EP0368712B1 - Regelbarer elektrischer Leistungsgenerator und seine Anwendung zur Produktion einer warmen Flüssigkeit - Google Patents

Regelbarer elektrischer Leistungsgenerator und seine Anwendung zur Produktion einer warmen Flüssigkeit 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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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP89402913A
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English (en)
French (fr)
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EP0368712A1 (de
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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Priority to AT89402913T priority Critical patent/ATE95657T1/de
Publication of EP0368712A1 publication Critical patent/EP0368712A1/de
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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)
  • Fluid-Pressure Circuits (AREA)
  • Catching Or Destruction (AREA)

Claims (10)

  1. Regelbarer elektrischer Leistungsgenerator, der einen magnetischen Umformer vom Typ "Transformator" mit Primärwicklung (3) und Sekundärwicklung (2) aufweist, die einen magnetischen Kern (4) umgeben, wobei eine der Wicklungen die andere umgibt, und der eine Anordnung zur Regelung der an der Sekundärwicklung verfügbaren Leistung aufweist, dadurch gekennzeichnet, daß die Anordnung zur Regelung der Leistung aus einem zusätzlichen magnetischen Kern (10) besteht, der vom magnetischen Hauptkern (4) getrennt ist, der mit einer elektrischen Steuerwicklung (12) versehen ist und der in dem Raum (11) angeordnet ist, welcher die Primärwicklung (3) von der Sekundärwicklung (2) trennt, sowie aus einer Einheit (13) zur Erzeugung eines Gleichstroms - oder gleichgerichteten Stroms - besteht, die die Steuerwicklung (12) speist und der eine Anordnung (14) zur Regelung der Intensität (Ic) des Steuerstroms als Funktion der gewünschten elektrischen Leistung zugeordnet ist.
  2. Generator nach Anspruch 1, der zur Erzeugung einer warmen Flüssigkeit im Inneren eines Induktions-Elektrodampfkessels verwendet wird, dadurch gekennzeichnet, daß die Sekundärwicklung (2) aus einer rohrförmigen Schlange (2) mit Kurzschlußüberbrückung (8) besteht, die dazu dient, von der zu erwärmenden Flüssigkeit durchflossen zu werden.
  3. Generator nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Sekundärwicklung (2) die Primärwicklung (3) außen umgibt.
  4. Generator nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der zusätzliche magnetische Kern (10) aus zwei getrennten Abschnitten (10a und 10b) besteht, deren jeder mit einer eigenen Steuerwicklung (12'a, 12'b) versehen ist, wobei diese Wicklungen dazu dienen, von elektrischen Gleichströmen - oder gleichgerichteten Strömen - (Ic, I'c) durchflossen zu werden, die in zueinander entgegengesetzten Richtungen fließen.
  5. Generator nach Anspruch 1, 2 oder 3, dadurch gekennzeichnet, daß die äußere Wicklung (2) von langgestreckter Form ist und daß die innere Wicklung (3), welche den magnetischen Hauptkern (4) umgibt sowie der zusätzliche magnetische Kern (10) nebeneinander innerhalb der äußeren Wicklung (2) angeordnet sind.
  6. Generator nach Ansprüchen 4 und 5, dadurch gekennzeichnet, daß die äußere Wicklung (2) von langgestreckter Form ist und daß die Abschnitte 10a, 10b, welche den zusätzlichen magnetischen Kern (10) bilden, beidseits der inneren Wicklung (3) angeordnet sind.
  7. Generator nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß er mit einer Anordnung (19, 20) zur automatischen Regelung der regelbaren elektrischen Leistung versehen ist.
  8. Generator nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß er aus drei magnetischen Umformern (1, 1' und 1'') besteht, deren jeder von einer anderen Phase einer dreiphasigen elektrischen Versorgung (5) gespeist wird.
  9. Generator nach Ansprüchen 1 oder 2 und 8, dadurch gekennzeichnet, daß die zusätzlichen magnetischen Kerne (10,...) untereinander durch einen magnetischen Schaltkreis verbunden sind, welcher gemeinsame Rückkehrsäulen (17, 18) und gemeinsame Verbindungsjoche (21, 21') aufweist.
  10. Generator nach Ansprüchen 1 oder 2 und 7, dadurch gekennzeichnet, daß die zusätzlichen magnetischen Kerne (10,...) jeweils mit einem eigenen magnetischen Schaltkreis (22, 23) versehen sind.
EP89402913A 1988-11-10 1989-10-23 Regelbarer elektrischer Leistungsgenerator und seine Anwendung zur Produktion einer warmen Flüssigkeit Expired - Lifetime EP0368712B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89402913T ATE95657T1 (de) 1988-11-10 1989-10-23 Regelbarer elektrischer leistungsgenerator und seine anwendung zur produktion einer warmen fluessigkeit.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8815063 1988-11-10
FR888815063A FR2638912B1 (fr) 1988-11-10 1988-11-10 Generateur de puissance electrique reglable et son utilisation pour la production d'un fluide chaud

Publications (2)

Publication Number Publication Date
EP0368712A1 EP0368712A1 (de) 1990-05-16
EP0368712B1 true EP0368712B1 (de) 1993-10-06

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EP89402913A Expired - Lifetime EP0368712B1 (de) 1988-11-10 1989-10-23 Regelbarer elektrischer Leistungsgenerator und seine Anwendung zur Produktion einer warmen Flüssigkeit

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EP (1) EP0368712B1 (de)
AT (1) ATE95657T1 (de)
DE (1) DE68909742D1 (de)
FR (1) FR2638912B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024220181A1 (en) * 2023-04-17 2024-10-24 Siemens Energy Global GmbH & Co. KG High-power electrical heater

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR527697A (fr) * 1920-11-26 1921-10-28 Societe Noel Aine Pellegrini & Cie Transformateur pour chauffage électrique
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 (de) * 1952-07-05 1957-04-18 Siemens Ag Verfahren und Einrichtung zum induktiven Erwaermen von gut leitenden Metallteilen in einem induktiven Hochfrequenzfeld
US2836694A (en) * 1954-05-25 1958-05-27 Westinghouse Electric Corp Induction heating unit
FR1335148A (fr) * 1962-07-06 1963-08-16 L Electronique Francaise Soc D Inductance variable, notamment pour le réglage de la puissance d'un appareil de chauffage par induction à haute fréquence
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 (fr) * 1985-02-28 1988-05-13 Alsthom Atlantique Generateur thermo-inductif pour la production de fluide chaud
FR2613896B1 (fr) * 1987-04-07 1995-07-13 France Transfo Sa Generateur de fluide chaud a thermo-induction
GB2205720B (en) * 1987-06-10 1991-01-02 Electricity Council Induction heater

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024220181A1 (en) * 2023-04-17 2024-10-24 Siemens Energy Global GmbH & Co. KG High-power electrical heater

Also Published As

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

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