EP0574478B1 - Inductive superconducting current accumulator - Google Patents

Abstract

The inductive superconducting current accumulator (2) proposed is characterized in that it comprises an inner coil (4) with windings of superconducting material and an outer coil (6), also with windings of superconducting material, wound round the inner coil (4) in the opposite direction a certain distance from the inner coil so that the same but opposite magnetic flux prevails in the annular gap (12) between the inner coil (4) and the outer coil (6) as in the interior (14) of the inner coil (4).

Description

Inductive, superconducting electricity storage

• (a) der eine Anordnung mehrerer, aus Supraleitmaterial gewickelter Spulen aufweist, die zur Ausbildung eines Speicherstromkreises miteinander verbunden sind,
• (b) und bei dem der Speicherstromkreis an einen Verbraucherstromkreis angeschlossen ist und eine mit Supraleitmaterial aufgebaute Entladungsschaltereinrichtung aufweist, die zum Unterbrechen des Speicherstromkreises und damit zum Entladen des Stromspeichers in den Verbraucherstromkreis in einen hochohmigen, normalleitenden Zustand gebracht wird,

dadurch gekennzeichnet,
   (c) daß der Speicherstromkreis des Stromspeichers eine aus Supraleitmaterial gewickelte Innenspule und eine mit Abstand um die Innenspule herum angeordnete, aus Supraleitmaterial gewickelte Außenspule aufweist, wobei im Betrieb die Innenspule und die Außenspule mit gegensinniger Stromrichtung durchflossen sind, so daß im Ringraum zwischen der Innenspule und der Außenspule der gleiche, jedoch entgegengesetzt gerichtete Magnetfluß herrscht wie im Innenraum der Innenspule.The invention relates to an inductive, superconducting current store,

• (a) which has an arrangement of a plurality of coils wound from superconducting material which are connected to one another to form a storage circuit,
• (b) and in which the storage circuit is connected to a consumer circuit and has a discharge switch device which is constructed with superconducting material and which is brought into a high-resistance, normally conductive state to interrupt the storage circuit and thus to discharge the current store into the consumer circuit,

characterized,
(c) that the storage circuit of the power store has an inner coil wound from superconducting material and an outer coil which is arranged at a distance around the inner coil and is wound from superconducting material, the inner coil and the outer coil being flowed through in opposite directions in current during operation, so that in the annulus between the inner coil and the outer coil has the same but opposite magnetic flux as in the interior of the inner coil.

An inductive, superconducting current storage device with the features (a) and (b) mentioned above is known from document FR 2 112 054 A. Nothing is said there about the geometrical arrangement of the coils relative to one another, but according to the drawings one normally thinks of a successive one in the axial direction of the coils Arrangement.

A device for image acquisition by means of magnetic resonance is known from document GB 2 205 444 A. This device has a superconducting main coil for generating the required magnetic field, which is surrounded by a superconducting shielding coil through which the current flows in opposite directions, so that the space outside the device is largely free of magnetic fields. However, the intended purpose of this device is not to store electricity in order to be able to supply a consumer if necessary. The device is designed to generate a magnetic field that is best suited for image acquisition, not to store the largest possible amount of electricity in a small space. A discharge switch device is not available.

In inductive, superconducting current storage devices with a cylindrical coil as the most important component, the magnetic field present in the interior of the coil emerges at both coil ends and closes outside the coil, so that a magnetic field with a generally very high magnetic field strength prevails in the vicinity of the coil. In contrast, in the current storage device according to the invention, the magnetic circuit runs in a first axial direction through the interior of the inner coil and then in the opposite, second axial direction through the annular space between the inner coil and the outer coil, so that - apart from areas close to the two ends of the coil arrangement - outside there is practically no magnetic field in the coil arrangement. The magnetic field is compensated or returned in the coil arrangement.

On the one hand, the term “superconducting material” denotes materials which have been known for a long time, as a rule metallic, and which are superconducting only at temperatures slightly above absolute zero. On the other hand called This term also applies to the mostly ceramic materials that have only been known for a few years and are still superconducting at a considerable temperature distance from absolute zero. These materials are often called high-temperature superconductors, and the division limit can be chosen as the temperature of liquid nitrogen; According to this classification, high-temperature superconductors are those that are still superconducting at least at the boiling point of liquid nitrogen.

