EP0368712B1 - Adjustable electrical power generator and its use in the production of a hot fluid - Google Patents

Adjustable electrical power generator and its use in the production of a hot fluid Download PDF

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Publication number
EP0368712B1
EP0368712B1 EP89402913A EP89402913A EP0368712B1 EP 0368712 B1 EP0368712 B1 EP 0368712B1 EP 89402913 A EP89402913 A EP 89402913A EP 89402913 A EP89402913 A EP 89402913A EP 0368712 B1 EP0368712 B1 EP 0368712B1
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EP
European Patent Office
Prior art keywords
winding
magnetic core
auxiliary
generator according
core
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EP89402913A
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German (de)
French (fr)
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EP0368712A1 (en
Inventor
Michel Sacotte
Guy Cachon
Isabelle Jaytener
Miguel Vazquez
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France Transfo SAS
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France Transfo SAS
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/105—Induction heating apparatus, other than furnaces, for specific applications using a susceptor
    • H05B6/108—Induction heating apparatus, other than furnaces, for specific applications using a susceptor for heating a fluid

Definitions

  • the present invention relates, in general, to the supply of an adjustable electrical power to a circuit of use. It relates more particularly to the production of a hot fluid, in particular a liquid, such as water, within an electric induction boiler with adjustable heating power.
  • Boilers of the type under consideration are designed as transformers, the secondary winding of which, short-circuited, consists of a metal tube wound in a coil and traversed by the fluid to be heated. This is heated in contact with the wall of the coil, itself brought to temperature by the Joule effect, due to the induced currents which the variable magnetic flux produced therein produced in the magnetic circuit by the electric current of the primary.
  • Thermo-inductive boilers of this type are already known, for example documents: FR-B-527697, GB-B-2178254 GB-A-2105159, USP 2,856,498, or even EP-A-0193843.
  • these devices have the particularity of completely dissociating the electrical supply circuit (the primary) from the "heating" part. User safety is thus reinforced.
  • the transformation ratio specific to transformers can be used to place the coil at low voltage while ensuring high power transmitted by the primary.
  • the document EP-A-0193843 proposes a solution more concerned with the energy efficiency of the device.
  • the regulation of the heating power is obtained by means of thyristors connected in cascade on the coil at secondary. To this end, it consists of a battery of hydraulic mini-circuits in parallel. The regulation can only be done by discrete jumps. In addition, the apparatus seems complex, costly and its reliability depends on the holding in use of electronic components.
  • the present invention applicable to boilers provided with co-axial windings, aims at a solution of "continuous" adjustment of the heating power, reliable just as much, but more economical and of even smaller footprint than the solution mentioned. above.
  • the invention relates to an adjustable electric power generator, in particular for the production of a hot fluid in an electric induction boiler, comprising a magnetic transducer, of the "transformer" type with primary and secondary windings surrounding a core.
  • magnetic one of the windings surrounding the other, and means for adjusting the electric power available in the secondary, generator
  • said power adjusting means are constituted by an auxiliary magnetic core, separate from the magnetic core main, provided with an electrical control winding and arranged between the primary and secondary windings, and by a direct current generator - or rectified - supplying said control winding and associated with means for adjusting the intensity of said direct current.
  • the secondary winding is constituted by a tubular coil in short circuit, intended to be traversed by a fluid to be heated.
  • the heating coil is arranged outside the primary winding.
  • the outer winding is of oblong conformation to be able to accommodate the auxiliary magnetic core arranged at side of the interior winding.
  • the auxiliary magnetic core is formed by two similar parts each provided with a control winding, in which the direct or rectified currents flow in opposite directions. These two parts are advantageously arranged on either side of the interior winding.
  • the idea underlying the invention is to vary the specific inductance of the heating coil using an additional (or auxiliary) magnetic core placed in the space separating the two windings and whose permeability is controlled by application of a stationary magnetic field produced by a control winding with direct current - or redesigned - wound around the auxiliary core and whose intensity is regulated.
  • This winding is of sufficient size to produce a magnetic field capable of saturating the auxiliary magnetic core when the control current is set to its maximum intensity, Ic max.
  • the auxiliary magnetic core is advantageously formed from two similar independent parts to take into account the fact that the excitation current at the primary is an alternating current. If it is a pure alternative with symmetrical alternations, the two constituent parts of the core may be strictly identical. Otherwise, they may have a difference between them, for example in the number of ampere-turns of the control windings, or of their mass of magnetic material.
  • control windings are traversed by direct currents (or straightened) flowing in opposite directions to take account of the alternating nature of the magnetic field created by the primary. At all times, this field is magnetizing for one of the parts of the auxiliary core and demagnetizing for the other, and "vice versa" at the next alternation. Overall, we balance the effect of alternations over a period.
  • the auxiliary core therefore operates completely independently of the direction of current flow in the primary winding.
  • the coil forms the outer winding 2 .
  • the inner winding 3 supplied by the electricity distribution network symbolized by the unit 5 , therefore constitutes the primary winding here.
  • the coil 2 is advantageously a stainless steel tube. It is traversed by a heat transfer fluid to be heated, which one will admit to be water. Cold water enters through the inlet tubing 6 at the base of the coil. It emerges from it via the outlet pipe 7 at the upper end, after having heated up in contact with the internal wall.
  • the coil is short-circuited on itself by an electrical connection 8 which interconnects the inlet 6 and outlet 7 pipes.
  • an earthing 9 of the secondary winding 2 is provided beyond the short-circuit bridging 8 .
  • an auxiliary magnetic core 10 is placed in the interior space 11 , between the interior primary winding 3 and the coil 2 .
  • This core formed by stacking magnetic sheets like the main core 4, has a control winding 12 surrounding it over part of its height.
  • This winding is supplied with direct current (or rectified) by a unit 13 equipped with a variator, symbolized at 14 at its output, for adjusting the intensity I c of this direct control current.
  • a switch 15 has also been provided on the primary circuit to allow rapid opening if necessary.
  • Figure 2 shows the complete boiler formed by three identical transducers 1 , 1 ′ and 1 ⁇ arranged side by side.
  • This conformation makes it possible to accommodate, in space 11 , within the coil 2 , the primary winding 3 and the auxiliary magnetic core 10 , by placing them one next to the other while minimizing space 11 .
  • each of the identical operational elements 1 , 1 ′ or 1 ⁇ constitutes an autonomous transducer.
  • Each transducer is connected to a different phase (U, V or W) of a three-phase power supply.
  • the three primary windings 3 , 3 ′ and 3 ⁇ are mounted here in a star shape . Each of them induces, via a magnetic circuit, in a coil 2 , 2 ′ or 2 ⁇ .
  • Each coil is mounted on a branch of a hydraulic heating circuit, which contains three in parallel.
  • Each elementary transducer shown in FIG. 1 works as follows:
  • This heat generation depends on the intensity of the current in the secondary 2 , which is determined by the voltage induced at the terminals of the latter. This voltage is linked to the voltage across the primary 3 , by the magnetic coupling between the two windings.
  • the invention modifies this coupling by virtue of the auxiliary core 10 placed in the space separating the coil from the internal primary winding.
  • this auxiliary magnetic core acts with respect to the coil like an iron core in an induction coil.
  • I c direct current (or recursed) I c flowing in the control winding 12 mounted for this purpose around the core:
  • the magnetic substance constituting the nucleus no longer has any influence on the inductance of the secondary.
  • the heating power delivered by the coil is then the same as that which the primary would provide to it in the absence of an auxiliary core.
  • this "sufficient" quantity of magnetic substance is produced with a mass equal to approximately once that of the main magnetic core 4 .
  • the magnetic cores all having the same height, this condition is reduced to a ratio of straight sections close to unity. This is shown by the curves in FIG. 6, to which we will refer in more detail later.
  • control current I c serves to regulate the initial magnetic state, or, which amounts to the same thing, to regulate the speed with which the magnetization at saturation will be reached during alternation of the primary current.
  • this saturating magnetization is carried out, in principle, only by one of the two half-waves, namely that creating in the auxiliary core a magnetic induction which is added to that already present, generated by the control current. .
  • each alternation is saturating it is possible, as shown in the alternative embodiment shown in Figures 4 and 5, to divide the auxiliary magnetic core into two identical parts 10a and 10b . These parts are arranged symmetrically on both sides of the primary winding 3 in the space 11 within the coil. Each part is provided with its own control winding 12a or 12b for the circulation of the control current I c (or I c ′) produced by the unit 13 .
  • the winding directions of the windings (or their mode of connection to the terminals of the source 13 ) are such that the control currents flow simultaneously in opposite directions in their respective windings.
  • control winding is provided so as to produce a sufficient number of ampere-turns to saturate the auxiliary core when I c reaches a maximum value I sat .
  • the mass of the auxiliary core will be determined in each case, according to the wishes or needs of the user as to the width of the power adjustment range.
  • the influence of the relative mass of the auxiliary core on the power adjustment range becomes insensitive beyond a certain threshold.
  • the curves show a clear decrease as soon as the ratio of the auxiliary / main magnetic masses becomes less than 1
  • auxiliary nucleus when the auxiliary nucleus is split into its two parts 10a , 10b (variant fig. 4 and 5), it is the sum of the masses of each part, and not the mass of each, which must be considered at this point. respect.
  • Adjustment can be easily automated, if desired.
  • a regulator 20 can be provided to control the current unit 13 , 14 continuous so as to maintain the temperature difference between a set value Vc and the value it receives from a sensor 19 , identifying the temperature of the water at the outlet 7 of the coil, below a desired threshold predetermined.
  • the voltage induced at the terminals of the coil depends on the transformation ratio, that is to say on the ratio between the number of turns of the coil 2 and that of the primary winding 3 . It will therefore be advantageous, in order to obtain high heating powers, to make the device work in step-down voltage by providing for a number of turns significantly lower for the coil than for the winding of the primary.
  • We can thus make boilers in a wide range of power ranging, for example, from 100 Kw to 10 Mw approximately, from a three-phase supply from the medium-voltage network, each phase supplying an elementary transducer 1 , 1 ′, 1 ⁇ of the device illustrated on fig. 2 or 5.
  • the regulation operates without difficulty over almost the entire range of the boiler's nominal power.
  • the cos ⁇ can change between 0.93 “front” and 0.93 “rear”, thanks to the presence of capacitors, not shown, conventionally mounted in parallel on the primary circuit, so as to best adapt on the conditions of the electricity distribution network.
  • the metal from which the coil is formed is advantageously stainless steel, or any other metal having a high electrical resistivity. This makes it possible to work with low current densities, of the order of 10 to 15 A / mm2, for example. In addition, with the use of an austenitic stainless steel, the resistance to hot corrosion is particularly satisfactory.
  • Usual measures to improve the heating efficiency can be taken without difficulty, for example an insulation 24 of the coil.
  • auxiliary core 10 many alternative embodiments can be envisaged. Whatever form or structure is chosen, it is important, as already said, that it can be saturated by the magnetic field created by the control current I c . A sufficient number of turns for the control winding 12 will be provided for this purpose, in order to avoid having to use high intensities (of more than 20 A approximately, to fix ideas).
  • the complete three-phase generator therefore comprises two separate magnetic circuits, one specific to the "transformer" part and including the main cores, the other looping between them the auxiliary cores 10a , ... or 10b ....
  • FIG. 5 An exemplary embodiment is well illustrated in FIG. 5.
  • upper 16 and lower 16 ′ yokes (the latter being visible only in FIG. 4) interconnect the main cores 4 , 4 ′ and 4 ⁇ , the assembly forming a magnetic circuit of the usual type for a three-phase transformer.
  • columns 17a and 18a for the return of the magnetic flux are arranged on either side of the group formed by the three auxiliary cores 10a , 10′a and 10 ⁇ a .
  • These five columns are interconnected by means of common upper 21a and lower 21′a yokes , also clearly visible in FIG. 4.
  • Identical arrangements are made for the other group formed by the three auxiliary cores 10b , 10 ′ B and 10 ⁇ b using the end columns 17b , 18b and the cylinder heads 21b and 21′b .
  • Figure 7 shows another embodiment of the auxiliary magnetic circuits. It consists schematically of replacing the common end columns and the cylinder heads common to a group of auxiliary cores by individual circuits for each core. These circuits are therefore in number equal to that of the auxiliary cores and each comprise a return column 23a ( 23b ) individually matched to its associated core using equally individual yokes 22a ( 22b ).
  • the first embodiment described (fig.5), known as "with five columns”, makes it possible jointly to reduce the number of constituent elements of the auxiliary magnetic circuits and to constitute, in itself, a rigid compact architecture which can possibly serve as a chassis for support for the rest.
  • the variant with individual yokes of FIG. 7, called “six columns” allows the control currents to flow in opposite directions in the windings of the auxiliary cores of the same group 10a , .. or 10b,.
  • We could, moreover, find advantage in sizing the magnetic circuit 10 so that, for a given nominal power available in the primary, we are already at the start of the saturation stage when I vs 0 .
  • the core could quickly become undersized, which would reduce the extent of the range of adjustment of the power transmissible to the secondary.
  • the core would be oversized. This, in itself, is not necessarily annoying, but nevertheless represents a factor of additional cost and goes against the aim sought, which is to reduce the size of the device as much as possible. In addition, this would help to tighten this time the power adjustment range and thereby impose an increased precision, therefore less easy, on the value of the power in this range.
  • auxiliary magnetic core rigorously has the same overall effect on the capture of the power transmissible to the secondary by the primary, insofar as it is placed between the two windings.
  • the primary winding is inside, around the main magnetic core, or outside, then surrounding not only the main core, but also the coil and the auxiliary magnetic core arranged side by side, when the modification the magnetic state of the latter adjusts the short-circuit current on the secondary, it also adjusts the supply current of the other winding, regardless of their relative position.
  • Practical considerations alone make it preferable to put the coil in an external position, such as the ease of access to the input-output thereof, or the reduction in the length of the average turn of the primary, which minimizes the losses and makes it possible to improve electrical efficiency.
  • the field of application of the invention includes the production of hot water, both for heating buildings and for use in industrial processes.
  • the invention also applies to the heating of heat transfer fluids other than water, for example oil, or even molten salts intended to be used as such or to generate steam at high temperature in exchangers.
  • the invention although initially carried out for heating fluids, is by no means limited to an induction boiler, but extends to any generator capable of delivering to the terminals of its secondary winding an adjustable electrical power. In order to achieve this, it suffices to replace, in the boiler exemplified above, the heating coil in short circuit with a simple electrical winding, connectable at its ends to a circuit for use.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Induction Heating (AREA)
  • Catching Or Destruction (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

