DOCSLIB.ORG

Magnetic Flux Controllers in Induction Heating and Melting

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Magnetic Flux Controllers in Induction Heating and Melting ASM Handbook, Volume 4C, Induction Heating and Heat Treatment Copyright # 2014 ASM InternationalW V. Rudnev and G.E. Totten, editors All rights reserved www.asminternational.org Magnetic Flux Controllers in Induction Heating and Melting Robert Goldstein, Fluxtrol, Inc. MAGNETIC FLUX CONTROLLERS are workpiece. For both cases, there are three closed is applied, it strongly reduces the reluctance of materials other than the copper coil that are used loops: flow of current in the coil, flow of mag- the back path for the magnetic flux (Ref 3). All in induction systems to alter the flow of the mag- netic flux, and flow of current in the workpiece. induction heating systems can be described in netic field. Magnetic flux controllers used in In most cases, the difference between induc- this way. power supplying components are not considered tion heating applications and transformers is that The benefits of a magnetic flux concentrator in this article. the magnetic circuit is open. The magnetic field on the electrical parameters for a given applica- Magnetic flux controllers have been in exis- path includes not only the area with the control- tion depends on the ratio of the reluctance of tence since the development of the induction ler, but also the workpiece surface layer and the the back path for magnetic flux to the overall technique. Michael Faraday used two coils of air between the surface and controller, which reluctance in the system. It is also possible to wire wrapped around an iron core in his experi- cannot be changed. Therefore, the reluctance of break down basic system components into sub- ments that led to Faraday’s law of electromagnetic the magnetic path only partially depends on the components to determine the most economical induction, which states that the electromotive magnetic permeability of the controller (Ref 3). use of magnetic flux controllers in a given appli- force (emf) induced in a circuit is directly propor- Reluctance is a term used in magnetics analo- cation. Other benefits of magnetic flux control- tional to the time rate of change of the magnetic gous to resistance in electricity. lers, such as shielding areas from heating, can flux through the circuit. After the development Figure 1 shows a diagram of the magnetic also be understood by describing induction sys- of the induction principle, magnetic flux control- circuit for a single-turn induction coil with a tems in this manner. lers, in the form of stacks of laminated steel, found magnetic flux concentrator heating a cylindrical widespread use in the development of transfor- workpiece from the outside. The magnetic flux mers for more efficient transmission of energy in the system is equal to the ampere turns of (Ref 1, 2). the coil divided by the reluctance of the magnetic Role of Magnetic Flux Controllers Magnetic cores gained widespread use in the circuit. The reluctance of the magnetic circuit in Induction Systems transformer industry because they increased consists of three basic components: the back path the amount of magnetic flux produced with for magnetic flux, the coupling gap, and the Magnetic flux controllers are powerful tools the same alternating current. The higher the workpiece. When a magnetic flux concentrator in induction heating technology. In general, magnetic flux, the higher the emf, which results two primary reasons to use magnetic flux con- in an increase in energy transfer efficiency from trollers in induction systems are to reduce and the primary winding to the secondary winding. increase magnetic fields in a given region. Similar to transformers, magnetic cores were Reducing magnetic fields is done by using used on early furnaces for induction melting either soft-magnetic materials or electrically (Ref 1, 2). The benefits of magnetic flux control- conductive materials in a closed loop perpen- lers vary depending on the application. For dicular to the flow of the magnetic flux between induction heating, magnetic flux controllers can the coil and the desired lower field area. Soft- provide favorable and unfavorable paths for mag- magnetic materials improve induction coil netic flux to flow, resulting in increased heating in parameters, while highly conductive materials desired areas and reduced the heating in undesir- have a negative effect. Soft-magnetic materials able areas, respectively. Magnetic flux controllers are primarily used to increase magnetic fields. are not used in every induction heating applica- The benefits of using magnetic flux control- tion, but their use has increased (Ref 3, 4). lers in an induction heating system include: Improvement of induction coil and process Magnetic Circuits in Induction efficiency Applications Improvement of coil power factor Reduction in coil current Induction heating applications are similar to Reduction in unintended heating of machine transformers with a short circuited secondary components Fig. 1 Magnetic circuit in a single turn coil with winding. The primary winding of the circuit magnetic flux concentrator heating cylindrical Reduction in