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WO2017037259A1 - Dispositif bobine doté d'un commutateur à courant permanent - Google Patents

Dispositif bobine doté d'un commutateur à courant permanent Download PDF

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Publication number
WO2017037259A1
WO2017037259A1 PCT/EP2016/070764 EP2016070764W WO2017037259A1 WO 2017037259 A1 WO2017037259 A1 WO 2017037259A1 EP 2016070764 W EP2016070764 W EP 2016070764W WO 2017037259 A1 WO2017037259 A1 WO 2017037259A1
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WIPO (PCT)
Prior art keywords
conductor
switchable
coil
superconducting
coil device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
PCT/EP2016/070764
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German (de)
English (en)
Inventor
Tabea Arndt
Marijn Pieter Oomen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
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Publication of WO2017037259A1 publication Critical patent/WO2017037259A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/006—Supplying energising or de-energising current; Flux pumps
    • H01F6/008—Electric circuit arrangements for energising superconductive electromagnets

Definitions

  • the present invention relates to a coil device having at least one electrical coil winding with superconducting conductor material, wherein the coil winding is part of a self-contained circuit for forming a continuous current, and wherein the closed circuit has a permanent current switch with a switchable conductor section which between a superconducting state and a normal conducting state is switchable. Furthermore, the invention relates to a continuous current switch for such a coil device and a method for loading or unloading a continuous current in a coil winding of such a coil device.
  • SMES superconducting magnetic energy storage
  • the present invention is concerned with the specific probing of loading and unloading of the current flowing in such coils.
  • a superconducting persistent current switch is typi cally ⁇ integrated into the closed circuit.
  • Such permanent current switch comprises a superconducting conductor portion which can be displaced by heating the pitch to a resistive conducting state at ⁇ . If the coil is simultaneously connected to a power source in an external circuit, it can be charged with an open permanent-current switch.
  • Discharging the current flowing in the closed circuit through the coil winding current can be triggered intentionally or unintentionally.
  • An intentional unloading can be done by a
  • Opening the persistent current switch are triggered, and the Spu ⁇ le can be connected to an external circuit, in which the previously flowing through the closed circuit current can at least partially discharge.
  • This can be used, for example, to retrieve the energy stored in an SMES.
  • the electromagnetic energy stored in the coil is completely dissipated as heat in the area of the persistent current switch. This heat could destroy the switch in large magnet systems. Such an opening of the switch without an external circuit is therefore to be avoided there.
  • Discharging the coil can also be triggered in other ways than by controlled opening of the permanent-current switch:
  • a local temperature increase in the coil winding can lead to the superconducting properties of the entire coil winding starting from this region. men mecanic.
  • the superconducting properties of the entire coil winding can break down, which is referred to as "quench.”
  • quench Such a quench can spread rapidly due to the thermal coupling of the various regions Typically, all of the helium will evaporate in such a quench, resulting in relatively high costs and failure in the useful life of the system In order to avoid damage to the superconducting conductor elements by locally overheating the conductors, the rapid propagation of such quench may even be promoted .
  • a local overheating can be detected, and other preparation ⁇ che the coil winding can then also be intentionally brought to quenching, so that the current flow collapses as soon as possible and no damage to the first locally heated semiconductor region occurs.
  • D This ti method is used üb ⁇ SHORT- in magnetic coils to protect the conductors from permanent overheating.
  • an emergency stop switch in order to enable a rapid shutdown of the magnetic field generated by the coil in the event of a fault of the coil device.
  • one of the coils can be heated intentional ⁇ Lich example, to trigger a collapse of the superconductivity in the entire coil winding in the sequence.
  • a disadvantage of the described prior art is that in the discharge and quenching processes, a high part of the energy stored in the coil winding is dissipated as heat in the region of the coil winding. This can lead to unnecessary loss of expensive coolant, loss of energy and / or thermal stress on the sensitive superconducting conductor materials. Particularly in the case of magnetic resonance coils, the loss of the liquid helium in such quenching processes is a high cost factor. With SMES storage reels, the loss of stored ones is the most important Energy disadvantageous when a part of it is lost by quenching or controlled discharge as heat in the coil winding.
  • Another disadvantage of the known persistent current switch is that the switching time for the opening of the switch is relatively slow and thus discharging the energy into an external circuit can be done only slowly. This, too, can lead to higher losses and higher heat development in the coil winding than would be the case with a faster discharge.
  • Object of the present invention is therefore to provide a coil device which avoids the disadvantages mentioned.
  • a continuous current switch is to be specified with which a reduction in the dissipation of heat in the region of the electrical coil winding can be achieved.
  • Another object is to provide such a continuous current switch for such a coil device and a method for loading or unloading a continuous current.
  • the closed circuit has a persistent current switch with a switchable conductor section which is switchable between a superconducting state and a normal conducting state.
  • the switchable conductor section has a high-temperature superconducting conductor and has a resistance of at least 300 ohms in the normal conducting state of the conductor.
  • the switchable conductor section is a Abklingwiderstand of at least 50 ohms and / or a consumer with an effective resistance of at least 50 ohms parallelge ⁇ switches.
  • HTS high-temperature superconductor or high-T c - superconductor
  • the critical temperature of these superconductors is even above 77 K, so that the operating tempera ⁇ ture can be achieved by cooling with other cryogenic materials as liquid helium.
