High temperature superconducting electric switches and rectifiers

Abstract

The rectifier includes an electrical switch including an HTS material segment having a critical current for conducting an AC switch current, a magnetic field generator for controlling a magnetic field generator to apply a magnetic field to the HTS material, and a control mechanism for switching the switch between a low resistance state when the magnetic field magnitude is relatively small and a high resistance state when the magnetic field magnitude is relatively large, the relatively large magnetic field magnitude being sufficient to reduce the critical current such that the current is close to, substantially equal to, or greater than the critical current for a portion of the AC switch current cycle. An electrical switch having two strands of superconducting material arranged in a bifilar configuration is also provided.

Description

[Technical field]

[0001] SUPERCONDUCTING ELECTRIC SWITCHES AND RECTIFIERS The present technology relates to superconducting electrical switches and rectifiers. The present technology may be particularly relevant to electrical switches and rectifiers that include components formed from superconducting materials, especially high temperature superconducting materials. [Background technology]

[0002] Superconducting circuits have a wide range of applications. Examples of applications for systems containing superconducting circuits include, but are not limited to, superconducting magnets, magnetic flux pumps, fault current limiters, magnetic energy storage systems, space propulsion, nuclear fusion, nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), suspension, water purification and induction heating.

[0003] Many applications of superconducting circuits require or benefit from rectifying electric current, that is, converting alternating current (AC, a current that cyclically reverses direction) to direct current (DC, a current that flows in only one direction).

[0004] Although rectifiers for superconducting circuits are known, there is a need for improvements to superconducting rectifiers and / or components of the rectifiers, e.g., switches, to reduce losses, provide greater efficiency compared to existing rectifiers, and / or provide other advantages.

[0005] High temperature superconductors (HTS) have many applications including those mentioned above. Advances in manufacturing processes for HTS coated conductors (CC) have resulted in wires capable of carrying high current densities under high magnetic fields. Coils wound with these CC have shown excellent performance as high field magnets / inserts. CC coils are also promising for many other applications such as motors / generators, DC induction heaters, and magnetic separators.

[0006] High-current HTS coils are ideal and not difficult to manufacture, but energizing them typically requires large and complex electronic current sources and thick current leads that must physically transition between room temperature and cryogenic environments. This requires advanced thermal design and results in significant heat losses in the cryostat and cooling system. Also, significant voltage drops occur across normal-conducting circuit components, necessitating a much higher power supply than would be required to energize the superconducting coils individually.

[0007] One approach to eliminating harmful metallic current leads from magnet systems is to wirelessly inject DC current into the closed-circuit HTS coil. This can be achieved by rectifying the AC current induced in the HTS secondary winding of a current transformer. Such an "induced DC current" can be achieved using a type of device known as an HTS flux pump, enabling more compact and flexible future HTS magnet systems.

[0008] Existing HTS magnetic flux pumps use cyclic actuation by high frequency electromagnetic switches, but these switches require separate independent power supplies and feedthroughs, adding complexity, and because the switches are located inside the cryostat, heat is dissipated in the cold environment, which negatively impacts efficiency.

[0009] Flux pumps using low-temperature superconductors (LTS) are known, including rectified flux pumps. However, there are significant differences between HTS and LTS, which may make HTS unsuitable for systems designed for LTS. For example, LTS materials typically have low critical magnetic fields (magnitudes <1T), while HTS have upper critical magnetic fields with magnitudes of tens of Tesla. Some existing flux pumps rely on transitions from the superconducting state by applying temperature or magnetic fields. For most applications, it is practically impossible to apply the magnetic field strengths or fast enough heat pulses required to transition HTS from the superconducting state.

[0010] Thus, there is a particular need for improved rectifiers and / or rectifier components, e.g., rectifiers including switches, adapted for use with HTS (e.g., magnetic flux pumps), particularly to reduce losses, provide greater efficiency compared to existing rectifiers, and / or provide other advantages. Summary of the Invention [Problem to be solved by the invention]

[0011] Object of the invention It is an object of the present technology to meet any one or more of the above advantages / needs by providing an electrical switch including at least one component formed of a superconducting material and / or by providing a rectifier including an electrical switch including at least one component formed of a superconducting material. Alternatively, it is an object of the present technology to provide the public with at least one useful choice. [Means for solving the problem]

[0012] According to one aspect of the invention, an electrical switch is provided that includes a superconducting material segment. In some forms, the electrical switch is configured to be controlled between a low resistance superconducting state and a high resistance superconducting state by selectively applying a magnetic field to the superconducting material segment, such that in the high resistance state, a current flowing through the superconducting material segment is close to, substantially equal to, or greater than a critical current of the superconducting material segment. In some forms, the superconducting material segment is a high temperature superconducting material segment.