The storage circuit can be completely or partially discharged by means of the discharge switch device. Switches constructed with superconducting material are known per se, as are means for bringing the switch into a high-resistance, normally conductive state for opening, for example a heating device, a device for applying energy to the switch (high-frequency radiation, laser radiation, etc.), a device for applying a current pulse of high current strength to the superconducting material of the switch. The latter is particularly preferred in the current storage device according to the invention, in particular in an embodiment in which the current pulse is generated by discharging one or more capacitors.

The windings of the inner coil and the outer coil and the magnetic flux cross sections of the annular space and the inner space are preferably designed in such a way that at least substantially the same magnetic flux densities result in the annular space and in the inner space. This also applies to the circumference of the inner coil and the outer coil. The superconducting material of the two coils can be used practically at all points.

Further preferred features of the invention are specified in claims 3 to 17 and are explained in more detail below in connection with the description of preferred exemplary embodiments.

Fig. 1

in einem schematisierten Achsenschnitt die geometrische Anordnung wesentlicher Bestandteile eines Stromspeichers;

Fig. 2

in schematisierter Draufsicht den Stromspeicher von Figur 1, wobei zusätzlich eine Einrichtung zum induktiven Laden des Stromspeichers zu sehen ist;

Fig. 3

ein Blockschaltbild des Stromspeichers von Figuren 1 und 2;

Fig. 4

in einem Achsenschnitt analog Figur 1 einen Stromspeicher, der aus mehreren Teil-Stromspeichern zusammengesetzt ist, wobei eine Einrichtung zum induktiven Laden des Stromspeichers mit eingezeichnet ist;

Fig. 5

ein Blockschaltbild des Stromspeichers von Fig. 4;

Fig. 6

einen Teilschnitt wie Fig. 1 einer modifizierten Spulenausführung.

The invention and refinements of the invention are explained in more detail below on the basis of exemplary embodiments, which are illustrated in a partially schematic manner. It shows:

Fig. 1

in a schematic axis section, the geometric arrangement of essential components of a power storage;

Fig. 2

In a schematic plan view of the power storage device of Figure 1, in addition, a device for inductive charging of the power storage device can be seen;

Fig. 3

a block diagram of the power storage of Figures 1 and 2;

Fig. 4

in an axial section analogous to FIG. 1, a power store which is composed of several partial power stores, a device for inductively charging the power store being shown;

Fig. 5

a block diagram of the power storage of Fig. 4;

Fig. 6

a partial section as Fig. 1 of a modified coil design.

The power store 2 according to FIGS. 1 and 2 essentially consists of a practically cylindrical inner coil 4 made of superconducting material, a practically cylindrical one concentrically aligned therewith Outer coil 6 made of superconducting material, a device 8 for inductively charging the coils 4 and 6, and a discharge switch device 10. The inner coil 4 is wound in a first winding direction, while the outer coil 6 is wound in the opposite winding direction. The annular space 12 between the outer coil 6 and the inner coil 4 has an annular magnetic flux cross-section (which can be seen in plan view in FIG. 2) which essentially corresponds to the cross-sectional area of the circular magnetic flux cross-section of the interior 14 of the inner coil 4 (which can be seen in plan view in FIG. 2) . The inner coil 4 and the outer coil 6 have essentially the same number of turns and are electrically connected in series in such a way that they flow through in opposite directions during operation. This can also be achieved by connecting the inner coil 4 and the outer coil 6 appropriately if the two coils 4 and 6 are not wound in opposite directions.

Preferably, the inner coil 4 and the outer coil 6 are axially of essentially the same length and in alignment with one another at their two axial ends.

The charging device 8 consists essentially of a primary coil and a secondary coil device, which is shown in FIG. 2 as a uniform arrangement 16, and two charge switches 18, 20, via which the secondary coil device is connected to a storage circuit. More detailed information is given below in connection with FIG. 3. The primary coil, the secondary coil device, the connections between the secondary coil device and the two charge switches 18, 20, the two charge switches 18, 20, and the connections between the charge switches 18, 20 and the discharge switch device 10 are constructed with superconducting material.