  • An advantage of high-temperature superconductors compared with many metallic low-temperature superconductors for use in said persistent current switch is that they often have a relatively high resistance in the normal conducting state and thus that the continuous current switch in the open state can also be made relatively resistant to breakdown.
  • the continuous-current switch has a decay resistance of at least 50 ohms or a corresponding load connected in parallel with it.
  • An essential advantage of this parallel current path is that, when the permanent current switch is opened, a large part of the electrical energy is diverted into this parallel current path and thus this part is not dissipated as heat in the coil winding or in the permanent current switch.
  • the Abing resistance or the effective resistance of the consumer is at least 50 ohms large enough to avoid Abflie ⁇ Shen the continuous current in this parallel-connected current path in the closed state of the persistent current switch, because then the current in the almost resistance-free closed superconducting Current path of the coil winding and the continuous current switch flows.
  • the resistance of the persistent current switch of at least 300 ohms in the normal, that is opened, causes a state that flows in the open state of the persistent current switch, the current to the RESIZE ⁇ ßeren part about the Abklingwiderstand or the consumer, and only to a lesser extent on the normal conducting conductor portion of the permanent current switch.
  • an energy loss within the closed circuit ⁇ ge of the coil winding and the continuous current switch is advantageously reduced.
  • the persistent current switch according to the invention is designed for a coil device according to the invention.
  • the inventive method is used for loading or unloading a continuous current in a coil device according to the invention.
  • the switchable conductor section of the permanent ⁇ current switch is switched from a superconducting state to a normal conducting state.
  • the advantages of this method are analogous to the advantages of the coil device described above.
  • Advantageous embodiments and further developments of the invention will become apparent from the dependent claims of claim 1 and the following description.
  • the described embodiments of the coil device, the Dauerstrom- switch and the method can be combined miteinan ⁇ generally advantageous.
  • the coil means may comprise a cryostat for cooling the superconducting conductor material, wherein the superconductors tend coil winding and the switchable conductor portion are disposed in ⁇ nergur of the cryostat.
  • the Abklingwiderstand and / or the consumer is then advantageously arranged outside the cryostat.
  • the cryostat With the help of the cryostat, the superconducting conductor materials of the coil winding and the switchable conductor section can be cooled to a temperature below the transition temperature of the respective superconductor, so that a continuous superconducting closed circuit can be obtained.
  • the cryostat can be, for example, an open bath cryostat from which the coolant used can optionally evaporate.
  • it may also be a cryostat with a closed coolant circuit, in which a coolant is either liquefied or can change between a liquid and a gaseous (or supercritical) state.
  • a coolant is either liquefied or can change between a liquid and a gaseous (or supercritical) state.
  • the arrangement of the Abklingwiderstands or consumer outside the cryostat advantageously has the effect that the transferred during a discharge of the coil winding in the Abklingwiderstand or the consumer energy does not contribute to a heating of the interior of the Kryosta- th.
  • a maintenance of the cooling and the superconducting operating state for the components arranged within the cryostat is thereby also made possible during the unloading of the coil.
  • the switchable conductor portion may have a resistance which is larger of the Abklingwiderstand and / or the consumer advantageous normallei ⁇ conducting condition of the conductor.
  • the main advantage of this embodiment is that after an opening of the persistent current switch, a greater part of the energy previously stored in the coil winding is dissipated via the Abklingwiderstand and / or the consumer and only a comparatively smaller part is dissipated in the region of the persistent current switch. Even a majority of the energy in the area of decay resistance and / or consumers is particularly advantageously dissipated.
  • the resistance of the switchable conductor section in its normal conducting state can be greater than a total resistance of the parallel current path having the decay resistance and / or the load.
  • the resistance of the switchable conductor section may be, for example, at least a factor of 5, in particular by at least a factor of 20 higher than the total resistance of the parallel current path in the normally-conductive state.
  • the switchable conductor portion may have in the normal conducting state of the conductor to ⁇ a resistivity of at least 1000 ohms, particularly at least 5000 ohms.
  • a resistivity of at least 1000 ohms particularly at least 5000 ohms.
  • Such high resistances are particularly advantageous in order to implement a particularly high, in particular a majority, part of the energy previously stored in the coil winding in the area of the decay resistance and / or of the load and only a small dissipation of energy in the region of the coil winding and / or or the permanent current switch to verursa ⁇ chen.
  • the higher resistance values of at least 5000 ohms are particularly advantageous in connection with the application in SMES systems, since there only a particularly small proportion is to be dissipated in the region of the coil winding.
  • ⁇ stand of the open persistent current switch is generally advantageous: For example, when a voltage of about 20 kV is applied during the decay time, a leakage current of at least 1 MOhm in the open ⁇ th state only about 0.02 A come about. This will be done during the a short-term power of only 400 W is dissipated in the continuous current switch, which the permanent-current switch can advantageously endure for the duration of the switching.
  • the switchable conductor portion in the normal stand to ⁇ of the conductor may have a generally advantageous fürschlagfes ⁇ ACTION for voltages of at least 20 kV. This can achieve that does not occur even during scarf ⁇ least, so especially during the transition from superconductivity Tenden in the normal state of the switchable conductor section to a flashover and the shorted continuous current can be switched off controlled.
