JP2013034277A - Superconducting motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting motor that is applied with an alternating current and does not spoil cooling efficiency of a superconducting wire while suppressing hysteresis loss of the superconducting wire.SOLUTION: There is provided an axial gap type superconducting motor characterized in that a stator 1 has a pair of superconducting wires 12a, 12b extending radially from a rotating shaft 2 as a center in point symmetry relationship, rotors 21, 22 are configured to have pairs of permanent magnets 21a, 21b and 22a, 22b with mutually opposite polarities in a direction of the rotating shaft allocated to two halved regions across a diameter having its center on the rotating shaft, an alternating current is supplied to one of the superconducting wires 12a, 12b in the point symmetry relationship from an inner periphery to an outer periphery, and an alternating current in phase is supplied to the other of the superconducting wires 12a, 12b from an outer periphery to an inner periphery.

Description

  The present invention relates to a superconducting motor using Lorentz force.

  The superconducting motor of the present invention is a device that supplies electric power and outputs rotational power, and can be used as a superconducting generator that outputs electric power when rotational power is input. In the following, the superconducting motor will be mainly described, and the superconducting generator will be referred to when necessary.

  A superconducting motor using a superconducting phenomenon in which the electric resistance becomes “0 (zero)” needs to cool a superconducting wire through which a current flows. For example, a superconducting motor (superconducting rotator) disclosed in Patent Document 1 is a refrigerator (Stirling pulse tube refrigerator (a type of cryocooler)) in which a rotor around which a superconducting wire (superconducting wire) is wound. 1 [Refer to [0026]), and the rotor and the refrigeration unit of the refrigerator are housed in the main body of the vacuum heat insulating structure to achieve high cooling efficiency (Patent Document 1 [Claim 1]. [Claim 2]). The superconducting wire that rotates together with the rotor is drawn out of the main body of the vacuum heat insulating structure and connected to the rotor rotary feeder (Patent Document 1 [Claim 5]).

  The motor structure disclosed in Patent Document 1 is either a radial gap type (Patent Document 1, [FIG. 1] to [FIG. 3]) or an axial gap type (Patent Document 1, [0053], [0054], [FIG. 4]). Also used for. In both cases, it is not clearly shown how the superconducting wire is wound. However, if the illustrated radial gap type or axial gap type is a conventional configuration, the superconducting wire is wound. When rotating units (rotor coils) are arranged at equal intervals in the circumferential direction, the magnet is assembled to the stator with the same polarity in the radial direction (radial gap type) or rotating shaft direction (axial gap type) over the entire circumference. Conceivable.

JP 2010-093886

  In a superconducting motor using a superconducting wire, a rotor coil in a conventional motor may be composed of a superconducting wire, and the electromagnetic force generated in the rotor coil and the repulsive force between permanent magnets may be used. In this case, since it is necessary to change the magnitude or polarity of the electromagnetic force, an alternating current is applied to the superconducting wire. In this way, when applying an alternating current to the superconducting wire of the superconducting motor, hysteresis loss occurs in the superconducting wire and it is heated, and prevents the superconducting wire from being cooled until the superconducting phenomenon occurs. It is known.

  The superconducting motor disclosed in Patent Document 1 is considered to apply an alternating current to the superconducting wire (see Patent Document 1 [0055]). Moreover, although patent document 1 does not specify the number of poles of the exemplified superconducting motor, if it is configured to apply a three-phase alternating current found in many alternating-current motors, a rotor that flows alternating-phase alternating current in a point-symmetric manner. It is considered that three sets of coils are arranged at equal intervals in the circumferential direction. In this case, the frequency of the applied alternating current is three times the rotational speed of the rotating shaft, and the hysteresis loss is also increased.

  Assuming that the material of the superconducting wire is appropriately selected to reduce the hysteresis loss, it is preferable that the applied AC frequency be lowered as much as possible and, if possible, equal to the rotational speed of the rotating shaft. Therefore, a configuration suitable for a superconducting motor that does not impair the cooling efficiency of the superconducting wire while suppressing the hysteresis loss of the superconducting wire in the superconducting motor that applies alternating current was studied.

  What has been developed as a result of the study is a superconducting wire in a plane perpendicular to the rotation axis of the stator having a rotation shaft that freely penetrates, and a plane perpendicular to the rotation axis of the rotor rotating together with the rotation axis In the axial gap type superconducting motor facing the inner permanent magnet, the stator has a pair of superconducting wires extending in the radial direction around the rotation axis in a point-symmetrical positional relationship, and rotates. The child is constructed by allocating a pair of permanent magnets whose polarities in the rotation axis direction are opposite to each other to each of the halved regions with a diameter around the rotation axis, and having a point-symmetrical positional relationship. The superconducting motor is characterized in that an alternating current is supplied to one of the conductive wires from the inner periphery to the outer periphery, and an alternating current of the same phase is supplied to the other of the superconductive wires from the outer periphery to the inner periphery. “Energizing the alternating current from the inner periphery to the outer periphery” means that, for example, when the polarity of the alternating current is positive, current flows from the inner periphery to the outer periphery, and when the polarity becomes negative, current flows from the outer periphery to the inner periphery. Means that. “Energizing alternating current from the outer circumference toward the inner circumference” has the same meaning.

  The superconducting wire in the plane orthogonal to the rotation axis of the stator means that the superconducting wire extends two-dimensionally along the plane orthogonal to the rotation axis. For example, the disk constituting the stator In addition, the superconducting wire is fixed to the surface of the disc, and the superconducting wire is embedded in the disk along a virtual plane orthogonal to the rotation axis. Similarly, a permanent magnet in a plane orthogonal to the rotation axis means that the permanent magnets are arranged in a plane orthogonal to the rotation axis. For example, the permanent magnet is fixed to the surface of the disk constituting the rotor. In addition to this, it includes a case where a permanent magnet is embedded in the disk following a virtual plane orthogonal to the rotation axis.

