The present invention relates to a magnetizing device for magnetizing a superconductor, and a superconducting synchronous machine.
In
The superconductor 5 is cooled down to and below a critical temperature at which the transition to a superconducting state occurs, using the liquid nitrogen 9 introduced to the coolant container 3 through the coolant piping 8. In this situation, a current is fed from the power source 6 to the coil 4 through the connection line 7. At this time, the coil 4 forms a magnetic field around the superconductor 5. Once this magnetic field has been made a magnetic field equal to or higher than the critical magnetic field in which the intrusion of a magnetic flux into the superconductor 5 starts, the superconductor 5 is magnetized. Consequently, even after the current for generating a magnetic field equal to or higher than the critical magnetic field in which the intrusion of a magnetic flux into the superconductor 5 starts, has become nonexistent, the superconductor 5 keeps the magnetized state and functions as a magnet for the equipment 1 using the superconductor 5 as a magnet. Here, the vacuum container 2 performs a heat insulating function.
Such a magnetizing device for superconductor is disclosed in [Patent Document 1] described later.
In
The superconductor 16 arranged in the heat-insulating container 11 is cooled down to or below a superconducting transition temperature together with the copper block 15 by thermal conduction, using the cold head 12 cooled down by the refrigerator 13. Upon receipt of the supply of different pulse currents from the pulse power source 18, the magnetizing coils 17 generate, around the superconductor 16, respective magnetic fluxes in proportion to the magnitudes of the different pulse currents. The magnetic fluxes are trapped by the superconductor 16 cooled down to or below a superconducting transition temperature. The amount of magnetic fluxes depends on how to feed pulse currents to the magnetizing coils 17. The pulse power source 18 firstly interconnects the direct-current variable voltage source 19 and the capacitor 21 by the changeover switch 20 and charges the capacitor 21. Then, the pulse power source 18 changes over the changeover switch 20, and interconnects the capacitor 21 and the magnetizing coils 17 to thereby feed a pulse current to the magnetizing coils 17. The repetition of this procedure allows the pulse power source 18 to feed a plurality of pulse currents to each of the magnetizing coils 17. Also, when interconnecting the direct-current variable voltage source 19 and the capacitor 21 to thereby charge the capacitor 21, changing the voltage of the direct-current variable voltage source 19 allows the charge voltage of the capacitor 21 to change, thereby enabling the amplitude of pulse current to change. The diode 22 operates so as to prevent the capacitor 21 from being subjected to a voltage in the direction opposite to the direction of the charging voltage.
Such a magnetizing device for superconductor is disclosed in the following [Patent Document 2] to [Patent Document 4].
[Patent Document 1]
Japanese Patent No. 3172611, pp. 2 to 4, and FIG. 1.
[Patent Document 2]
Japanese Unexamined Patent Application Publication No. 10-12429, pp. 5 to 6, and FIG. 1.
[Patent Document 3]
Japanese Unexamined Patent Application Publication No. 10-154620, pp. 3 to 4, and FIG. 1.
[Patent Document 4]
Japanese Unexamined Patent Application Publication No. 2001-110637, p. 5, and FIG. 1.
To such one that, in a state where a superconductor has been cooled down to or below a critical temperature at which the transition to a superconducting state occurs, generates, around the superconductor, a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, to thereby magnetize the superconductor, the positional relationship and the magnitude relationship between the superconductor and coils are important depending on the equipment using the superconductor as a magnet. For example, when attempting to use the superconductor as a field magnet for a synchronous machine, armature coils are indispensable in the vicinity thereof. Also, when attempting to use the armature coils in combination with coils as an element constituting means for generating a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, it is necessary to allow the superconductor to be placed outside the armature coils, and to enable the relative positional relationship between the superconductor and the armature coils to be modified.
In the conventional magnetizing device for superconductor as shown in
Also in the differently configured magnetizing device for superconductor as shown in
In the light of the above-described situations, the object of the present invention is to provide a magnetizing device for superconductor and a superconducting synchronous machine capable of constituting more compact and simple equipment that uses a superconductor as a magnet.
In order to achieve the above-described object, the present invention provides:
[1] a magnetizing device for superconductor, the magnetizing device being characterized by including a superconductor; cooling means for cooling the superconductor down to or below a critical temperature at which the transition to a superconducting state occurs; magnetic field generating means that generates a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to the superconducting state occurs; and position modification means capable of arranging the superconductor outside a coil as an element constituting the magnetic field generating means, and modifying the relative positional relationship between the superconductor and the coil;
[2] the magnetizing device for superconductor as recited in the above [1], wherein the position modification means is disposed on the fixed sides as the magnetic field generating means, and wherein the superconductor can be disposed by the position modification means so as to be sandwiched between a pair of opposing coils;
[3] the magnetizing device for superconductor as recited in the above [2], wherein the superconductor is a high temperature superconductor arranged on a rotating plate.