  • a dielectric strength of at least 20 kV is appropriate to ⁇ particular for solenoid coils for magnetic resonance imaging, since very high local stresses at the persistent current switch can come about by the very high magnetic fields and very high continuous current during switching.
  • the resistance of the switchable conductor portion in the normal conducting state and its thermal coupling to the other components can be chosen so that the remaining leakage current, the continuous current switch at the maximum voltage occurring at a temperature in the range below 320 K. heated.
  • the distance of the switchable conductor section should generally be long enough to achieve the required resistance in the normal conducting state.
  • the cross section of the conductor section should be large enough to reach the current carrying capacity required for the respective continuous current.
  • the switchable conductor section may comprise a ceramic high-temperature superconductor.
  • a ceramic material has a high dielectric strength can it be enough ⁇ particularly well.
  • metallic low-temperature superconductors with such a ceramic material also a high resistance in the open state of the switch can be easily achieved.
  • this conductor section has no continuous metallic conductive elements.
  • the ceramic superconducting material is deposited as a layer on a carrier, it is therefore advantageous if this carrier is not metallic, but is formed from poorly conductive or non-conductive materials such as glass, ceramic and / or composite materials.
  • the conductor section can also have a ceramic superconducting conductor element present in bulk, that is to say in a solid form. If the superconducting ceramics are too high or too undefined resistance to the demands of continuous current scarf ⁇ ters, then a relatively poorly conducting paralleling stand parallel. Such a resistance can, for example, values in the range between 0.3 kOhm and
  • the switchable conductor section may comprise a material of the BaKBiO type.
  • a material to be understood which is present as the compound of these four elements, in particular the compound of the composition Ba x to ⁇ K y Bi03, wherein, for example, x is about 0.6 and y may be about 0.4.
  • This is a ceramic superconducting material, which is characterized by one for a
  • HTS material is ⁇ rich in comparatively low transition temperature in the loading of about 30 K and a relatively low upper critical magnetic field of approximately 60 mT.
  • the upper critical magnetic field strength B C 2 for the superconducting material of the switchable conductor section may be below or at 100 mT.
  • Such a low kriti ⁇ specific magnetic field strength B C 2 causes the shiftable LEI terabêt can be easily switched by a change of a locally we ⁇ kenden magnetic field.
  • the upper critical magnetic field strength B in the range C 2 Zvi ⁇ rule 40 mT and 80 mT may be.
  • the transition temperature for the superconducting material of the switchable conductor section is at most 50 K, for example between 25 K and 35 K. Such a relatively low transition temperature for a high-temperature superconductor causes the switchable conductor section to be easily switched by local heating.
  • a superconducting material with a jump can in principle also similarly be temperature used below 25 K for the switchable conductor region, provided they are in this material is a ceramic material which is therefore not metal ⁇ cally conductive .
  • An operating temperature for the superconducting state of the switchable conductor section can advantageously be between 4 K and 40 K. With such an operating temperature can be achieved that the conductor section can be brought into the normal ⁇ conductive state by a relatively small increase in temperature and / or a relatively small increase in a locally acting magnetic field. Particularly advantageously, the operating temperature of the superconducting state of the switchable conductor section between 10 K and 25 K.
  • the switching time for switching the switchable Kirab ⁇ section from the superconducting to the normally conducting state can advantageously be at most 0.5 s, in particular at Hoechsmann ⁇ least 0 , 1 s lie.
  • Such a short opening time has the advantage that, for a discharge of the superconducting coil, a high proportion of data stored in the coil electrical energy to the Abklingwiderstand or Ver ⁇ consumers is transmitted and is thus not dissipated at constant current scarf ⁇ ter or the coil winding.
  • the electric Coil winding are discharged and still remain essentially in the superconducting state, for example, after a local heating, the opening of the persistent current switch takes place fast enough that only a small proportion of the stored energy is dissipated in the coil winding and thus remain the remaining portions of the coil winding supra ⁇ conductive ,
  • the locally heated area can quickly reach its operating temperature after such a rapid unloading. For example, very quickly return back to its original operating state ⁇ a magnetic coil of a magnetic resonance apparatus according to such a local heating and a subsequent discharge of the coil when there is no quenching of the magnet coil and thus no complete evaporation of the surrounding liquid helium around takes place. This reduces downtime and coolant consumption.
  • the system can be remotely restarted, and after a complete quench usually required visit of a service technician to refill the helium can be omitted.
  • the persistent current switch need not be designed for sudden discharge upon local heating of the coil winding, it is sufficient if the switch opens fast enough to allow controlled discharge of the current to the decay resistance. and / or to the consumer. So if in a magnetic resonance coil no sudden quench must be prevented, but only a controlled discharge or shutdown of the system is to be made possible, a switch opening time of up to 10 s may be sufficient. This is the case even in SMES systems or excitation coils of electric machines, which typically do not ge with such sudden quenching processes ⁇ expects to be and when unloading not as large amounts of energy must be dissipated as Magnetreso ⁇ nanzsystemen.
  • the coil device may have a further magnetic coil for generating a local magnetic field B ext for switching the switchable conductor section.