This generator, usable in a hot water induction boiler, of the "transformer" type having primary 3 and secondary concentric windings surrounding a magnetic core 4 and whose secondary winding, preferably disposed externally, is constituted by a short-circuited 8 tubular coil 2, comprises means of adjusting the power available to the secondary which are constituted by an auxiliary magnetic core 10 disposed in the space 11 separating the primary and secondary windings, without connection with the main core 4 and provided with an electrical control winding 12 and by a unit 13, 14 with adjustable direct -or rectified- current Ic supplying the control winding. Preferably, the auxiliary core is divided into two parts 10a and 10b each provided with its own control winding 12a and 12b in which the adjustable direct currents circulate together in opposite senses. The invention allows direct linear adjustment of the power, and, by comparison with the known generators of the same type, it is such as to procure appreciable advantages in size, simplicity and reliability. <IMAGE>

Description

La présente invention a trait, de façon générale, à la fourniture d'une puissance électrique réglable à un circuit d'utilisation. Elle concerne plus particulièrement la production d'un fluide chaud, notamment d'un liquide, tel de l'eau, au sein d'une chaudière électrique à induction à puissance de chauffage réglable.The present invention relates, in general, to the supply of an adjustable electrical power to a circuit of use. It relates more particularly to the production of a hot fluid, in particular a liquid, such as water, within an electric induction boiler with adjustable heating power.

Les chaudières du type considéré sont conçus comme des transformateurs dont l'enroulement secondaire, mis en court-circuit, est constitué par un tube métallique enroulé en serpentin et parcouru par le fluide à chauffer.Celui-ci s'échauf fe au contact de la paroi du serpentin, elle-même portée en température par effet Joule, en raison des courants induits qu'y développe le flux magnétique variable produit dans le circuit magnétique par le courant électrique du primaire.Boilers of the type under consideration are designed as transformers, the secondary winding of which, short-circuited, consists of a metal tube wound in a coil and traversed by the fluid to be heated. This is heated in contact with the wall of the coil, itself brought to temperature by the Joule effect, due to the induced currents which the variable magnetic flux produced therein produced in the magnetic circuit by the electric current of the primary.

