Electromagnetic Coil Assembly

Abstract

To provide an electromagnet coil assembly implementing HTS (high temperature superconducting) materials, which can be mass-manufactured in a reliable, robust and highly cost-effective manner.SOLUTION: An electromagnet coil assembly 10 includes core 11, a winding wound in a plurality of turns around the core to constitute a coil 12, and multiple power taps 13a, 13b for electrically connecting the winding to an external power circuit. The winding is formed as a tape component comprising a HTS material. The multiple power taps are connected to the winding exiting the plane of the coil at a predetermined angle. The multiple windings of the coil consist of N turns. A first power tap 13a is connected with the first turn of the winding. A second power tap 13b is connected with a M-th turn of the winding, with M<N.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic coil assembly, and more particularly to an electromagnetic coil assembly including at least a core, a winding wound multiple times around the core to form a coil, and multiple power taps for electrically connecting the winding to an external power circuit. [Background technology]

[0002] The above-mentioned electromagnetic coil assembly is disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-305861. Summary of the Invention [Problem to be solved by the invention]

[0003] Generally, superconducting coils are widely used in commercial and research applications in medical fields such as NMR and MRI, and in rotating machines such as motors and generators. Meanwhile, cables made from high-temperature superconducting (HTS) wires are known, which can carry up to ten times more current than conventional cables. Alternatively, there are HTS cables that can carry the same current at a lower voltage. HTS can be used in both direct current (DC) and alternating current (AC) systems. Generally, high-temperature superconducting materials (abbreviated as high T c HTS (Hypertonic Superconductors or HTS) is operationally defined as a material that exhibits superconductivity near -200°C (73.15K), especially near the boiling point of nitrogen (N2), which is -196.5°C (77K).

[0004] The field of high-temperature superconductivity is very new, and the cutting edge is seeing rapidly changing application areas. Most electromagnetic coils implementing HTS materials are for academic purposes and are typically hand-wound. These coils require some sort of power cable or power strip. However, for academic applications, the coils are typically "disposable" and cannot be manufactured on a large-scale, quantitative basis for a sufficiently long time.

[0005] Accordingly, it is an object of the present invention to provide an electromagnetic coil assembly incorporating HTS materials that is reliable, robust, and cost-effectively mass-produced. [Means for solving the problem]

[0006] To solve this problem, an electromagnetic coil assembly is provided. The electromagnetic coil assembly includes a core, a winding wound multiple times around the core to form a coil, and a plurality of power taps for electrically connecting the winding to an external power circuit. The winding is formed as a tape component comprising a high-temperature superconducting (HTS) material. The multiple power taps are connected to the winding exiting the face of the coil at a predetermined angle.

[0007] Typically, power taps on known coils are connected to conductors using solder connections to copper bus bars. When the conductors are formed from tape components containing high temperature superconducting (HTS) material, multiple power taps are connected to the HTS tape windings, exiting at an angle from the plane of the coil to provide a strong and reliable electrical connection between the coil and an external power source or the like.

[0008] In particular, if the power tap is also made of a superconducting material, the electromagnetic properties of the HTS coil are further improved. That is, in this case, more specifically, the power tap is formed as a tape-shaped power tap containing a high-temperature superconducting (HTS) material. In particular, the tape-shaped power tap is made from HTS tape components as windings.

[0009] In one example, the power tap is connected to the tape winding at an angle α of between 30° and 90°, in particular 90°, which increases the contact surface between the HTS tape winding and the tape-like power tap.

[0010] In another advantageous embodiment, the power tap has a curved portion extending from the position where it exits the coil to the position where it is connected to the power terminal of the external power supply circuit. This curvature coincides with the magnetic field lines of the magnetic field generated by the coil during operation. Thereby, even when the power tap is exposed to the magnetic field, the disturbance and exposure to electromagnetic force (Lorentz force) caused thereby are minimized.

[0011] In a further embodiment of the HTS coil, a plurality of windings of the coil are composed of N turns, a first power tap is connected to the first turn of the winding, a second power tap is connected to the M-th turn of the winding, and M < N. In particular, the first and second power taps are used to electrically connect the coil and the external power supply.