  • an opening of the permanent current switch may be effected by a turning of such a magnetic coil by ext by the Mag ⁇ netfeld B exceeding the upper critical magnetic field strength B ⁇ C 2 of the superconductive material of the permanent current switch is effected.
  • the opening of the persistent current switch can in principle be effected solely by a change in the lo ⁇ cal magnetic field or by a combination of magnetic and thermal switching.
  • the magnetic field of the further magnet coil can also be an already superimposed pre handenen magnetic field thereby to generate a magnetic field B ext with which the magnetic field strength exceeded B C 2 who can ⁇ .
  • the coil means may comprise a switchable arranged around the conductor portion with a shielding shorted ⁇ closed in itself current path, the short-circuited current path can be opened by a switchable portion of the conductor from ⁇ screen coil.
  • the closed current path of the shielding coil can be opened via this further switchable conductor section, which considerably reduces the magnetically shielding effect.
  • a magnetic background field which was previously largely shielded by the shielding, on the switchable conductor area of the persistent current switch act and this brin ⁇ gene by exceeding its upper critical magnetic field strength B C 2 in its normal conducting state, so open the persistent current switch.
  • the coil means may be copy in the coil means, for example, a Magnetspu ⁇ len adopted for generating a magnetic field in a magnetic resonance imaging apparatus or Magnetresonanzspektros-.
  • it can be an excitation coil device for generating an electromagnetic exciter field in a rotating electrical machine.
  • it may, for example, be a magnetic coil device for storing energy in a superconducting magnetic energy store (SMES).
  • SMES superconducting magnetic energy store
  • the basic idea of the present invention is suitable for all systems in which a continuous current flows in a short-circuited superconducting coil system.
  • the superconducting conductor material of the coil winding may in principle be a different material than the superconducting material of the switchable conductor section.
  • the material of the coil winding can also magnesium diboride aufwei ⁇ sen or it may be a metallic superconductor, so for example, a system based on NbTi or Nb3Sn material.
  • the superconducting material of the coil winding and the persistent current switch may also be identical or at least have the same components.
  • the SPU ⁇ lenwicklung may also have another ceramic HTS material than the persistent current switch, for example a material of the type REBa 2 Cu 3 O x (short REBCO), where RE stands for a Ele ⁇ element of the rare earths or a mixture of such elements.
  • RE stands for a Ele ⁇ element of the rare earths or a mixture of such elements.
  • these materials for the closed circuit must be superconducting or with a minimum of gene connection resistance are interconnected.
  • Superconducting connections between a ceramic superconductor and an NbTi-based conductor are already known from the prior art. Due to the large coherence length of NbTi, such superconducting compounds are relatively easy to produce.
  • a solid ceramic superconductor can be provided with holes that are filled for contacting with NbTi filaments and superconducting solder.
  • a contact can be created via a press sintering.
  • a magnetic field B ex t acting at the location of the switchable conductor section can be changed for switching over.
  • This change can be effected, for example, by switching a magnetic coil on or off or by breaking or joining a magnetic shielding coil.
  • opening of the switch can be effected by heating the switchable region, or closure of the switch can be effected by removal of the heating.
  • the persistent current switch can be switched either magnetically or thermally or by a combination of both methods.
  • the continuous current switch is generally opened for loading or unloading the coil winding and closed for operation of the coil winding in the continuous current mode.
  • the discharging of the continuous current can for example be selectively eliminated from ⁇ if a local heating is detected in the coil winding.
  • the discharge can also be triggered manually or otherwise controlled by a control unit, in ⁇ example, in a controlled shutdown of the system, in the removal of stored energy in an SMES system or even when pressing an emergency stop switch.
  • Figure 2 shows a schematic equivalent circuit diagram of a Spulenein ⁇ device according to a first embodiment
  • Figure 3 shows a schematic equivalent circuit diagram of a Spulenein ⁇ direction according to a second embodiment
  • FIG. 4 shows a schematic representation of the dependency of the upper critical magnetic field strength on the temperature for a persistent current switch according to a third exemplary embodiment
  • FIG. 5 shows a persistent current switch according to a fourth exemplary embodiment
  • Figure 6 shows a persistent current switch according to a fifth embodiment
  • Figure 7 shows a persistent current switch according to a sixth embodiment.
  • FIG. 1 shows a schematic equivalent circuit diagram of an SPU ⁇ len sexual 1 according to the prior art is shown. Shown is a superconducting coil winding 3, which is arranged together with a persistent current switch 6 within a cryostat 11. By the cryostat, the superconducting conductor elements of the coil winding 3 and the Treasurestromschal ⁇ ters 6 to a temperature below their respective jump temperature to be cooled. About the coil winding 3 and the persistent current switch 6, a closed circuit 5 is formed in which a continuous current I i can flow almost lossless due to the supra ⁇ conductive properties and thus does not decay or only extremely slowly over time.
  • the coil device 1 may be, for example, punching han ⁇ a magnet coil means of a magnetic resonance apparatus.
  • the hitherto described part of the closed circuit to an external power source 13 may be connected ⁇ the in such a way that this current source is connected in parallel with the continuous current ⁇ switch 6.
  • the current source 13 is in this case arranged outside the cryostat 11. It can be electrically connected via a switch 10 with the other components.
  • the continuous current switch is opened, that is, it is set from its superconducting state to a normal conducting state, whereby its line resistance increases greatly.