  In the superconducting motor of the present invention, when the magnetic flux extending from a permanent magnet in a plane perpendicular to the rotation axis of the rotor intersects the superconducting wire in the point-symmetrical positional relationship of the stator, the left hand of Fleming According to the law, a Lorentz force is generated in each superconducting wire, and the rotor is rotated using the reaction of the Lorentz force. A superconducting wire that is in a point-symmetrical positional relationship causes current to flow in the opposite direction in the radial direction, but the magnetism of the magnet facing each superconducting wire is also reversed, so the Lorentz that occurs in each superconducting wire The force is directed in the same direction in the circumferential direction. From this, the reaction of the Lorentz force is also directed in the same direction in the circumferential direction, and the rotational force in the same direction is given to the rotor in a point-symmetric positional relationship. In addition, when the superconducting motor of the present invention is a superconducting generator, a current whose polarity is switched, that is, an alternating current is generated in each superconducting wire according to Fleming's right-hand rule.

  The superconducting motor of the present invention has only two permanent magnets for the rotor, and it is only necessary to reverse the polarity of the alternating current flowing through the superconducting wire corresponding to each pole that is switched by rotation. This means that one rotation of the rotor and one cycle of alternating current are synchronized, that is, the number of rotations of the rotating shaft and the frequency of the alternating current applied are the same. Thereby, the hysteresis loss proportional to the frequency of the alternating current to apply can be suppressed to the minimum. The superconducting motor of the present invention utilizes the Lorentz force as described above, and even if the number of poles of the permanent magnet is two, the Lorentz force obtained can be increased if there are many superconducting wires orthogonal to the magnetic flux of the permanent magnet. And increase the rotational force. Similarly, when the superconducting motor of the present invention is a superconducting generator, the current obtained according to the number of superconducting wires increases.

  In order for the superconducting motor of the present invention to rotate the rotor stably, the reaction of the Lorentz force generated in the superconducting wire may be exhibited over the entire circumference. Specifically, the stator has 2n superconducting wires (n is a natural number of 2 or more) that are equally spaced in the circumferential direction, and is a halved region that is divided into two with a diameter around the rotation axis. An alternating current having a phase delayed by π / n from the reference phase from the upstream to the downstream of the rotor is energized from the inner periphery to the outer periphery to the n superconducting wires assigned to one side, From the outer circumference to the inner circumference, an alternating current with a phase delayed by π / n from the reference phase from the upstream of the rotor to the downstream of rotation is applied to the n superconducting wires assigned to the other half of the halved region. To energize.

  When superconducting wires are arranged in 2n strips at equal intervals in the circumferential direction, the superconducting motor of the present invention can suppress coupling loss in addition to hysteresis loss. In the superconducting motor of the present invention, since the rotor has only two permanent magnets, the AC applied to each superconducting wire only needs to change by one period while the rotor makes one revolution. For this reason, hysteresis loss can be suppressed by making the frequency of the alternating current applied and the rotation speed of the rotating shaft the same. In addition, the magnetic fields formed by adjacent superconducting wires other than the adjacent superconducting wires straddling the boundary of the permanent magnets of the rotor are generated according to the right-handed screw law and cancel each other. It is suppressed. Thus, the present invention reduces hysteresis loss and coupling loss by an axial gap type suitable for a superconducting motor.

  Here, n superconducting wires include the case where each strip is a single superconducting wire, as well as the case where a single strip is formed as a bundle of a large number of superconducting wires in the same direction. A 2n superconducting wire means that there is an even number of superconducting wires having the above-described configuration. Further, assuming that the rotor rotates from upstream to downstream, the upstream is referred to as the rotational upstream of the rotor, and the downstream is also referred to as the rotational downstream. Specifically, when the rotor rotates clockwise in plan view, the counterclockwise direction is the upstream rotation of the rotor and the clockwise direction is the downstream rotation of the rotor. In this case, if Lorentz force is generated in the stator superconducting wire from downstream to upstream, the rotor rotates in the direction opposite to the direction of the Lorentz force, that is, clockwise.

  The stator may be a set of two superconducting wires extending in the radial direction around the rotation axis in a point-symmetrical positional relationship. However, the superconducting wire cannot provide only a portion extending in the radial direction around the rotation axis in the point-symmetrical positional relationship, and there are portions other than the portion extending in the radial direction. The superconducting wire other than the portion extending in the radial direction may be extended in an arc shape along the circumferential direction. The Lorentz force generated in the superconducting wire extending in an arc along the circumferential direction faces the radial direction and does not affect the rotation of the rotor. Thereby, the superconducting wire in the plane orthogonal to the rotation axis can be routed like a single stroke, and for example, the entrance / exit of the superconducting wire can be concentrated at one place on the outer periphery of the stator.

  In order to maximize the Lorentz force generated from the downstream of the rotation to the upstream of the rotation, it is desirable that the superconducting wire and the magnetic flux are orthogonal to each other as accurately as possible. From this, the stator is sandwiched between a pair of rotors, and each of the rotors has a permanent direction whose direction of polarity in the direction of the rotation axis is opposite to each of the halved regions with a diameter centered on the rotation axis. The magnets may be assigned with the polarities in the direction of the rotation axis aligned and the halved regions aligned in the circumferential direction. Thereby, the magnetic flux formed by the N pole and S pole of the permanent magnet across the stator is orthogonal to the superconducting wires, and the Lorentz force generated in each superconducting wire can be maximized. Also, multiple (m + 1, m is a natural number) rotors and multiple (m) stators with the same polarity in the rotation axis direction of the permanent magnet and with the halved region aligned in the circumferential direction are stacked alternately. By doing so, it is possible to realize a configuration in which a plurality of stacked units in which the magnetic flux formed by a pair of rotors sandwiching each stator is perpendicular to the superconducting wires of each stator are stacked, and the rotational driving force is increased as a superconducting motor. Or the amount of power generation can be increased as a superconducting generator.

