EP1743181A1 - Sensor for alternating currents - Google Patents

Sensor for alternating currents

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Publication number
EP1743181A1
EP1743181A1 EP05731501A EP05731501A EP1743181A1 EP 1743181 A1 EP1743181 A1 EP 1743181A1 EP 05731501 A EP05731501 A EP 05731501A EP 05731501 A EP05731501 A EP 05731501A EP 1743181 A1 EP1743181 A1 EP 1743181A1
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EP
European Patent Office
Prior art keywords
coil
winding
coils
beginning
conductors
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EP05731501A
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German (de)
French (fr)
Inventor
Werner Zumbrunn
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Individual
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Individual
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils

Definitions

  • the common sensors for the measurement of alternating currents generally consist of an annular core made of magnetically highly conductive material, on which a toroidal coil is seated, which in turn is short-circuited via a measuring device. Alternating currents in conductors, which are enclosed by the ring-shaped core, generate short-circuit alternating currents in the toroidal coil - like in a transformer. By a suitable choice of the number of turns of the toroid, the current to be measured is reduced so that it can be measured with conventional measuring devices.
  • the sensor described is called "current transformer” or “push-through current transformer”.
  • current transformer or "push-through current transformer”.
  • One of its properties is that the core material can be saturated by strong magnetic fields, either because the current to be measured is too large or because currents flowing outside, for example short-circuit currents, in adjacent busbars are too large, and the proportional relationship between primary and secondary current is lost.
  • the invention relates to current sensors based on coils without a magnetic core material, also called air coils. Because of the lack of core material, they cannot saturate.
  • the sensors generally consist of an air coil or a plurality of air coils connected in series, which are arranged symmetrically around the current-carrying conductor. The alternating current in this conductor is measured using the mutual inductance between the coil or the coils and the current-carrying conductor. The current to be measured induces a voltage in the coil or in the coils. The voltage corresponds to the product of the time derivative of the current and the mutual inductance and must be integrated after the time so that an image of the measured variable can be obtained. State of the art
  • the Rogowski coil has been known since 1912, and many applications, manufacturing methods, and embodiments have been patented over the years. Some of these patents are briefly discussed below.
  • the individual coils are also arranged symmetrically around the current-carrying conductor.
  • the coils can be flat coils and two sets of concentric coils can be used. In the latter case, thanks to a suitable linear combination of the signals from the two sets of coils, the mutual inductance to conductors passing outside is reduced.
  • the Winding body have a constant curvature. All manufacturing processes are based on printed circuits.
  • the winding consists of conductor tracks on at least two different levels and vias that connect the conductor tracks on the different levels. These embodiments come quite close to ideal Rogowski coils. They could be used to measure magnetic voltages, as inventor W. Rogowski suggested in 1912. However, they are only of limited suitability for the measurement of alternating currents, because the spiral winding has a non-negligible mutual inductance with the conductors passing outside.
  • K the above-mentioned K.
  • sensors according to US 6313623 B1 and US 6680608 B2 therefore use two or more closely spaced bobbins with identical dimensions.
  • the windings have different winding senses and are connected in series; this eliminates the need for the return conductor.
  • the geometries of the different windings are similar, but the two bobbins are spatially separated; the sum of the mutual inductances towards outside conductors is therefore not negligible.
  • JP 580056668 two spiral windings connected in series with different winding senses are also used.
  • the spiral windings are interrupted at regular intervals by windings with a single turn in order to improve the signal-to-noise ratio of the current measurement.
  • the two spiral windings penetrate each other, so that the mutual inductance is negligibly small compared to conductors passing outside.
  • Certain sensors with Rogowski coils mentioned above are easy to manufacture, but are less suitable as accurate ammeters because of spirally wound coils, because of the lack of a return conductor, or because of bobbins with variable curvature.
  • Others are complex to manufacture because a plurality of helical coils or coil sets lying side by side or penetrating one another are required, or the connecting conductors between the coils or flat coils have a non-negligible mutual inductance with respect to conductors passing outside.
  • the aim of the invention is a sensor with air coils which is simple to manufacture and is nevertheless suitable as an accurate ammeter.
  • the invention is based on a number of identical coils, each of which has only one turn and which are arranged symmetrically around a circle.
  • the turn can have any shape, but preferably has a circular or rectangular shape.
  • Each individual turn must lie in a plane that is perpendicular to the circle mentioned.
  • the turn must be practically closed, i.e. the beginning and end must be as close as possible to one another.
  • the individual flat coils are connected in series by connecting conductors. So that these connecting conductors have no mutual inductance with respect to conductors passing outside the sensor, they are closely coupled to a connecting conductor which leads from the end of the last coil to the beginning of the first coil.
  • the single flat coil can also have more than one turn; all turns then lie in a common plane that is perpendicular to the circle mentioned.
  • the individual turns are connected in series via connecting conductors, and the connecting conductor, which leads from the last winding to the first, is so closely coupled to the other connecting conductors that their sum has no mutual inductance with respect to conductors passing outside the sensor.
  • Less ideal - but also usable under certain circumstances - are flat coils, the winding of which is spiral.
  • the coils can be produced by other methods such as etching or printing on a flat substrate instead of by winding. This makes the coils accessible for mass production.
  • K. Heumann it is known that the naturally always limited winding density of an otherwise ideal sensor means that conductors that lead close to the outside have a noticeable mutual inductance with the sensor. This annoying mutual inductance quickly decreases with increasing distance between the outer conductor and the sensor.
  • the density of the flat coils distributed over the above-mentioned circle should therefore be selected in individual cases so that these influences remain tolerable.
  • FIG. 1 shows an inventive coil arrangement with individual coils, each of which has only one turn.