Des chaudières thermo-inductives de ce type sont déjà connues, par exemple des documents: FR-B-527697, GB-B-2178254 GB-A-2105159, USP 2,856,498, ou encore l'EP-A-0193843.Thermo-inductive boilers of this type are already known, for example documents: FR-B-527697, GB-B-2178254 GB-A-2105159, USP 2,856,498, or even EP-A-0193843.

Contrairement aux chaudières électriques classiques, ces appareils présentent la particularité de dissocier totalement le circuit d'alimentation électrique (le primaire) de la partie"chauffage".La sécurité des utilisateurs s'en trouve ainsi renforcée. De plus, le rapport de transformation propre aux transformateurs peut être mis à profit pour placer le serpentin à la basse tension tout en assurant une puissance élevée transmise par le primaire.Unlike conventional electric boilers, these devices have the particularity of completely dissociating the electrical supply circuit (the primary) from the "heating" part. User safety is thus reinforced. In addition, the transformation ratio specific to transformers can be used to place the coil at low voltage while ensuring high power transmitted by the primary.

Un aspect essentiel non encore parfaitement résolu, semble t'il, demeure cependant le réglage de la puissance qui doit permettre de doser le chauffage du fluide selon les besoins.An essential aspect which has not yet been fully resolved, it seems, remains the adjustment of the power which must make it possible to adjust the heating of the fluid as required.

Le premier des documents précités (FR-B-527697) suggère, à cette fin de se servir d'un simple rhéostat placé en série avec l'enroulement primaire d'un transformateur à enrou lements concentriques.The first of the aforementioned documents (FR-B-527697) suggests, for this purpose, using a simple rheostat placed in series with the primary winding of a transformer with concentric windings.

Le document EP-A-0193843 également précité, propose une solution plus soucieuse du rendement énergétique de l'appareil. La régulation de la puissance de chauffage s'obtient au moyen de thyristors montés en cascade sur la serpentin au secondaire. A cet effet, celui-ci est constitué d'une batterie de mini-circuits hydrauliques en parallèle. La régulation ne peut se faire cependant que par sauts discréts. De plus, l'appareillage semble complexe, côuteux et sa fiabilité dépend de la tenue en usage de composants électroniques.The document EP-A-0193843 also cited above, proposes a solution more concerned with the energy efficiency of the device. The regulation of the heating power is obtained by means of thyristors connected in cascade on the coil at secondary. To this end, it consists of a battery of hydraulic mini-circuits in parallel. The regulation can only be done by discrete jumps. In addition, the apparatus seems complex, costly and its reliability depends on the holding in use of electronic components.

Dans sa demande de brevet français n° 87.04925 du 07-04-87, le Demandeur a déjà proposé une solution de réglage de la puissance " en continu ", consistant à utiliser une inductance saturable en série dans le circuit primaire. Le noyau magnétique de l'inductance est pourvu d'un enroulement de commande dans lequel circule un courant continu -ou redressé-modifiant l'état magnétique du noyau.In its French patent application no. 87.04925 of 07-04-87, the Applicant has already proposed a solution for regulating the power "continuously", consisting in using a saturable inductor in series in the primary circuit. The magnetic core of the inductor is provided with a control winding in which a direct current - or rectified current - modifying the magnetic state of the core.

La présente invention, applicable aux chaudières dotées d'enroulements co-axiaux, a pour but une solution de réglage "en continu" de la puissance de chauffe, fiable tout autant, mais plus économique et d'encombrement plus réduit encore que la solution évoquée çi-dessus.The present invention, applicable to boilers provided with co-axial windings, aims at a solution of "continuous" adjustment of the heating power, reliable just as much, but more economical and of even smaller footprint than the solution mentioned. above.

A cet effet, l'invention pour objet un générateur de puissance électrique réglable, notamment pour la production d'un fluide chaud dans une chaudière électrique à induction, comprenant un transducteur magnétique, du type"transformateur" à enroulements primaire et secondaire entourant un noyau magnétique, l'un des enroulements entourant l'autre, et des moyens de réglage de la puissance électrique disponible au secondaire, générateur caractérisé en ce que lesdits moyens de réglage de la puissance sont cons titués par un noyau magnétique auxiliaire, séparé du noyau magnétique principal, pourvu d'un enroulement électrique de commande et disposé entre les enroulements primaire et secondaire, et par un générateur de courant continu -ou redressé-alimentant ledit enroulement de commande et associé à des moyens de réglage de l'intensité dudit courant continu.To this end, the invention relates to an adjustable electric power generator, in particular for the production of a hot fluid in an electric induction boiler, comprising a magnetic transducer, of the "transformer" type with primary and secondary windings surrounding a core. magnetic, one of the windings surrounding the other, and means for adjusting the electric power available in the secondary, generator characterized in that said power adjusting means are constituted by an auxiliary magnetic core, separate from the magnetic core main, provided with an electrical control winding and arranged between the primary and secondary windings, and by a direct current generator - or rectified - supplying said control winding and associated with means for adjusting the intensity of said direct current.

Dans l'utilisation du générateur en tant que chaudière, l'enroulement secondaire est constitué par un serpentin tubulaire en court-circuit, destiné à être parcouru par un fluide à chauffer.In the use of the generator as a boiler, the secondary winding is constituted by a tubular coil in short circuit, intended to be traversed by a fluid to be heated.

De préférence, le serpentin de chauffe est disposé extérieurement à l'enroulement primaire.Preferably, the heating coil is arranged outside the primary winding.

Conformément à une variante de réalisation préférée, l'enroulement extérieur est de conformation oblongue pour pouvoir accueillir le noyau magnétique auxiliaire disposé à coté de l'enroulement intérieur.According to a preferred embodiment, the outer winding is of oblong conformation to be able to accommodate the auxiliary magnetic core arranged at side of the interior winding.

Conformément à une autre variante de réalisation préférée, le noyau magnétique auxiliaire est formé de deux parties semblables dotées chacune d'un enroulement de commande, dans lesquels les courants continus -ou redressés- circulent dans dans des sens opposés. Ces deux parties sont avantageusement disposées de part et d'autre de l'enroulement intérieur.According to another preferred alternative embodiment, the auxiliary magnetic core is formed by two similar parts each provided with a control winding, in which the direct or rectified currents flow in opposite directions. These two parts are advantageously arranged on either side of the interior winding.

Pour des raisons pratiques, on se réfèrera dans ce qui suit uniquement à la chaudière, étant entendu que tout ce qui sera dit à ce sujet concerne tout autant l'invention dans son acception plus générale en tant que générateur de puissance électrique réglable.For practical reasons, reference will be made in the following only to the boiler, it being understood that everything that will be said on this subject concerns the invention just as much in its more general sense as an adjustable electric power generator.

Comme on l'aura sans doute déjà compris, l'idée à la base de l'invention est de faire varier l'inductance propre du serpentin de chauffe à l'aide d'un noyau magnétique additionnel (ou auxiliaire) placé dans l'espace séparant les deux enroulements et dont la perméabilité est controlée par application d'un champ magnétique stationnaire produit,lui, par un enroulement de commande à courant continu-ou redréssé- bobiné autour du noyau auxiliaire et dont on règle l'intensité.As will no doubt have already been understood, the idea underlying the invention is to vary the specific inductance of the heating coil using an additional (or auxiliary) magnetic core placed in the space separating the two windings and whose permeability is controlled by application of a stationary magnetic field produced by a control winding with direct current - or redesigned - wound around the auxiliary core and whose intensity is regulated.

Ce bobinage est de taille suffisante pour produire un champ magnétique capable de saturer le noyau magnétique auxiliaire quand le courant de commande est réglé à son intensité maximale, Ic max.This winding is of sufficient size to produce a magnetic field capable of saturating the auxiliary magnetic core when the control current is set to its maximum intensity, Ic max.

Le noyau magnétique auxiliaire est avantageusement formé de deux parties indépendantes analogues pour prendre en compte le fait que le courant d'exitation au primaire est un courant alternatif. S'il s'agit d'un alternatif pûr à alternances symétriques, les deux parties constitutives du noyau pourront être rigoureusement identiques. Sinon,elles pourront présenter entre-elles une différence, par exemple dans le nombre d'ampères-tours des enroulements de commande, ou de leur masse de matière magnétique.The auxiliary magnetic core is advantageously formed from two similar independent parts to take into account the fact that the excitation current at the primary is an alternating current. If it is a pure alternative with symmetrical alternations, the two constituent parts of the core may be strictly identical. Otherwise, they may have a difference between them, for example in the number of ampere-turns of the control windings, or of their mass of magnetic material.