[0012] In yet another embodiment of the HTS coil, the electromagnetic coil assembly further includes a plurality of voltage taps for measuring the voltage between at least some of the plurality of turns of the winding, a first voltage tap is connected to the (M + 1)-th turn of the winding, a second voltage tap is connected to the O-th turn of the winding, O ≈ N, and in particular O = N. Thereby, the first and second voltage taps can be connected to other types of peripheral devices (more specifically, a quench detection or protection system). Thereby, the potential difference between the (M + 1)-th turn and the O-th turn of the winding can be detected. This potential difference is induced by external disturbances of the magnetic field of the electromagnetic coil assembly. It further includes a plurality of voltage taps for measuring the voltage across at least some of the plurality of turns of the winding, a first voltage tap is electrically connected to the turn M + 1 of the winding, a second voltage tap is electrically connected to the turn O of the winding, O ≈ N, and in particular O = N

[0013] The electromagnetic coil assembly implementing the HTS tape winding is further characterized by the following specific winding principle. (N - M) / N << 1

[0014] The winding principle of a specific embodiment is represented as follows. 0.01 << (N - M) / N << 0.10

[0015] In yet another embodiment, the average winding tension of turns 1 through M in the plurality of turns is lower than the average winding tension of turns M+1 through N in the plurality of turns. This further improves the performance of the electromagnetic coil assembly. In particular, when turns M+1 through N in the second winding section 12b are subjected to a higher average winding tension than turns 1 through M in the first winding section 12a, the inner winding section consisting of turns [1...M] is confined by the outer winding section consisting of turns [M+1...N]. This also improves the mechanical stability of the coil.

[0016] In some embodiments of the HTS coil assembly, the core is a ferromagnetic core, while in other advantageous embodiments the core is a non-ferromagnetic core.

[0017] In a further advantageous embodiment, each of the power taps comprises a sub-tap, which improves electrical conductivity between the HTS coil assembly and external peripherals, and in particular reduces contact resistance between each sub-tap and the HTS tape winding.

[0018] Advantageously, the HTS material comprises at least one of the group consisting of (RE)BCO, BSCCO, TBCCO. [Brief explanation of the drawings]

[0019] The present invention will now be described in more detail with reference to the accompanying drawings. [Figure 1A] 1A and 1B are diagrams showing a first embodiment of an electromagnetic coil assembly according to the present invention. [Figure 1B] 1A and 1B are diagrams showing a first embodiment of an electromagnetic coil assembly according to the present invention. [Figure 2A] FIG. 10 is a diagram showing a second embodiment of an electromagnetic coil assembly according to the present invention. [Figure 2B]FIG. 10 is a diagram showing a second embodiment of an electromagnetic coil assembly according to the present invention. [Figure 2C] FIG. 10 is a diagram showing a second embodiment of an electromagnetic coil assembly according to the present invention. [Figure 3] FIG. 3 is a detailed view of the second embodiment of FIG. 2. For a proper understanding of the present invention, in the following detailed description, corresponding elements or parts are designated by the same reference numerals. DETAILED DESCRIPTION OF THE INVENTION

[0020] 1a-1b show a first embodiment of an electromagnetic coil assembly according to the present invention. The electromagnetic coil assembly 10 comprises a core 11 and a winding 12. The winding 12 is composed of a coil wound multiple times around the core 11. Preferably, the core 11 is a ferromagnetic core, although other materials such as a non-ferromagnetic core may also be used.

[0021] The coil assembly typically also includes a plurality of power taps for electrically connecting the winding 12 to external peripheral devices (particularly an external power source). In this regard, a first power tap 13a and a second power tap 13b connect the winding 12 (particularly the first winding section 12a of the winding 12) to the external power source. The first power tap (or first tap) 13a is the positive terminal (+), and the second power tap (or second tap) 13b is the negative terminal (-). Another embodiment of the electromagnetic coil assembly 10' shown in FIG. 2a and particularly FIG. 3 includes additional taps connected to the HTS winding 12. These additional taps are shown as a first voltage tap 14a and a second voltage tap 14b and serve to electrically connect the winding 12 to other types of external peripheral devices (particularly a voltmeter 21, described below).

[0022] Each of the power taps 13a-13b and voltage taps 14a-14b may include multiple sub-taps 130a-130b and 140a-140b to improve reliability and connectivity.

[0023] Quench detection and protection circuitry connected to voltage taps 14a-14b of second winding section 12b of winding 12 is essential in most coil applications because of the large amount of energy stored in the superconducting coil assembly. If currents of hundreds of amperes flow through the windings of the coil assembly and the coil loses its superconductivity, it can lead to a "meltdown" scenario, a catastrophic failure of the system. Therefore, a reliable and safe quench detection mechanism is essential in nearly all applications.

[0024] As shown in Figures 1-3, the windings 12 are formed as tape components that are narrow relative to their length. Such tape components 12 include a high temperature superconducting (HTS) material. Examples of HTS materials may include at least one of the group consisting of (RE)BCO, BSCCO, and TBCCO. However, the material of the tape components 12 may also be other HTS materials.