The discharge switch device 10 essentially consists of a coil wound in two strands of superconducting material, as a result of which the discharge switch device 10 has a large superconducting material length. The discharge switch device 10 is arranged concentrically to the inner coil 4 and the outer coil 6 at a small distance around the outer coil 6. The discharge switch device 10 is electrically connected on the one hand to the charging device 8 and on the other hand to the outer coil 6 and the inner coil 4, in such a way that the two winding strands of the switch coil flow through in opposite directions. More details on this are described below in connection with FIG. 3. The switch coil 10 is thus closely integrated with the arrangement of the inner coil 4 and the outer coil 6, but is located radially outside the outer coil 6 in the practically magnetic field-free space. There is practically no effect of the magnetic field of the storage coil arrangement on the discharge switch device and vice versa.

Figure 3 illustrates the electrical connection of the components of the power store 2 described so far. It can be seen that the inner coil 4 and the outer coil 6 are electrically connected in series, that the charge secondary coil device has a first secondary coil 24 and a second secondary coil 26 (which are connected to one another in the center) has an electrical connection from the connection point 28 of the two charge secondary coils 24, 26 via a first discharge switch 30 to one end of the inner coil 4, and that between the free ends of the charge Secondary coils 24 and 26 are electrically connected to the outer coil 6 via the charge switches 18, 20 and a second discharge switch 32. All components and electrical connections now described in connection with FIG. 3 consist electrically of superconducting material, namely of a continuous superconducting material strand, in which only the connection point 28 between the two charge secondary coils 24, 26 and the connection points 34 and 36 to be described further below available.

The first discharge switch 30 is the one winding strand of the discharge switch device 10, and the second discharge switch 32 is the second winding strand of the discharge switch device 10, the first discharge switch 30 and the second discharge switch 32 being spatially combined as a common discharge switch coil.

In FIG. 3 it can also be seen that the upper end of the first charge secondary coil 24 is connected via an electrical connection 38 to a connection point 34 which lies in the electrical connection between the lower end of the second charge secondary coil 26 and the outer coil 6, specifically between the second charge switch 20 and the second discharge switch 32. The first charge switch 18 is located in the connection 38. The two secondary coils 24 and 26 act inductively together with the charge primary coil 40, which likewise consists of superconducting material and is fed with alternating current for charging the current store 2. All of the components of the power store 2 described so far in connection with FIG. 3 are located in a common cryogenic area 42 which is within the dash-dotted line in FIG. 3.

The charge primary coil 40 can alternatively be wound from normally conductive material and located outside the cryogenic area 42.

The alternating current flowing in the charge primary coil 40 induces periodically alternating signs in the two charge secondary coils 24 and 26. The charge switches 18 and 20 are opened and closed accordingly alternately, so that alternately either the first charge secondary coil 24 or the second charge secondary coil 26 is switched on in the storage circuit 44 and feeds a charge current pulse there with the correct sign. The storage circuit 44 thus leads from the upper end of the inner coil 4 via the first discharge switch 30, then either via the first charge secondary coil 24 and the closed, first charge switch 18 or the second charge secondary coil 26 and the closed, second charge switch 20 to the connection point 34,
thence via the second discharge switch 32 to the lower end of the outer coil 6, finally from the upper end of the outer coil 6 to the lower end of the inner coil 4. It is understood that at times when the storage circuit 44 is not recharged, only one of the two charge switches 18, 20 is closed and the other of the two charge switches 18, 20 is open and that at times when the storage circuit 44 is not discharged, the two discharge switches 30, 32 are closed.

What has been said further above regarding the device for opening the discharge switch device 10 constructed with superconducting material applies analogously to the two charge switches 18, 20. The switching power to be managed by each charge switch 18, 20 is substantially lower than the switching power to be managed by the discharge switch device 10, so that the Charge switches 18, 20 can be constructed less expensively and smaller than the discharge switch device 10. In addition, the circuit sequence of the charge switches 18, 20 can be set up in such a way that the charge switches 18, 20 open and close in a practically current-free state.

Alternatively, you can work with only one charge secondary coil and only one charge switch (half-wave charging device.

There is a connection point 36 in the connection between the upper end of the inner coil 4 and the first discharge switch 30, and analogously there is a connection point 36 in the connection between the lower end of the inner coil 6 and the second discharge switch 32 Discharge connection 46 or consumer connection, which is also shown in FIG. 2, out of cryogenic area 42. Each discharge port 46 consists of at least the boundary of the cryogenic area 42 of normal conducting material. A consumer circuit 48 connects to the discharge connections 46 and contains one or more current consumers 50 (not shown). A circuit 52 with a capacitor 54 is also connected to the discharge connections 46.