Les enroulements de commande sont parcourus par des courants continus (ou redréssés) circulant en sens opposés pour tenir compte du caractère alternatif du champ magnétique crée par le primaire.A tout instant, ce champ est donc magnétisant pour l'une des parties du noyau auxiliaire et démagnétisant pour l'autre,et "vice et versa"à l'alternance suivante. Globalement, on équilibre ainsi sur une période l'effet des alternances. Le noyau auxiliaire fonctionne donc de manière totalement indépendante du sens de circulation du courant dans l'enroulement primaire.The control windings are traversed by direct currents (or straightened) flowing in opposite directions to take account of the alternating nature of the magnetic field created by the primary. At all times, this field is magnetizing for one of the parts of the auxiliary core and demagnetizing for the other, and "vice versa" at the next alternation. Overall, we balance the effect of alternations over a period. The auxiliary core therefore operates completely independently of the direction of current flow in the primary winding.

L'invention sera bien comprise et d'autres aspects et avantages ressortiront plus clairement au vu de la description qui suit, donnée à titre d'exemple, en référence aux planches de dessins annexées sur lesquelles:

  • la figure 1 représente schématiquement un transducteur monophasé élémentaire constitutif d'une chaudière triphasée selon l'invention, dans sa version de base la plus simple, vue en coupe longitudinale selon le plan B -B de la figure 2, et comportant un noyau magnétique auxiliaire unique à enroulement de commande unique;
  • la figure 2 montre en coupe transversale selon le plan A-A de la figure 1 les trois transducteurs élémentaires monophasés formant ensemble la chaudière;
  • la figure 3 est un schéma de montage électrique illustrant le regroupement des trois transducteurs de la figure 2 pour former le générateur triphasé unique constituant la chaudière;
  • la figure 4 représente,vue en coupe longitudinale selon le plan C-C de la figure 5, une réalisation de la chaudière à noyau magnétique auxiliaire dédoublé en deux parties dotées chacune d'un enroulement de commande;
  • la figure 5 représente la chaudière de la figure 4 vue en coupe transversale selon le plan D-D de la figure 4;
  • la figure 6 est un diagramme montrant,dans le cas d'une installation expérimentale de taille industrielle,l'évolution de la fraction de puissance de chauffage disponible"capturée" par le noyau magnétique auxiliaire en fonction de la section relative de ce noyau par rapport à celle du noyau principal;
  • la figure 7 est une vue analogue à la figure 5, mais montrant une autre forme de réalisation du circuit magnétique auxiliaire.
The invention will be well understood and other aspects and advantages will emerge more clearly in the light of the description which follows, given by way of example, with reference to the plates of attached drawings in which:
  • FIG. 1 schematically represents an elementary single-phase transducer constituting a three-phase boiler according to the invention, in its simplest basic version, seen in longitudinal section along plane B -B in FIG. 2, and comprising an auxiliary magnetic core single with single control winding;
  • Figure 2 shows in cross section along the plane AA of Figure 1 the three single-phase elementary transducers together forming the boiler;
  • Figure 3 is an electrical circuit diagram illustrating the grouping of the three transducers of Figure 2 to form the single three-phase generator constituting the boiler;
  • 4 shows, in longitudinal section along the plane CC of Figure 5, an embodiment of the auxiliary magnetic core boiler split into two parts each with a control winding;
  • 5 shows the boiler of Figure 4 seen in cross section along the plane DD of Figure 4;
  • FIG. 6 is a diagram showing, in the case of an experimental installation of industrial size, the evolution of the fraction of available heating power "captured" by the auxiliary magnetic core as a function of the relative section of this core with respect to to that of the main nucleus;
  • Figure 7 is a view similar to Figure 5, but showing another embodiment of the auxiliary magnetic circuit.

Sur toutes ces figures, les mêmes éléments sont désignés par des références identiques.In all these figures, the same elements are designated by identical references.

On reconnait, dans le transducteur élémentaire 1 de la figure 1, la structure habituelle d'un transformateur à enroulements extérieur 2 et intérieur 3, entourant un noyau magnétique central 4. Dans l'exemple considéré, le serpentin forme l'enroulement extérieur 2. L'enroulement intérieur 3, alimenté par le réseau de distribution de l'électricité symbolisé par l'unité 5, constitue donc ici l'enroulement primaire.We recognize, in the elementary transducer 1 of FIG. 1, the usual structure of a transformer with external windings 2 and internal 3 , surrounding a central magnetic core 4 . In the example considered, the coil forms the outer winding 2 . The inner winding 3 , supplied by the electricity distribution network symbolized by the unit 5 , therefore constitutes the primary winding here.

Le serpentin 2 est avantageusement un tube en acier inoxydable. Il est parcouru par un fluide caloporteur à chauffer, que l'on admettra être de l'eau. L'eau froide pénètre par la tubulure d'entrée 6 à la base du serpentin. Elle en ressort par la conduite de sortie 7 à l'extrémité supérieure, après s'être échauffée au contact de la paroi interne.The coil 2 is advantageously a stainless steel tube. It is traversed by a heat transfer fluid to be heated, which one will admit to be water. Cold water enters through the inlet tubing 6 at the base of the coil. It emerges from it via the outlet pipe 7 at the upper end, after having heated up in contact with the internal wall.

Le serpentin est mis en court-circuit sur lui-même par une liaison électrique 8 qui relie entre-elles les conduites d'entrée 6 et de sortie 7. Par sécurité, une mise à la terre 9 de l'enroulement secondaire 2 est prévue au delà du pontage de court-circuit 8.The coil is short-circuited on itself by an electrical connection 8 which interconnects the inlet 6 and outlet 7 pipes. For safety, an earthing 9 of the secondary winding 2 is provided beyond the short-circuit bridging 8 .

Comme on le voit, un noyau magnétique auxiliaire 10 est disposé dans l'espace intérieur 11 ,entre l'enroulement primaire intérieur 3 et le serpentin 2. Ce noyau, formé par empilage de toles magnétiques à l'instar du noyau principal 4, est doté d'un enroulement de commande 12 l'entourant sur une partie de sa hauteur. Cet enroulement est alimenté en courant continu (ou redressé) par une unité 13 équipée d'un variateur, symbolisé en 14 à sa sortie, pour le réglage de l'intensité Ic de ce courant continu de commande.As can be seen, an auxiliary magnetic core 10 is placed in the interior space 11 , between the interior primary winding 3 and the coil 2 . This core, formed by stacking magnetic sheets like the main core 4, has a control winding 12 surrounding it over part of its height. This winding is supplied with direct current (or rectified) by a unit 13 equipped with a variator, symbolized at 14 at its output, for adjusting the intensity I c of this direct control current.

Un interrupteur 15 a également été prévu sur le circuit du primaire pour permettre son ouverture rapide en cas de besoin.A switch 15 has also been provided on the primary circuit to allow rapid opening if necessary.

La figure 2 montre la chaudière complète formée de trois transducteurs identiques 1, 1′ et 1˝ disposés côte-à-côte. On se rend mieux compte, au vu de cette figure, de la forme oblongue avantageusement conférée à l'enroulement extérieur 2. Cette conformation permet d'acceuillir,dans l'espace 11, au sein du serpentin 2, l'enroulement primaire 3 et le noyau magnétique auxiliaire 10, en les disposant l'un à côté de l'autre tout en minimisant l'espace 11.Figure 2 shows the complete boiler formed by three identical transducers 1 , 1 ′ and 1˝ arranged side by side. We are better aware, in view of this figure, of the oblong shape advantageously imparted to the outer winding 2 . This conformation makes it possible to accommodate, in space 11 , within the coil 2 , the primary winding 3 and the auxiliary magnetic core 10 , by placing them one next to the other while minimizing space 11 .

On se rend également bien compte, au vu de cette figure et de la figure 3, que la chaudière selon l'invention peut parfaitement être construite sur la base d'un transformateur triphasé. Chacun des éléments opérationnels identiques 1, 1′ ou 1˝ constitue un transducteur autonome. Chaque transducteur est relié à une phase différente( U, V ou W) d'une alimentation électrique triphasée. Les trois enroulements primaires 3,3′et 3˝ sont montés ici en étoile. Chacun d'eux induit, par l'intermédiaire d'un circuit magnétique, dans un serpentin 2, 2′ ou 2˝. Chaque serpentin est monté sur une branche d'un circuit hydraulique de chauffage, qui en contient trois en parallèle.It is also very clear, in view of this figure and of FIG. 3, that the boiler according to the invention can perfectly be built on the basis of a transformer three phase. Each of the identical operational elements 1 , 1 ′ or 1˝ constitutes an autonomous transducer. Each transducer is connected to a different phase (U, V or W) of a three-phase power supply. The three primary windings 3 , 3 ′ and 3˝ are mounted here in a star shape . Each of them induces, via a magnetic circuit, in a coil 2 , 2 ′ or 2 ˝. Each coil is mounted on a branch of a hydraulic heating circuit, which contains three in parallel.