[0025] As shown in FIG. 1a, the first and second taps 13a-13b (first and second connection taps) are connected to the HTS winding at an angle emerging from the coil surface. In the embodiment of FIG. 1a, the first and second connection taps 13a-13b are connected to the HTS winding 12 at a 90° angle. FIG. 3 shows another embodiment in which the first and second taps 14a-14b are connected to the tape winding 12 at a sharper angle α (30°-90°, in particular 70°-85°). The power taps 13a-13b are also connected to the tape winding 12 at a sharper angle α (30°-90°, in particular 70°-85°). The second type of taps 14a-14b may also be connected to the tape winding 12 at an angle α=90°.

[0026] The sharp angle at which the taps 13a-13b; 14a-14b are connected to the HTS winding 12 allows for a proper exit from the winding 12 and a proper and stable electrical connection. An angle α=90° ensures a stable electrical connection with limited stress.

[0027] In manufacturing such an electromagnetic coil assembly 10-10', tape windings 12 are wound onto a robin or core 11. During this winding step, at least one electrical tap 13a-13b; 14a-14b is connected at a desired angle α (the angle at which the taps exit the plane of the coil 12). Typically, this angle is 90° so that only the angular component in the lead direction remains. However, depending on the specific application, other angles may be useful. In this way, the several power taps 13a-13b and voltage taps 14a-14b are mechanically trapped between the windings, ensuring a proper and stable electrical connection.

[0028] Preferably, the voltage taps 13a-13b are made of a superconducting material. In an advantageous embodiment, the voltage taps 13a-13b are formed of tape-like taps containing an HTS material. More specifically, the tape-like voltage taps 13a-13b are fabricated from the same HTS material as the HTS tape winding 12 (which includes at least one of the group consisting of (RE)BCO, BSCCO, and TBCCO). However, again, other HTS materials may be used for the voltage taps 13a-13b and voltage taps 14a-14b. In another example, the voltage taps 14a-14b may be fabricated from known copper wire.

[0029] FIG. 1b shows a detail of an alternative embodiment to FIG. 1a, illustrating the electrical connection of power taps 13a and 13b from coil 12 to power terminals of an external power circuit. For clarity, only power tap 13b is shown as a short HTS tape component that emerges from the plane of coil 12 at an angle α=90°. HTS tape component (power tap) 13b (and its sub-tap 130b) extends with an additional HTS tape component 13b'. The additional HTS tape component 13b' functions as an extension of power tap 13b (or sub-tap 130b). The additional HTS tape component 13b' is connected at its first end 13b'-a to HTS tape component 13b by solder connection 13z. The additional HTS tape component 13b' is electrically connected at its second end 13b'-b to a power terminal of an external power circuit (not shown).

[0030] Similarly (not shown), another power tap 13a in the form of an HTS tape component (and its sub-tap 130a) may extend with this additional HTS tape component 13a'. The additional HTS tape component 13a' functions as an extension of the power tap 13a (or sub-tap 130a). The additional HTS tape component 13a' is connected at its first end 13a'-a to the HTS tape component 13a by a solder connection 13z. The additional HTS tape component 13a' is electrically connected at its second end 13a'-b to a power terminal of another external power circuit (not shown).

[0031] Each of the tape-like power taps 13a and 13b (shown as additional HTS tape component 13b') is curved from its exit 13b'-a from the coil 12 to its connection point 13b'-b with a power terminal of an external power circuit (not shown). This curve conforms to the magnetic field lines of the magnetic field generated by the coil assembly 10-10' during operation. This minimizes the power taps 13a-13b's exposure to the magnetic field and its resulting disturbances and exposure to electromagnetic forces (Lorentz forces). Similarly, the first power tap 13a (and its sub-tap 130a) can extend with an additional HTS tape component 13a' (not shown). The additional HTS tape component 13a' is connected at its first end 13a'-a to the HTS tape component 13a by a solder connection 13z. The additional HTS tape component 13a' is electrically connected at its second end 13a'-b to a power terminal of an external power circuit (not shown).

[0032] It will be appreciated that both the first and second power taps 13a-13b (together with their sub-taps 130a-130b) can be formed directly as a stretched HTS tape component that exits the face of the coil 12 and connects at its free end (corresponding to ends 13a'-b or 13b'-b of the tape component) to a power terminal of an external power circuit. In this embodiment, no solder connection 13z is required.