  In the superconducting motor of the present invention, a stator constituted by adhering a superconducting wire to a cooling plate formed of a material having non-magnetic properties, electrical insulation properties, and thermal conductivity has a single vacuum together with a rotor. The cooling plate is fixed to the vacuum vessel by a support body that is built in the container and has heat insulation properties, and the cooling plate and the refrigerator are connected by a heat conductor that penetrates from the outside to the inside of the vacuum vessel. It is preferable that the external power line and the superconducting wire are connected by an electric conductor that penetrates from the outside to the inside of the container. An example of the refrigerator is a cryocooler including a Stirling pulse tube refrigerator described in Patent Document 1.

  The vacuum container is a sealed container made of one or both of a metal and a resin formed of a heat insulating material, and preferably a silver thin film having a small radiant heat is formed on the inner surface. The gas inside the vacuum vessel is discharged by a vacuum pump through an exhaust pipe. The remaining gas and the gas entering from the outside are brought into contact and solidified by the cooled stator, so that there is an advantage that the vacuum degree of the vacuum vessel can be extremely increased. Thereby, the high heat insulation with respect to a superconducting wire is exhibited, and it becomes easy to maintain the cooling state of a superconducting wire.

  Since the stator is cooled by the refrigerator until the superconducting wire exhibits a superconducting phenomenon, it is desirable that the material forming the cooling plate has sufficient strength at the low temperature and has a thermal expansion coefficient comparable to that of metal. Examples thereof include aluminum nitride, silicon nitride, silicon carbide, and alumina having high thermal conductivity. In particular, aluminum nitride has an advantage that the thermal conductivity increases as the temperature decreases. In order to suppress radiant heat, the stator is preferably covered with a silver thin film like the vacuum vessel. In this case, the stator may be covered with a silver thin film integrally with the superconducting wire in close contact with the cooling plate. The rotor preferably has a structure in which a permanent magnet is held by a non-magnetized resin rotating body, and in order to suppress radiant heat, the rotor is preferably covered with a silver thin film like the stator. In this case, the rotating body may be covered with a silver thin film integrally with the permanent magnet.

  The support body may be a member having a heat insulating property that connects the stator and the vacuum vessel and can support the stator in a non-rotatable manner, and is configured as a pin (bar material) or a flange (plate material), for example. . The heat conductor is a member that thermally connects the low-temperature head of the refrigerator and the stator, and is preferably a member having a high thermal conductivity like the stator, and is configured as a pin (bar), for example. When the refrigerator is a cryocooler, the thermal conductor desirably absorbs a change in the distance between the low-temperature head and the stator because the low-temperature head moves back and forth. The electrical conductor is a member that electrically connects the superconducting wire and the power supply source or the power output destination, and is configured as, for example, a lead wire. The electrical conductor is preferably a superconducting lead having a low thermal conductivity while having the same electrical conductivity as the superconducting wire.

  The superconducting motor of the present invention is divided into two parts with a stator having a pair of two superconducting wires extending in the radial direction centered on the rotation axis in a point-symmetrical positional relationship and a diameter centered on the rotation axis. By adopting an axial gap type composed of a pair of permanent magnets with opposite polarities in the rotation axis direction in each of the halved regions, the hysteresis loss of the superconducting wire is suppressed. By preventing the heating of the superconducting wire and increasing the number of superconducting wires, the coupling loss is reduced and the permanent magnet is prevented from being heated, thereby improving the cooling efficiency of the superconducting wire and making the best use of the Lorentz force Thus, the effect of rotating the rotor or reducing the size of the entire apparatus is obtained.

  Suppression of hysteresis loss is an effect obtained by making the frequency of the alternating current applied to the superconducting wire equal to the number of rotations of the rotating shaft because the permanent magnet of the rotor has two poles. Further, the suppression of the coupling loss is brought about by canceling out the magnetic field formed by each superconducting wire when the number of superconducting wires extending in the radial direction around the rotation axis increases and adjacent superconducting wires are close to each other. This is an effect. Suppression of hysteresis loss and coupling loss eliminates a factor that impedes cooling of the superconducting wire. Then, the superconducting wire is brought into close contact with the cooling plate constituting the stator, and the cooling plate is built in the vacuum vessel and cooled by the refrigerator to efficiently cool the superconducting wire, thereby improving the cooling efficiency of the superconducting wire. I am letting.

  The superconducting motor of the present invention adopting the axial gap type is the superconducting wire in which the superconducting wire extending in the radial direction of the stator and the magnetic flux in the rotation axis direction formed by the permanent magnet of the rotor are orthogonally crossed correctly. In addition, maximize the circumferential Lorentz force. This brings about the effect which improves the rotational efficiency as a superconducting motor, and the power generation efficiency as a superconducting generator. Further, if the pair of rotors sandwich the stator, the magnetic flux that the permanent magnet makes perpendicular to the superconducting wire is uniform with respect to the stator, and it is easy to draw out the advantage due to the anisotropy of the superconducting wire with respect to the magnetic field. An effect is also obtained. In addition, since the cooling system that does not use a refrigerant allows the stator and the rotor to be combined and incorporated in the vacuum vessel, the superconducting motor of the present invention is coupled with the thinning that is characteristic of the axial gap type. There is also an effect of reducing the overall size.