undesired heating of areas of is the induction coil and the secondary is the part from the outside: F = total. Source: Ref 3 the workpiece 634 / Equipment Precise control of the magnetic field and efficiency of the system, and are not desirable. Other important properties of soft magnetic resulting heat pattern Therefore, nonmagnetic materials with high materials, such as good saturation flux density, Improvement in efficiency of high-frequency electrical conductivity are preferred for use as stable mechanical properties, low magnetic power supplying circuitry Faraday rings. Copper is the most common losses, chemical resistance, and resistance to Reduction of external magnetic fields in material used, but other materials, such as alu- elevated temperature depend on the application. close proximity to the coil minum, are used due to cost and/or weight Laminations are commonly made of coated considerations. thin sheets of silicon electrical steel with 3 or In most applications, more than one of these 4% silicon. The laminates are cut (by water benefits usually occurs (Ref 3–7). Recently, jet, laser, CNC, and electrical discharge machin- better understanding of the role magnetic flux Soft Magnetic Materials for ing) or stamped to the required shape for use in controllers in induction heating systems has been Magnetic Flux Control induction coils. obtained through comprehensive studies using For induction coils, multiple laminations are computer simulation and experiments, such as Soft magnetic materials most commonly used stacked between mechanical supports called those conducted at Fluxtrol, Inc. Results show in induction systems are laminations and soft keepers (Fig. 3). The large lamination cross that a magnetic flux controller properly used magnetic composites. Soft magnetic ferrites are section is oriented so it is in the plane of the is typically beneficial in an induction heating used occasionally in some high-frequency appli- flow of the magnetic field; intense eddy current system (Ref 3). Magnetic flux controllers play cations. The main requirements are that it should heating occurs if it is not in the plane. different roles in induction heating installations. have a relative magnetic permeability >1 and Lamination thickness varies based on fre- Depending on the application, they are referred should not have a good electrically conductive quency used to limit eddy-current losses from to as concentrators, controllers, diverters, cores, path for strong eddy current generation. the in-plane magnetic field. The lamination coat- impeders, yokes, shunts, and screens. The effects Placing the material in the path of magnetic ing prevents an electrical connection between of controllers in different types of induction heat- flux lowers the reluctance of that part of the individual laminations. In line-frequency appli- ing applications are described here. magnetic circuit. Therefore, it requires less cur- cations, individual laminations are typically rent to drive the magnetic flux through that between 0.020 to 0.040 in. (0.5 to 1 mm) thick. part of the circuit, and a higher percentage of Laminations can be as thin as 0.002 in. in appli- Materials for Magnetic flux flows in the magnetic material than would cations using higher frequencies. Flux Control flow in the same space containing only air. Laminations have very high magnetic perme- However, this positive effect has some limita- ability and saturation flux density. They also Two main categories of materials for mag- tions because the magnetic circuit is almost have high temperature resistance limited pri- netic flux control are electrically conductive always open. marily by the coating. The primary drawbacks materials and magnetic materials. Electrically For the same coil current, workpiece power of laminations are intense heating in 3-D mag- conductive materials typically are used in the increases with increasing concentrator per- netic fields and limited frequency range (up to form of shunts and screens to reduce external meability very fast initially, then approaches about 30 kHz). magnetic fields. the threshold value asymptotically. At the Soft Magnetic Composites consist of a Two main forms of magnetic materials are hard same time, losses in the induction coil often soft-magnetic component (typically iron and and soft. The difference is the amount of flux den- increase slowly with increasing concentrator iron-base alloy powder metal) and a dielectric sity that remains after they are no longer exposed permeability. component (usually an organic polymer binder). to a magnetic field. Hard magnetic materials Computer simulation was used to demon- The soft-magnetic component provides a favor- retain a significant amount of the magnetic field, strate the diminishing positive effect of very able path in which the magnetic field can flow. while soft materials retain almost no magnetic high permeabilities in induction applications. The dielectric component electrically insulates field when the source is turned off. Soft magnetic In a real induction heating application, the mag- magnetic particles from each other to limit eddy materials are used almost exclusively as con- netic permeability of a magnetic flux controller current losses.