  • Figure 2 A single coil with several circular turns.
  • Figure 3 A single coil with two mirror-symmetrical, spiral windings.
  • Figure 4 A single coil with several rectangular turns.
  • Figure 5 An advantageous coil arrangement with flat coils, each having a plurality of rectangular turns.
  • FIG. 1 shows a coil arrangement which, for the sake of clarity, consists of only 8 identical individual coils (1), each with one turn. They are arranged symmetrically around a circle; each individual turn lies in a plane that is perpendicular to the circle and is practically closed.
  • the coils (1) are connected in series via connecting lines (2).
  • the end of the last coil is connected to the connecting conductor (3) via a short connecting conductor (4).
  • the connecting conductor (3) is coupled as closely as possible to the connecting conductor (2) so that the mutual inductance of the
  • connection conductor to conductors passing outside is negligible.
  • the connecting conductors (2) and (3) can, for example, be guided close together, twisted together or they can be designed as coaxial lines.
  • the sensor can be connected via the connection conductors (5) and (6); these, of course, must also be closely linked.
  • Figure 2 shows a single coil with a practically closed winding. It can be connected via the connection points (11) and (12) which are close together.
  • the winding consists of several circular, practically closed turns (10).
  • the connecting lines (13) between the turns and the connecting conductor (14), which leads from the end of the coil to the beginning of the coil, are so closely coupled that the mutual inductance of the connecting conductors to conductors passing outside is negligible.
  • FIG. 3 also shows a single coil with several turns.
  • the winding (20) is a spiral; the individual turns are not closed.
  • the rewinding (21) is carried out axially symmetrically to the rewinding.
  • the two windings are in two different, parallel planes; their distance should be kept as short as possible.
  • the two windings are connected in series via a short connecting conductor (24); it connects the end of winding (20) with the beginning of winding (21).
  • the single coil as a series connection of the two windings (20) and (21) can be connected via the connection points (22) and (23).
  • FIG. 4 shows a flat coil on a coil carrier (48) with a plurality of rectangular turns (37) which are practically closed.
  • the connecting conductors (33) connect the individual turns in series.
  • the connecting conductor (34) connects the end of the innermost with the outermost turn of the coil just behind the turns (37).
  • the connecting conductors (33, 34) are so closely coupled that their mutual inductance towards conductors that lead outside the sensor is small.
  • the coil can be connected via connection points (31) and (32).
  • FIG. 5 shows a sensor made of identical flat coils (41, 49, 50).
  • the flat coils consist of rectangular windings, as shown in Figure 4. 8 flat coils were selected for FIG. 5; however, the number can be any number. The greater the number, the smaller the mutual inductance of the sensor to conductors leading close to the outside.
  • the flat coils are arranged symmetrically around a circle. The winding of each coil lies in a plane that is perpendicular to the circle and therefore also contains its center.
  • the flat coils are housed on flat bobbins (48).
  • the connecting conductor (45) of the sensor is connected to the start of the winding of the first coil (41).
  • the end of the winding of each coil is connected to the start of the winding of the next coil by a connecting conductor (42); the coils are connected in series in this way.
  • the end of the winding of the last coil (50) is connected to the beginning of the connecting conductor (43) via the short connecting conductor (44). This leads back to the first coil (41) and is connected from here to the second connecting conductor (46) of the sensor.
  • the connecting conductors (45, 46) and the connecting conductors (42, 43) are closely coupled, for example coaxially or twisted, so that the sum of the mutual inductances to conductors passing outside is minimal.

Abstract

A sensor for measuring alternating currents comprises flat coils (41, 49, 50) which have the same structure and are symmetrically distributed around a circle. Each coil winding lies in a plane perpendicular to the circle. The beginning and end of each coil winding lie as close as possible to one another. The sensor connection conductor (45) is connected to the beginning of the winding of the first coil (41). The end of each coil winding is connected by a connecting line (42) to the beginning of the winding of the next coil. The end of the winding of the last coil (50) is connected by the short connecting line (44) to the beginning of the connecting line (43), which leads back to the first coil (41) and is connected there to the second sensor connection conductor (46). The connection conductors (45, 46) and the connecting lines (42, 43) are closely coupled by transposition for the mutual inductance sum to outward leading lines to be minimal.

Description

Sensor für WechselströmeAC current sensor
Beschreibungdescription
Technisches GebietTechnical field
Die gängigen Sensoren für die Messung von Wechselströmen bestehen im allgemeinen aus einem ringförmigen Kern aus magnetisch gut leitendem Material, auf dem eine Ringspule sitzt, die ihrerseits über eine Messeinrichtung kurzgeschlossen ist. Wechselströme in Leitern, die vom ringförmigen Kern umschlossen werden, erzeugen in der Ringspule Kurzschluss-Wechselströme - wie in einem Transformator. Durch geeignete Wahl der Windungszahl der Ringspule wird der zu messende Strom so verkleinert, dass er mit üblichen Messeinrichtungen gemessen werden kann.The common sensors for the measurement of alternating currents generally consist of an annular core made of magnetically highly conductive material, on which a toroidal coil is seated, which in turn is short-circuited via a measuring device. Alternating currents in conductors, which are enclosed by the ring-shaped core, generate short-circuit alternating currents in the toroidal coil - like in a transformer. By a suitable choice of the number of turns of the toroid, the current to be measured is reduced so that it can be measured with conventional measuring devices.