Chaque transducteur élémentaire représenté sur la fig. 1 fonctionne de la manière suivante:Each elementary transducer shown in FIG. 1 works as follows:

Du fait que le serpentin 2 est en court-circuit sur lui même, un courant électrique y circule lorsque l'interrupteur 15 est en position fermée.Ce courant induit provoque un dégagement de chaleur par effet Joule, qui est transférée à l'eau à chauffer lors du passage de celle-ci au contact de la surface interne du serpentin.Because the coil 2 is short-circuited on itself, an electric current flows there when the switch 15 is in the closed position. This induced current causes heat generation by the Joule effect, which is transferred to the water at heat when it passes in contact with the internal surface of the coil.

Ce dégagement de chaleur dépend de l'intensité du courant dans le secondaire 2, laquelle est déterminée par la tension induite aux bornes de ce dernier. Cette tension est liée à la tension aux bornes du primaire 3, par le couplage magnétique entre les deux enroulements.This heat generation depends on the intensity of the current in the secondary 2 , which is determined by the voltage induced at the terminals of the latter. This voltage is linked to the voltage across the primary 3 , by the magnetic coupling between the two windings.

Afin de régler la puissance de chauffage développée par le serpentin, l'invention modifie ce couplage grâce au noyau auxiliaire 10 placé dans l'espace séparant le serpentin de l'enroulement primaire intérieur.In order to regulate the heating power developed by the coil, the invention modifies this coupling by virtue of the auxiliary core 10 placed in the space separating the coil from the internal primary winding.

En fait, ce noyau magnétique auxiliaire, là où il se trouve entre les deux enroulements du transducteur, agit à l'égard du serpentin comme un noyau de fer dans une bobine à induction.On modifie le coefficient de self induction du serpentin en faisant varier l'état magnétique du noyau auxiliaire à l'aide du courant continu (ou redréssé) Ic circulant dans l'enroulement de commande 12 monté à cet effet autour du noyau:In fact, this auxiliary magnetic core, where it is between the two windings of the transducer, acts with respect to the coil like an iron core in an induction coil. We modify the coefficient of self induction of the coil by varying the magnetic state of the auxiliary core by means of direct current (or recursed) I c flowing in the control winding 12 mounted for this purpose around the core:

Quand I c = 0

Figure imgb0001
, l'effet de self est maximal ("self dans le fer"). La puissance active, c'est-à-dire la puissance de chauffage du secondaire, est donc minimale.When I vs = 0
Figure imgb0001
 , the self effect is maximum ("self in the iron"). The active power, that is to say the heating power of the secondary, is therefore minimal.

Quand Ic est maximale (I c =I max )

Figure imgb0002
, l'effet de self est le plus faible. La puissance de chauffage est alors maximale.When I c is maximum (I vs = I max )
Figure imgb0002
 , the self effect is the weakest. The heating power is then maximum.

Si, conformément à l'invention, Imax parvient à saturer le noyau auxiliaire (I max = I sat )

Figure imgb0003
, on est alors dans une situation de type "self dans l'air". La substance magnétique constitutive du noyau n'a plus aucune influence sur l'inductance du secondaire. La puissance de chauffe délivrée par le serpentin est alors la même que celle que lui fournirait le primaire en l'absence de noyau auxiliaire.If, according to the invention, I max manages to saturate the auxiliary nucleus (I max = I sat )
Figure imgb0003
 , we are then in a situation of type "self in the air". The magnetic substance constituting the nucleus no longer has any influence on the inductance of the secondary. The heating power delivered by the coil is then the same as that which the primary would provide to it in the absence of an auxiliary core.

Entre ces deux points de fonctionnement extrêmes, le choix de la valeur de Ic permet de régler la puissance de chauffage au niveau désiré.Between these two extreme operating points, the choice of the value of I c allows the heating power to be adjusted to the desired level.

Par ailleurs,conformément à une réalisation avantageuse de l'invention, la substance magnétique du noyau auxiliaire est en quantité suffisante pour éviter, lorsque I c = 0

Figure imgb0004
, que le noyau sature avant d'être à son aimantation maximale sous l'effet du champ magnétique créé par le serpentin. L'effet de self pûre est alors très grand et la puissance de chauffage est, en contrepartie, quasi-nulle. L'expérience a montré que cette quantité "suffisante" de substance magnétique est réalisée avec une masse égale à environ une fois celle du noyau magnétique principal 4. Dans les formes de réalisation les plus fréquentes, les noyaux magnétiques ayant tous même hauteur, cette condition se ramène à un rapport des sections droites voisin de l'unité. C'est ce que montrent les courbes de la figure 6, à laquelle on se reportera plus en détails par la suite.Furthermore, in accordance with an advantageous embodiment of the invention, the magnetic substance of the auxiliary core is in sufficient quantity to avoid, when I vs = 0
Figure imgb0004
 , that the nucleus saturates before being at its maximum magnetization under the effect of the magnetic field created by the coil. The pure self effect is then very large and the heating power is, in return, almost zero. Experience has shown that this "sufficient" quantity of magnetic substance is produced with a mass equal to approximately once that of the main magnetic core 4 . In the most frequent embodiments, the magnetic cores all having the same height, this condition is reduced to a ratio of straight sections close to unity. This is shown by the curves in FIG. 6, to which we will refer in more detail later.

On a en fait compris que le noyau auxiliaire travaille toujours à saturation.Le courant de commande Ic sert à régler l'état magnétique initial, ou,ce qui revient au même,à régler la rapidité avec laquelle l'aimantation à saturation sera atteinte au cours d'une alternance du courant au primaire.We have in fact understood that the auxiliary core is always working at saturation. The control current I c serves to regulate the initial magnetic state, or, which amounts to the same thing, to regulate the speed with which the magnetization at saturation will be reached during alternation of the primary current.

En fait, cette aimantation saturante n'est réalisée, en principe, que par l'une des deux alternances, à savoir celle créant dans le noyau auxiliaire une induction magnétique qui vient s'ajouter à celle déjà présente, générée par le courant de commande.In fact, this saturating magnetization is carried out, in principle, only by one of the two half-waves, namely that creating in the auxiliary core a magnetic induction which is added to that already present, generated by the control current. .

Pour parvenir à ce que chaque alternance soit saturante il est possible, comme le montre la variante de réalisation représentée sur les figures 4 et 5 , de diviser le noyau magnétique auxiliaire en deux parties identiques 10a et 10b. Ces parties sont disposées symétriquement de part et d'autre de l'enroulement primaire 3 dans l'espace 11 au sein du serpentin. Chaque partie est pourvue de son enroulement de commande propre 12a ou 12b pour la circulation du courant de commande Ic(ou Ic′) produit par l'unité 13. Les sens de bobinage des enroulements (ou leur mode de connexion aux bornes de la source 13)sont tels que les courants de commande circulent simultanément en sens opposés dans leurs enroulements respectifs.To achieve that each alternation is saturating it is possible, as shown in the alternative embodiment shown in Figures 4 and 5, to divide the auxiliary magnetic core into two identical parts 10a and 10b . These parts are arranged symmetrically on both sides of the primary winding 3 in the space 11 within the coil. Each part is provided with its own control winding 12a or 12b for the circulation of the control current I c (or I c ′) produced by the unit 13 . The winding directions of the windings (or their mode of connection to the terminals of the source 13 ) are such that the control currents flow simultaneously in opposite directions in their respective windings.