Load more

Recommended publications
  • Optimal Design of High-Frequency Induction Heating Apparatus for Wafer Cleaning Equipment Using Superheated Steam
    energies Article Optimal Design of High-Frequency Induction Heating Apparatus for Wafer Cleaning Equipment Using Superheated Steam Sang Min Park 1 , Eunsu Jang 2, Joon Sung Park 1 , Jin-Hong Kim 1, Jun-Hyuk Choi 1 and Byoung Kuk Lee 2,* 1 Intelligent Mechatronics Research Center, Korea Electronics Technology Institute (KETI), Bucheon 14502, Korea; [email protected] (S.M.P.); [email protected] (J.S.P.); [email protected] (J.-H.K.); [email protected] (J.-H.C.) 2 Department of Electrical and Computer Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Korea; [email protected] * Correspondence: [email protected]; Tel.: +82-31-299-4581 Received: 19 October 2020; Accepted: 22 November 2020; Published: 25 November 2020 Abstract: In this study, wafer cleaning equipment was designed and fabricated using the induction heating (IH) method and a short-time superheated steam (SHS) generation process. To prevent problems arising from the presence of particulate matter in the fluid flow region, pure grade 2 titanium (Ti) R50400 was used in the wafer cleaning equipment for heating objects via induction. The Ti load was designed and manufactured with a specific shape, along with the resonant network, to efficiently generate high-temperature steam by increasing the residence time of the fluid in the heating object. The IH performance of various shapes of heating objects made of Ti was analyzed and the results were compared. In addition, the heat capacity required to generate SHS was mathematically calculated and analyzed. The SHS heating performance was verified by conducting experiments using the designed 2.2 kW wafer cleaning equipment.
    [Show full text]
  • Design of a Wireless Power Transfer System Using Inductive Coupling and MATLAB Programming Apoorva.P1 Deeksha.K.S2 Pavithra.N3 Student, Dept
    International Journal on Recent and Innovation Trends in Computing and Communication ISSN: 2321-8169 Volume: 3 Issue: 6 3817 - 3825 _______________________________________________________________________________________________ Design of a Wireless Power Transfer System using Inductive Coupling and MATLAB programming Apoorva.P1 Deeksha.K.S2 Pavithra.N3 Student, Dept. Of EEE, Student, Dept. Of EEE Student, Dept. Of EEE, Dr. T. Thimmaiah Institute of Dr. T. Thimmaiah Institute of Dr. T. Thimmaiah Institute of Technology Technology Technology K.G.F,India K.G.F, India K.G.F, India [email protected] [email protected] [email protected] Vijayalakshmi.M.N4 Somashekar.B5 David Livingston.D6 Student, Dept. Of EEE Asst Professor Dept. Of EEE, Asst Professor Dept. Of EEE, Dr. T. Thimmaiah Institute of Dr. T. Thimmaiah Institute of Dr. T. Thimmaiah Institute of Technology Technology Technology K.G.F, India K.G.F, India K.G.F, India [email protected] [email protected] [email protected] Abstract—Wireless power transfer (WPT) is the propagation of electrical energy from a power source to an electrical load without the use of interconnecting wires. It is becoming very popular in recent applications. Wireless transmission is useful in cases where interconnecting wires are difficult, hazardous, or non-existent. Wireless power transfer is becoming popular for induction heating, charging of consumer electronics (electric toothbrush, charger), biomedical implants, radio frequency identification (RFID), contact-less smart cards, and even for transmission of electrical energy from space to earth. In the design of the coils, the parameters of coils are obtained by using the basic calculations and measurements.