It is sectional drawing showing an example of the superconducting motor of this invention. It is a disassembled perspective view showing the relationship between the rotor of this example, and a stator. It is a wave form diagram of electric current i sent through the superconducting wire of the stator of this example. It is a time-dependent relationship figure showing the stator and rotor in the rotation state of the superconducting motor of this example. FIG. 4 is an exploded perspective view corresponding to FIG. 2 illustrating a relationship between a rotor and a stator of another example. It is a disassembled perspective view showing the structure of the stator of another example. It is a wave form diagram of electric current i1-electric current i4 sent through a superconducting wire of a stator of another example. It is a time-dependent relationship figure showing the stator and rotor in the rotation state of the superconducting motor of another example.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the superconducting motor to which the present invention is applied includes a stator 1 that has a rotating shaft 2 rotatably inserted therein, and an upper stage that rotates with the rotating shaft 2 across the stator 1. It is an axial gap type in which the rotor 21 and the lower rotor 22 are built in the vacuum vessel 3. Since the thickness of the superconducting motor in the rotation axis direction depends on the thickness of the stator 1 and the rotors 21 and 22, if the stator 1 and the rotors 21 and 22 are thinned, the rotation axis direction of the superconducting motor is reduced. Can be reduced in thickness. In FIG. 1, the superconducting wire 12 of the stator 1 is shown as one extending in the diametrical direction. Specifically, as shown in FIG. It hangs around the wall 112.

  The vacuum vessel 3 has a flat cylindrical shape made of metal or resin, and has a circular bottom in plan view, a circular bottom in plan view for supporting the rotary shaft 2 from below, and the rotary shaft 2 by a magnetic fluid bearing 37. It is hermetically sealed by assembling a circular upper surface in plan view that is penetrated while being supported. The magnetic fluid bearing 37 allows the rotary shaft 2 to pass through while blocking the flow of gas inside and outside the vacuum vessel 3 (hermetic seal). Thereby, rotational power can be output outside, maintaining the vacuum degree of the vacuum vessel 3. From this, when the rotating shaft 2 is protruded from the bottom surface, the rotating shaft 2 is preferably protruded through the magnetic fluid bearing 37 provided on the bottom surface.

  The upper surface and the bottom surface of the vacuum vessel 3 may be fixed to the side surfaces so as not to be removed by, for example, an adhesive or a bolt. In this example, when the rotors 21 and 22 are rotated, the inside of the vacuum vessel 3 is evacuated, and the upper surface and the bottom surface cannot be detached from the side surfaces. Therefore, a seal ring having heat insulation and airtightness is interposed, In addition, the bottom surface is simply detachably attached to the side surface. The side surface, the top surface, and the bottom surface may all be made of the same material. For example, only the side surface and the top surface may be made of resin, and only the bottom surface may be made of metal. In order to suppress radiant heat from the vacuum vessel 3 to the stator 1 and the superconducting wire 12, a silver thin film may be formed inside the side surface, the top surface, and the bottom surface.

  The cryocooler 32 is fixed to the outside of the bottom surface of the vacuum vessel 3 so that the low-temperature head 321 protrudes inside the vacuum vessel 3, and the heat conduction pin 31 protruding radially outward from the stator 1 and the low-temperature head 321 are They are connected by a heat conduction plate 321 made of a copper plate. The heat conduction pin 31 of this example protrudes from the stator 1 separately from the support pin 36 that supports the stator 1 with respect to the vacuum vessel 3 (in FIG. 1, for convenience of illustration, it overlaps with the support pin 36. ) The heat conduction plate 321 absorbs a change in the distance between the low temperature head 321 moving back and forth in the vertical direction and the heat conduction pin 31 by elastic deformation. The cryogenic head 321 of the cryocooler 4 is passed through a through-hole opened in the bottom surface of the vacuum vessel 6 so as not to contact the bottom surface.

  The vacuum vessel 3 has an exhaust pipe 35 that is connected to a vacuum pump (not shown) through an open / close valve 351, protrudes from the bottom surface of the vacuum vessel 3, and is exhausted by the vacuum pump. Apply vacuum. In the vacuum chamber 3 in which the inside is sufficiently evacuated, the remaining gas and the invading gas are solidified at a low temperature, so that the vacuum is maintained if the on-off valve 351 is closed to sufficiently prevent the gas from entering. This means that it is not necessary to always operate the vacuum pump while driving the superconducting motor, and this has the effect of reducing the energy required to drive the superconducting motor.

  As seen in FIG. 2, the stator 1 has fan-shaped convex portions 111 and 111 similar to the halved shape of the cooling plate 11 on the front and rear surfaces of the cooling plate 11 that is a disk made of aluminum nitride. Provided in line symmetry, an annular wall 112 is provided surrounding the rotary shaft 2, and a single superconducting wire 12 is wound around the convex portion 111 and the annular wall 112. The position is fixed to the vacuum vessel 3 via The convex portion 111 includes a pair of radial wall surfaces extending in parallel with the radial direction around the rotation axis, and an arcuate inner wall surface concentrically connected to the rotation shaft and connecting the inner and outer circumferences of the pair of radial wall surfaces. And a fan shape composed of an outer peripheral wall surface.

  For convenience of explanation, the left side in FIG. 2 is defined as a half area A and the right side is defined as a half area B with the diameter orthogonal to the radial wall surface of each convex portion 111 as a boundary. From now on, as will be described later, the superconducting wire 12 is wound around the convex portion 111 with a single stroke as described later. In particular, the superconducting wire 12a in the halved region A, and similarly the superconducting wire 12b in the halved region B Call. Correspondingly, the current i flowing through the superconducting wire 12 also distinguishes the portion of the superconducting wire 12a from the current ia and the portion of the superconducting wire 12b from the current ib. Both the current ia and the current ib are currents. Since it does not change to i, the phase is the same.

