Electromagnet 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 around the core a plurality of times to form a coil, and a plurality of power taps for electrically connecting the winding to an external power circuit.

Background Art

[0002] The above electromagnetic coil assembly is disclosed, for example, in JP-A-2008-305861.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Generally, superconducting coils are widely used commercially and for research in medical fields such as NMR and MRI, or in rotating machines such as motors and generators. On the other hand, cables made of high-temperature superconducting (HTS) wires are known, and can transmit 10 times the current of conventional cables. Alternatively, there are also HTS cables that can transmit the same current at a lower voltage. HTS can be used in both direct current (DC) systems and alternating current (AC) systems. Generally, high-temperature superconducting materials (abbreviated as high-T c or HTS) are operationally defined as materials that exhibit superconductivity near -200°C (73.15K), particularly near -196.5°C (=77K), which is the boiling point of nitrogen N2.

[0004] Since the field of high-temperature superconductivity is very new, the application areas are rapidly changing at the forefront. Most electromagnetic coils incorporating HTS materials are for academic purposes and are usually wound by hand. Such coils require a certain type of power cable or power tap. However, in academic applications, the coils are usually "disposable" and cannot be manufactured on a large scale and quantitatively over a sufficiently long period of time.

[0005] For these reasons, an object of the present invention is to provide an electromagnetic coil assembly for mounting HTS substances, which can be mass-produced with high reliability, robustness, and high cost-effectiveness.

Means for Solving the Problems

[0006] To solve this problem, an electromagnetic coil assembly is provided. This electromagnetic coil assembly includes a core, a winding wound around the core a plurality of times 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 including a high-temperature superconducting (HTS) substance. The plurality of power taps are connected to the winding extending from the surface of the coil at a predetermined angle.

[0007] Normally, the power taps of known coils are connected to the conducting wires using soldering connections to copper busbars. When the conducting wires are formed of tape components containing high-temperature superconducting (HTS) substances and the plurality of power taps are connected to this HTS tape winding, it is possible to have a strong and highly reliable electrical connection between the surface of the coil at a predetermined angle and an external power source or the like.

[0008] In particular, when the power taps are also made of superconducting substances, the electromagnetic characteristics of the HTS coil are further improved. That is, in this case, more specifically, the power taps are formed as tape-shaped power taps containing high-temperature superconducting (HTS) substances. In particular, the tape-shaped power taps are made from the HTS tape component as the winding.

[0009] As an example, the power taps are connected to the tape winding at an angle α of 30° or more and 90° or less, particularly 90°. Thereby, the contact surface between the HTS tape winding and the tape-shaped power tap is enlarged.

[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. As a result, 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 Mth 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 comprises 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 Oth 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, quench detection or protection systems). Thereby, the potential difference between the (M + 1)th turn and the Oth 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 from turn 1 to turn M in a plurality of turns is lower than the average winding tension from turn M + 1 to turn N in the plurality of turns. Thereby, the performance of the electromagnetic coil assembly is further improved. In particular, when the turns from turn M + 1 to turn N of the second winding section 12b give a higher average winding tension than the turns from turn 1 to turn M of the first winding section 12a, the inner winding section composed of turns [1...M] is confined by the outer winding section composed of turns [M + 1...N]. This also improves the mechanical stability of the coil.

[0016] In an HTS coil assembly of an embodiment, the core is a ferromagnetic core. On the other hand, in another advantageous example, the core is a non-ferromagnetic core.

[0017] In a further advantageous embodiment, each of the power taps comprises a sub-tap. Thereby, the electrical conductivity between the HTS coil assembly and external peripheral devices is improved, and in particular, the contact resistance between each sub-tap and the HTS tape winding is reduced.