    [Show full text]
  • Induction Heating Principles PRESENTATION
    Induction Heating Principles PRESENTATION www.ceia-power.com This document is property of CEIA which reserves all rights. Total or partial copying, modification and translation is forbidden FC040K0068V1000UK Main Applications of Induction Heating ¾ Hard (Silver) Brazing ¾ Tin Soldering ¾ Heat Treatment (Hardening, Annealing, Tempering, …) ¾ Melting Applications (ferrous and non ferrous metal) ¾ Forging This document is property of CEIA which reserves all rights. Total or partial copying, modification and translation is forbidden FC040K0068V1000UK Examples of induction heating applications This document is property of CEIA which reserves all rights. Total or partial copying, modification and translation is forbidden FC040K0068V1000UK Advantages of Induction Reduced Heating Time Localized Heating Efficient Energy Consumption Heating Process Controllable and Repeatable Improved Product Quality Safety for User Improving of the working condition This document is property of CEIA which reserves all rights. Total or partial copying, modification and translation is forbidden FC040K0068V1000UK Basics of Induction INDUCTIVE HEATING is based on the supply of energy by means of electromagnetic induction. A coil, suitably dimensioned, placed close to the metal parts to be heated, conducting high or medium frequency alternated current, induces on the work piece currents (eddy currents) whose intensity can be controlled and modulated. This document is property of CEIA which reserves all rights. Total or partial copying, modification and translation is forbidden FC040K0068V1000UK Basics of induction The heating occurs without physical contact, it involves only the metal parts to be treated and it is characterized by a high efficiency transfer without loss of heat. The depth of penetration of the generated currents is directly correlated to the working frequency of the generator used; higher it is, much more the induced currents concentrate on the surface.
    [Show full text]
  • Handbook of Induction Heating Theoretical Background
    This article was downloaded by: 10.3.98.104 On: 28 Sep 2021 Access details: subscription number Publisher: CRC Press Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: 5 Howick Place, London SW1P 1WG, UK Handbook of Induction Heating Valery Rudnev, Don Loveless, Raymond L. Cook Theoretical Background Publication details https://www.routledgehandbooks.com/doi/10.1201/9781315117485-3 Valery Rudnev, Don Loveless, Raymond L. Cook Published online on: 11 Jul 2017 How to cite :- Valery Rudnev, Don Loveless, Raymond L. Cook. 11 Jul 2017, Theoretical Background from: Handbook of Induction Heating CRC Press Accessed on: 28 Sep 2021 https://www.routledgehandbooks.com/doi/10.1201/9781315117485-3 PLEASE SCROLL DOWN FOR DOCUMENT Full terms and conditions of use: https://www.routledgehandbooks.com/legal-notices/terms This Document PDF may be used for research, teaching and private study purposes. Any substantial or systematic reproductions, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The publisher shall not be liable for an loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. 3 Theoretical Background Induction heating (IH) is a multiphysical phenomenon comprising a complex interac- tion of electromagnetic, heat transfer, metallurgical phenomena, and circuit analysis that are tightly interrelated and highly nonlinear because the physical properties of materi- als depend on magnetic field intensity, temperature, and microstructure.