  • a discharging of the coil device 1 shown in FIG. 1 can be triggered, for example, by a Lei ⁇ terabêt of the coil winding 3 is locally heated and there- through normal conducting becomes. According to the state of the art, such a region spreads rapidly and leads to a quenching of the entire coil, whereby the coil winding 3 is strongly heated. Controlled discharge into the parallel loading circuit external to the cryostat, similar to loading, would also be theoretically possible, but the known persistent current switches 6 are generally too slow to prevent complete quenching after initial local heating of a portion of the superconducting conductor ,
  • FIG 2 shows a similar schematic equivalent circuit diagram of a coil device 1 according to a first embodiment of the invention. Shown is an analogous to Figure 1 arrangement of coil winding 3, persistent current switch 6, cryostat 11 and external current source 13. In addition to these components, the persistent current switch 6 is a decay resistor 9a arranged outside the cryostat 11 is connected in parallel. The ⁇ ser Abklingwiderstand 9a has a resistance of 50 ohms WE tendonss. The loading of the coil device 1 by means of the current source 13 is analogous as for Figure 1 ⁇ written . Again, the power source after loading can either be disconnected or remain connected to the rest of the system. During charging, only an extremely small proportion of the charging current I 2 flows through the Abklingwiderstand 9a, since this resistance is significantly higher than the total resistance of the coil winding 3 in the superconducting state.
  • the ratio between the current flowing through the discharge Abklingwiderstand 9a Ström I3 and the current flowing through the switch 6 open leakage current I 4 is provided over give the ratio of the resistances of the Abklingwiderstands 9a and the opened switch ⁇ . Therefore, a highest possible resistance of the geöffne ⁇ th permanent current switch 6 is advantageous in order to flow on unloading a very high proportion of the current through the Abklingwiderstand 9a and to avoid in particular an undesirable heating of the elements arranged in the cryostat.
  • a controlled discharge can be triggered by switching the persistent current switch 6 in its normal conducting state. At a favorable resistance ratio may be dependent on voltage applied in the circuit 5, current and stored energy as well as the operating points of the superconducting conductor elements advantageously a quench the
  • An uncontrolled, ie spontaneously triggered discharge can be triggered as described by a local heating of a conductor region of the coil winding 3.
  • a local quench can be detected by a sensor, and then an opening of the persistent current switch 6 can be triggered, which as described above subsequently causes a discharge of a large part of the current as discharge current I3 via the Abklingwiderstand.
  • a sufficiently high resistance ratio and in turn dependent on voltage, current, energy and operating points due to the rapid discharge quenching of the entire coil winding 3 can be advantageously avoided.
  • Advantageous for a successful avoidance of such a complete constant quench is a sufficiently fast opening time of the persistent current switch 6, which may advantageously be less than 0.5 s.
  • Such rapid switching may in particular be possible when switching between the superconducting state and the normal conducting state is caused at least in part of a locally acting Magnetfel ⁇ by the change of, since such a magnetic field can be switched much faster typically as the temperature of the switchable conductor portion can be changed. Due to the heat capacities of the elements typically thermally coupled to such a conductor section, purely thermal switching is normally slower than switching based at least in part on the change of electromagnetic fields. Fast switching is thus advantageous, above all, for avoiding quenching in the event of spontaneous discharge.
  • Figure 3 shows a schematic equivalent circuit diagram of an SPU ⁇ len prepared 1 according to a second embodiment of the invention.
  • the coil device 1 is similarly constructed as in the example of Figure 2.
  • a consumer 9b parallel to the constant current circuit 5 is arranged.
  • the example of FIG. 3 may be, in particular, an SMES system, in which excess electrical energy of a superordinate energy source is used
  • a controlled discharging process can again be triggered by opening the persistent current switch 6.
  • a discharge current I 5 flows through the load 9b, so that the electrical energy previously stored in the coil winding can be used by the consumer 9b.
  • the relationship between the resistance of the open persistent current switch 6 and the effective resistance of the Ver ⁇ brauchers 9b should therefor be very high, for example at least 10: 1, especially at least 100: 1.
  • An additional, optional switch 10a can be arranged in the example of FIG. 3 between the consumer and the coil winding 3 in order to connect the consumer to the energy storage system only when required.
  • FIG. 4 shows a plot of the locally acting magnetic field B ex t in the region of a continuous current switch 6 against the temperature T.
  • T the dependence of the upper critical magnetic field strength B C 2 of the superconducting material of the switchable conductor section on the operating temperature T, ie B, is in this coordinate system C 2 (T) shown.
  • This curve B C 2 (T) is a relatively shallowly decreasing function of temperature in the low temperature range and decreases steeper and steeper towards higher temperatures.
  • T c indicates the critical temperature of the material for a local magnetic field B ext going to zero. Above this temperature no superconducting state is possible. Shown is a schematic exemplary course for a ceramic superconductor material, wherein the exact values are highly dependent on material.
  • the switchable conductor material is superconducting, for operating points right above the curve, it is normally conducting.
  • initially superconducting operating point P on the curve B C 2 (T) addition thus opening the persistent current switch is possible.
  • such a opening Dau ⁇ erstromschalters can be ⁇ acts in different ways in principle because either the temperature dependence of the sup- ra réelleden properties or the magnetic field dependence or both can be exploited simultaneously.