[0018] Advantageously, the HTS material includes at least one of the group consisting of (RE)BCO, BSCCO, and TBCCO. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 2C

Figure 3

Mode for Carrying Out the Invention

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

[0021] A normal coil assembly also includes a plurality of power taps for electrically connecting the winding 12 to external peripheral devices (especially an external power source). In this regard, a first power tap 13a and a second power tap 13b connect the winding 12 (especially the first winding section 12a of the winding 12) to an external power source. The first power tap (or the first tap) 13a is the positive terminal (+), and the second power tap (or the second tap) 13b is the negative terminal (-). The electromagnetic coil assembly 10' of another embodiment shown in FIGS. 2a and especially 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 function to electrically connect the winding 12 to other types of external peripheral devices (especially a voltmeter 21 described later).

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

[0023] The quench detection and protection circuit connected to the voltage taps 14a - 14b of the second winding section 12b of the winding 12 is essential in most coil applications. This is because a large amount of energy is stored in the superconducting coil assembly. When a current of several hundred amperes flows through the windings of the coil assembly and the coil loses its superconductivity, it can lead to a "meltdown" scenario, which is a catastrophic failure of the system. Therefore, a highly reliable and safe quench detection mechanism is essential for almost all applications.

[0024] As shown in FIGS. 1 - 3, the winding 12 is formed as a tape component that is narrow in width compared to its length. Such a tape component 12 contains a high-temperature superconducting (HTS) material. Examples of HTS materials may be at least one of the group consisting of (RE)BCO, BSCCO, and TBCCO. However, the material of the tape component 12 may 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 emerging from the coil surface at a certain angle. In the embodiment of FIG. 1a, the first and second connection taps 13a - 13b are connected to the HTS winding 12 at an angle of 90°. FIG. 3 shows another embodiment, where the first and second taps 14a - 14b are connected to the tape winding 12 at a sharper angle α (30° - 90°, particularly 70° - 85°). Similarly, the power taps 13a - 13b are connected to the tape winding 12 at a sharper angle α (30° - 90°, particularly 70° - 85°). The second type of taps 14a - 14b may also be connected to the tape winding 12 at an angle α = 90°.

[0026] When the taps 13a - 13b; 14a - 14b are connected to the HTS winding 12 at a sharp angle, the winding 12 can exit properly, enabling a proper and stable electrical connection. When the angle α = 90°, a stable electrical connection under limited stress is guaranteed.

[0027] Regarding the manufacture of such electromagnetic coil assemblies 10 - 10’, the tape winding 12 is wound on the bobbin or core 11. At the stage of winding this, at least one electrical tap 13a - 13b; 14a - 14b is connected at a desired angle α (the angle at which these taps emerge from the plane of the coil 12). Typically, this angle is 90° such that only the angular component in the lead direction remains. However, depending on the specific application, another angle may be useful. In this way, several power taps 13a - 13b and voltage taps 14a - 14b are mechanically confined 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 - shaped taps containing an HTS material. More specifically, the tape - shaped voltage taps 13a - 13b are manufactured from the same HTS material as the HTS tape winding 12 (including at least one from the group consisting of (RE)BCO, BSCCO, TBCCO). However, again here, 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 made from known copper wires.

[0029] Figure 1b shows details of another embodiment different from Figure 1a, showing the electrical connection between the power taps 13a and 13b from the coil 12 and the power terminals of an external power supply circuit. For clarity, only the power tap 13b is shown as a short HTS tape component emerging from the plane of the coil 12 at an angle α = 90°. The HTS tape component (power tap) 13b (and its sub - tap 130b also) extends together with an additional HTS tape component 13b’. The additional HTS tape component 13b’ functions as an extension of the power tap 13b (or sub - tap 130b). The additional HTS tape component 13b’ is connected to the HTS tape component 13b by a solder connection 13z at its first end 13b’ - a. The additional HTS tape component 13b’ is electrically connected to the power terminal of an external power supply circuit (not shown) at its second end 13b’ - b.