  The superconducting wire 12 is guided from the support pin 36 to the front surface (or the back surface) of the cooling plate 11 and radially inward while pressing against the radial wall surface from the outer peripheral side to the inner peripheral side of the convex portion 111 in the halved region B. While extending to the inner peripheral wall surface or annular wall 112 and extending in the circumferential direction while avoiding the rotating shaft 2, the outer surface of the projection 111 in the halved region A is radially outward from the inner peripheral side to the outer peripheral side while pressing against the radial wall surface. It extends in the direction, extends in the circumferential direction while addressing to the outer peripheral wall, returns to the support pin 36, and is wound around the convex portion 111 with a single stroke. Thus, when the cooling plate 11 is cooled by the cryocooler 32, the superconducting wire 12 is also cooled via the convex portion 111 and the annular wall 112 that are thermally integrated with the cooling plate 11.

  The superconducting wire 12 is wound around each of the two convex portions 111 provided on the front surface and the back surface of the cooling plate 11, respectively. From here on, each of the superconducting wires 12a, 12b extending in the radial direction is composed of at least two superconducting wires 12. Actually, since a plurality of superconducting wires 12 are wound around each convex portion 111, each of the superconducting wires 12a and 12b extending in the radial direction has 2M pieces (M is a superconducting wire 12 hung around the convex portion). Number). Each superconducting wire 12 is connected to a superconducting lead wire 33 extending from the bottom surface of the vacuum vessel 3 to the support pin 36, and the superconducting lead wire is connected to an external power line 34 outside the vacuum vessel 3. Supplied (as a superconducting motor) or output (as a superconducting generator).

  Since the support pin 36 supports the cooling plate 11 cooled to a low temperature in a non-rotatable manner with respect to the vacuum vessel 3, a material excellent in heat resistance and strength (for example, polybenzimidazole (PBI) resin) is preferable. In addition, the cooling plate 11 is slightly contracted by cooling, and the support pins 36 are moved forward and backward with respect to the side surface of the vacuum vessel 3, so that each support pin 36 is connected to the vacuum vessel 3 through a seal ring having heat insulation and airtightness. It is held on the side. A plurality of support pins 36 may be arranged at equal intervals in the circumferential direction. In this example, the superconducting wire 12 is taken from one of the plurality of support pins 36 (see FIG. 1).

  The rotors 21 and 22 have a pair of upper and lower sides with the stator 1 sandwiched therebetween, and the polarities in the direction of the rotational axis from the top in FIG. Planar fan-shaped permanent magnets 21a, 22a that are poles (hatched in each figure; the same applies hereinafter) -N poles (not hatched in the figures; the same applies hereinafter) and the remaining semi-active region B (right side in FIG. 2) In addition, the fan-shaped permanent magnets 21a and 22a having a polarity in the direction of the rotation axis from the top in FIG. As described above, the permanent magnets 21a and 22a and the permanent magnets 21b and 22b have the same polarity in the rotation axis direction and the semi-active regions A and B are aligned in the circumferential direction. As a result, the downward magnetic flux Bd and the upward magnetic flux Bu connecting the N and S poles of the permanent magnets 21a and 22a and the permanent magnets 21b and 22b across the stator 1 are applied to the superconducting wire 12 of the stator 1. Orthogonal.

  It is difficult for the rotors 21 and 22 to be directly attached to the rotary shaft 2 using the permanent magnets 21a and 22a and the permanent magnets 21b and 22b constituting the rotors as structural materials, and the permanent magnets 21a and 22a and the permanent magnets 21b and 22b are attached. It is preferable to provide a structural material on the rotating shaft 2 separately. For example, a pair of iron discs are attached to the rotating shaft 2 and permanent magnets 21a, 22a and permanent magnets 21b, 22b are attached to the opposing surfaces of the discs. That is, the permanent magnets 21a, 22a in FIG. A configuration in which an iron disk is in contact with the lower surfaces of the magnets 21b and 22b is preferable. The iron disk also functions as a magnetic shield.

  The rotation of the rotors 21 and 22 in this example will be described. The stator 1 has two superconducting wires 12a and 12b at intervals of 180 degrees in the circumferential direction, and as shown in FIG. 3, energizes an alternating current i having the same period as one rotation of the rotors 21 and 22. . However, since the superconducting wires 12a and 12b are a part of the superconducting wire 12 extending with a single stroke, even if an alternating current i having the same phase is applied, the superconducting wire 12a is directed from the inner periphery toward the outer periphery. When the current ia is flowing, the current ib flows through the superconducting wire 12b from the inner periphery toward the outer periphery (see FIG. 4). That is, the current ia flowing through the superconducting wire 12a and the current ib flowing through the superconducting wire 12b have a relationship in which the flowing direction is reversed when viewed in the radial direction.

  FIG. 4 shows that the rotors 21 and 22 are arranged in a straight line by developing the stator 1 and the rotors 21 and 22 in the right rotation direction from the position where the rotors 21 and 22 are 0 degrees (see FIG. 2). Permanent magnets 21a, 21b, 22a, 22b and superconducting wires 12a at each rotation angle when the angle is rotated clockwise from 0 degree to 45 degrees (rotation of the circular arrow attached to the rotor 21 in FIG. 2). The correspondence with currents ia and ib flowing through 12b is shown. For convenience of illustration, the cooling plate 11 is omitted. The superconducting wires 12a and 12b are also not shown, and are represented by currents ia and ib flowing through the superconducting wires 12a and 12b. Permanent magnets 21a, 21b, 22a, 22b show only the N pole (no hatching, permanent magnet 21a and permanent magnet 21b) and the S pole (with hatching, permanent magnet 21b and permanent magnet 21a) facing the stator 1. ing.

