WO2006003111A1 - Dispositif a circuit magnetique - Google Patents

Dispositif a circuit magnetique Download PDF

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Publication number
WO2006003111A1
WO2006003111A1 PCT/EP2005/052944 EP2005052944W WO2006003111A1 WO 2006003111 A1 WO2006003111 A1 WO 2006003111A1 EP 2005052944 W EP2005052944 W EP 2005052944W WO 2006003111 A1 WO2006003111 A1 WO 2006003111A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnetic circuit
circuit device
permanent magnet
power supply
permanent magnets
Prior art date
Application number
PCT/EP2005/052944
Other languages
English (en)
Inventor
Christian Sasse
Original Assignee
Areva T & D Uk Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Areva T & D Uk Ltd filed Critical Areva T & D Uk Ltd
Publication of WO2006003111A1 publication Critical patent/WO2006003111A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/10—Composite arrangements of magnetic circuits
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F13/00—Apparatus or processes for magnetising or demagnetising
    • H01F13/003—Methods and devices for magnetising permanent magnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F29/00—Variable transformers or inductances not covered by group H01F21/00
    • H01F29/14—Variable transformers or inductances not covered by group H01F21/00 with variable magnetic bias
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F13/00—Apparatus or processes for magnetising or demagnetising
    • H01F13/006—Methods and devices for demagnetising of magnetic bodies, e.g. workpieces, sheet material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/10—Composite arrangements of magnetic circuits
    • H01F2003/103—Magnetic circuits with permanent magnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F2006/001—Constructive details of inductive current limiters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/02—Adaptations of transformers or inductances for specific applications or functions for non-linear operation
    • H01F38/023—Adaptations of transformers or inductances for specific applications or functions for non-linear operation of inductances