[4] the magnetizing device for superconductor as recited in the above [2], wherein each of the pair of coils is formed as a spiral shape coil opposed to a surface of the superconductor;
[5] a superconducting synchronous machine characterized by including a superconductor arranged on a disk; cooling means for cooling the superconductor down to or below a critical temperature at which the transition to a superconducting state occurs; magnetic field generating means that generates a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to the superconducting state occurs; an alternating current power source for supplying the magnetic field generating means with a current for driving the superconductor; and a mode changeover switch for performing a changeover between a magnetic field generation mode and an alternating current supply mode;
[6] a superconducting synchronous machine characterized by including a superconductor arranged on a disk; cooling means for cooling the superconductor down to or below a critical temperature at which the transition to a superconducting state occurs; magnetic field generating means that generates a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to the superconducting state occurs; a prime mover for rotationally driving the disk with the superconductor provided thereon; and a mode changeover switch for performing a changeover between a magnetic field generation mode and a power generation mode;
[7] a superconducting synchronous machine characterized by including a superconductor arranged on a disk; cooling means for cooling the superconductor down to or below a critical temperature at which the transition to a superconducting state occurs; magnetic field generating means that generates a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to the superconducting state occurs; an alternating current power source for supplying the magnetic field generating means with a current for driving the superconductor; a prime mover for rotationally driving the disk with the superconductor provided thereon; and a mode changeover switch for performing a changeover among a magnetic field generation mode, an alternating current supply mode, and a power generation mode;
[8] the superconducting synchronous machine as recited in the above [5], [6], or [7], further including a sensor for detecting the strength of a magnetic field of the superconductor to control the magnetization of the superconductor;
[9] the superconducting synchronous machine as recited in the above [5], [6], or [7], wherein the magnetic field generating means is disposed on the fixed sides; and wherein the superconductor can be disposed so as to be sandwiched between a pair of opposing armature coils;
[10] the superconducting synchronous machine as recited in the above [9], wherein each of the pair of coils is formed as a spiral shape coil opposed to a surface of the superconductor;
[11] the superconducting synchronous machine as recited in the above [9], wherein the number of the pairs of armature coils is an integral multiple of three; and wherein the number of the superconductors is an integral multiple of two;
[12] the superconducting synchronous machine as recited in the above [5], [6], or [7], wherein the superconductor is a high temperature superconductor; and
[13] the superconducting synchronous machine as recited in the above [5], [6], or [7], wherein the disk is cooled down by the cooling means.
Hereinafter, embodiments according to the present invention will be described in detail.
In
Hereinafter, operations of this magnetizing device for superconductor will be described.
First, eight superconductors 131 to 138 mounted to the disk 120 are cooled down to or below a critical temperature at which the transition to a superconducting state occurs, with a coolant in the coolant chamber 142, such as liquid nitrogen. Next, the disk 120 is rotated about the shaft 145 relative to the coils 111 and 111′-116 and 116′ serving as an element of magnetic field generating means and mounted to the side portions 103A and 103B of the inner casing 103 by six so as to mutually opposed, and, e.g., the coils 111 and 111′ and the superconductor 131 are center-aligned with one another (at this time, as shown in
As described above, with respect to the coils serving as an element of magnetic field generating means and generating a magnetic field equal to or higher than the critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to a superconducting state occurs, the disk having superconductors mounted thereon is arranged so as to rotate. This makes it possible to easily magnetize the superconductor.
In
As shown in
As the high temperature superconducting bulk body 151, it is desirable to use an RE-Ba—Cu—O superconductor (RE: a rare-earth element such as Gd, Sm, or Y) out of high temperature superconductors, the RE-Ba—Cu—O superconductor exhibiting a high critical current density without being suffered from the destruction of its superconductivity, even in a high magnetic field in the vicinity of 77 kelvins (absolute temperature), i.e., −196° C., which is easily attained with liquid nitrogen.
Such an RE-Ba—Cu—O bulk superconductor is a lump (bulk) of a high temperature superconductor obtained by dispersing a non-superconducting phase exhibiting the pinning effect into a raw material and melting it to grow, and it can trap a higher magnetic field (i.e., can be magnetized so as to have a higher magnetic field) than a high-performance permanent magnet. However, in order to utilize this bulk superconducting magnet, it is necessary to magnetize the superconducting bulk body by any method.
In the present invention, focusing attention on the fact that the magnetic field distribution of a magnetized high temperature superconducting bulk body becomes a cone-shaped distribution having a highest magnetic field at the center thereof, a cone-shaped magnetic field distribution is generated by passing a pulse current through the above-described coils formed by spirally winding copper line, and at 77 kelvins, as shown in
Such a Gd-based bulk high temperature superconductor is efficiently magnetized so as to have a high magnetic field with a strength over 1 Tesla.