L'explication de telles dispositions a déjà été exposée auparavant. Elle tient au caractère "alternatif" du courant au primaire, par opposition au caractère "continu" du courant de commande. Le fait d'avoir des courants de commande circulant dans des sens opposés dans leurs enroulements respectifs 12a et 12b rend le champ magnétique produit par le serpentin de chauffe 2 plus rapidement saturant dans l'une des parties du noyau auxiliaire au cours d'une alternance, et plus rapidement saturant, de façon symétrique, dans l'autre à l'alternance suivante. Globalement, celà revient à rendre les variations du courant alternatif du primaire sans effet aucun sur le comportement du noyau auxiliaire.The explanation of such provisions has already been explained before. It is due to the "alternating" character of the primary current, as opposed to the "continuous" character of the control current. Having control currents flowing in opposite directions in their respective windings 12a and 12b makes the magnetic field produced by the heating coil 2 more quickly saturating in one of the parts of the auxiliary core during alternation. , and more quickly saturating, symmetrically, in the other at the next alternation. Overall, this amounts to rendering variations in the alternating current of the primary without any effect on the behavior of the auxiliary core.

On rappelle qu'il importe que l'enroulement de commande soit prévu de façon à réaliser un nombre d'Ampères-tours suffisant pour saturer le noyau auxiliaire quand Ic atteint une valeur maximale Isat.It is recalled that it is important that the control winding is provided so as to produce a sufficient number of ampere-turns to saturate the auxiliary core when I c reaches a maximum value I sat .

Par ailleurs, la masse magnétique constitutive du noyau auxiliaire doit être suffisante pour pouvoir "capter" à vide (c'est-à-dire quand I c =0

Figure imgb0005
) une fraction du flux magnétique généré au sein du serpentin la plus grande possible avant d'atteindre la saturation.Furthermore, the magnetic mass constituting the auxiliary core must be sufficient to be able to "pick up" when empty (that is to say when I vs = 0
Figure imgb0005
 ) the largest possible fraction of the magnetic flux generated within the coil before reaching saturation.

Ces deux considérations sont à la base de la définition de la plage de réglage de la puissance de chauffage. Pour mieux l'illustrer, les courbes de la figure 6 ont été construites à partir d'une chaudière expérimentale conforme aux figures 4 et 5. Ces courbes,paramétrées sur l'intensité Ic du courant de commande, montrent que la fraction de puissance transmise au serpentin par le primaire cro t avec Ic et décro t quand la masse du noyau magnétique auxiliaire augmente. Par exemple, avec une masse magnétique 10 égale à celle du noyau principal 4 (rapport de sections de 1), on parvient"à vide" ( I c =0

Figure imgb0006
) à "capturer" plus de 98 % de la puissance de chauffage transmissible au serpentin par le primaire En revanche, sous un courant de commande saturant ( I c = I sat.
Figure imgb0007
 ) quelques pourcents seulement de la puissance disponible ne sont pas transmis au serpentin. On remarque d'ailleurs que sous Isat. , cette faible fraction de puissance"capturée"par le noyau auxiliaire est une quantité invariante de la masse de ce dernier.Ceci exprime sans doute l'effet de la conformation oblongue donnée à l'espace de séparation 11, qui localement éloigne les deux enroulements 2 et 3 et dégrade donc légèrement leur couplage magnétique.These two considerations are the basis for the definition of the heating power adjustment range. To better illustrate this, the curves in Figure 6 were constructed from an experimental boiler conforming to Figures 4 and 5. These curves, set to the intensity I c of the control current, show that the power fraction transmitted to the coil by the primary increases with I c and decreases when the mass of the auxiliary magnetic core increases. For example, with a magnetic mass 10 equal to that of the main core 4 (section ratio of 1), we arrive "empty" ( I vs = 0
Figure imgb0006
 ) to "capture" more than 98% of the power heating transmissible to the coil by the primary On the other hand, under a saturated control current ( I vs = I sat.
Figure imgb0007
 ) only a few percent of the available power is not transmitted to the coil. We also note that under I sat. , this small fraction of power "captured" by the auxiliary core is an invariant quantity of the mass of the latter. This undoubtedly expresses the effect of the oblong conformation given to the separation space 11 , which locally distances the two windings 2 and 3 and therefore slightly degrades their magnetic coupling.

On déterminera la masse du noyau auxiliaire dans chaque cas, en fonction des souhaits ou des nécessités de l'utilisateur quant à la largeur de la plage de réglage en puissance. Cependant, en raison de l'allure logarithmique que doivent avoir les tracés complets des courbes (allure déjà visible avec les points expérimentaux de la courbe I c =0

Figure imgb0008
), l'influence de la masse relative du noyau auxiliaire sur la plage de réglage de la puissance devient peu sensible au delà d'un certain seuil. Dans les conditions d'établissement de la figure 6, le seuil n'est pas encore atteint pour une masse égale à 1 fois environ celle du noyau principal 4, sauf "à vide" c'est-à-dire quand I c =0
Figure imgb0009
 . Par contre, les courbes présentent une décroissance nette dès que le rapport des masses magnétiques auxiliaire/principal devient inférieur à 1The mass of the auxiliary core will be determined in each case, according to the wishes or needs of the user as to the width of the power adjustment range. However, due to the logarithmic shape that the complete plots of the curves must have (shape already visible with the experimental points of the curve I vs = 0
Figure imgb0008
 ), the influence of the relative mass of the auxiliary core on the power adjustment range becomes insensitive beyond a certain threshold. Under the conditions of establishment of FIG. 6, the threshold has not yet been reached for a mass equal to approximately 1 times that of the main core 4 , except "empty", that is to say when I vs = 0
Figure imgb0009
 . On the other hand, the curves show a clear decrease as soon as the ratio of the auxiliary / main magnetic masses becomes less than 1

Ce phénomène est particulièrement bien vérifié pour la courbe I c =0

Figure imgb0010
: pour un rapport de masses de 1.0, quasiment les 100% de la puissance disponible au primaire est captée par le noyau auxiliaire, alors que celui-ci ne capte déjà plus que 85% de cette puissance quand ce rapport chute à 0.86, soit de 0.16 point seulement. Ceci montre clairement qu'on a avantage à conserver un rapport de masses voisin de l'unité, puisqu'on recherche une captation maximale de la puissance transmissible la plus proche de 100%, quand I c =0
Figure imgb0011
 ) par définition.This phenomenon is particularly well verified for the curve I vs = 0
Figure imgb0010
 : for a mass ratio of 1.0, almost 100% of the power available in the primary is captured by the auxiliary nucleus, while the latter already only captures 85% of this power when this ratio drops to 0.86, or 0.16 point only. This clearly shows that it is advantageous to keep a mass ratio close to unity, since we are looking for maximum capture of the transmissible power closest to 100%, when I vs = 0
Figure imgb0011
 ) by definition.

On notera que, lorsque le noyau auxiliaire est dédoublé en ses deux parties 10a, 10b (variante fig.4 et 5), c'est la somme des masses de chaque partie,et non la masse de chacune, qui doit être considérée à cet égard.It will be noted that, when the auxiliary nucleus is split into its two parts 10a , 10b (variant fig. 4 and 5), it is the sum of the masses of each part, and not the mass of each, which must be considered at this point. respect.

Le réglage peut être aisément automatisé, si on le souhaite. Par exemple,comme le montre la figure 4, un régulateur 20 peut être prévu pour piloter l'unité 13,14 de courant continu de façon à maintenir l'écart de température entre une valeur de consigne Vc et la valeur qu'il reçoit d'un capteur 19, repèrant la température de l'eau à la sortie 7 du serpentin, en deçà d'un seuil voulu prédéterminé.Adjustment can be easily automated, if desired. For example, as shown in FIG. 4, a regulator 20 can be provided to control the current unit 13 , 14 continuous so as to maintain the temperature difference between a set value Vc and the value it receives from a sensor 19 , identifying the temperature of the water at the outlet 7 of the coil, below a desired threshold predetermined.

Bien entendu, la tension induite aux bornes du serpentin dépend du rapport de transformation, c'est-à-dire du rapport entre le nombre de spires du serpentin 2 et celui de l'enroulement primaire 3. On aura donc avantage, pour obtenir des puissances élevées de chauffage,à faire travailler l'appareil en abaisseur de tension en prévoyant un nombre de spires sensiblement plus faible pour le serpentin que pour l'enroulement du primaire.On peut ainsi réaliser des chaudières dans une large gamme de puissance,allant, par exemple, de 100 Kw à 10 Mw environ,à partir d'une alimentation triphasée du réseau moyenne tension, chaque phase alimentant un transducteur élémentaire 1,1′ ,1˝ de l'appareil illustré sur les fig. 2 ou 5.Of course, the voltage induced at the terminals of the coil depends on the transformation ratio, that is to say on the ratio between the number of turns of the coil 2 and that of the primary winding 3 . It will therefore be advantageous, in order to obtain high heating powers, to make the device work in step-down voltage by providing for a number of turns significantly lower for the coil than for the winding of the primary. We can thus make boilers in a wide range of power, ranging, for example, from 100 Kw to 10 Mw approximately, from a three-phase supply from the medium-voltage network, each phase supplying an elementary transducer 1 , 1 ′, 1 ˝ of the device illustrated on fig. 2 or 5.