[0013] According to another aspect of the present technology, a rectifier configured to rectify an AC input current is provided. The rectifier includes an electrical switch including a high temperature superconducting (HTS) material segment configured to pass an AC switch current, the HTS material segment having a critical current. The rectifier may further include a magnetic field generator configured and arranged to apply a magnetic field to the HTS material. The rectifier may further include a control mechanism for controlling the magnetic field generator to switch the electrical switch between a low resistance state when the magnitude of the magnetic field is relatively small and a high resistance state when the magnitude of the magnetic field is relatively large, the relatively large magnitude being sufficient to reduce the critical current of the HTS material segment such that the AC switch current is close to, substantially equal to, or greater than the critical current for a portion of a cycle of the AC switch current. The electrical switch may be configured to rectify the AC input current to generate a DC output.

[0014] In some examples, a) The electrical switch may be configured to half-wave rectify an AC input current, and a DC output is delivered to a load connected in parallel across the electrical switch. b) The control mechanism may be configured to control the magnetic field generator such that the magnitude of the magnetic field is based on the phase of the alternating input current. c) The control mechanism may supply an AC generator current to the magnetic field generator such that the magnitude of the magnetic field varies in phase with the phase of the AC switch current. d) the rectifier may include a current control mechanism that controls the AC switch current such that, when the AC switch current flows in a first direction, a first peak current of the AC switch current is close to, substantially equal to, or greater than a critical current of the HTS material segment when the magnitude of the magnetic field applied by the magnetic field generator is relatively large, and, when the AC switch current flows in a second direction opposite to the first direction, a second peak current of the AC switch current is less than the critical current of the HTS material segment when the magnitude of the magnetic field applied by the magnetic field generator is relatively small. e) The magnetic field generator may include a magnetic core forming a gap, the magnetic field generator may include a conductor wound around a portion of the magnetic core in a coil that carries an AC generator current, and the HTS material segment is located in the gap. f) The AC input current may be supplied directly to the conductors as an AC generator current, and the AC switch current is based on the AC input current. g) The rectifier may include a transformer including a primary side and a secondary side, the primary side receiving the AC input current and the secondary side connected to an electrical switch. h) The conductor may be connected to the primary side of a transformer. i) The conductor may be connected to the secondary side of a transformer. j) The transformer may include a magnetic core that defines a gap. k) The control mechanism may include a current flow control device configured to control an AC generator current through the magnetic field generator. l) The current flow control device may include a diode connected in parallel across the magnetic field generator such that the magnetic field generator is activated when the AC generator current flows in a first direction and the magnetic field generator is deactivated when the AC generator current flows in a second direction opposite to the first direction. m) The current flow control device may include a generator control switch connected in parallel across the magnetic field generator such that the magnetic field generator is activated when the generator control switch is open and is deactivated when the generator control switch is closed, and the control mechanism includes a controller configured to control the opening and closing of the generator control switch. n) The rectifier may further include at least one additional electrical switch configured to conduct an additional AC switch current and including an additional high temperature superconducting (HTS) material segment having a critical current. o) The rectifier may further include, for each of the at least one additional electrical switch, an additional magnetic field generator constructed and arranged to apply an additional magnetic field to the additional HTS material segment. p) the control mechanism is configured to control the additional magnetic field generator to switch each additional electrical switch between a low resistance state when the magnitude of the additional magnetic field is relatively small and a high resistance state when the magnitude of the additional magnetic field is relatively large, the relatively large magnitude being sufficient to reduce the critical current of the additional HTS material segment such that the alternating switch current is close to, substantially equal to, or greater than the critical current for a portion of a cycle of the alternating switch current. q) At least one additional electrical switch may be configured to operate with the electrical switch to rectify the AC input current to generate a DC output. r) The control mechanism may be configured to activate and deactivate each magnetic field generator and to switch each electrical switch between a low resistance state when each magnetic field generator is deactivated and a high resistance state when each magnetic field generator is activated. s) The additional magnetic field generator may include a second magnetic field generator and the control mechanism may be configured such that the magnetic field generator is activated when the second magnetic field generator is deactivated and that the magnetic field generator is deactivated when the second magnetic field generator is activated. t) the at least one additional electrical switch may include a second electrical switch, the electrical switch and the second electrical switch may be connected in series, and the DC output is delivered to a load connected in parallel across one of the switches. u) The at least one additional electrical switch may include a second electrical switch, and the electrical switch and the second electrical switch may be configured to full-wave rectify the AC input current. v) The electrical switch and the second electrical switch may be connected in series, and the DC output is delivered to a load connected in parallel between the two electrical switches. w) the at least one additional electrical switch may include a second, a third, and a fourth electrical switch, a first pair of electrical switches may include an electrical switch connected in series to the second electrical switch, a second pair of electrical switches may include a third electrical switch connected in series to the fourth electrical switch, the first pair of electrical switches may be connected in parallel to the second pair of electrical switches, and the DC output may be delivered to a load connected between the first terminal and the second terminal, the first terminal may be between the first electrical switch and the second electrical switch, and the second terminal may be between the third electrical switch and the fourth electrical switch. x) The core may include a first core portion and a second core portion, the first core portion and the second core portion separated by a thermal break. y) The transformer may include a core including a first core portion and a second core portion, the primary side may include the first core portion, the secondary side may include the second core portion, and the first core portion and the second core portion may be separated by the thermal break. z) The first core may be located outside the cryostat and the second core may be located inside the cryostat.

