates to improve the performance of the energy transfer.
    [Show full text]
  • Analytical Model for Effects of Twisting on Litz-Wire Losses
    Analytical Model for Effects of Twisting on Litz-Wire Losses Charles R. Sullivan Richard Y. Zhang Thayer School of Engineering at Dartmouth Dept. Elec. Eng. & Comp. Sci., M.I.T. 14 Engineering Drive, Hanover, NH 03755, USA Cambridge, MA, USA Email: [email protected] Email: [email protected] Abstract—Litz wire uses complex twisting to balance currents allows answering these questions for any litz-wire construc- between strands. Most models are not helpful for choosing the tion in any transformer or inductor winding application. The twisting configuration because they assume that the twisting ultimate goal is a practical goal, to verify existing design works perfectly. A complete model that shows the effect of twisting on loss is introduced. The model can predict loss for guidelines, such as those provided in [12], and to extend a precise configuration, but in practice, it is difficult to achieve them to provide guidance on all aspects of litz-wire design. sufficient manufacturing precision to use this approach. More In particular, many design methods provide guidance on the practically, the model can predict worst-case loss over the range number and diameter of strands to use. The method in [12] of expected production variation. The model is useful for making is particularly recommended because it provides a simple-to- design choices for the twisting configuration and the pitch of the twisting at each level of construction. use method that takes into account trade-offs between cost and loss in choosing the number and diameter of strands. I. INTRODUCTION Also provided in [12] is a simple and systematic method for Litz wire uses complex twisting configurations to balance choosing some of the construction details— the number of currents between strands.
    [Show full text]
  • Winding Resistance and Winding Power Loss of High-Frequency Power Inductors
    Wright State University CORE Scholar Browse all Theses and Dissertations Theses and Dissertations 2012 Winding Resistance and Winding Power Loss of High-Frequency Power Inductors Rafal P. Wojda Wright State University Follow this and additional works at: https://corescholar.libraries.wright.edu/etd_all Part of the Computer Engineering Commons, and the Computer Sciences Commons Repository Citation Wojda, Rafal P., "Winding Resistance and Winding Power Loss of High-Frequency Power Inductors" (2012). Browse all Theses and Dissertations. 1095. https://corescholar.libraries.wright.edu/etd_all/1095 This Dissertation is brought to you for free and open access by the Theses and Dissertations at CORE Scholar. It has been accepted for inclusion in Browse all Theses and Dissertations by an authorized administrator of CORE Scholar. For more information, please contact [email protected]. WINDING RESISTANCE AND WINDING POWER LOSS OF HIGH-FREQUENCY POWER INDUCTORS A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy By Rafal Piotr Wojda B. Tech., Warsaw University of Technology, Warsaw, Poland, 2007 M. S., Warsaw University of Technology, Warsaw, Poland, 2009 2012 Wright State University WRIGHT STATE UNIVERSITY GRADUATE SCHOOL August 20, 2012 I HEREBY RECOMMEND THAT THE DISSERTATION PREPARED UNDER MY SUPERVISION BY Rafal Piotr Wojda ENTITLED Winding Resistance and Winding Power Loss of High-Frequency Power Inductors BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy. Marian K. Kazimierczuk, Ph.D. Dissertation Director Ramana V. Grandhi, Ph.D. Director, Ph.D. in Engineering Program Andrew Hsu, Ph.D. Dean, Graduate School Committee on Final Examination Marian K.
    [Show full text]
  • A Coil for Wireless Power Transmission by Using Sewing Technique with Litz Wire
    APSAEM18 Journal of the Japan Society of Applied Electromagnetics and Mechanics Vol.27, No.1 (2019) Regular Paper A Coil for Wireless Power Transmission by Using Sewing Technique with Litz Wire Ryohei SUWAHARA (Stu. Mem.), Ryota KATO (Stu. Mem.), Koki MURATA (Stu. Mem.), Tomoki WATANABE (Stu. Mem.), Yuichi SHIMATANI and Shogo KIRYU (Mem.) A Coil for wireless power transmission was manufactured by using of sewing techniques. The sewing methods and electric characteristics were described. The coils were sewn with a cross stitch. The inductance and loss resistance of the sewn coils was measured. It is assumed that the power receiving side coil is attached to biomedical implantable devices. The coupling coefficient between the power receiving side coil and the sewn coil was measured. The maximum coupling coefficient was 0.75. The maximum efficiency of 75.0% was obtained when the coupling coefficient was maximum. Inverter and rectifier were attached the circuit and the load voltage was measured. The maximum load voltage was 4.77 V. Keywords: wireless power transmission, sewn coil, magnetic resonance (Received: 22 July 2018, Revised: 19 December 2018) 1. Introduction In recent years, smart textiles have been drawing attention as a new wearable device following smart watches and smart glasses [1]. Some devices in the smart textiles can be fabricated on clothes. They, therefore, can be set as close to the human body as possible. Due to its Fig. 1 Expected transmission to the implantable characteristic, it is considered to be applied to devices for device measuring a human vital sensor such as blood pressure, heart rate, and calorie consumption [2].