Definitions

  • the present invention relates to the use of permanent magnets in magnetic circuits, such as may be particularly useful in. fault current limiters for alternating currents, but also in other electric power related circuits that include magnetic circuits, for example, transformers, generators, motors and actuators.
  • FIG. 1 illustrate diagrammatica ⁇ ly why a permanent magnet makes an effective fault current limiter.
  • a magnetic circuit 1 in a fault current limiter for AC comprises a "C"-shaped magnetically soft iron core 10 and a demagnetised permanent magnet 12, around which a coil 14 is wound. Magnetic flux can flow around the magnetic circuit, e.g., as indicated by the arrows.
  • the permanent magnet 12 is in the demagnetised state.
  • the permanent magnet will follow a characteristic hystereses loop as shown in Figure 2, which plots magnetic flux against current.
  • the area inside the curve represents the energy dissipated into the magnet.
  • the large area inside the loop illustrates why a permanent magnet is, from one point of view, ideal for limiting fault currents.
  • a problem with using permanent magnets in fault current lirniters is that permanent magnets by definition comprise magnetically hard material, and therefore require use of high power electric currents to magnetise them and equally high powers to demagnetise them.
  • a so-called soft magnet is made of a material with a slender hystereses curve, and thus has small values of remanence M R (the remaining magnetisation, in the material for zero external magnetic field) and coercivity (or coercive field strength Hc, the magnitude of the external field needed to bring the magnetisation of the material down to zero again).
  • a hard or permanent magnefs hystereses curve encloses a large area, and its material has large values of rema ⁇ ence and coercivity.
  • the permanent magnet 12 in the fault current Hmiter circuit of Figure 1 remains magnetised. This is not desirable because it offsets (biases) the flux in the magnetic circuit 1 under normal operation. In general, it is essential to demagnetise the magnet again. The problem is that this requires a very large current: impulse and thus a large power supply, similar in size to the fault current, to demagnetise the permanent magnet
  • a magnetic circuit device comprises: permanent magnet means for conducting magnetic flux around part of a magnetic circuit, electrical coil means wound around the permanent magnet means, and means for connecting the electrical coil means to an electrical power supply, thereby to selectively magnetise and demagnetise the permanent magnet means, wherein the permanent magnet means comprises a plurality of smaller permanent magnets connected into the magnetic circuit in parallel with each other, at least some of the plurality of permanent magnets each having an electrical coil wound around it, each coil being individually connectable to the electrical power supply.
  • each one of the plurality of permanent magnets has an electrical coil wound around it
  • the magnetic circuit devices of the present invention can, for example, be used in fault current limiting devices that in normal (non-fault) operation have low inductances and thus are not seen as a significant impedance in a circuit, but under fault current conditions show a higher inductance that limits the fault current.
  • the use of a plurality of relatively small permanent magnets hi parallel with each other as part of a magnetic circuit in a fault current limiter mitigates the problems associated with demagnetising permanent magnets.
  • the individual permanent magnets may have cross-sectional shapes selected from the group comprising round, rectangular, and polygonal cross-sections.
  • the power supply is selectively connectable to each one of the coils through switches controlled by a control unit that also controls the power supply; the power supply and the switches are preferably of the solid state type.
  • control unit is operative to control the value and sense of the current applied to the coils through the switches such that the polarity and strength of each permanent magnet is individually selectable.
  • Figure 1 is a diagrammatic side elevation of a known type of magnetic circuit forming part of e.g., a fault current limiter for alternating currents;
  • Figure 2 is a graph of a hystereses curve for magnetisation and demagnetisation, of a permanent magnet
  • Figure 3 is a view similar to Figure I 5 but modified in accordance with the invention.
  • Figure 4 j a diagram illustrating how a magnetic circuit constructed with the invention may be controlled; and Figures 5A and 5B illustrate how the principle of the invention may be employed to accomplish magnetic flux commutation or switching.
  • the invention divides the large cross-section permanent magnet part 12 1 of the magnetic circuit into a number (typically ten, but may be more or less) of smaller cross-section permanent magnets 20 connected in parallel with each other such that each of the smaller permanent magnets can be relatively easily magnetised or demagnetised by a coil 22.
  • the individual permanent magnets 20 may be of any convenient cross-sectional shape, such as round, rectangular, or polygonal.
  • each permanent magnet 20 (of which only three are shown for illustrative convenience) is in fact provided with its own coil 22, a demagnetising power supply 24 being connectable to each of the coils through switches 26 controlled by a control unit 28 which also controls the demagnetising power supply 24 by activating it upon receipt of a command signal 30.
  • each magnet-cored winding 22 may be compensated by a polarised electrolytic capacitor (not shown), of appropriate capacitance, the arrangement being such that the compensating capacitors are temporarily switched out of the limiter circuits while the demagnetisation process proceeds.
  • the demagnetising power supply 24 is a reversible polarity DC supply so that the individual permanent magnets 20 can be demagnetised at will.
  • the polarities of the small permanent magnets 20 can be individually selected, e.g., neutralised or reversed as desired.
  • the switches 26 are closed and opened in sequence so that individual permanent magnets 20 are demagnetised sequentially.
  • the invention achieves the advantage of considerably reducing the size of the power supply needed to perform the demagnetisation in comparison with the power supply required to demagnetise the much larger permanent magnet of Figure 1. Stated another way, if a large permanent magnet is sub-divided into N smaller permanent magnets, then the power supply will only require 1/N of the power of the original source.
  • the power supply 24 and switches 26 are of course preferably of the solid state type, the switches being GTO's or the like, as known per se.
  • the controller 28 is preferably a programmable controller (e.g., a PID controller) that can be programmed so that the power supply operates -with desired voltage and current characteristics and the switches operate with desired switching frequency characteristics.
  • the only limit on switching frequency is imposed by the time taken to magnetise, demagnetise, or reverse the polarity of the permanent magnets, tut this is not a severe limitation because this time is in the range microseconds to milliseconds, according to the size of the permanent magnets and the power applied to their coils.
  • the principle of operation of the. invention can also be utilised to commutate flmq i.e., the invention can be used to provide a sort of magnetic switch or variable resistor.
  • the permanent magnets 20 will have a high inductance - i.e., they will be magnetically conductive to the flux in the magnetic circuit - when in their magnetised state and when aligned with the same polarity as the magnetic field in the iron core 10, but will tend to block the flux when either demagnetised, or magnetised in. reverse polarity to the flux field.
  • Figures 4 aad 5 This principle is illustrated by Figures 4 aad 5.
  • the polarity and degree of magnetisation of the permanent magnets 20 can be controlled by means of one power supply 24 linked to the magnets through switches and controlled by programmable controller 28.
  • the permanent magnets 40 would therefore be conductive of the magnetic flux.
  • flux path B in Figure 5B would exhibit much higher reluctance, because the permanent magnets 40 are magnetised with opposite polarity to the flux.
  • the permanent magnets 40 were put into a demagnetised state by the circuit of Figure 4, they would exhibit an intermediate value of reluctance.
  • inductance/reluctance could be increased or decreased in a number of steps according to the number of parallel permanent magnets used, and according to how many of the parallel permanent magnets are magnetised -with the same polarity as the field, demagnetised, or magnetised with opposite polarity.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

Dans une palette de dispositifs électriques à puissance élevée, tels que des limiteurs de courant de défaut, un aimant permanent peut être utilisé comme une partie d'un circuit magnétique et l'inductance de celui-ci peut être modifiée par passage de courant électrique dans une bobine enroulée autour de celui-ci, aux fins de changement de la polarité de celui-ci ou de démagnétisation complète de celui-ci. On peut citer comme problème relatif à une telle conception le fait que des aimants permanents forts, tels que ceux nécessaires dans des limitateurs de courant de défaut, ont besoin de courants électriques de puissance élevée soit pour magnétiser, soit pour démagnétiser ceux-ci. Le dispositif selon l'invention permet de réduire la puissance nécessaire à l'obtention d'une telle magnétisation ou démagnétisation et consiste à diviser les sections transversales des aimants permanents en un certain nombre d'aimants permanents plus petits (20) connectés dans le circuit magnétique en parallèle les uns avec les autres, chaque aimant permanent plus petit comprenant une bobine (22) enroulée autour de celui-ci et chaque bobine pouvant être connectée de manière individuelle à une alimentation électrique (24) par le biais de commutateurs (26).
PCT/EP2005/052944 2004-06-30 2005-06-23 Dispositif a circuit magnetique WO2006003111A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0414603.1 2004-06-30
GB0414603A GB2415833A (en) 2004-06-30 2004-06-30 Inductive device with parallel permanent magnets in a magnetic circuit