  • the arrow marked with the reference numeral 14a shows a change of the operating point P, in which only the temperature is changed.
  • Such a purely thermal switching in the normallei ⁇ border operating range can therefore be triggered by a local heating of the switchable conductor section.
  • the arrow marked with the reference symbol 14b shows a change of the operating point P, in which only the locally acting magnetic field B ex t is changed.
  • the arrow indicated by the reference numeral 14c shows a combined thermal-magnetic switching in which the material is brought into the normal conducting state by simultaneous change of temperature and magnetic field.
  • the proportion of the change of these two operating parameters can also be chosen differently. It is essential that such a change can be effected particularly effectively by a combination of both changes.
  • the switching variants 14b and 14c in which the opening is effected at least in part by the change ⁇ tion of the magnetic field B ex t, the switching can generally generally be faster than in the purely thermal switching 14a.
  • a purely thermal switching by the poor thermal conductivity is typically slower than an at least magnetically supported Schal ⁇ th.
  • the distance with respect to the temperature coordinate can be advantageous ⁇ at least 3 K, in particular between 10 K and 40 K.
  • the switchable conductor section in the permanent ⁇ current switch of the third embodiment based on a Ma ⁇ material of the type BaKBiO.
  • This switchable Porterab can ⁇ cut advantageous see at an operating point be- 10 and 25 K and between 0 and 50 mT are operated. As a result, a fast switching, which is at least partially triggered magnetically, facilitated.
  • the operating temperature of the persistent current switch is also relatively close to Be ⁇ operating temperature of the coil winding, so that no excessively high temperature gradient within the cryostat 11 or via the conductor loop of the circuit. 5 must keep away upright ⁇ .
  • Figure 5 shows a persistent current switch 6 according to a fourth embodiment of the invention. Shown is a supralei ⁇ tender conductor 23 which is connected in the further course not shown here with a coil winding 3 to a closed circuit 5, similar to the figures 2 and 3.
  • the superconducting conductor 23 has a switchable autismab ⁇ section 7, which is arranged in this example within a Ab ⁇ screen coil 15.
  • This shielding coil 15 serves to shield an existing external magnetic field in the region of the switched conductor section 7, wherein the Mag ⁇ netfeld is without shielding above the given at the operating temperature Tempe ⁇ B C 2 (T).
  • this existing external magnetic field it may be at least partially that of the Coil winding 3 field generated act. In particular, it may be the comparatively strong background field of Mag ⁇ netresonanz réelles.
  • the arranged around the switchable Porterab ⁇ section shielding coil 15 reduces this external magnetic field in its interior considerably, so that the section 7 is largely shielded in normal operation of the magnetic field.
  • an operating point P can be set below the B C 2 (T) curve.
  • the shielding effect of the coil 15 can in turn be canceled out or at least reduced by switching over the coil properties.
  • the shielding effect of the coil 15 can in turn be canceled out or at least reduced by switching over the coil properties.
  • For this purpose can be geöff within the shielding 15 ⁇ net connect.
  • the shielding coil 15 may be a cylindrical coil. It can in turn also have a superconducting material, in particular a zy ⁇ lindhariwitzs superconducting element. To open the switch, the superconductivity is interrupted at least in a portion of the cylinder, whereby the shielding effect is largely eliminated. Then, also acts in the interior of the shielding coil a local magnetic field B above C 2 (T), and the switchable conductor portion 7 is put in a normal direct ⁇ the state of the persistent current switch 6 is so ge ⁇ opens.
  • a hollow cylinder made of solid (bulk) superconductor material can be used as the shielding coil .
  • a hollow cylinder coated with a cylindrical superconducting layer may be used.
  • Suitable superconducting materials for Abtenspu ⁇ le 15 are for example magnesium diboride or a material of the type REBCO.
  • a peripheral segment 15a of the cylinder can be heated with a heating element 17 so far that the superconductivity breaks down in this section 15a.
  • the magnetic switching shown in Figure 5, in which a superconducting shielding coil 15 is in turn thermally switched can be realized much faster than if the switchable conductor section would be directly thermally switched. A major reason for this is that the shielding must be dimensioned as a second switch for much lower withstand voltages and / or current carrying capacities than the continuous current Turn 6 in the main circuit 5.
  • the conductor cross-section and / or circuit ⁇ mass can be lower.
  • the shielding coil can be designed so that even with purely thermal switching a rapid change in their superconducting properties is possible.
  • FIG. 6 shows a schematic representation of another continuous-current circuit breaker according to a fifth exemplary embodiment of the invention. Shown again is a switchable conductor section 7, around which a shielding coil 15 is arranged.
  • a switchable conductor section 7 around which a shielding coil 15 is arranged.
  • the conductors of the outermost windings are in this case connected via a superconducting contact 19 to a closed shielding circuit.
  • a switchable conductor section 15a of this shielding circuit is in turn thermally gekop- with a heating element 17 pelt over which the conductor portion can be brought into a conducting condition normallei ⁇ 15a.
  • a secondary thermal switch exists, via which a superconducting shielding can be switched off, so that a switchable conductor section 7 of the persistent current switch 6 is switched indirectly magnetically into a normally conducting state.