Der beschriebene Sensor wird „Stromwandler" oder "Durchsteck-Stromwandler" genannt. Einer seiner Eigenschaften ist, dass das Kernmaterial durch starke Magnetfelder gesättigt werden kann, entweder weil der zu messende Strom zu gross ist oder weil aussen vorbei fliessende Ströme, zum Beispiel Kurzschlussströme in benachbarten Stromschienen, zu gross sind. Dabei geht der proportionale Zusammenhang zwischen primärem und sekundärem Strom verloren.The sensor described is called "current transformer" or "push-through current transformer". One of its properties is that the core material can be saturated by strong magnetic fields, either because the current to be measured is too large or because currents flowing outside, for example short-circuit currents, in adjacent busbars are too large, and the proportional relationship between primary and secondary current is lost.
Die Erfindung bezieht sich auf Stromsensoren auf der Basis von Spulen ohne magnetisches Kernmaterial, auch Luftspulen genannt. Wegen des Fehlens des Kernmaterials können sie nicht in Sättigung gehen. Die Sensoren bestehen im allgemeinen aus einer Luftspule oder mehreren in Reihe geschalteten Luftspulen, die symmetrisch um den Strom führenden Leiter angeordnet ist oder sind. Man misst den Wechselstrom in diesem Leiter, indem man die Gegeninduktivität zwischen der Spule oder den Spulen und dem Strom führenden Leiter nutzt. Der zu messende Strom induziert in der Spule oder in den Spulen eine Spannung. Die Spannung entspricht dem Produkt aus der zeitlichen Ableitung des Stromes und der Gegeninduktivität und muss nach der Zeit integriert werden, damit man ein Abbild der Messgrösse erhält. Stand der TechnikThe invention relates to current sensors based on coils without a magnetic core material, also called air coils. Because of the lack of core material, they cannot saturate. The sensors generally consist of an air coil or a plurality of air coils connected in series, which are arranged symmetrically around the current-carrying conductor. The alternating current in this conductor is measured using the mutual inductance between the coil or the coils and the current-carrying conductor. The current to be measured induces a voltage in the coil or in the coils. The voltage corresponds to the product of the time derivative of the current and the mutual inductance and must be integrated after the time so that an image of the measured variable can be obtained. State of the art
Verschiedene Strommesser mit Luftspulen sind unter dem Namen des Erfinders Walter Rogowski bekannt - obwohl Rogowski-Spulen im engeren Sinne nicht für die Messung von Wechselströmen, sondern für die Messung von magnetischen Spannungen vorgesehen sind. Diese spiralförmig auf einen ringförmigen Träger gewickelten Spulen umschliessen den Leiter mit dem zu messenden Strom vollständig. Mit zwei Massnahmen kann man dafür sorgen, dass die erwähnte Gegeninduktivität möglichst wenig von der Lage des Strom führenden Leiters abhängt und die störende Gegeninduktivität zu aussen vorbei führenden Leitern so klein wie möglich ist: Erstens sollte die Spule eine Wicklung haben, bei der das Produkt aus Wicklungsquerschnitt und Dichte der Windungen überall gleich gross ist. Meistens ist der Wicklungsquerschnitt über den ganzen Umfang konstant; folglich sollte dann die Dichte der Windungen überall gleich sein. Zweitens sollte die Krümmung des Wicklungskörpers überall gleich sein, das heisst, er muss einen Ringtorus darstellen.Various ammeters with air coils are known under the name of the inventor Walter Rogowski - although Rogowski coils are not intended for the measurement of alternating currents, but for the measurement of magnetic voltages. These coils, which are spirally wound on an annular support, completely surround the conductor with the current to be measured. Two measures can be taken to ensure that the mutual inductance mentioned depends as little as possible on the position of the current-carrying conductor and that the disturbing mutual inductance with conductors passing outside is as small as possible: First, the coil should have a winding in which the product is made Winding cross-section and density of the turns is the same everywhere. The winding cross section is mostly constant over the entire circumference; consequently the density of the turns should be the same everywhere. Second, the curvature of the winding body should be the same everywhere, that is, it must represent a ring torus.
Die Rogowski-Spule ist seit 1912 bekannt, und im Verlaufe der Jahre sind viele Anwendungen, Herstellungsmethoden und Ausführungsformen patentiert worden. Im folgenden wird kurz auf einige dieser Patente eingegangen.The Rogowski coil has been known since 1912, and many applications, manufacturing methods, and embodiments have been patented over the years. Some of these patents are briefly discussed below.