  In the state where the stator 1 and the rotors 21 and 22 match the halved areas A and B (see FIG. 2), the polarity of the alternating current to be supplied is negative (rotation angle of the rotor is 0 degree in FIG. 3) Then, the current ia flows through the superconducting wire 12a from the inner periphery toward the outer periphery, and the current ib flows through the superconducting wire 12b from the outer periphery toward the inner periphery. As shown in FIG. 4, the superconducting wire 12a in the downward magnetic flux Bd has a Lorentz force L (rotation opposite to the circular arrow attached to the rotor 21 in FIG. 2) as shown in FIG. The rotors 21 and 22 are rotated to the right by the reaction. Similarly, the superconducting wire 12b in the upward magnetic flux Bu receives the left-rotating Lorentz force L, and rotates the rotors 21 and 22 to the right by the reaction.

  At this time, the current i flows in addition to the portion extending in the radial direction of the superconducting wire 12, and the Lorentz force L is generated by the magnetic flux Bd or the magnetic flux Bu. However, in the superconducting motor of this example, since the superconducting wires 12 other than the portion extending in the radial direction all extend in an arc shape along the circumferential direction, the superconducting wires 12 other than the portion extending in the radial direction are included. The Lorentz force generated in the direction is directed in the radial direction and does not hinder the rotation of the rotors 21 and 22. Further, since the superconducting wire 12 other than the portion extending in the radial direction does not have the resistance loss of the conventional conductive wire, even if there is a portion other than the portion extending in the radial direction, power is not wasted.

  In the superconducting motor of this example, the number of rotations of the rotors 21 and 22 and the frequency of the alternating current applied to the superconducting wire 12 are the same, so when the rotation of the rotors 21 and 22 proceeds, the superconducting wire The polarities of the flowing currents ia and ib are switched at the timing when the boundaries between the permanent magnets 21a and 21b and the permanent magnets 22a and 22b pass through 12a and 12b (rotation angle of 90 degrees in FIG. 4, etc.) (see FIG. 3). When the polarity is switched, the current ia flows from the outer periphery to the outer periphery of the superconducting wire 12a, and the current ib flows from the inner periphery to the outer periphery of the superconducting wire 12b. Under the force L, the rotors 21 and 22 are rotated to the right by the reaction, and the superconducting wire 12b receives the Lorentz force L of the left rotation, and to the right by the reaction.

  Thus, when the rotors 21 and 22 continue to rotate, the downward magnetic flux Bd and the upward magnetic flux Bu are moved in the rotational direction, but the currents ia and ib flowing through the superconducting wires 12a and 12b are the rotor 21 and Since the direction of flow is switched in synchronization with the rotation of 22, the Lorentz force generated in each of the superconducting wires 12 a, 12 b is always left-rotated, and the reaction of the Lorentz force is the rotation of the rotor 21, 22 to the right rotation You can continue to give power. And since the rotation speed of the rotors 21 and 22 is matched with the frequency of the alternating current supplied to the superconducting wire 12, even when obtaining the same rotation speed as a conventional conduction motor or other superconducting motors, superconductivity Hysteresis loss occurring in the wire 12 can be suppressed.

  As shown in FIG. 5, when the stator 1 has a plurality of superconducting wires 14, 15, 16, and 17 at equal intervals in the circumferential direction, as shown in FIG. , 16, and 17, the rotational force of the rotors 21 and 22, which is the reaction of the Lorentz force generated respectively, can be obtained evenly in the circumferential direction. Since the superconducting motor of another example is the same as the above example (see FIG. 1) except for the stator 1, only the configuration of the stator 1 different from the above example will be described. As shown in FIG. 6, the stator 1 of another example is configured by laminating four unit cooling plates 13 which are aluminum nitride discs, and is equally spaced in the circumferential direction as in the above example (see FIG. 1). The position is fixed to the vacuum vessel 3 through the support pins 36. The unit cooling plates 13 are thermally connected to each other. For example, if the low-temperature head 321 of the cryocooler 32 (see FIG. 1) is connected to the unit cooling plate 13 in the fourth layer, the entire stator 1 is cooled. .

  Each unit cooling plate 13 is provided with a fitting groove 131 extending in a fan shape in plan view, and connected to a superconducting lead wire 33 (see FIG. 1) extending from the bottom surface of the vacuum vessel 3 to the support pin 36, 15, 16 and 17 are fitted around the fitting groove 131, and are filled with aluminum nitride powder or synthetic resin containing the aluminum nitride powder to embed the superconducting wires 14, 15, 16, and 17. The fitting groove 131 has a plan view path following the radial wall surface, the inner peripheral surface, and the outer peripheral surface of the convex portion 111 (see FIG. 2) in the above example. As a result, the superconducting wires 14, 15, 16, 17 come into contact with the aluminum nitride in the cross section 3 direction or the cross section 4 direction, and the unit cooling plate 13 cooled by the cryocooler 32 stabilizes the superconducting phenomenon. It is possible to obtain a low-temperature state sufficient to develop

  In another example of the stator 1, the first unit cooling plate 13 and the second unit cooling plate 13 are laminated with the superconducting wire 14 and the superconducting wire 15 being shifted by 90 degrees in the circumferential direction. The unit cooling plate 13 in the third layer and the unit cooling plate 13 in the fourth layer shift the superconducting wire 16 and the superconducting wire 17 by 90 degrees in the circumferential direction and surround the superconducting wire 16 and the superconducting wire 14 with each other. Laminated by 90 degrees in the direction. Accordingly, as shown in FIG. 7, the current i4, the current i1, and the current i3 having a phase difference of 45 degrees from each other in the order of the superconducting wire 17, the superconducting wire 14, the superconducting wire 16, and the superconducting wire 17. Then, the current i2 is supplied (four-phase alternating current). Each current i1, i2, i3, i4 is an alternating current whose cycle coincides with one rotation of the rotors 21,22.