    [Show full text]
  • Induction Heating: Fundamentals
    30/10/17 LEP ELECTROMAGNETIC PROCESSING OF MATERIALS TECNOLGIE DEI PROCESSI ELETTROTERMICI Induction Heating: fundamentals Fabrizio Dughiero 2017-2018 Induction heating fundamentals May 28-30, 2014 1 30/10/17 Summary 1. Induction heating physical principles 2. Characteristics of the induction heating process • Physical parameters that affect induction heating 3. The skin effect: • What parameters modify the skin effect? • Change of skin effect during the heating 4. Examples: • Heating of a magnetic billet • Choosing the frequency appropriate to the workpiece • Coil thickness as a function of frequency 5. Proximity effect, ring effect, flux concentrators effect 1. Induction heating physical principles May 28-30, 2014 2 30/10/17 Induction heating physical principles Characteristics of induction heating • High temperature in the workpiece (in most cases). • High power density for a short heating time (in many applications). • High frequency (in many applications). • Thermal sources are inside the workpiece. Induction heating physical principles Induction heating: fundamental laws ? They state: A. Maxwell’s equations • how the electromagnetic (e.m.) field is generated rd 3 Maxwell’s equation or • how the e.m. field propagates and is Faraday-Neumann-Lenz’s law distributed in the space 4th Maxwell’s equation or • how the e.m. field interacts with the Ampere’s law charged particles. • they state what is the (approximate) B. Constitutive relations response of a specific material to an for materials external field or force. ? Ohm’s law Magnetic
    [Show full text]
  • Induction Heat Treatment
    a ...... ...... ....... ..... ...... .... ... ..... ...... .... ... ..... ...... ....... ..... ...... ....,...... ..... ...... .... ... ..... ...... ....... ..... ...... ....... ..... ...... .... ... ....I ...... ....... ..... ...... ....... ..... ...... ....... ..... ...... ....... ..... ...... .... ... ..... ...... .... ... ...... .... ... ...... .... ... ...... ....... ...... .... ... ...... ,....... ... ...... .... ... .....I .... .... ..... ... ... .....(... ....... ... ..... ... ........ ... ... ..... ...... i iG -i Publishedby the EPRl Center for MaterialsFabrication Vol. 2, No. 2, 1985Reprinted March, 1990 Using Induction Heat speed and selective heating capabil- Vol. 2, No. 1. Advantages specific to Treatment to Obtain ity, to produce quality parts cost induction heat treating are: Special Properties effectively. It will answer such ques- Speed - In heat treatment, the Cost Effectively tions as: What are the advantages higher heating rates play a central of induction heat treatment? What role in designing rapid, high- Heat treatment is often one of the heat treatments can I conduct with temperature heat treating most important stages of metal induction? What are some typical processes. Induction heat treating of processing because it determines parts and materials that are induc- steel may take as little as the final properties that enable tion heat treated? What properties 10 percent or less of the time cqmponents to perform under such can I obtain with induction heat required for furnace treatment. demanding service conditions
    [Show full text]
  • Induction Heating Work Coils
    Induction Heating Work Coils The work coil, also known as the inductor, is the component in the induction heating system that defines how effective and how efficiently the work piece is heated. Work coils range in complexity from a simple helical (or solenoid) wound coil consisting of a number of turns of copper tube wound around a mandrel to a coil precision machined from solid copper and brazed together. The work coil is used to transfer the energy from the induction heating power supply and workhead to the work piece by generating an alternating electromagnetic field. The electromagnetic field generates a current that flows in the work piece as a mirror image to the current flowing in the work coil. As the current flows through the resistivity of the work piece it generates the heat within the work piece from I²R losses. A second heating principle, hysteretic heating is also in effect when the work piece is a magnetic material such as carbon steel. Energy is generated within the work piece by the alternating magnetic field changing the magnetic polarity within the work piece. Hysteretic heating occurs in the work piece only up to the Curie temperature (750° C for steel) when the material’s magnetic permeability decreases to 1. Work Coil Basics A current flowing in a conductor creates a magnetic field. An alternating current creates an alternating field which produces an alternating current in a second conductor (the work piece). The current in the work piece is proportional to the field strength. The transformer effect where the amount of current induced in the work piece is proportional to the number of turns on the coil and is generated as a mirror image of the work coil.