As shown in
This method has made it possible to easily and efficiently perform magnetization providing a magnetic field strength over 1 Tesla by using liquid nitrogen, the magnetization providing a magnetic field strength over 1 Tesla having conventionally been performed by using a helium refrigerator or a superconducting magnet.
As shown in
In relation with this respect, detailed explanations are given below. As shown in the conventional example, the magnetizing methods for bulk superconducting magnet include the magnetostatic field magnetizing method (see
On the other hand, according to the present invention, focusing attention on the fact that the magnetic field distribution of a magnetized high temperature superconducting bulk body becomes a cone-shaped distribution having a highest magnetic field at the center thereof, a cone-shaped magnetic field distribution is generated by passing a pulse current through the coils formed by spirally winding copper line, and at 77 kelvins, a Gd-based bulk high temperature superconductor (see
In
Meanwhile, the disk 220 may be cooled one. In that case, extra cooling means is to be added although it is not shown.
Hereinafter, operations of the induction motor type synchronous machine having a magnetizing device for superconductor will be described.
First, descriptions are made of the magnetization mode.
Eight superconductors 231 to 238 mounted to the disk 220 are cooled down to or below a critical temperature at which the transition to a superconducting state occurs, with a coolant in the coolant chamber 272, such as liquid nitrogen. The disk 220 is rotated about the shaft 275 relative to the armature coils 211 and 211′-216 and 216′ serving as an element of magnetic field generating means and mounted to the side portions 203A and 203B of the inner casing 203 by six so as to mutually opposed, and, e.g., the armature coils 211 and 211′ and the superconductor 231 are center-aligned with one another (at this time, as shown in
Once the superconductors 231 to 238 have been magnetized, the present superconducting synchronous machine is brought into the alternating current supply mode (electromotive mode) by changing over the mode changeover switch 242 from the magnetizing power source 206 to the alternating current power source 241, so that it functions as a superconducting synchronous motor in accordance with Fleming's left-hand rule between the magnetized superconductors 231 to 238 and the armature coils 211 and 211′-216 and 216′. In a driven state of this synchronous machine, as described above, the strength of magnetic force of the superconductor thereof is monitored by the magnetic field sensor 243 and the controller 244, and if the strength of magnetic force falls short of a predetermined value, a mode changeover to the magnetization mode for the superconductor can automatically be performed.
As described above, with respect to the armature coils serving as an element of magnetic generating means and generating a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to a superconducting state occurs, the disk with superconductors mounted thereon has been enabled to rotate, and the superconductor and the armature coils have been allowed to function as the field magnet and the armature coils of the synchronous machine, respectively. This makes it possible to downsize the induction motor type superconducting synchronous machine.
The difference of this embodiment from the above-described second embodiment will be described below. During the power generation mode, which has been brought about by the mode changeover switch 252 for performing the changeover between the magnetic field generation mode (magnetization mode) and the power generation mode, the present superconducting synchronous machine is adapted to rotationally drive the shaft 275 by the prime mover 251, and thereby to generate power by an electromagnetic induction action occurring between the magnetized superconductors 231 to 238 and the armature coils 211 and 211′-216 and 216′ in accordance with Fleming's right-hand rule so as to supply power to a load 253. In the magnetization mode to be used, e.g., when the reduction in magnetic forces of the superconductors 231 to 238 is detected by the magnetic field sensor 243 and the controller 244, the present superconducting synchronous machine can be adapted to magnetize the superconductors 231 to 238 by the same method as that in the first and second embodiments.
As described above, with respect to the armature coils serving as an element of magnetic field generating means and generating a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to a superconducting state occurs, the disk with superconductors mounted thereon has been enabled to rotate, and the superconductor and the armature coils have been allowed to function as the field magnet and the armature coils of the synchronous machine, respectively. This makes it possible to downsize the inductive power generator type superconducting synchronous machine.
In this embodiment, (1) when the present superconducting synchronous machine has been brought into the alternating current supply mode (electromotive mode) by changing over the mode changeover switch 261 for performing the changeover among the magnetic field generation mode (magnetization mode), the alternating current supply mode (electromotive mode), and the power generation mode, it functions as a superconducting synchronous motor by being subjected to the supply of alternating currents from the alternating current source 241 to the armature coils 211 and 211′-216 and 216′, as in the illustrated second embodiment;
(2) when the present superconducting synchronous machine has been brought into the power generation mode by changing over the mode changeover switch 261 for performing the changeover among the magnetic field generation mode (magnetization mode), the alternating current supply mode (electromotive mode), and the power generation mode, it is adapted to rotationally drive the shaft 275 by the prime mover 251, and thereby to generate power by an electromagnetic induction action occurring between the magnetized superconductors 231 to 238 and the armature coils 211 and 211′-216 and 216′ in accordance with Fleming's right-hand rule so as to supply power to a load 262, as in the case of the third embodiment;
(3) no matter whether being in the power generation mode or electromotive mode, in the magnetization mode to be used, e.g., when the reduction in magnetic forces of the superconductors 231 to 238 is detected by the magnetic field sensor 243 and the controller 244, the present superconducting synchronous machine can be adapted to magnetize the superconductors 231 to 238 by the same method as that in the first and second embodiments.