  For convenience of explanation, the diameter perpendicular to the superconducting wire 14 embedded in the first unit cooling plate 13 is defined as a boundary, and the left side in FIG. 5 or 6 is defined as a half area A and the right side is defined as a half area B. . From now on, the superconducting wire 14 is divided into a superconducting wire 14a in the half region A and a superconducting wire 14b in the half region B, and the current i1 flowing in the superconducting wire 12 is also the current i1a in the superconducting wire 14a. Distinguish from the current i1b of 14b. Similarly, the superconducting wire 15 embedded in the unit cooling plate 13 in the second layer is also divided into a superconducting wire 15a and a superconducting wire 15b, and the current i2 flowing through the superconducting wire 15 is also distinguished from the current i2a and current i2b. The superconducting wire 16 embedded in the unit cooling plate 13 in the third layer is also divided into a superconducting wire 16a and a superconducting wire 16b. The current i3 flowing through the superconducting wire 16 is also distinguished from the current i3a and current i3b. The superconducting wire 17 embedded in the unit cooling plate 13 of the eye is also divided into a superconducting wire 17a and a superconducting wire 17b, and the current i4 flowing through the superconducting wire 17 is also distinguished from the current i4a and the current i4b.

  The rotation of the rotors 21 and 22 in another example will be described. The rotors 21 and 22 are the same as in the above example (see FIG. 1). As described above, the stator 1 has a phase difference of 45 degrees between the superconducting wires 14, 15, 16, and 17 of each layer, and an alternating current whose cycle matches that of one rotation of the rotors 21 and 22. i is energized. For example, in the superconducting wire 14, a current i1a flows from the inner periphery to the outer periphery through the superconducting wire 14a, and a current i1b flows from the inner periphery to the outer periphery through the superconducting wire 14b (see FIG. 6). Similarly, a current i2a flows from the inner periphery to the outer periphery in the superconducting wire 15a, a current i2b flows from the inner periphery to the outer periphery in the superconducting wire 15b, and from the inner periphery to the outer periphery in the superconducting wire 16a. Current i3a flows, the current i3b flows from the inner periphery to the outer periphery in the superconducting wire 16b, and the current i4a flows from the inner periphery to the outer periphery in the superconducting wire 17a. A current i4b flows toward the outer periphery.

  FIG. 8 shows the rotation of the rotors 21 and 22 in a straight line by developing the stator 1 and the rotors 21 and 22 in the clockwise direction from the position where the rotors 21 and 22 are 0 degrees (see FIG. 2). The permanent magnets 21a, 21b, 22a, 22b and the superconducting wire 14a at each rotation angle when the angle is rotated clockwise from 0 degree to 45 degrees (rotation of the circular arrow attached to the rotor 21 in FIG. 2). 14b, 15a, 15b, 16a, 16b, 17a, 17b, the currents i1a, i1b, i2a, i2b, i3a, i3b, i4a, i4b are shown. For convenience of illustration, the cooling plate 13 is omitted. The superconducting wires 14a, 14b, 15a, 15b, 16a, 16b, 17a, and 17b are also omitted from the drawing and are represented by currents i1a, i1b, i2a, i2b, i3a, i3b, i4a, and i4b. Permanent magnets 21a, 21b, 22a, 22b show only the N pole (no hatching, permanent magnet 21a and permanent magnet 21b) and the S pole (with hatching, permanent magnet 21b and permanent magnet 21a) facing the stator 1. ing.

  In addition to the superconducting wire 15 located at the boundary of the permanent magnets 21a, 21b, 22a, 22b in a state where the stator 1 and the rotors 21, 22 are aligned with the respective half regions A, B (see FIG. 5). If the polarity of the alternating current to be energized is negative (rotation angle 0 degree in FIG. 7), the currents i1a, i3a, i4a flow from the inner circumference to the outer circumference in the superconducting wires 14a, 16a, 17a, Currents i1b, i3b, i4b flow through the superconducting wires 14b, 16b, 17b from the outer periphery toward the inner periphery. From this, the superconducting wires 14a, 16a, and 17a in the downward magnetic flux Bd (see FIG. 4) receive the left-rotating Lorentz force L and rotate the rotors 21 and 22 to the right by the reaction. Similarly, the superconducting wires 14b, 16b, and 16b in the upward magnetic flux Bu (see FIG. 4) receive the left-rotating Lorentz force L, and rotate the rotors 21 and 22 to the right by the reaction.

  At this time, the currents i1, i3, i4 flow other than the portions of the superconducting wires 14, 16, 17 extending in the radial direction, and the Lorentz force L is generated by the magnetic flux Bd or the magnetic flux Bu. However, in the superconducting motor of another example, since the superconducting wires 14, 16, 17 other than the portion extending in the radial direction all extend in an arc shape along the circumferential direction, the portion other than the portion extending in the radial direction is used. Lorentz force generated in the superconducting wires 14, 16, and 17 is directed in the radial direction and does not hinder the rotation of the rotors 21 and 22. Further, since the superconducting wires 14, 16, and 17 other than the portion extending in the radial direction do not have the resistance loss of the conventional conducting wire, even if there is a portion other than the portion extending in the radial direction, power is not consumed wastefully.

  In another superconducting motor, the rotational speed of the rotors 21 and 22 and the frequency of the alternating current applied to the superconducting wire 14, for example, coincide with each other. The polarity of the flowing currents i1a and i1b is switched at the timing when the boundaries between the permanent magnets 21a and 21b and the permanent magnets 22a and 22b pass through the wires 14a and 14b (rotation angle of 90 degrees in FIG. 8, etc.) (see FIG. 7). However, in another superconducting motor, even when the polarity of the flowing currents i1a, i1b is switched, the currents i2, i3, i4 continue to flow through the superconducting wires 15, 16, 17, and the superconducting wires 15a, 15b, The rotors 21 and 22 can be rotated to the right by the reaction of the left-rotating Lorentz force L generated at 16a, 16b, 17a and 17b. Thus, in another example of the superconducting motor, the remaining three phases generate Lorentz force to rotate the rotors 21 and 22 even when one of the superconducting wires 14, 15, 16, and 17 is switched. Therefore, the rotation of the rotors 21 and 22 is stabilized.