    [Show full text]
  • Development of a High Quality Resonant Coil for Low Frequency Wireless Power Transfer
    DEVELOPMENT OF A HIGH QUALITY RESONANT COIL FOR LOW FREQUENCY WIRELESS POWER TRANSFER Kevin Van Acker Supervisor: Prof. dr. ir. Guillaume Crevecoeur Counsellor: Ir. Matthias Vandeputte Master's dissertation submitted in order to obtain the academic degree of Master of Science in de industriële wetenschappen: elektromechanica Department of Electrical Energy, Metals, Mechanical Constructions & Systems Chair: Prof. dr. ir. Luc Dupré Faculty of Engineering and Architecture Academic year 2017-2018 DEVELOPMENT OF A HIGH QUALITY RESONANT COIL FOR LOW FREQUENCY WIRELESS POWER TRANSFER Kevin Van Acker Supervisor: Prof. dr. ir. Guillaume Crevecoeur Counsellor: Ir. Matthias Vandeputte Master's dissertation submitted in order to obtain the academic degree of Master of Science in de industriële wetenschappen: elektromechanica Department of Electrical Energy, Metals, Mechanical Constructions & Systems Chair: Prof. dr. ir. Luc Dupré Faculty of Engineering and Architecture Academic year 2017-2018 Preface Before you lies the dissertation “Development of a High Quality Resonant Coil for Low Frequency Wireless Power Transfer”, the basis of this dissertation is to find a way to easily develop an optimal resonant coil for low frequency wireless power transfer by only having some boundary conditions for the dimensions of this coil. The dissertation has been written to obtain the academic degree of Master of Science in de industriële wetenschappen: elektromechanica at the faculty of Engineering and Architecture at Ghent university. I was engaged in researching and writing this dissertation from January to June 2018. The title and goal of this dissertation was formulated by my supervisor, Prof. dr. ir. Guillaume Crevecoeur, and my counsellor, ir. Matthias Vandeputte. Throughout the researching period the goal of this dissertation was refined by my counsellor and myself.
    [Show full text]
  • Litz-Wire.Pdf
    Product Catalogue About Us Parashar Vidyut Udyog, an enterprise registered under government of India’s ministry of micro, small and medium enterprises is located in NOIDA, the modern industrial city in Delhi’s National Capital Region, is today India’s most reputed manufacturer of Litz Wires for the HF Transformer and Induction heating components and Electrical & Electronics industry. We are known for our HF Litz Wire expertise, our development and manufacturing capabilities thereof. Beside that we are known for Tinsil copper/silver wire for speaker industry and flexible wires/PVC insulated cables for electrical and electronics industry. Our focus on quality, our R & D capabilities, market responsiveness and the ability to scale up manufacturing capacities for meeting clients’ needs distinguishes us, making us a preferred supplier for HF Litz Wire in electrical & Electronic industry. Parashar Vidyut Udyog is a highly proactive, professional organization that seeks to understand the market, identify opportunities and develop capabilities to create competitive advantage for its customers. A proactive, forward thinking organization which has eliminated all odds in creating a global level manufacturing setup, Parashar Vidyut Udyog is today moving forward with a well-defined, time bound executable plan to establish a global footprint for advanced HF Litz Wire. Our dedicated and efficient personnel that include engineers, developers and operators among several others work in complete unison fulfilling every demand of the customer in the most credible manner. Our adequate quality testing facility includes various equipment & tools to test the products on standard parameters. Parashar Vidyut Udyog business philosophy can be summed up in just two words – Customer Focused.