  • the thermal switching of Abnespu ⁇ le 15 can be done faster than would be possible with a purely thermal switching of the conductor portion 7, since the conductor the coil 15 does not have to be dimensioned for the high voltage strengths and current carrying capacities of the circuit 5 of the coil winding 3.
  • a switching of the switchable conductor portion may additionally through another optional and therefore not shown here heating element Be ⁇ rich of the conductor portion are supported 7, or ge ⁇ showed heating element 17 may alternatively be arranged so that this conductor portion 7 is with heated.
  • the head of the shield coil 15 may for example be formed of similarity ⁇ Lichem superconducting wire as the coil 3.
  • a Tieftemperatursupra- conductor or a magnesium diboride-based conductor can be used here. And technologies are known for such materials to the required superconducting contact 19 herzustel ⁇ len.
  • the thermal conductivity of the material of the shielding winding supra ⁇ conductive 15 may be higher than in the superconducting material of the switchable conductor section 7, since no resistor to a high electric Wi possible in the normal state must be taken into consideration.
  • the coil winding 15 with a fast magnetically switchable conductor material such as
  • BaKBiO be trained. This can be switched, for example, with a magnetically coupled thereto magnetic coil. In other words, such a fast switching via a cascade of two superconducting magnetically switchable conductor regions.
  • the shielded from ⁇ volume is comparatively small.
  • the shielding should be chosen small in order to avoid magnetic field distortions in the imaged or measured volume.
  • the volume of the continuous current switch is generally not more than 100 cm 3 .
  • a second, not shown in the figures is provided with a heating element thermally switchable conductor section.
  • a serial second switch can be advantageously used to load the coil winding 3 with a charging current.
  • the second switch should be opened, because at an initial charging of the coil system 1, the background field generated by the coil winding 3 is not yet large enough to enable a magnetic switching by canceling a shield.
  • a field winding which, as described below, interacts with a background field to exceed the B C 2 (T) curve.
  • an additional thermal switch is useful to allow for initial charging and possibly complete discharge without the nominal background field. In this case, however, complete discharge is less critical, since a leakage current I 4 flowing in the persistent current switch generally leads to a thermal load of the switchable conductor discharge during discharge. Section 7 and thus leads to a prolonged leaving the superconducting work area.
  • Figure 7 shows a schematic representation of another continuous current switch according to a sixth embodiment of the invention.
  • simplified two different variants of the switching are shown in a figure, which can either be used separately or optionally can be combined with each other.
  • a switchable conductor section 7 of a continuous current switch 6, which is connected in this example via two sup ⁇ ra decisionsde contacts 19 with a superconducting conductor 23 which forms a closed circuit 5 together with a coil winding 3, not shown here, similar to the figures 2 and 3.
  • the switchable conductor portion 7 is formed of a different superconducting material than the remaining superconducting conductor 23.
  • Such a choice of another material and the introduction of additional superconducting contacts 19 may optionally also in the embodiments of Figures 5 and 6 are used, so for each of the described switching variants.
  • a uniform superconducting material for switchable conductor section 7 and the remaining conductor 23 as well as the coil winding 3 can also be used for the respective variants.
  • a magnetic field winding 21 is arranged around the switchable conductor section 7 or at least a part thereof.
  • This magnetic field winding 21 is vorteilhat small compared to the coil winding 3, but they should be sufficient in the area of the conductor portion 7 a local Mag ⁇ netfeld B ex t to reach above the respective B C 2 (T). It advantageously has a comparatively low inductance, so that the magnetic field can be switched on quickly to ermögli ⁇ chen a rapid opening of the persistent current switch 6.
  • the magnetic field winding 21 can be a superconducting conductor. However, they can in principle also be normally conductive.
  • the persistent current switch 6 is advantageous in this Kunststoffme- Thode in a region within the cryostat 11 angeord ⁇ net, in which the magnetic field of the coil winding 3 ⁇ comparison example is low. This is particularly important for magnetic ⁇ systems with high background magnetic fields, so B 2 (T) is not already exceeded the background field C, but 21 only when switching on the magnetic field coil, the magnetic field of the magnetic coil 21 can then interact favorably with the background magnetic field B C 2 (T), so that the magnetic field generated by the additional winding 21 need not be very large.
  • a material with anisotropic, ie direction-dependent B C 2 (T) can be used.
  • a crystalline material having a high B C 2 (T) in crystallographic ab direction and a low B C 2 (T) in crystallographic c direction can be used.
  • the persistent current switch can then be aligned so that the background field is aligned in the down direction of the mate rials ⁇ and thus the superconducting portion of the curve according to Figure 4 is not left. Only by switching on the magnetic field winding 21 in the c-direction, a sufficiently high magnetic field B ex t is generated to leave the supra agenda ⁇ the area below the B C 2 (T) curve.
  • the Benö for the magnetic switching ⁇ preferential magnetic field strength can be reduced by forming a conductor geometry is chosen for the switchable semiconductor region 7, which promotes the formation of local field enhancements.
  • a conductor geometry is chosen for the switchable semiconductor region 7, which promotes the formation of local field enhancements.