Walter Rogowski selbst hat 1913 zwei Patente für die Messung von magnetischen Spannungen angemeldet (CH 66158 und GB 191318103). In EP 0933639 A2 wird eine Rogowski-Spule als Bestandteil eines Isolierstücks einer Strommesseinrichtung erwähnt. In der US-Offenlegungsschrift 2004/0201373 A1 wird vorgeschlagen, eine Rogowski-Spule zu verwenden, um in einer Strommesseinrichtung für Gleich- und Wechselströme die Wechselströme ab einer bestimmten Frequenz zu messen. In DE 4229678 wird ein Verfahren zur Herstellung von Rogowski-Spulen für Stromwandler geschildert; ein elastischer, ringförmiger Hohlkörper kann auf einen geraden Dorn aufgebracht und nach dem Wickeln wieder zu einem Ringtorus zusammengefügt werden. Um grosse Rogowski-Spulen zu bauen, kann der Ringtorus aufgeteilt werden - zum Beispiel in 4 Teile gemäss JP 10282154. Um. die Forderung nach einer homogenenWalter Rogowski himself registered two patents for measuring magnetic voltages in 1913 (CH 66158 and GB 191318103). EP 0933639 A2 mentions a Rogowski coil as part of an insulating piece of a current measuring device. In US patent application 2004/0201373 A1 it is proposed to use a Rogowski coil to measure the AC currents above a certain frequency in a current measuring device for direct and alternating currents. DE 4229678 describes a method for producing Rogowski coils for current transformers; an elastic, ring-shaped hollow body can be applied to a straight mandrel and, after winding, can be put together again to form a ring torus. In order to build large Rogowski coils, the ring torus can be divided - for example into 4 parts according to JP 10282154 . the demand for a homogeneous
Windungsdichte zu erfüllen, wird in US 5852395 vorgeschlagen, den ringförmigen Wicklungskörper mit Hilfe von Nocken in mehrere gleiche Segmente aufzuteilen; auf diese Art und Weise wird eine symmetrische Verteilung der Wicklung über den ganzen Umfang erzwungen. In DE 4424368 wird ein Herstellverfahren für Rogowski-Spulen beschrieben; dabei wird auf Teilstücke eines ringförmigen Wicklungsträgers eine elektrisch leitende Schicht aufgebraucht, die anschliessend wendeiförmig unterbrochen wird. Die Teilstücke können durch Verbindungsstücke elektrisch und mechanisch verbunden werden. Zylindrische Spulen, die auf einem regelmässigen Polygon um den Strom führenden Leiter angeordnet sind, werden in US 4709205 beschrieben. Träger der Spulen ist eine gedruckte Schaltung, mit deren Hilfe die Reihenschaltung der einzelnen Spulen bewerkstelligt wird. Eine ähnliche Konstruktion ist auch aus den US-Patentschriften 6,717,397 und 6,825,650 bekannt. Die einzelnen Spulen sind auch hier symmetrisch um den Strom führenden Leiter angeordnet. Im besonderen können die Spulen Flachspulen sein, und es können zwei konzentrische Spulensätze verwendet werden. Im letzteren Fall wird dank einer geeigneten Linearkombination der Signale der beiden Spulensätze die Gegeninduktivität zu aussen vorbei führenden Leitern verringert.In US 5852395 it is proposed to meet the winding density to divide the annular winding body into several identical segments with the aid of cams; in this way a symmetrical distribution of the winding over the entire circumference is enforced. DE 4424368 describes a manufacturing process for Rogowski coils; an electrically conductive layer is used up on parts of an annular winding support, which is then interrupted in a helical manner. The sections can be electrically and mechanically connected by connecting pieces. Cylindrical coils, which are arranged on a regular polygon around the current-carrying conductor, are described in US 4709205. The carrier of the coils is a printed circuit, with the help of which the individual coils are connected in series. A similar construction is also known from US Pat. Nos. 6,717,397 and 6,825,650. The individual coils are also arranged symmetrically around the current-carrying conductor. In particular, the coils can be flat coils and two sets of concentric coils can be used. In the latter case, thanks to a suitable linear combination of the signals from the two sets of coils, the mutual inductance to conductors passing outside is reduced.
Die Herstellung eines gleichmässig bewickelten Ringtorus ist aufwendig. Die letzten der oben erwähnten Veröffentlichungen zeigen auf, wie durch die Aufteilung des Spulenkörpers in Teilstücke die Herstellung vereinfacht werden kann. Zum Teil werden sogar gerade, zylindrische Teilspulen vorgeschlagen.The production of a uniformly wound ring torus is complex. The last of the publications mentioned above show how the division can be simplified by dividing the coil body into parts. In some cases, straight, cylindrical partial coils are even proposed.
Allerdings bleiben dann die idealen Eigenschaften des Sensors nur erhalten, wenn der Spulenquerschnitt sehr klein gewählt wird; dies haben schon W. Rogowski und W. Steinhaus 1912 in ihrer Veröffentlichung im Archiv für Elektrotechnik, 1. Band, Heft 4, beschrieben. Eine der Voraussetzungen für einen idealen Sensor bei technisch nutzbaren, grossen Spulenquerschnitten ist, dass der Spulenkörper eine konstante Krümmung hat. Dies hat zum Beispiel K. Heumann 1961 in seiner Dissertation an der Fakultät für Elektrotechnik der TU Berlin-Charlottenburg mit dem Titel „Magnetischer Spannungsmesser zur Präzisionsmessung hoher Ströme" bewiesen. In den Patenten US 5442280, JP 6186255 und GB 2342783, derHowever, the ideal properties of the sensor are only retained if the coil cross section is chosen to be very small; W. Rogowski and W. Steinhaus described this in their publication in the Archive for Electrical Engineering, Volume 1, Volume 4, in 1912. One of the prerequisites for an ideal sensor with large, technically usable coil cross sections is that the coil body has a constant curvature. This was demonstrated, for example, by K. Heumann in his doctoral thesis in 1961 at the Faculty of Electrical Engineering at the TU Berlin-Charlottenburg with the title "Magnetic voltmeter for precision measurement of high currents". In patents US 5442280, JP 6186255 and GB 2342783, the