    [Show full text]
  • Introduction
    Elements of Induction Heating Copyright © 1988 ASM International® Stanley Zinn, Lee Semiatin, p 1-8 All rights reserved. DOI: 10.1361/eoih1988p001 www.asminternational.org Chapter 1 Introduction Electromagnetic induction, or simply "induction," is a method of heating electrically conductive materials such as metals. It is commonly used in process heating prior to metalworking, and in heat treating, welding, and melting (Table 1.1). This technique also lends itself to various other applications involving packaging and curing. The number of industrial and consumer items which undergo induction heating during some stage of their production is very large and rapidly expanding. As its name implies, induction heating relies on electrical currents that are induced internally in the material to be heated-i.e., the workpiece. These Table 1,1. Induction heating applications and typical products Preheating prior to metalworking Heat treating Welding Melting Forging Surface Hardening, Seam Welding Air Melting of Steels Gears Tempering Oil-country Ingots Shafts Gears tubular Billets Hand tools Shafts products Castings Ordnance Valves Refrigeration Vacuum Induction Machine tools tubing Melting Extrusion Hand tools Line pipe Structural Ingots members Through Hardening, Billets Shafts Tempering Castings Structural "Clean" steels Heading members Nickel-base Bolts Spring steel superalloys Other fasteners Chain links Titanium alloys Rolling Slab Annealing Aluminum strip Sheet (can, ap- pliance, and Steel strip automotive industries) 2 Elements of Induction Heating: Design, Control, and Applications so-called eddy currents dissipate energy and bring about heating. The basic components of an induction heating system are an induction coil, an alter- nating-current (ac) power supply, and the workpiece itself.
    [Show full text]
  • Specifics of Induction Hardening of Powder Metallurgy (P/M) Components
    INDUCTION THOUGHTS INDUCTIONINDUCTION THOUGHTSTHOUGHTS Dr. Valery Rudnev, known as “Professor Induction”, discusses in the heat processing diffe- rent aspects of induction heating, novel theoretical and practical knowledge related to dif- ferent heat treating technologies accumulated in the North America and around the globe. Specifics of induction hardening of powder metallurgy (P/M) components uring the last decade, the use of advanced powder metallurgy type of heat treatment. However, differences in electromagnetic D(P/M) materials in several industries has been expanded at properties are specific for processing those materials applying an impressive pace further penetrating markets of demanding electromagnetic induction. Table 1 summarizes the effect of applications; however, the biggest market for ferrous P/M com- density reduction and porosity increase on IH. ponents remains to be the transportation industry, particularly The relative magnetic permeability μr of P/M materials is consid- the automotive and agricultural sectors. An ability to manufacture erably lower than the μr of the corresponding wrought steels, while net-shape complex geometries offering competitive performance their electrical resistivities ρ are greater to some extent. Both factors at an economical cost is an attractive feature of P/M parts (e. g. gears, lead to noticeably larger current penetration depth (δ) during the timing sprockets, cams, splined hubs, shafts, shock absorbers etc.) heating cycle, affecting not only heat generation and temperature [1]. Density and porosity in the sintered compact are major factors profiles but also the magnitude and distribution of transient and affecting strength and hardenability of ferrous P/M materials; both residual stresses as well as coil electrical parameters.
    [Show full text]
  • Induction Melt Thermoforming of Advanced Multi-Axial Thermoplastic Composite Laminates
    Journal of Manufacturing Processes 60 (2020) 673–683 Contents lists available at ScienceDirect Journal of Manufacturing Processes journal homepage: www.elsevier.com/locate/manpro Induction melt thermoforming of advanced multi-axial thermoplastic composite laminates P. Harrison a, I. Campbell a,*, E. Guliyev a, B. McLelland a, R. Gomes b, N. Curado-Correia b, E. McGookin a, D.M. Mulvihill a a James Watt School of Engineering, University of Glasgow, University Avenue, G12 8QQ, United Kingdom b INEGI, Composite Materials and Structures Research, Institute of Mechanical Engineering and Industrial Management, Porto 4200-465, Portugal ARTICLE INFO ABSTRACT Keywords: The viability of using induction heating to facilitate the wrinkle-free forming of multi-axial pre-consolidated Forming advanced thermoplastic composites over complex geometries is explored. The research focuses on the use of tin Thermoplastic resin as a medium to both heat and lubricate the forming laminate. Initial tests demonstrate the viability of the Carbon fibres fundamental ideas of the process; induction heating is used to melt the tin sheet, which is then shown to melt the Defects matrix phase of carbon-nylon composite laminates when stacked in a hybrid composite/tin layup. A novel low- cost reconfigurablemulti-step forming tool is used to demonstrate how most of the tin can be squeezed out of the layup prior to consolidation. The multi-step tool can be augmented with segmented tooling to rapidly manu­ facture composite parts of high geometric complexity. In this investigation, a ’ripple’ geometry containing three ’cavities’ is used to demonstrate the technique. Tests demonstrated that at least three sheets of inter-laminar tin can be simultaneously melted using the induction heating system.