[0033] As shown in FIGS. 1-3, the winding 12 is composed of two winding sections, which are respectively denoted by reference numerals 12a and 12b. To complete the coil, a plurality of turns are required, or it is assumed that the winding 12 is composed of N turns. The first winding section 12a of the winding 12 is composed of M turns, and the second winding section 12b is composed of N - M turns. When composed of these two winding sections 12a and 12b, the first power tap 13a is electrically connected to the first turn closest to the core 11 of the winding 12. The second power tap 13b is electrically connected to the Mth turn of the winding 12. Note again that M < N. The first and second power taps 13a-13b are respectively electrically connected to the positive and negative terminals of an external power source of the electromagnetic coil assembly 10-10' for supplying power to the coil 12.

[0034] Regarding the second winding section 12b, the first voltage tap 14a is electrically connected to the (M + 1)th turn of the second winding section 12b of the winding 12. And the second voltage tap 14b is electrically connected to the Oth turn of the winding 12. The Oth turn of the winding 12 is located on the outer periphery of the coil assembly. On the other hand, the first turn (turn 1) is located on the side of the core 11 of the coil assembly. Preferably, O ≈ N, particularly O = N.

[0035] Regarding the comparison of the number of turns of each winding section 12a and 12b, the following holds. (N - M) / N << 1

[0036] In particular, 0.01 << (N - M) / N << 0.10 That is.

[0037] In any of the above formulas, N is the total number of turns of the coil, and M is the number of turns between the first power tap 13a and the second power tap 13b.

[0038] In particular, the average winding tension of the multiple turns of the first winding section 12a (i.e., turn 1 through turn M) is lower than the average winding tension of the multiple turns of the second winding section 12b (i.e., turn M+1 through turn N). In particular, when the (M+1)th through Nth turns of the second winding section 12b are given a higher average winding tension than the 1st through Mth turns of the first winding section 12a, the inner winding section consisting of turns [1...M] is confined by the outer winding section consisting of turns [M+1...N]. This also improves the mechanical stability of the coil.

[0039] The use of two winding sections 12a and 12b in a coil assembly is known as "overbanding." However, in electromagnetic coil assembly embodiments 10 and 10', the "overbanding" is formed by providing an additional winding section 12b that radially surrounds the first winding section 12a. That is, the second winding section 12b surrounds the complete coil 12 to form a ring consisting of NM turns.

[0040] In one embodiment, the winding of the second winding section 12b is constructed from the same HTS tape as the first winding section 12a. In another embodiment, a different material, such as a metal tape, is used, having the same width as the HTS winding 12 forming the first winding section 12a. In this particular embodiment, the HTS tape terminates at the second connection tap 13b after M turns. The HTS tape then continues for N M turns, consisting solely of the metal tape forming the second winding section 12b. After M turns, continuing the winding with a similarly shaped tape (the same HTS tape or a different metal tape) beyond the connection point of the second power tap 13b prevents the creation of free or loss ends in the winding. The existence of such free or loss ends in the winding would expose them to the generated magnetic field, which could cause disturbances due to electromagnetic (Lorentz) forces.

[0041] In another embodiment, the HTS tape winding continues from the first winding section 12a to the second winding section 12b.

[0042] As shown in Figures 2b-2c, the electromagnetic coil assembly 10' includes a third voltage tap 14c and a fourth voltage tap 14d. The third voltage tap 14c and the fourth voltage tap 14d are each connected to a turn of the coil within the first winding section 12a. As shown in Figure 2b, the third voltage tap 14c and the fourth voltage tap 14d may each be electrically connected to the first voltage tap 13a and the second voltage tap 13b (at the first turn and the Mth turn of the first winding section 12a, respectively). Alternatively, as shown in Figure 2c, the third voltage tap 14c and the fourth voltage tap 14d may each be electrically connected to a turn of the first winding section 12a.

[0043] Additionally, each of the third and fourth voltage taps 14c, 14d is electrically connected to a quench voltage detection system 20 using conductors 20a-20b.

[0044] A quench voltage detection system 20 between the third voltage tap 14c and the fourth voltage tap 14d can be used to detect the quench voltage. However, the electromagnetic coil assembly of the present invention may also be implemented with a non-contact actuating system. An actuator (carrier) passing through the electromagnetic coil assembly will disturb the magnetic field generated by the coil. Such external disturbances or changes in the magnetic field induce currents in the turns / windings of the first winding section 12a. Unfortunately, these currents can result in false positive quench triggers.