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

[0031] Each of the tape-shaped power taps 13a and 13b (shown as additional HTS tape component 13b') has a curved portion extending from the outlet 13b'-a from the coil 12 to the connection position 13b'-b with the power terminal of the external power circuit (not shown). This curvature coincides with the magnetic field lines of the magnetic field generated by the operating coil assembly 10-10'. Thereby, even when the power taps 13a-13b are exposed to the magnetic field, the disturbance and exposure to the electromagnetic force (Lorentz force) caused thereby are minimized. Similarly, the first power tap 13a (and its sub-tap 130a as well) can extend together with an additional HTS tape component 13a' (not shown). The additional HTS tape component 13a' is connected to the HTS tape component 13a by a solder connection 13z at its first end 13a'-a. The additional HTS tape component 13a' is electrically connected to a power terminal of the external power circuit (not shown) at its second end 13a'-b.

[0032] It can be seen that both the first and second power taps 13a-13b (along with their sub-taps 130a-130b) can be directly formed as an extended HTS tape component. This extended HTS tape component exits the plane of the coil 12 and is connected to the power terminal of the external power circuit at its free end (corresponding to the end 13a'-b or 13b'-b of the tape component). In the case of this embodiment, the solder connection 13z is not 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. And it is assumed that 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 M-th 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 O-th turn of the winding 12. The O-th 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, and in particular, 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 a plurality of turns (i.e., from turn 1 to turn M) of the first winding section 12a is lower than the average winding tension of a plurality of turns (i.e., from turn M + 1 to turn N) of the second winding section 12b. In particular, when the (M + 1)-th turn to the N-th turn of the second winding section 12b provide a higher average winding tension than the first turn to the M-th turn of the first winding section 12a, the inner winding section composed of turns [1...M] is confined by the outer winding section composed of turns [M + 1...N]. This also improves the mechanical stability of the coil.

[0039] Using the two winding sections 12a and 12b of the coil assembly is known as "overbanding". However, in embodiments 10 and 10' of the electromagnetic coil assembly, "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 composed of N - M turns.

[0040] In one embodiment, the winding of the second winding section 12b is composed of the same HTS tape winding as the first winding section 12a. In another example, another material such as a metal tape having the same width as the HTS winding 12 forming the first winding section 12a is used. In this particular example, the HTS tape winding is terminated with a second connection tap 13b after being wound M times. Thereafter, the HTS tape winding continues to be wound N - M times only by the metal tape winding forming the second winding section 12b. After winding M times, by continuing to wind with a tape winding of a similar shape (the same HTS tape winding or a different metal tape winding) beyond the connection point of the second power tap 13b, the generation of free ends or loss ends in the winding portion can be prevented. If such free ends or loss ends of the winding portion exist, they are exposed to the generated magnetic field, which can cause the generation of disturbances due to electromagnetic force (Lorentz force).

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

[0042] As shown in FIGS. 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 turns of the coil within the first winding section 12a. As shown in FIG. 2b, each of the third voltage tap 14c and the fourth voltage tap 14d may be electrically connected to the first power tap 13a and the second voltage tap 13b (at the first turn and the M-th turn of the first winding section 12a, respectively). Alternatively, as shown in FIG. 2c, each of the third voltage tap 14c and the fourth voltage tap 14d may be electrically connected to turns of the first winding section 12a.

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

[0044] Using the quench voltage detection system 20 between the third voltage tap 14c and the fourth voltage tap 14d, the quench voltage can be detected. However, the electromagnetic coil assembly according to the present invention may be realized by a non-contact actuating system. The actuator (carrier) passing through the electromagnetic coil assembly will disrupt the magnetic field generated by the coil. Such an external disturbance or change in the magnetic field induces a current in the turns / windings of the first winding section 12a. Unfortunately, this current may produce a false positive quench trigger.