In order to discharge the current store 2, the capacitor 54 is brought to discharge, so that a corresponding current pulse arrives in the storage circuit 44 (the current pulse does not flow through the consumer circuit 48 because this is high-impedance because of the current consumer 50). The current pulse is dimensioned so high that in the discharge switches 30, 32 the superconductivity breaks down over a large length of the switch winding and this makes it highly resistive. As a result, the current stored in the now opened storage circuit 44 flows through the discharge circuit 48 through the current consumer (s) 50. To recharge the current store 2, the discharge switches 30, 32 are closed again by converting them again to the superconducting state. It is pointed out that in principle it is sufficient if the storage circuit 44 is interrupted at only one point for discharging.

Alternatively, the capacitor circuit 52 can be connected at other points in the storage circuit 44 or a separate capacitor circuit 52 connected in front of and behind it can be provided for each discharge switch 30, 32. In the latter case, one can connect so that when the capacitor 54 is discharged, the closed one of the two charge switches 18, 20 is also opened becomes.

The term "cryogenic area" 42 means that a temperature prevails in this area at which the superconducting material of the components and compounds described is in the superconducting state. Specifically, it is a bath made of liquid helium or liquid nitrogen, for example. This bath is also in the interior 14 of the inner coil 4 and in the annular space 12 between the inner coil 4 and the outer coil 6.

It is pointed out that in the case of the power store according to FIGS. 1 to 3, the inner coil 4 and / or the outer coil 6 can each be composed of a plurality of partial coils arranged one above the other, which are electrically connected in series or in parallel.

FIG. 4 shows an embodiment of a power store 2 in which a plurality of partial power stores 60, which are each constructed individually as described with reference to FIGS. 1 to 3, are stacked on top of one another. Each partial power store 60 has a lower, plate-like support part 62 made of non-magnetizable material. An inductive charging device 8 for each of the partial current stores 60 is also shown. The partial current stores 60 are stacked on one another in such a way that the vertical central axes of the inner storage coils 4 coincide to form a common axis 64. The same applies to the outer coils 6 and the discharge switch coils 10. Furthermore, it is shown that the magnetic field in the interior 14 is directed overall from top to bottom, while the magnetic field in the annular space 12 is directed overall from bottom to top.

FIG. 5 shows that the components within each partial current store 60 are connected in exactly the same way as in the current store 2 according to FIGS. 1 to 3. It can also be seen that the individual charge primary coils 40 are electrically connected in series. Alternatively, a common charge primary coil can be provided for all partial current storage devices 60. Finally, it can be seen that the discharge connections 46 of the individual storage circuits 44 are connected to one another in such a way that the storage coil pairs 4, 6 are connected in parallel to one or more consumers 50 (not shown).

Alternatively, it is possible to interconnect the consumer connections 46 of the individual storage circuits 44 in such a way that the storage coils 4, 6 are connected in series to the consumer (s) 50. The circuits 52 for applying a current pulse to the storage circuits 44 are not shown. It is generally noted that the current direction in the various coils is identified by the symbols x for a first current direction and for the opposite current direction. Finally, it is pointed out that the annular space 12 between the inner coil 4 or the inner coils 6 and the outer coil 6 or the outer coils 6 can, for example, also be filled with a plastic compound which produces or supports the physical cohesion of the coils. Similarly, the discharge switch coil 10 or the discharge coils 10 can also be combined with the outer coil 6 or the outer coils 6 by means of a plastic compound.

6 illustrates a modified coil design. The outer coil 6 is divided into an upper outer coil 6a and a lower outer coil 6b. The upper outer coil 6a has a first connection 46 at the top, radially on the outside. A connection leads from the lower end of the upper part outer coil 6a to the upper end of the inner coil 4. A connection leads from the lower end of the inner coil 4 to the upper end of the lower part outer coil 6b. At the lower end of the lower coil 6b, a second connection 46 is provided radially on the outside. In this way, no connection 46 has to be passed above or below the outer coil 6 to the inner coil 4. If it is advantageous for technical reasons, the inner coil 4 can be divided into an upper and a lower coil section.