Gebrauchsmusterschrift DE 20101454 U1 sowie der Offenlegungsschrift US 2003/090356 werden Rogowski-Spulen vorgeschlagen, deren Wicklungskörper eine konstante Krümmung haben. Alle Herstellverfahren basieren auf gedruckten Schaltungen. Die Wicklung besteht aus Leiterbahnen auf mindestens zwei verschiedenen Ebenen und aus Durchkontaktierungen, die die Leiterbahnen auf den verschiedenen Ebenen verbinden. Diese Ausführungsformen kommen idealen Rogowski-Spulen schon ziemlich nahe. Mit ihnen könnte man -wie es der Erfinder W. Rogowski 1912 vorgeschlagen hat - magnetische Spannungen messen. Für die Messung von Wechselströmen eignen sie sich aber nur bedingt, denn die spiralförmige Wicklung hat eine nicht vernachlässigbare Gegeninduktivität zu aussen vorbei führenden Leitern. Unter anderen schlägt deshalb der oben erwähnte K. Heumann in seiner Dissertation vor, einen Rückleiter in Reihe mit der Rogowski-Spule zu schalten. Der Rückleiter führt vom Ende der Rogowski-Spule zum Anfang der Rogowski-Spule, entweder als eine einzige Windung im Inneren des Ringtorus, als eine einzige Windung auf seiner Oberfläche oder als Rückwicklung mit geringerer Windungsdichte als die primäre Wicklung auf der Oberfläche des Ringtorus. Mit dieser Massnahme kann die Gegeninduktivität des Sensors gegenüber aussen vorbei führenden Leitern verringert werden. Sie bleibt aber immer noch ziemlich gross, denn die spiralförmig gewickelte Spule und der Rückleiter haben unterschiedliche Geometrien. Auch im Fall des aus US 6717397 bekannten Sensors ist trotz der Verwendung von Flachspulen diese Gegeninduktivität nicht vernachlässigbar.Utility model DE 20101454 U1 and the published US 2003/090356 Rogowski coils are proposed, the Winding body have a constant curvature. All manufacturing processes are based on printed circuits. The winding consists of conductor tracks on at least two different levels and vias that connect the conductor tracks on the different levels. These embodiments come quite close to ideal Rogowski coils. They could be used to measure magnetic voltages, as inventor W. Rogowski suggested in 1912. However, they are only of limited suitability for the measurement of alternating currents, because the spiral winding has a non-negligible mutual inductance with the conductors passing outside. Among other things, the above-mentioned K. Heumann proposed in his dissertation to connect a return conductor in series with the Rogowski coil. The return conductor leads from the end of the Rogowski coil to the beginning of the Rogowski coil, either as a single turn inside the ring torus, as a single turn on its surface, or as a winding with a lower winding density than the primary winding on the surface of the ring torus. With this measure, the mutual inductance of the sensor with respect to conductors passing outside can be reduced. However, it still remains quite large, because the spiral wound coil and the return conductor have different geometries. Even in the case of the sensor known from US 6717397, despite the use of flat coils, this mutual inductance is not negligible.
Um den Rückleiter zu vermeiden, verwenden deshalb Sensoren gemäss US 6313623 B1 und US 6680608 B2 zwei oder mehr dicht beieinander liegende Spulenkörper mit identischen Abmessungen. Die Wicklungen haben unterschiedliche Wicklungssinne und sind in Serie geschaltet; damit erübrigt sich der Rückleiter. Die Geometrien der verschiedenen Wicklungen sind zwar ähnlich, aber die beiden Spulenkörper sind räumlich getrennt; die Summe der Gegeninduktivitäten gegenüber aussen vorbei führenden Leitern ist deshalb nicht vernachlässigbar. Gemäss JP 580056668 werden ebenfalls zwei in Reihe geschaltete, spiralförmige Wicklungen mit unterschiedlichem Wicklungssinn verwendet. Zusätzlich werden die spiralförmigen Wicklungen in gleichmässigen Abständen durch Wicklungen mit einer einzigen Windung unterbrochen, um das Signal-Rausch-Verhältnis der Strommessung zu verbessern. Die beiden spiralförmigen Wicklungen durchdringen sich, so dass hier die Gegeninduktivität gegenüber aussen vorbei führenden Leitern vernachlässigbar klein ist.In order to avoid the return conductor, sensors according to US 6313623 B1 and US 6680608 B2 therefore use two or more closely spaced bobbins with identical dimensions. The windings have different winding senses and are connected in series; this eliminates the need for the return conductor. The geometries of the different windings are similar, but the two bobbins are spatially separated; the sum of the mutual inductances towards outside conductors is therefore not negligible. According to JP 580056668, two spiral windings connected in series with different winding senses are also used. In addition, the spiral windings are interrupted at regular intervals by windings with a single turn in order to improve the signal-to-noise ratio of the current measurement. The two spiral windings penetrate each other, so that the mutual inductance is negligibly small compared to conductors passing outside.
Bestimmte oben erwähnte Sensoren mit Rogowski-Spulen sind einfach herzustellen, aber wegen spiralförmig gewickelten Spulen, wegen fehlendem Rückleiter oder wegen Spulenkörpern mit variabler Krümmung als genaue Strommesser weniger geeignet. Andere sind aufwendig in der Herstellung, weil mehrere nebeneinander liegende oder sich durchdringende spiralförmige Spulen oder Spulensätze benötigt werden, oder die Verbindungsleiter zwischen den Spulen oder Flachspulen haben gegenüber aussen vorbei führenden Leitern eine nicht vernachlässigbare Gegeninduktivität. Die Erfindung hat einen Sensor mit Luftspulen zum Ziel, der einfach herstellbar und trotzdem als genauer Strommesser geeignet ist.Certain sensors with Rogowski coils mentioned above are easy to manufacture, but are less suitable as accurate ammeters because of spirally wound coils, because of the lack of a return conductor, or because of bobbins with variable curvature. Others are complex to manufacture because a plurality of helical coils or coil sets lying side by side or penetrating one another are required, or the connecting conductors between the coils or flat coils have a non-negligible mutual inductance with respect to conductors passing outside. The aim of the invention is a sensor with air coils which is simple to manufacture and is nevertheless suitable as an accurate ammeter.
Darstellung der ErfindungPresentation of the invention
Im folgenden wird der ideale Aufbau des erfindungsgemässen Stromsensors beschrieben. In der Praxis können die Anforderungen natürlich nur annähernd erfüllt werden, und zwar umso besser, je mehr Aufwand betrieben wird.The ideal structure of the current sensor according to the invention is described below. In practice, of course, the requirements can only be met approximately, and the more effort is made, the better.