    [Show full text]
  • Rigorous Electromagnetic Analysis of Domestic Induction Heating Appliances
    PIERS ONLINE, VOL. 5, NO. 5, 2009 491 Rigorous Electromagnetic Analysis of Domestic Induction Heating Appliances G. Cerri, S. A. Kovyryalov, V. Mariani Primiani, and P. Russo Universit`aPolitecnica Delle Marche | DIBET, Via Brecce Bianche, Ancona 60100, Italy Abstract| In this paper the developed analytical electromagnetic model of induction heating system is presented. The model was built up assuming equivalent electric and magnetic currents flowing in each planar element of the typical structure used for an induction heating system: the load disk represents the pan steel bottom, the copper inductor, and ferrite flux conveyor. A system of integral equations system was then obtained enforcing the boundary conditions on each element of the structure for the electric and magnetic ¯elds, produced by the equivalent currents. The numerical solution of the system is a matrix equation with a known voltage vector in the left-hand side, and product of impedance coe±cients matrix and unknown electric and magnetic currents vector in the right-hand side. Since the feeding voltage is known, and impedance coe±cients are calculated using of geometry and material parameters, currents vector can be also calculated. Thus, the whole model is solved and it gives a detailed picture of currents distribution in the system, which in its turn allows to analyze heating process in the load. Each step of developing of the model was veri¯ed by appropriate experimental measurements. Achieved results give a possibility to analyze and develop improvements to increase e±ciency, safety and to reduce the cost. 1. INTRODUCTION Domestic induction cookers become more and more popular because of their high e±ciency, safety and ease in use.
    [Show full text]
  • Losalamos NATIONAL LABORATORY
    LA-UR- 94-2627 T/h% (’)\● ZONE REFINING OF PLUTONIUM METAL Author(s); Michael S. Blau Submitted to: University of Idaho for the Partial Fulfillment of the Requirements for the Degree of Master of Science with a Major in Metallurgical Engineering in the College of Mines I and Earth Resources. ~- -— .—— .. .. --— LosAlamos NATIONAL LABORATORY LOSAlarnoaNationalLaboratory,an affirmativeadkxVequaloppornmifyarnpk%ar,ia operatedby the Uniwrsify of Caliiomia for tha U.S. Depanmenf of Energy undercommuW-740S-ENG-3S.Sy accuptsncaoffhiaartida. tha pubkher racqnizes thal the U.S. Oovammemrafains ● norKIxduo&o,royalfy-frea Iicenw to J .——_ L/ publishof faproducathe publishedformd thiscontribution,or to allowothersto do 00, for U.S. (iovemmanf w-. The LOOk ~~ ~ -~ti-ti~hk-MWPdwM Utitiwdti U.S. -roof E~y. FOm Noaa3R5 ST26201G91 ZONE REFINING OF PLUTONIUM METAL A THESIS Presented in Partial Fulfillment of the Requirements for the Degree of Master of Science with a Major in MetaUurgical Engineering in the College of Mines and Earth Resources University of Idaho by Michael S. Blau August 1994 Major Professors: Gene E. Bobeck and J. David Olivas AUTHORIZATION TO SUBMIT THESIS This thesis of Michael Steven Blau, submitted for the degree of Master of Science with a major in Metallurgical Engineering and titled “Zone Refining of Plutonium Metal,” has been reviewed in final form and approved, as indicated by the signatures and dates given below. Permission is now granted to submit final copies to the college of Graduate Studies for approval. First Major Professor Date Gene E. Bobeck Second Major Professor Date J. David Olivas Committee Members Date Sarit Bhaduri Date Dennis R.
    [Show full text]