  • a flat, band-shaped conductor can be used and the magnetic field of the field winding 21 can impinge substantially perpendicular to such a strip conductor. Shielding currents in the conductor cause a field increase in the conductor Range of edges. Once these are 2 by exceeding the C B (T) curve of normal-conductive, the field enhancement penetrates further into the interior before until all switchable autismab ⁇ section 7 becomes normally conductive. Thus, with a relatively small additional magnetic field of the field winding 21, the conductor portion 7 can be effectively and rapidly switched.
  • the field winding 21 may be omitted, and the switchable conductor portion 7 can in principle only by the heating ⁇ element 17 according to variant 14a of Figure 4 can be switched between its superconductive state and its normally conducting state.
  • the thermal switching of ceramic superconductive conductor portions 7 can take place quickly, since a smaller mass of ceramic conductor material is Benö ⁇ Untitled for the expedient to be achieved resistors.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Containers, Films, And Cooling For Superconductive Devices (AREA)

Abstract

L'invention concerne un dispositif bobine comprenant au moins un enroulement de bobine électrique pourvu d'un matériau supraconducteur, l'enroulement de bobine faisant partie d'un circuit électrique fermé pour former un courant permanent. Le circuit électrique fermé comprend un commutateur à courant permanent présentant une partie conducteur commutable qui peut être commutée entre un état supraconducteur et un état de conduction normale. La partie conducteur commutable comprend un conducteur supraconducteur à haute température et présente, à l'état de conduction normale du conducteur, une résistance d'au moins 300 ohms. Une résistance d'amortissement d'au moins 50 ohms et/ou un consommateur présentant une résistance effective d'au moins 50 ohms sont montés en parallèle à la partie conducteur commutable. L'invention concerne en outre un commutateur à courant permanent pour un tel dispositif bobine ainsi qu'un procédé de charge et de décharge d'un courant permanent.
PCT/EP2016/070764 2015-09-03 2016-09-02 Dispositif bobine doté d'un commutateur à courant permanent Ceased WO2017037259A1 (fr)

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DE102015216882.4A DE102015216882A1 (de) 2015-09-03 2015-09-03 Spuleneinrichtung mit Dauerstromschalter

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Cited By (4)

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WO2019091842A1 (fr) * 2017-11-08 2019-05-16 Siemens Aktiengesellschaft Rotor et machine à enroulement de rotor à p pôles
CN113169658A (zh) * 2018-08-21 2021-07-23 劳斯莱斯德国有限两合公司 带有用于在持续电流模式中运行的超导的绕组的转子
CN115527740A (zh) * 2022-11-24 2022-12-27 杭州慧翔电液技术开发有限公司 一种自循环超导磁体及半导体单晶炉
US11871683B2 (en) * 2020-10-26 2024-01-09 Shanghai Jiao Tong University Charging and field supplement circuit for superconducting magnets based on pulsed current

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CN107123504B (zh) 2017-07-03 2019-06-28 上海联影医疗科技有限公司 磁共振磁体降场系统及降场方法
EP3425415B1 (fr) * 2017-07-03 2023-08-16 Shanghai United Imaging Healthcare Co., Ltd. Systèmes et procédés pour ralentir un aimant de résonance magnétique
CN109660235B (zh) * 2018-11-30 2021-12-31 同济大学 一种用于高温超导电磁铁的热控式持续电流开关电路

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WO2014058871A1 (fr) * 2012-10-12 2014-04-17 Brookhaven Science Associates/Brookhaven National Laboratory Commutateur supraconducteur rapide pour dispositifs de puissance supraconducteurs

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EP0115797A1 (fr) * 1983-02-02 1984-08-15 Siemens Aktiengesellschaft Dispositif de protection pour une bobine d'électro-aimant supraconducteur
EP0150361A2 (fr) * 1984-01-27 1985-08-07 Siemens Aktiengesellschaft Dispositif interrupteur pour le court-circuitage d'un enroulement super-conducteur
GB2162712A (en) * 1984-07-20 1986-02-05 Ga Technologies Inc Electrical switch
EP0211551A1 (fr) * 1985-07-20 1987-02-25 Kabushiki Kaisha Toshiba Dispositif et méthode pour la commande d'un appareil de supraconduction
US20100001821A1 (en) * 2007-01-05 2010-01-07 Quantum Design, Inc. Superconducting quick switch
WO2014058871A1 (fr) * 2012-10-12 2014-04-17 Brookhaven Science Associates/Brookhaven National Laboratory Commutateur supraconducteur rapide pour dispositifs de puissance supraconducteurs

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019091842A1 (fr) * 2017-11-08 2019-05-16 Siemens Aktiengesellschaft Rotor et machine à enroulement de rotor à p pôles
CN113169658A (zh) * 2018-08-21 2021-07-23 劳斯莱斯德国有限两合公司 带有用于在持续电流模式中运行的超导的绕组的转子
US11871683B2 (en) * 2020-10-26 2024-01-09 Shanghai Jiao Tong University Charging and field supplement circuit for superconducting magnets based on pulsed current
CN115527740A (zh) * 2022-11-24 2022-12-27 杭州慧翔电液技术开发有限公司 一种自循环超导磁体及半导体单晶炉
CN115527740B (zh) * 2022-11-24 2023-03-10 杭州慧翔电液技术开发有限公司 一种自循环超导磁体及半导体单晶炉

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