Die Erfindung geht von einer Anzahl identischer Spulen aus, die jeweils nur eine Windung haben und die symmetrisch um einen Kreis angeordnet sind. Die Windung kann eine beliebige Form haben, hat aber vorzugsweise eine Kreis- oder Rechteckform. Jede einzelne Windung muss in einer Ebene liegen, die senkrecht zum erwähnten Kreis steht. Die Windung muss praktisch geschlossen sein, das heisst, Anfang und Ende müssen so nahe wie möglich beieinander liegen. Die einzelnen Flachspulen sind durch Verbindungsleiter in Reihe geschaltet. Damit diese Verbindungsleiter gegenüber aussen am Sensor vorbei führenden Leitern keine Gegeninduktivität haben, werden sie mit einem Verbindungsleiter, der vom Ende der letzten Spule zum Anfang der ersten Spule führt, eng gekoppelt. Wegen Flachspulen anstelle einer spiralförmigen Wicklung, wegen der engen Kopplung der Verbindungsleiter und wegen der praktisch geschlossenen Windungen wird erreicht, dass ausschliesslich in den Flachspulen elektrische Spannungen induziert werden können. Die einzelne Flachspule kann auch mehr als eine Windung haben; alle Windungen liegen dann in einer gemeinsamen Ebene, die senkrecht zum erwähnten Kreis steht. Im Idealfall ist hier nicht nur die Spule, sondern auch jede einzelne Windung praktisch geschlossen, das heisst, Anfang und Ende liegen nahe beieinander. Innerhalb der Spule werden die einzelnen Windungen über Verbindungsleiter in Reihe geschaltet, und der Verbindungsleiter, der von der letzten Wicklung zur ersten führt, wird mit den andern Verbindungsleitern so eng gekoppelt, dass ihre Summe gegenüber aussen am Sensor vorbei führenden Leitern keine Gegeninduktivität hat. Weniger ideal - aber unter Umständen auch brauchbar - sind Flachspulen, deren Wicklung spiralförmig ist.The invention is based on a number of identical coils, each of which has only one turn and which are arranged symmetrically around a circle. The turn can have any shape, but preferably has a circular or rectangular shape. Each individual turn must lie in a plane that is perpendicular to the circle mentioned. The turn must be practically closed, i.e. the beginning and end must be as close as possible to one another. The individual flat coils are connected in series by connecting conductors. So that these connecting conductors have no mutual inductance with respect to conductors passing outside the sensor, they are closely coupled to a connecting conductor which leads from the end of the last coil to the beginning of the first coil. Because of flat coils instead of a spiral winding, because of the close coupling of the connecting conductors and because of the practically closed turns, it can be achieved that only in the flat coils can electrical voltages be induced. The single flat coil can also have more than one turn; all turns then lie in a common plane that is perpendicular to the circle mentioned. Ideally, not only the coil is closed here, but also each individual turn, which means that the start and end are close to each other. Within the coil, the individual turns are connected in series via connecting conductors, and the connecting conductor, which leads from the last winding to the first, is so closely coupled to the other connecting conductors that their sum has no mutual inductance with respect to conductors passing outside the sensor. Less ideal - but also usable under certain circumstances - are flat coils, the winding of which is spiral.
Weil die Windungen einer Spule jeweils in einer Ebene liegen, können die Spulen statt durch Wickeln durch andere Methoden wie Ätzen oder Bedrucken eines ebenen Substrates hergestellt werden. Damit sind die Spulen der Massenherstellung zugänglich. Aus der oben erwähnten Dissertation von K. Heumann ist bekannt, dass die natürlicherweise immer beschränkte Windungsdichte eines sonst idealen Sensors zur Folge hat, dass Leiter, die aussen nahe vorbei führen, eine merkbare Gegeninduktivität zum Sensor haben. Diese störende Gegeninduktivität nimmt mit zunehmender Distanz zwischen Aussenleiter und Sensor schnell ab. Die Dichte der über den erwähnten Kreis verteilten Flachspulen ist im Einzelfall deshalb so zu wählen, dass diese Einflüsse tolerierbar bleiben.Because the turns of a coil lie in one plane, the coils can be produced by other methods such as etching or printing on a flat substrate instead of by winding. This makes the coils accessible for mass production. From the above-mentioned dissertation by K. Heumann it is known that the naturally always limited winding density of an otherwise ideal sensor means that conductors that lead close to the outside have a noticeable mutual inductance with the sensor. This annoying mutual inductance quickly decreases with increasing distance between the outer conductor and the sensor. The density of the flat coils distributed over the above-mentioned circle should therefore be selected in individual cases so that these influences remain tolerable.
Kurze Beschreibung der Zeichnungen Es zeigen: Figur 1 : Eine erfind ungsgemässe Spulenanordnung mit Einzelspulen, die jeweils nur eine Windung haben.BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an inventive coil arrangement with individual coils, each of which has only one turn.
Figur 2: Eine Einzelspule mit mehreren, kreisförmigen Windungen.Figure 2: A single coil with several circular turns.
Figur 3: Eine Einzelspule mit zwei spiegelsymmetrischen, spiralförmigen Wicklungen. Figur 4: Eine Einzelspule mit mehreren, rechteckförmigen Windungen. Figur 5: Eine vorteilhafte Spulenanordnung mit Flachspulen, die jeweils mehrere, rechteckförmige Windungen haben.Figure 3: A single coil with two mirror-symmetrical, spiral windings. Figure 4: A single coil with several rectangular turns. Figure 5: An advantageous coil arrangement with flat coils, each having a plurality of rectangular turns.