La régulation s'opère sans difficultés sur la quasi-totalité de la plage de puissance nominale de la chaudière. En fonction du point de régulation, le cos Φ peut évoluer entre 0.93 "avant" et 0.93 "arrière", grâce à la présence de capacités, non représentées, montées classiquement en parallèle sur le circuit primaire, de manière à s'adapter au mieux aux conditions du réseau de distribution de l'électricité.The regulation operates without difficulty over almost the entire range of the boiler's nominal power. Depending on the regulation point, the cos Φ can change between 0.93 "front" and 0.93 "rear", thanks to the presence of capacitors, not shown, conventionally mounted in parallel on the primary circuit, so as to best adapt on the conditions of the electricity distribution network.

Le métal dont est formé le serpentin est avantageusement de l'acier inoxydable, ou tout autre métal ayant une résistivité électrique élevée. Ceci permet de travailler avec des densites de courant faibles, de l'ordre de 10 à 15 A/mm², par exemple. En outre, avec l'emploi d'un acier inoxydable austénitique, la tenue à la corrosion à chaud est particulièrement satisfaisante.The metal from which the coil is formed is advantageously stainless steel, or any other metal having a high electrical resistivity. This makes it possible to work with low current densities, of the order of 10 to 15 A / mm², for example. In addition, with the use of an austenitic stainless steel, the resistance to hot corrosion is particularly satisfactory.

Des dispositions habituelles pour améliorer le rendement de chauffage peuvent être prises sans difficultés,par exemple un calorifugeage 24 du serpentin.Usual measures to improve the heating efficiency can be taken without difficulty, for example an insulation 24 of the coil.

Quant au noyau auxiliaire 10, de nombreuses variantes de réalisation peuvent être envisagées. Quelle que soit la forme ou la structure retenues, il importe, comme déjà dit, qu'il puisse être saturé par le champ magnétique créé par le courant de commande Ic. On prévoira à cet effet un nombre de spires suffisant pour l'enroulement de commande 12, afin d'éviter de devoir faire appel à des intensités élevées (de plus de 20 A environ, pour fixer les idées).As for the auxiliary core 10 , many alternative embodiments can be envisaged. Whatever form or structure is chosen, it is important, as already said, that it can be saturated by the magnetic field created by the control current I c . A sufficient number of turns for the control winding 12 will be provided for this purpose, in order to avoid having to use high intensities (of more than 20 A approximately, to fix ideas).

Il importe aussi que le noyau auxiliaire demeure distinct et sans continuité matérielle avec le noyau magnétique principal 4. Le générateur triphasé complet comporte donc deux circuits magnétiques séparés, l'un propre à la partie "transformateur" et incluant les noyaux principaux, l'autre bouclant entre-eux les noyaux auxiliaires 10a, ... ou 10b... .It is also important that the auxiliary core remains distinct and without material continuity with the main magnetic core 4 . The complete three-phase generator therefore comprises two separate magnetic circuits, one specific to the "transformer" part and including the main cores, the other looping between them the auxiliary cores 10a , ... or 10b ....

Un exemple de réalisation est bien illustré sur la figure 5. D'un côté, des culasses supérieure 16 et inférieure 16′ (cette dernière étant visible seulement sur la figure 4) relient entre-eux les noyaux principaux 4,4′ et 4˝,l'ensemble formant un circuit magnétique de type habituel pour un transformateur triphasé. De l'autre, des colonnes 17a et 18a de retour du flux magnétique sont disposées de part et d'autre du groupe formé par les trois noyaux auxiliaires 10a, 10′a et 10˝a. Ces cinq colonnes sont reliées entre-elles à l'aide de culasses communes supérieure 21a et inférieure 21′a,également bien visibles sur la figure 4. Des dispositions identiques sont prises pour l'autre groupe formé par les trois noyaux auxiliaires 10b, 10′b et 10˝b à l'aide des colonnes d'extrémité 17b, 18b et des culasses 21b et 21′b.An exemplary embodiment is well illustrated in FIG. 5. On one side, upper 16 and lower 16 ′ yokes (the latter being visible only in FIG. 4) interconnect the main cores 4 , 4 ′ and 4˝ , the assembly forming a magnetic circuit of the usual type for a three-phase transformer. On the other, columns 17a and 18a for the return of the magnetic flux are arranged on either side of the group formed by the three auxiliary cores 10a , 10′a and 10˝a . These five columns are interconnected by means of common upper 21a and lower 21′a yokes , also clearly visible in FIG. 4. Identical arrangements are made for the other group formed by the three auxiliary cores 10b , 10 ′ B and 10˝b using the end columns 17b , 18b and the cylinder heads 21b and 21′b .

La figure 7 montre une autre forme de réalisation des circuits magnétiques auxiliaires. Elle consiste schématiquement à remplacer les colonnes d'extrémité communes et les culasses communes à un groupe de noyaux auxiliaires par des circuits individuels pour chaque noyau.Ces circuits sont donc en nombre égal à celui des noyaux auxiliaires et comprennent chacun une colonne de retour 23a (23b) appariée individuellement à son noyau associé à l'aide de culasses également individuelles 22a (22b).Figure 7 shows another embodiment of the auxiliary magnetic circuits. It consists schematically of replacing the common end columns and the cylinder heads common to a group of auxiliary cores by individual circuits for each core. These circuits are therefore in number equal to that of the auxiliary cores and each comprise a return column 23a ( 23b ) individually matched to its associated core using equally individual yokes 22a ( 22b ).

La première forme de réalisation décrite (fig.5), dite "à cinq colonnes", permet conjointement de réduire les nombre d'éléments constitutifs des circuits magnétiques auxiliaires et de constituer, en soi, une architecture compacte rigide pouvant éventuellement servir de chassis de support pour le reste. En revanche, la variante à culasses individuelles de la figure 7, dite "à six colonnes", permet aux courants de commande de circuler dans des sens opposés dans les enroulements des noyaux auxiliaires d'un même groupe 10a,..ou 10b,.. On pourra, par ailleurs, trouver avantage à dimensionner le circuit magnétique 10 de façon que, pour une puissance nominale donnée disponible au primaire, on se situe déjà au début du palier de saturation quand I c =0

Figure imgb0012
. Au delà, le noyau pourrait rapidement se trouver sous-dimensionné, ce qui réduirait l'étendue de la plage de réglage de la puissance transmissible au secondaire. En deçà, le noyau serait surdimensionné. Ceci, en soi, n'est pas nécessairement gènant, mais représente cependant un facteur de surcoût et va à l'encontre du but recherché, qui est de réduire au maximum la taille de l'appareil. De plus,celà contribuerait à ressérrer cette fois la plage de réglage de la puissance et imposerait de ce fait une précision accrue, donc moins aisée, sur la valeur de la puissance dans cette plage.The first embodiment described (fig.5), known as "with five columns", makes it possible jointly to reduce the number of constituent elements of the auxiliary magnetic circuits and to constitute, in itself, a rigid compact architecture which can possibly serve as a chassis for support for the rest. On the other hand, the variant with individual yokes of FIG. 7, called "six columns", allows the control currents to flow in opposite directions in the windings of the auxiliary cores of the same group 10a , .. or 10b,. We could, moreover, find advantage in sizing the magnetic circuit 10 so that, for a given nominal power available in the primary, we are already at the start of the saturation stage when I vs = 0
Figure imgb0012
 . Beyond this, the core could quickly become undersized, which would reduce the extent of the range of adjustment of the power transmissible to the secondary. Below that, the core would be oversized. This, in itself, is not necessarily annoying, but nevertheless represents a factor of additional cost and goes against the aim sought, which is to reduce the size of the device as much as possible. In addition, this would help to tighten this time the power adjustment range and thereby impose an increased precision, therefore less easy, on the value of the power in this range.

Il va de soi que l'invention ne se limite pas aux exemples de réalisation qui viennent d'être décrits, mais s'étend à de multiples variantes ou équivalents dans la mesure où sont respectées les caractéristiques énoncées dans les revendications jointes.It goes without saying that the invention is not limited to the embodiments which have just been described, but extends to multiple variants or equivalents insofar as the characteristics set out in the appended claims are respected.