Claims (17)

1. An inductive superconducting current storage (2), comprising

   (a) an assembly of a plurality of coils (4, 6) wound from superconducting material and interconnected so as to form a storage circuit (44),

   (b) the storage circuit (44) being connected to a load circuit (48) and having a discharge switch means (10) which is composed with superconducting material and which is brought to a high-resistance, normally conducting state for interrupting the storage circuit (44) and thus for discharging the current storage (2) into the load circuit (48),

   characterized in
      (c) that the storage circuit (44) of the current storage (2) comprises an inner coil (4) wound from superconducting material and an outer coil (6) wound from superconducting material and disposed around the inner coil (4) in spaced manner therefrom, said inner coil (4) and said outer coil (6) in operation having current flowing therethrough in opposite directions so that the same magnetic flux as in the inner space (14) of the inner coil (4), but of opposite direction, is present in the annular space (12) between inner coil (4) and outer coil (6).
2. A current storage according to claim 1,
   characterized in that the windings of the inner coil (4) and the outer coil (6) as well as the magnetic flux cross-sections of the annular space (12) and of the inner space are designed such that at least substantially the same magnetic flux densities result in the annular space (12) and the inner space (14).
3. A current storage according to claim 1 or 2,
   characterized in that the discharge switch means (10) comprises a superconducting material section of great length wound in the manner of a coil.
4. A current storage according to claim 3,
   characterized in that the discharge switch means (10) is disposed externally around the outside of the outer coil (6).
5. A current storage according to at least one of claims 3 and 4,
   characterized in that the discharge switch means (10) is provided with two superconducting material sections of great length wound in coil-like manner in opposite directions.
6. A current storage according to at least one of claims 1 to 5,
   characterized in that the storage circuit (44) comprises one discharge switch (30, 32) each at two locations.
7. A current storage according to claim 6,
   characterized in that the two discharge switches (30, 32) are combined to form the discharge switch means (10).
8. A current storage according to at least one of the preceding claims,
   characterized in that, for inductive charging of the storage (2), a charging primary coil (40) and a charging secondary coil means (24, 26) cooperating therewith are provided in the storage circuit (44) containing the inner coil (4) and the outer coil (6).
9. A current storage according to claim 8,
   characterized in that the charging secondary coil means comprises two charging secondary coils (24, 26) which, via an interconnection of one charging switch (18, 20) each adapted to be opened and closed in intermittent manner, are connected to the storage circuit (44) such that in both directions of current flow through the charging primary coil (40) the currents induced in the charging secondary coils (24, 26) are fed into the storage circuit (44) with the correct sign.
10. A current storage according to claim 9,
    characterized in that the two charging switches (18, 20) are composed with superconducting material and for opening thereof are brought into a high-resistance, normally conducting state.
11. A current storage according to at least one of the preceding claims,
    characterized in that the storage inner coil (4), the storage outer coil (6), the discharge switch means (10), the charging secondary coil means (24, 26) and optionally the charging switch or switches (18, 20), preferably also the charging primary coil (40), are commonly disposed in a cryogenic portion (42) of the current storage (2).
12. A current storage according to at least one of the preceding claims,
    characterized in that the storage inner coil (4) and the storage outer coil (6), preferably in addition thereto also the discharge switch means (10) and/or the charging secondary coil means (24, 26) and/or one of the charging switches (18, 20), are commonly composed of continuous superconducting material.
13. A current storage according to at least one of the preceding claims,
    characterized in that at least the outer coil (6) is divided in two axially adjacent partial coils (6a, 6b), and in that the current leads (46) to the assembly of inner coil (4) and outer coil (6) are provided only from radially outside of the outer coil (6).
14. A current storage according to at least one of the preceding claims,
    characterized in that it consists of several partial current storages (60) each comprising a storage inner coil (4), a storage outer coil (6), a discharge switch means (10) and a charging secondary coil means (24, 26) optionally with charging switch(es) (18, 20), with a common charging primary coil (40) being provided for the entire current storage (2) or individual charging primary coils being provided for one partial current storage (60) each.
15. A current storage according to claim 14,
    characterized in that the partial current storages (60) are provided in a stack-like arrangement which is at least substantially aligned along a common axis (64) of the storage inner coils (4).
16. A current storage according to at least one of claims 14 and 15,
    characterized in that the partial current storages (60) are connected in series on the discharge side.
17. A current storage according to at least one of claims 14 and 15,
    characterized in that the partial current storages (60) are connected in parallel on the discharge side.

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