    [Show full text]
  • Qualitative FEM Study of Proximity Loss Reduction by Various Winding Configurations – Part I
    EVENTSLOSSES Qualitative FEM study of proximity loss reduction by various winding configurations – Part I ABSTRACT How to make a 1 MHz transformer without Skin depth and proximity effects in expensive Litz wire transformer windings are important phenomena influencing the design even 1. Introduction power transformers (e.g. as opposed to at power frequencies (50-60 Hz). How- signal transformers). Electrical resistance ever, they become critically important Efficiency of energy transformation is of a given winding has an immediate im- at elevated frequencies, especially for affected by multiple loss components oc- pact on the total efficiency at full load due high-frequency transformers, operating curring in transformers. These compo- to Joule‘s heating. Conductors with grea- in switched-mode power supplies for nents depend on the given application, ter effective cross-sectional area must be example, at any power level. This article topology of conversion (conventional or used to reduce the losses and improve the presents a numerical study of optimum switched mode), frequency of operation, efficiency. winding configurations which can dras- energy required for forced cooling, etc. tically reduce the proximity effects. It However, transformer designers also have is possible to make transformers ope- Loss in the windings (copper loss) is a to take into account other, more complex rating even at 1 MHz without the use of significant part of the total loss in most phenomena, such as the skin effect. Elec- very expensive Litz wire. KEYWORDS With an appropriate core-winding configuration it copper loss, proximity effect, proximity loss, skin effect, eddy currents, wind- is possible to use solid wire instead of expensive ings multi-strand Litz wire, even at 1 MHz 70 TRANSFORMERS MAGAZINE | Volume 3, Issue 1 Stan ZUREK Efficiency of energy transformation is affected by multiple loss components occurring in transform- ers, which depend on the given application, top- ology of conversion, frequency of operation, etc.
    [Show full text]
  • Simplified Design Method for Litz Wire
    Simplified Design Method for Litz Wire Charles R. Sullivan Richard Y. Zhang Thayer School of Engineering at Dartmouth Dept. Elec. Eng. & Comp. Sci., M.I.T. Hanover, NH, USA Cambridge, MA, USA Email: [email protected] Email: [email protected] Abstract—A simplified approach to choosing number and di- A. Choosing number and diameter of strands ameter of strands in litz wire is presented. Compared to previous analyses, the method is easier to use. The parameters needed are The four steps in the process to choose the number and only the skin depth at the frequency of operation, the number diameter of strands correspond to the first four boxes in Fig. 1. of turns, the breadth of the core window, and a constant from a 1) Compute skin depth: The skin depth is given as table provided in the paper. In addition, guidance is provided on litz wire construction—how many strands or sub-bundles ρ to combine at each twisting operation. The maximum number δ = (1) of strands to combine in the first twisting operation is given πfμ0 by a simple formula requiring only the skin depth and strand diameter. Different constructions are compared experimentally. −8 where ρ is the resistivity of the conductor (1.72 × 10 Ω·m for copper at room temperature, or 2×10−8Ω·mat60◦C), f is NTRODUCTION I. I the frequency of a sinusoidal current in the winding, and μ0 is 4 × 10−7π Litz wire has become an essential tool for power electronics, the permeability of free space ( H/m).
    [Show full text]
  • Litz Wire – When Is It an Advantage? 2 © All Rights Reserved by Wurth Electronics, Also in the Event of Industrial Property Rights
    Litz wire -When is it an Advantage? George Slama Senior Application and Content Engineer APEC 2018, San Antonio, TX In 1943… 05.01.2018 | GSl | Public | APEC 2018 – Litz Wire – When is it an Advantage? 2 © All rights reserved by Wurth Electronics, also in the event of industrial property rights. All rights of disposal such as copying and redistribution rights with us. www.we-online.com 75 years later… Pack Litz Wire. (2018, Jan 5). HF litz wire as a permanent impulse driver for automotive solutions [Online]. Available: URL https://www.packlitzwire.com/applications/automotive-industry/ C. Sullivan, “High-frequency magnetics design: overview and winding loss”, in Conf. APEC, Long Beach, CA, 2016 05.01.2018 | GSl | Public | APEC 2018 – Litz Wire – When is it an Advantage? 3 © All rights reserved by Wurth Electronics, also in the event of industrial property rights. All rights of disposal such as copying and redistribution rights with us. www.we-online.com The trend ° Switchers are getting faster ° Everybody wants their power supply smaller ° SiC and GaN hold the promise to go faster still Image from magaripoa.com 05.01.2018 | GSl | Public | APEC 2018 – Litz Wire – When is it an Advantage? 4 © All rights reserved by Wurth Electronics, also in the event of industrial property rights. All rights of disposal such as copying and redistribution rights with us. www.we-online.com The problem ° Size limit depends on losses – coil and core ° Winding losses increase with frequency ° Winding losses increase with layers ° High frequency eddy currents − Skin effect − Proximity effect ° Inductors are worse than transformers 05.01.2018 | GSl | Public | APEC 2018 – Litz Wire – When is it an Advantage? 5 © All rights reserved by Wurth Electronics, also in the event of industrial property rights.
    [Show full text]