In Figur 1 ist eine Spulenanordnung dargestellt, die der Übersichtlichkeit halber aus nur 8 baugleichen Einzelspulen (1) mit je einer Windung besteht. Sie sind symmetrisch um einen Kreis angeordnet; jede einzelne Windung liegt in einer Ebene, die senkrecht auf dem Kreis steht, und ist praktisch geschlossen. Die Spulen (1) sind über Verbindungsleitungen (2) in Reihe geschaltet. Das Ende der letzten Spule ist über einen kurzen Verbindungsleiter (4) mit dem Verbindungsleiter (3) verbunden. Der Verbindungsleiter (3) ist so eng wie möglich an die Verbindungsleiter (2) gekoppelt, damit die Gegeninduktivität der1 shows a coil arrangement which, for the sake of clarity, consists of only 8 identical individual coils (1), each with one turn. They are arranged symmetrically around a circle; each individual turn lies in a plane that is perpendicular to the circle and is practically closed. The coils (1) are connected in series via connecting lines (2). The end of the last coil is connected to the connecting conductor (3) via a short connecting conductor (4). The connecting conductor (3) is coupled as closely as possible to the connecting conductor (2) so that the mutual inductance of the
Verbindungsleiter zu aussen vorbei führenden Leitern vernachlässigbar ist. Für diesen Zweck kann man die Verbindungsleiter (2) und (3) zum Beispiel dicht beieinander führen, miteinander verdrillen oder sie als koaxiale Leitungen ausführen. Der Sensor ist über die Anschlussleiter (5) und (6) anschliessbar; auch diese müssen natürlich eng gekoppelt sein.Connection conductor to conductors passing outside is negligible. For this purpose, the connecting conductors (2) and (3) can, for example, be guided close together, twisted together or they can be designed as coaxial lines. The sensor can be connected via the connection conductors (5) and (6); these, of course, must also be closely linked.
Figur 2 zeigt eine Einzelspule mit einer praktisch geschlossenen Wicklung. Sie kann über die dicht beieinander liegenden Anschlusspunkte (11) und (12) angeschlossen werden. Die Wicklung besteht aus mehreren kreisförmigen, praktisch geschlossenen Windungen (10). Die Verbindungsleitungen (13) zwischen den Windungen und der Verbindungsleiter (14), der vom Ende der Spule zum Anfang der Spule führt, sind so eng gekoppelt, dass die Gegeninduktivität der Verbindungsleiter zu aussen vorbei führenden Leitern vernachlässigbar ist.Figure 2 shows a single coil with a practically closed winding. It can be connected via the connection points (11) and (12) which are close together. The winding consists of several circular, practically closed turns (10). The connecting lines (13) between the turns and the connecting conductor (14), which leads from the end of the coil to the beginning of the coil, are so closely coupled that the mutual inductance of the connecting conductors to conductors passing outside is negligible.
Auch Figur 3 zeigt eine Einzelspule mit mehreren Windungen. Allerdings ist die Hinwicklung (20) eine Spirale; die einzelnen Windungen sind also nicht geschlossen. Um diesen Fehler teilweise zu kompensieren, ist die Rückwicklung (21) axialsymmetrisch zur Hinwicklung ausgeführt. Die beiden Wicklungen befinden sich in zwei verschiedenen, parallelen Ebenen; ihr Abstand ist so gering wie möglich zu halten. Die beiden Wicklungen sind über einen kurzen Verbindungsleiter (24) in Reihe geschaltet; er verbindet das Ende der Hinwicklung (20) mit dem Anfang der Rückwicklung (21). Die Einzelspule als Reihenschaltung der beiden Wicklungen (20) und (21) ist über die Anschlusspunkte (22) und (23) anschliessbar. Figur 4 zeigt eine Flachspule auf einem Spulenträger (48) mit mehreren, rechteckförmigen Windungen (37), die praktisch geschlossen sind. Die Verbindungsleiter (33) schalten die einzelnen Windungen in Reihe. Der Verbindungsleiter (34) verbindet dicht hinter den Windungen (37) das Ende der innersten mit der äussersten Windung der Spule. Die Verbindungsleiter (33, 34) sind so eng gekoppelt, dass ihre Gegeninduktivität gegenüber Leitern, die aussen am Sensor vorbei führen, klein ist. Die Spule kann über die Anschlusspunkte (31) und (32) angeschlossen werden.Figure 3 also shows a single coil with several turns. However, the winding (20) is a spiral; the individual turns are not closed. In order to partially compensate for this error, the rewinding (21) is carried out axially symmetrically to the rewinding. The two windings are in two different, parallel planes; their distance should be kept as short as possible. The two windings are connected in series via a short connecting conductor (24); it connects the end of winding (20) with the beginning of winding (21). The single coil as a series connection of the two windings (20) and (21) can be connected via the connection points (22) and (23). FIG. 4 shows a flat coil on a coil carrier (48) with a plurality of rectangular turns (37) which are practically closed. The connecting conductors (33) connect the individual turns in series. The connecting conductor (34) connects the end of the innermost with the outermost turn of the coil just behind the turns (37). The connecting conductors (33, 34) are so closely coupled that their mutual inductance towards conductors that lead outside the sensor is small. The coil can be connected via connection points (31) and (32).