En particulier, on aura certainement compris que la position relative des deux enroulements entre-eux est parfaitement interchangeable. Le noyau magnétique auxiliaire a rigoureusement le même effet global sur la captation de la puissance transmissible au secondaire par le primaire, dans la mesure où il est placé entre les deux enroulements. Que l'enroulement primaire soit à l'intérieur, autour du noyau magnétique principal, ou à l'extérieur, entourant alors non seulement le noyau principal, mais également le serpentin et le noyau magnétique auxiliaire disposés côte-à-côte, quand la modification de l'état magnétique de ce dernier règle le courant de court-circuit sur le secondaire, il règle de même le courant d'alimentation de l'autre enroulement, et ce,indépendamment de leur position relative. Des considérations pratiques seules font préférer la mise du serpentin en position extérieure, comme la facilité d'accès aux entrée-sortie de celui-ci, ou la diminution de la longueur de la spire moyenne du primaire, qui minimise les pertes et permet d'améliorer le rendement électrique.In particular, it will certainly be understood that the relative position of the two windings between them is perfectly interchangeable. The auxiliary magnetic core rigorously has the same overall effect on the capture of the power transmissible to the secondary by the primary, insofar as it is placed between the two windings. Whether the primary winding is inside, around the main magnetic core, or outside, then surrounding not only the main core, but also the coil and the auxiliary magnetic core arranged side by side, when the modification the magnetic state of the latter adjusts the short-circuit current on the secondary, it also adjusts the supply current of the other winding, regardless of their relative position. Practical considerations alone make it preferable to put the coil in an external position, such as the ease of access to the input-output thereof, or the reduction in the length of the average turn of the primary, which minimizes the losses and makes it possible to improve electrical efficiency.

On notera que le domaine d'application de l'invention englobe la production d'eau chaude, tant pour le chauffage d'immeubles que pour usage en procédes industriels. De même, l'invention s'applique également au chauffage de fluides calo porteurs autres que l'eau, par exemple de l'huile, ou même des sels fondus destinés à être utilisés tels quels ou à générer de la vapeur à haute température dans des échangeurs.Note that the field of application of the invention includes the production of hot water, both for heating buildings and for use in industrial processes. Likewise, the invention also applies to the heating of heat transfer fluids other than water, for example oil, or even molten salts intended to be used as such or to generate steam at high temperature in exchangers.

On rappelle également que l'invention,bien que réalisée initialement pour le chauffage de fluides,ne se limite nullement à une chaudière à induction, mais s'étend à tout générateur capable de délivrer aux bornes de son enroulement secondaire une puissance électrique réglable. Il suffit, pour le le réaliser, de remplacer, dans la chaudière exemplifiée auparavant, le serpentin de chauffe en court-circuit par un simple enroulement électrique, connectable par ses extrémités à un circuit d'utilisation.It is also recalled that the invention, although initially carried out for heating fluids, is by no means limited to an induction boiler, but extends to any generator capable of delivering to the terminals of its secondary winding an adjustable electrical power. In order to achieve this, it suffices to replace, in the boiler exemplified above, the heating coil in short circuit with a simple electrical winding, connectable at its ends to a circuit for use.

Claims (10)

  1. Adjustable electrical power generator comprising a magnetic transducer of the "transformer" type having primary (3) and secondary (2) windings surrounding a magnetic core (4), one of the windings surrounding the other, and means for adjusting the power available to the secondary, which generator is characterised in that the said means for adjusting the power are constituted by an auxiliary magnetic core (10) separated from the main magnetic core (4), provided with an electrical control winding (12) and arranged in the space (11) separating the primary (3) and secondary (2) windings, and by a unit (13) for producing a direct or rectified current supplying the said control winding (12) and connected to means (14) for adjusting the strength Ic of the said control current as a function of the desired electrical power.
  2. Generator according to Claim 1, used in the production of a hot fluid within an electrical induction boiler, characterised in that the secondary winding (2) is constituted by a tubular coil (2), which is short-circuited (8), through which the fluid to be heated is intended to flow.
  3. Generator according to Claim 1 or 2, characterised in that the secondary winding (2) is arranged outside the primary winding (3).
  4. Generator according to Claim 1 or 2, characterised in that the auxiliary magnetic core (10) is split into two parts (10a, 10b), each provided with its own control winding (12'a, 12'b), direct or rectified electrical currents Ic, I'c circulating in opposite directions being intended to flow through these windings.
  5. Generator according to Claim 1, 2 or 3, characterised in that the outer winding (2) has an oblong shape and in that the inner winding (3), surrounding the main magnetic core (4), and the auxiliary magnetic core (10) are placed side by side within the outer winding (2).
  6. Generator according to Claims 4 and 5, characterised in that the outer winding (2) has an oblong shape and in that the component parts (10a, 10b) of the auxiliary magnetic core (10) are arranged on either side of the inner winding (3).
  7. Generator according to Claim 1 or 2, characterised in that it is equipped with means (19, 20) for automatically adjusting the adjustable electrical power.
  8. Generator according to Claim 1 or 2, characterised in that it consists of three magnetic transducers (1, 1' and 1'') each supplied by a different phase of a three-phase electrical supply (5).
  9. Generator according to Claims 1 or 2 and 8, characterised in that the auxiliary magnetic cores (10...) are connected up to each other via a magnetic circuit comprising common return columns (17, 18) and common linking yokes (21, 21').
  10. Generator according to Claims 1 or 2 and 7, characterised in that the auxiliary magnetic cores (10...) are each provided with an individual magnetic circuit (22, 23).
EP89402913A 1988-11-10 1989-10-23 Adjustable electrical power generator and its use in the production of a hot fluid Expired - Lifetime EP0368712B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89402913T ATE95657T1 (en) 1988-11-10 1989-10-23 ADJUSTABLE ELECTRIC POWER GENERATOR AND ITS APPLICATION TO THE PRODUCTION OF A WARM LIQUID.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8815063 1988-11-10
FR888815063A FR2638912B1 (en) 1988-11-10 1988-11-10 ADJUSTABLE ELECTRIC POWER GENERATOR AND ITS USE FOR THE PRODUCTION OF A HOT FLUID

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EP0368712A1 EP0368712A1 (en) 1990-05-16
EP0368712B1 true EP0368712B1 (en) 1993-10-06

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EP89402913A Expired - Lifetime EP0368712B1 (en) 1988-11-10 1989-10-23 Adjustable electrical power generator and its use in the production of a hot fluid

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AT (1) ATE95657T1 (en)
DE (1) DE68909742D1 (en)
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Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR527697A (en) * 1920-11-26 1921-10-28 Societe Noel Aine Pellegrini & Cie Transformer for electric heating
US1668711A (en) * 1923-08-02 1928-05-08 Cutler Hammer Mfg Co Regulation of electric circuits
US1714962A (en) * 1927-03-12 1929-05-28 Thomson Electric Welding Compa Means for regulating secondary current and voltage in transformers
US2586657A (en) * 1948-08-24 1952-02-19 Varo Mfg Co Inc Saturable transformer
DE1006545B (en) * 1952-07-05 1957-04-18 Siemens Ag Method and device for inductive heating of highly conductive metal parts in an inductive high-frequency field
US2836694A (en) * 1954-05-25 1958-05-27 Westinghouse Electric Corp Induction heating unit
FR1335148A (en) * 1962-07-06 1963-08-16 L Electronique Francaise Soc D Variable inductance, in particular for controlling the power of a high frequency induction heater
US3505588A (en) * 1968-03-27 1970-04-07 Elwood M Brock Load impedance responsive feedback for variable reactance transformer
US3679966A (en) * 1968-07-31 1972-07-25 Ambac Ind Closed loop parametric voltage regulator
FR2578135B1 (en) * 1985-02-28 1988-05-13 Alsthom Atlantique THERMO-INDUCTIVE GENERATOR FOR THE PRODUCTION OF HOT FLUID
FR2613896B1 (en) * 1987-04-07 1995-07-13 France Transfo Sa THERMO-INDUCTION HOT FLUID GENERATOR
GB2205720B (en) * 1987-06-10 1991-01-02 Electricity Council Induction heater

Also Published As

Publication number Publication date
FR2638912B1 (en) 1994-11-18
EP0368712A1 (en) 1990-05-16
ATE95657T1 (en) 1993-10-15
DE68909742D1 (en) 1993-11-11
FR2638912A1 (en) 1990-05-11

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