  In addition, the superconducting motor of another example has more superconducting wires 14, 15, 16, 17 arranged in the circumferential direction than the superconducting motor illustrated above, and permanent magnets 21a, 21b, 22, a, 22b and This has the effect of reducing the coupling loss. For example, as shown in FIG. 8, the superconducting wire 14a and the superconducting wire 16a that flow currents i1a and i3a from the inner circumference toward the outer circumference at the rotation angle of the rotors 21 and 22 are adjacent to each other in the circumferential direction. Since both forms a clockwise magnetic flux Hp (clockwise toward the back of the page in FIG. 8), the magnetic flux Hp formed by the current i1a is downward between the superconducting wire 14a and the superconducting wire 16a. The component and the upward component of the magnetic flux Hp formed by the current i3a cancel each other, and the coupling loss with the permanent magnets 21a and 21b is reduced (cross-hatched portion in FIG. 8).

  Similarly, the superconducting wire 14b and the superconducting wire 16b that pass the currents i1b and i3b from the outer circumference toward the inner circumference at the rotation angle of 0 degrees of the rotors 21 and 22 are adjacent to each other in the circumferential direction, both of which are clockwise. Since the magnetic flux Hm (counterclockwise toward the back of the page in FIG. 8) is formed, the downward component of the magnetic flux Hm formed by the current i1b and the current i3b are intermediate between the superconducting wire 14b and the superconducting wire 16b. The upward component of the magnetic flux Hp to be formed cancels out, and the coupling loss with the permanent magnets 21a and 21b is reduced. As described above, the magnetic fluxes Hp and Hm formed by the superconducting wires 14, 15, 16, and 17 cancel each other out in the same manner as the adjacent superconducting wires 14, 15, 16, and 17 except when the polarity is switched. This is the effect of flowing a current in the direction. Thus, the superconducting motor of the present invention can reduce the coupling loss as the number of superconducting wires extending in the radial direction is increased.

1 Stator
11 Cooling plate (aluminum nitride plate)
12 Superconducting wire
13 Unit cooling plate
14 Unit cooling plate 1st layer superconducting wire
15 Unit cooling plate 2nd layer superconducting wire
16 Unit cooling plate 3rd layer superconducting wire
17 Unit cooling plate 4th layer superconducting wire 2 Rotating axis
21 Upper rotor
22 Lower rotor 3 Vacuum container
31 Heat conduction pin
32 Cryocooler
33 Superconducting lead
34 External power line
35 Exhaust pipe
36 Support pin
37 Magnetic fluid bearing A A semi-active region across the diameter (A on the left side of each figure)
B Semi-active region across the diameter (B on the right in each figure)
Bd Downward magnetic flux Bu Upward magnetic flux L Lorentz force Hp Right-handed magnetic flux formed according to right-handed screw rule Hm Left-handed magnetic flux formed according to right-handed screw rule i Current flowing in superconducting wire i1 unit Current flowing in the superconducting wire on the first layer of the cooling plate i2 Current flowing in the superconducting wire on the second layer of the unit cooling plate i3 Current flowing in the superconducting wire on the third layer of the unit cooling plate i4 Unit Superconducting on the fourth layer of the cooling plate Current flowing in the wire

Claims (5)

A superconducting wire in a plane orthogonal to the rotation axis of the stator having a rotation shaft rotatably passing therethrough is opposed to a permanent magnet in a plane orthogonal to the rotation axis of the rotor rotating together with the rotation axis. In the axial gap type superconducting motor,
The stator has a pair of superconducting wires extending in the radial direction around the rotation axis in a point-symmetrical positional relationship.
The rotor is configured by allocating a pair of permanent magnets whose polarities in the rotation axis direction are opposite to each other in each of the halved regions that are bisected across the diameter around the rotation axis,
One of the superconducting wires in a point-symmetrical positional relationship is energized with an alternating current from the inner periphery toward the outer periphery, and the other phase of the superconducting wire is energized with an in-phase alternating current from the outer periphery toward the inner periphery. Superconducting motor. The stator has 2n strips (n is a natural number of 2 or more) that are equidistant in the circumferential direction,
The n-layer superconducting wire assigned to one of the halved regions with the diameter centered on the rotation axis is delayed by π / n from the reference phase from the upstream to the downstream of the rotor. Energized from the inner circumference to the outer circumference,
An alternating current with a phase delayed by π / n from the reference phase from the upstream to the downstream of the rotor is applied to the n superconducting wires assigned to the other of the halved regions. The superconducting motor according to claim 1, which is energized toward.   The superconducting motor according to claim 1, wherein the stator extends a superconducting wire other than a portion extending in the radial direction in an arc shape along the circumferential direction. The stator is sandwiched between a pair of rotors,
In the rotor, permanent magnets having opposite polarities in the direction of the rotation axis are aligned in the halves of the halves and divided in half with respect to the diameter around the rotation axis. The superconducting motor according to any one of claims 1 to 3, wherein the regions are respectively assigned in the circumferential direction. The stator is constructed by adhering a superconducting wire to a cooling plate made of a material having non-magnetic properties, electrical insulation and thermal conductivity, and is built in a single vacuum vessel together with the rotor to provide heat insulation. The cooling plate is fixed to the vacuum vessel by the support provided, and the cooling plate and the refrigerator are connected by a heat conductor that penetrates from the outside of the vacuum vessel to the inside of the vacuum vessel. The superconducting motor according to any one of claims 1 to 4, wherein an external power line and a superconducting wire are connected by an electric conductor.

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