Vorteilhafteste AusführungsformMost advantageous embodiment
In Figur 5 ist ein Sensor aus baugleichen Flachspulen (41, 49, 50) dargestellt. Die Flachspulen bestehen aus rechteckförmigen Wicklungen, wie sie in Figur 4 dargestellt sind. Für die Figur 5 wurden 8 Flachspulen gewählt; die Anzahl kann aber eine beliebige sein. Je grösser die Anzahl ist, desto kleiner wird die Gegeninduktivität des Sensors zu aussen nahe vorbei führenden Leitern. Die Flachspulen sind symmetrisch um einen Kreis angeordnet. Die Wicklung jeder Spule liegt jeweils in einer Ebene, die senkrecht zum Kreis ist und daher auch dessen Mittelpunkt enthält. Die Flachspulen sind auf ebenen Spulenträgern (48) untergebracht. Der Anschlussleiter (45) des Sensors ist mit dem Anfang der Wicklung der ersten Spule (41) verbunden. Jeweils das Ende der Wicklung jeder Spule ist mit einem Verbindungsleiter (42) mit dem Anfang der Wicklung der nächsten Spule verbunden; die Spulen sind derart in Reihe geschaltet. Das Ende der Wicklung der letzten Spule (50) ist über den kurzen Verbindungsleiter (44) mit dem Anfang des Verbindungsleiters (43) verbunden. Dieser führt zur ersten Spule (41) zurück und ist von hier aus mit dem zweiten Anschlussleiter (46) des Sensors verbunden. Die Anschlussleiter (45, 46) und die Verbindungsleiter (42, 43) sind eng gekoppelt, zum Beispiel koaxial oder verdrillt, damit die Summe der Gegeninduktivitäten zu aussen vorbei führenden Leitern minimal ist. FIG. 5 shows a sensor made of identical flat coils (41, 49, 50). The flat coils consist of rectangular windings, as shown in Figure 4. 8 flat coils were selected for FIG. 5; however, the number can be any number. The greater the number, the smaller the mutual inductance of the sensor to conductors leading close to the outside. The flat coils are arranged symmetrically around a circle. The winding of each coil lies in a plane that is perpendicular to the circle and therefore also contains its center. The flat coils are housed on flat bobbins (48). The connecting conductor (45) of the sensor is connected to the start of the winding of the first coil (41). The end of the winding of each coil is connected to the start of the winding of the next coil by a connecting conductor (42); the coils are connected in series in this way. The end of the winding of the last coil (50) is connected to the beginning of the connecting conductor (43) via the short connecting conductor (44). This leads back to the first coil (41) and is connected from here to the second connecting conductor (46) of the sensor. The connecting conductors (45, 46) and the connecting conductors (42, 43) are closely coupled, for example coaxially or twisted, so that the sum of the mutual inductances to conductors passing outside is minimal.

Claims

Patentansprüche claims
1. Vorrichtung aus baugleichen, symmetrisch um einen Kreis angeordneten und in Reihe geschalteten Luftspulen zur Messung elektrischer Wechselströme, die den besagten Kreis durchfluten, dadurch gekennzeichnet, dass die Einzelspule eine praktisch geschlossene Wicklung hat, die aus einer in einer Ebene liegenden Windung besteht oder die mehrere in einer Ebene oder in parallelen Ebenen liegende, in Reihe geschaltete Windungen hat, und dass die Summe aus Verbindungsleitern zwischen den Spulen, allenfalls aus Verbindungsleitern zwischen den Windungen, aus dem Verbindungsleiter, der vom Ende der letzten Spule zum Anfang der ersten Spule führt, und allenfalls aus Verbindungsleitern, die von der letzten Windung einer Teilspule zum ihrem Anfang führen, eine gegenüber aussen vorbei führenden Leitern minimale Gegeninduktivität hat. 1.Device of identical, symmetrically arranged around a circle and connected in series air coils for measuring electrical alternating currents which flow through the said circle, characterized in that the single coil has a practically closed winding, which consists of a winding lying in one plane or the has a plurality of turns connected in a plane or in parallel planes, and that the sum of connecting conductors between the coils, possibly connecting conductors between the turns, from the connecting conductor leading from the end of the last coil to the beginning of the first coil, and at most from connecting conductors that lead from the last turn of a partial coil to its beginning, a conductor that leads past to the outside has minimal mutual inductance.
2. Vorrichtung nach Anspruch 1 , dadurch gekennzeichnet, dass die Einzelspule aus in Reihe geschalteten, spiegelbildlichen Wicklungen besteht, die möglichst nahe beieinander in parallelen Ebenen liegen.2. Device according to claim 1, characterized in that the single coil consists of series-connected, mirror-image windings which are as close together as possible in parallel planes.
3. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Wicklung einer Spule und allenfalls die dazu gehörenden Verbindungsleiter durch Bedrucken, Aufdampfen, Sputtern oder galvanisches Abscheiden auf ein ebenes, nicht leitendes Substrat oder durch partielles Ätzen, Verdampfen mittels Laser-, Ionen- oder Gasstrahl oder partielle mechanische Abrasion einer leitfähigen, ebenen Schicht hergestellt werden.3. Apparatus according to claim 1 or 2, characterized in that the winding of a coil and possibly the associated connecting conductors by printing, vapor deposition, sputtering or galvanic deposition on a flat, non-conductive substrate or by partial etching, evaporation by means of lasers, ions - or gas jet or partial mechanical abrasion of a conductive, flat layer.
4. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Vorrichtung aufgetrennt, über die Leiter mit den zu messenden Strömen geschoben und wieder zusammengefügt werden kann. 4. The device according to claim 1 or 2, characterized in that the device can be separated, pushed over the conductors with the currents to be measured and put together again.
EP05731501A 2004-04-24 2005-04-22 Sensor for alternating currents Ceased EP1743181A1 (en)

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WO2010041139A1 (en) * 2008-10-11 2010-04-15 University Of Witwatersrand, Johannesburg Electrical current measuring coil
EP2643704B1 (en) 2010-11-26 2018-01-24 The National Microelectronics Applications Centre An ac current or voltage sensor
DE102011089204A1 (en) * 2011-12-20 2013-05-23 Siemens Aktiengesellschaft Switch designed as low-voltage circuit breaker, has converter comprising non-magnetic core whose dimensions are equal, so that number of layers and/or windings per layer is increased with increase in switch size
CN112352163A (en) * 2018-07-04 2021-02-09 新电元工业株式会社 Electronic module
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