[0045] The winding arrangements of the two winding sections 12a and 12b form two concentric coils. When using the additional windings from the (M + 1)-th turn to the N-th turn forming the second winding section 12b, even when there is no external disturbance in the magnetic field when the coil assembly is powered from an external power source via the first voltage tap 14a and the second voltage tap 14b, a zero voltage may be observed between the first voltage tap 14a and the second voltage tap 14b. However, when an external disturbance occurs in the magnetic field (e.g., due to the actuator of a non-contact actuating system passing through the electromagnetic coil assembly), this external disturbance in the magnetic field induces a current in the second winding section 12b. Then, using the additional voltage detection system 21 connected to the first and second power taps 14a - 14b via the connection conductors 21a - 21b, the potential difference induced between the turn M + 1 and the turn O(N) across the power taps 14a and 14b can be observed.

[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, with at least less than turn M), the potential difference between the third and fourth voltage taps 14c-14d can be measured using the quench voltage detection system 20, so that quenches or superconducting losses leading to a rapid increase in ohmic resistance within the winding section 12a can be effectively detected.

[0047] However, the above external magnetic field disturbances are also detected at the third and fourth voltage taps 14c-14d. Therefore, alone, it is not possible to distinguish between a real quench within the first winding section 12a of the coil 12 and an external magnetic field disturbance. In this case, by further implementing a quench voltage detection system 21 for the overbanding winding section 12b, any potential difference observed between the two voltage taps 14a-14b can be directly correlated to an external magnetic field disturbance. Thus, by performing potential difference measurements at 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 cancelled out, enabling more reliable quench detection.

Explanation of Symbols

[0048] 10-10’ ··· Embodiment of the electromagnetic coil assembly, 11 ··· Core, 12 ··· Winding constituting a coil formed as an HTS tape, 12a ··· First group of a plurality of turns [1;M], 12b ··· Second group of a plurality of turns [M+1;N], 13a ··· First power tap, 13b ··· Second power tap, 13b’ ··· Extension of additional HTS component / power tap, 13z ·· Solder connection, 14a ·· First voltage tap, 14b ·· Second voltage tap, 14c ·· Third voltage tap, 14d ·· Fourth voltage tap, 130a - 130b ·· Sub - taps of power tap, 140a - 140b ·· Sub - taps of voltage tap.

Claims

1. A core, a winding wound around the core multiple times to form a coil, and a plurality of power taps for electrically connecting the winding to an external power circuit, characterized in that the winding is formed as a tape component provided with a high-temperature superconducting (HTS) material, the plurality of power taps are connected to the winding emerging from 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 is connected to the first turn of the winding, a second power tap is connected to the Mth turn of the winding, and an electromagnetic coil assembly, wherein M < N.

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

3. The electromagnetic coil assembly according to claim 1 or 2, wherein the power tap is made of a superconducting material.

4. The electromagnetic coil assembly according to claim 3, wherein the power tap is formed as a tape-shaped power tap containing a high-temperature superconducting (HTS) material.

5. The electromagnetic coil assembly according to any one of claims 1 to 4, wherein the power tap is connected to the tape component at an angle α of 30° or more and 90° or less, particularly 90°.

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

7. (N - M) / N << 1 The electromagnetic coil assembly according to claim 1 or 2, characterized in that.

8. 0.01 << (N - M) / N << 0.10 The electromagnetic coil assembly according to claim 7, characterized in that.

9. The electromagnetic coil assembly according to any one of claims 1 to 8, wherein the average winding tension from the first turn to the Mth turn in the plurality of turns is lower than the average winding tension from the (M + 1)th turn to the Nth turn in the plurality of turns.

10. The electromagnetic coil assembly according to any one of claims 1 to 9, wherein the core is a ferromagnetic core.

11. The electromagnetic coil assembly according to any one of claims 1 to 10, wherein each of the power taps includes a sub-tap.

12. The electromagnetic coil assembly according to any one of claims 1 to 11, wherein the HTS material contains at least one of the group consisting of (RE)BCO, BSCCo, and TBCCo.

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