Subjecting the superconductors to sufficient magnetization provides a cone-shaped magnetic flux density distribution to the superconductor. At this time, use of spiral type coils has also the effect of rendering the electromotive force of the synchronous machine sinusoidal.
Conversely, the magnetic field formed when a current is passed through the spiral coils generates a cone-shaped magnetic flux density. Since this has the same form of magnetic flux density distribution as that of the above-described superconductor subjected to sufficient magnetization, it has also the effect of being easy to magnetize the superconductor.
As described above, with respect to the armature coils serving as an element of magnetic field generating means and generating a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor starts, around the superconductor cooled down to or below the critical temperature at which the transition to a superconducting state occurs, the disk with superconductors mounted thereon has been enabled to rotate, and the superconductor and the armature coils have been allowed to function as the field magnet and the armature coils of the synchronous machine, respectively. This makes it possible to downsize the induction electromotion/generation type superconducting synchronous machine.
According to the present invention, as described above, a simple and downsized magnetizing device for superconductor can be provided.
Also, the present invention can easily provide a superconducting synchronous machine having the function of magnetizing a superconductor.
Such a superconducting synchronous machine can also be constructed as a superconducting synchronous motor and/or a superconducting induction generator.
Therefore, when attempting to use the superconducting synchronous machine as a superconducting synchronous machine for a small ship, the superconducting synchronous machine is caused to function as a superconducting induction generator during mooring at night, and in turn, using the power source thus charged, the superconducting synchronous machine is caused to function as a superconducting synchronous motor to serve the operation of the ship during daytime, whereby a downsized superconducting synchronous machine can be constructed.
Also, because the magnetic forces of the superconductors can be subjected to continuous monitoring, it is possible to keep high-efficiency inductive electromotion and/or inductive power generation.
Furthermore, according to the superconducting synchronous machine of the present invention, a high torque can be generated by a strong magnetic field. This superconducting synchronous machine is also high in the power conversion efficiency, and thereby it can be significantly reduced in size and weight as compared with conventional superconducting synchronous machines. From the viewpoints of the conservation of the global environment and marine environment, the electric propulsion ship has a great prospect, and the research-and-development and commercialization of POD type electric propulsion ship are progressing in Europe and USA. The present invention, in a high temperature superconducting synchronous machine for a ship that rotates an electric propulsion propeller, enables a combined use of magnetization coils and coreless armature coils, and thereby it can greatly contribute to the design and production thereof.
The present invention is not limited to the above-described embodiments, but various modifications may be made without departing from the true spirit of the present invention. These modifications should be considered to be within the scope of the invention.
As described in detail so far, according to the present invention, the following effects are produced:
(A) a simple and compact magnetizing device for superconductor can be attained;
(B) an inductive motor type superconducting synchronous machine capable of magnetization and electromotive drive can be achieved;
(C) an inductive generator type superconducting synchronous machine capable of magnetization and inductive power generation can be achieved;
(D) when the magnetic force of the superconductor for the superconducting synchronous machine decreases, it is possible to automatically detect it, and perform a mode changeover to the magnetization mode to thereby magnetize the superconductor;
(E) a flat and compact magnetizing device for superconductor or superconducting synchronous machine can be attained;
(F) in the high temperature superconducting synchronous machine for a ship, rotating an electric propulsion propeller, the present invention allows a combined use of magnetization coils and coreless armature coils, and enables the superconducting synchronous machine to be significantly reduced in size and weight, as well as offers an advantage in the conservation of the global environment and marine environment; and
(G) when attempting to use the superconducting synchronous machine as a superconducting synchronous machine for a small ship, the superconducting synchronous machine is caused to function as a superconducting induction generator during mooring at night, and in turn, using the power source thus charged, the superconducting synchronous machine is caused to function as a superconducting synchronous motor to serve the operation of the ship during daytime, whereby a downsized superconducting synchronous machine can be constructed. This offers a significant practical effect.
The magnetizing device for superconductor and the superconducting synchronous machine according to the present invention, are especially suitable for a ship prime mover for rotating an electric propulsion propeller, thereby offering an advantage in the conservation of the global environment and marine environment.
Number | Date | Country | Kind |
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2002-258402 | Sep 2002 | JP | national |
2002-300631 | Oct 2002 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP03/08963 | 7/15/2003 | WO | 11/16/2005 |