Publications (1)

Publication Number Publication Date
WO2006003111A1 true WO2006003111A1 (fr) 2006-01-12

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2005/052944 WO2006003111A1 (fr) 2004-06-30 2005-06-23 Dispositif a circuit magnetique

Country Status (2)

Country Link
GB (1) GB2415833A (fr)
WO (1) WO2006003111A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2091054A2 (fr) 2008-02-12 2009-08-19 Deo Prafulla Rajabhau Dispositif électromagnétique de limiteur de courant
WO2014087074A1 (fr) 2012-12-03 2014-06-12 Schneider Electric Industries Sas Dispositif magnetothermique de limitation de courant
CN110690690A (zh) * 2018-07-06 2020-01-14 劳斯莱斯有限公司 电流控制设备

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101930823B (zh) * 2009-12-04 2013-06-19 上海昊德电气有限公司 一种预充磁电子线路装置
WO2012013237A1 (fr) * 2010-07-29 2012-02-02 Areva T&D Uk Limited Limiteur de courant
RU2539564C2 (ru) * 2010-08-03 2015-01-20 Альстом Текнолоджи Лтд Магнитный сердечник
DE102011000980B9 (de) * 2011-02-28 2014-12-31 Sma Solar Technology Ag Drossel mit dynamischer Vormagnetisierung
JP6047887B2 (ja) * 2012-02-21 2016-12-21 Fdk株式会社 チョークコイル
US20160005525A1 (en) * 2013-03-11 2016-01-07 Sts Spezial-Transformatoren-Stockach Gmbh & Co. Kg Inductive component
GB201408855D0 (en) * 2014-05-19 2014-07-02 Faultcurrent Ltd Fault current limiter
IT201600117005A1 (it) * 2016-11-18 2018-05-18 Laboratorio Elettrofisico Eng S R L Apparecchiatura di magnetizzazione a impulso veloce

Citations (3)

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Publication number Priority date Publication date Assignee Title
US2813256A (en) * 1953-09-01 1957-11-12 Philips Corp Inductance controllable by premagnetisation
US2875952A (en) * 1956-04-23 1959-03-03 Collins Radio Co Magnetic integrator
US4015174A (en) * 1974-07-30 1977-03-29 Le Materiel Magnetique Devices for magnetic control with permanent magnets

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Publication number Priority date Publication date Assignee Title
BE546763A (fr) * 1955-04-07
US3968465A (en) * 1973-05-18 1976-07-06 Hitachi Metals, Ltd. Inductor and method for producing same
JP3230647B2 (ja) * 1994-12-09 2001-11-19 株式会社安川電機 直流リアクトル

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2813256A (en) * 1953-09-01 1957-11-12 Philips Corp Inductance controllable by premagnetisation
US2875952A (en) * 1956-04-23 1959-03-03 Collins Radio Co Magnetic integrator
US4015174A (en) * 1974-07-30 1977-03-29 Le Materiel Magnetique Devices for magnetic control with permanent magnets

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
MUKHOPADHYAY S C ET AL: "INVESTIGATION OF THE PERFORMANCES OF A PERMANENT MAGNET BIASED FAULT CURRENT LIMITING REACTOR WITH A STEEL CORE", IEEE TRANSACTIONS ON MAGNETICS, IEEE INC. NEW YORK, US, vol. 34, no. 4, PART 1, July 1998 (1998-07-01), pages 2150 - 2152, XP000833301, ISSN: 0018-9464 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2091054A2 (fr) 2008-02-12 2009-08-19 Deo Prafulla Rajabhau Dispositif électromagnétique de limiteur de courant
WO2014087074A1 (fr) 2012-12-03 2014-06-12 Schneider Electric Industries Sas Dispositif magnetothermique de limitation de courant
US9685779B2 (en) 2012-12-03 2017-06-20 Schneider Electric Industries Sas Magnetothermal current limiting device
CN110690690A (zh) * 2018-07-06 2020-01-14 劳斯莱斯有限公司 电流控制设备
CN110690690B (zh) * 2018-07-06 2023-08-25 劳斯莱斯有限公司 电流控制设备

Also Published As

Publication number Publication date
GB2415833A (en) 2006-01-04
GB0414603D0 (en) 2004-08-04

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