[0045] The winding arrangement of the two winding sections 12a and 12b forms two concentric coils. With the additional windings from the (M+1)th turn through the (N)th turn forming the second winding section 12b, when the coil assembly is powered by an external power source via the voltage taps 14a and 14b, zero voltage may be observed between the first and second voltage taps 14a and 14b, even if no external disturbances to the magnetic field occur. However, if an external disturbance to the magnetic field occurs (e.g., due to an actuator of a non-contact actuating system through the electromagnetic coil assembly), the external disturbance to the magnetic field induces a current in the second winding section 12b. An additional voltage detection system 21 connected to the first and second power taps 14a and 14b using connecting conductors 21a and 21b can then be used to observe the induced potential difference between the (M+1)th turn and the (O(N))th turn across the power taps 14a and 14b.

[0046] By implementing two additional (third and fourth) voltage taps 14c-14d within the first winding section (e.g., by electrically connecting the third voltage tap 14c to the first power tap 13a and the fourth voltage tap 14d to the second power tap 13b by at least less than turn M), the quench voltage detection system 20 can be used to measure the potential difference between the third and fourth voltage taps 14c-14d, thereby effectively detecting a quench or loss of superconductivity that leads to a sudden increase in ohmic resistance within the winding section 12a.

[0047] However, the above-mentioned external disturbances in the magnetic field are also detected at the third and fourth voltage taps 14c-14d. Therefore, by itself, it is not possible to distinguish between a true quench in the first winding section 12a of the coil 12 and an external disturbance in the magnetic field. In this case, by further implementing a quench voltage detection system 21 for the overwinding winding section 12b, any potential difference observed between the two voltage taps 14a-14b can be directly correlated to the external disturbance in the magnetic field. In this way, by performing potential difference measurements both between the two voltage taps 14c-14d and between the two voltage taps 14a-14b (more specifically, between the two winding sections 12a and 12b), external influences can be counteracted, resulting in more reliable quench detection. [Explanation of symbols]

[0048] 10-10'··An embodiment of an electromagnetic coil assembly; 11··cores, 12··Winding to form a coil formed as HTS tape, 12a··First group of multiple turns [1;M], 12b··A second group of turns [M+1;N], 13a··First power tap; 13b··Second power tap; 13b' Additional HTS components / power tap extensions, 13z··Solder connection, 14a··first voltage tap; 14b··Second voltage tap; 14c··Third voltage tap, 14d··Fourth voltage tap, 130a-130b··Sub-tap of power tap, 140a-140b··Sub-tap of voltage tap.

Claims

1. The core and a winding wound around the core a plurality of times to form a coil; a plurality of power taps for electrically connecting the windings to an external power circuit; the windings are formed as tape components comprising high temperature superconducting (HTS) material; the plurality of power taps are connected to the windings that exit the plane of the coil at a predetermined angle; The plurality of windings of the coil are composed of N turns, a first power tap connected to a first turn of the winding; a second power tap connected to the Mth turn of the winding; An electromagnetic coil assembly, wherein M<N.

2. a plurality of voltage taps for measuring voltages between at least some of the plurality of windings; a first voltage tap connected to the (M+1)th turn of the winding; a second voltage tap connected to the Oth turn of the winding; 2. An electromagnetic coil assembly according to claim 1, characterized in that O≈N, in particular O=N.

3. 3. The electromagnetic coil assembly of claim 1, wherein the power tap is made of a superconducting material.

4. 4. The electromagnetic coil assembly of claim 3, wherein the power tap is formed as a tape power tap comprising high temperature superconducting (HTS) material.

5. 5. An electromagnetic coil assembly according to any one of claims 1 to 4, characterized in that the power tap is connected to the tape component at an angle α between 30° and 90°, in particular 90°.

6. the power tap has a curved portion extending from a position where it exits the coil to a position where it is connected to a power terminal of an external power supply circuit; 6. An electromagnetic coil assembly according to any one of claims 1 to 5, wherein the curvature corresponds to the magnetic field lines of the magnetic field generated by the coil during operation.

7. (N-M) / N<<1 3. The electromagnetic coil assembly according to claim 1, wherein:

8. 0.01<<(NM) / N<<0.10 8. The electromagnetic coil assembly according to claim 7, wherein:

9. 9. The electromagnetic coil assembly according to claim 1, wherein an average winding tension from the 1st turn to the Mth turn in the plurality of turns is lower than an average winding tension from the (M+1)th turn to the Nth turn in the plurality of turns.

10. 10. An electromagnetic coil assembly according to claim 1, wherein the core is a ferromagnetic core.

11. 11. An electromagnetic coil assembly according to any preceding claim, wherein each of the power taps comprises a sub-tap.

12. 12. The electromagnetic coil assembly according to claim 1, wherein the HTS material comprises at least one of the group consisting of (RE)BCO, BSCCO, and TBCCO.

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