[0015] aa) The magnetic field generator may include a thermal break between the magnetic core and the conductor. bb) The transformer may include a magnetic core and a thermal break between the magnetic core and one or more conductors forming the primary and / or secondary. cc) the thermal break may comprise an insulating material.

[0016] According to another aspect of the invention, an electrical switch is provided that includes a superconducting material segment configured to carry a transport current and having a critical current. The electrical switch may further include a magnetic field generator configured and arranged to apply a magnetic field to the superconducting material segment. The superconducting material segment may be in a bifilar arrangement. The magnetic field generator may include a high permeability magnetic core. The magnetic field generator may be configured to be selectively controlled to switch the electrical switch between a low resistance state, where the magnitude of the magnetic field is relatively small, and a high resistance state, where the magnitude of the magnetic field is relatively large. In the low resistance state, the transport current may be significantly less than the critical current. In the high resistance state, the transport current may be close to, substantially equal to, or greater than the critical current.

[0017] According to another aspect of the invention, an electrical switch is provided that includes a first strand and a second strand of superconducting material, each configured to carry a transport current and having a critical current. The electrical switch may further include a magnetic field generator configured and arranged to apply a magnetic field to the first strand and the second strand of superconducting material. The magnetic field generator may include a high permeability magnetic core. The magnetic field generator may be configured to be selectively controlled to switch the electrical switch between a low resistance state, where the magnitude of the magnetic field is relatively small, and a high resistance state, where the magnitude of the magnetic field is relatively large. In the low resistance state, the transport current may be significantly less than the critical current. In the high resistance state, the transport current may be close to, substantially equal to, or greater than the critical current. The first and second superconducting material strands may be spatially arranged substantially parallel to one another within the region of the magnetic field and may be electrically connected such that a transport current flows in opposite directions through the first and second superconducting material strands within the region of the magnetic field.

[0018] In some examples, a) A high permeability magnetic core may include a first end and a second end separated by a gap, with a first strand of superconducting material and a second strand of superconducting material disposed within the gap. b) The first strand of superconducting material and the second strand of superconducting material may each be in the form of a tape having two opposing surfaces. c) The tape may be arranged such that opposing faces of the first strand of superconducting material are parallel to opposing faces of the second strand of superconducting material. d) The tape may be oriented such that a magnetic field applied to the first strand of superconducting material and the second strand of superconducting material is substantially perpendicular to each of said two opposing faces. e) The electrical switch may include a superconducting material segment including a first strand of superconducting material and a second strand of superconducting material, or the first strand of superconducting material and the second strand of superconducting material may be electrically connected by connecting one side of the first strand to one side of the second strand. f) The superconducting material is a high temperature superconducting (HTS) material.

[0019] According to another aspect of the invention, an electrical switch is provided that includes a superconducting material segment configured to carry a transport current and having a critical current. The electrical switch may further include a magnetic field generator configured and arranged to apply a magnetic field to the superconducting material segment. The magnetic field generator may include a high permeability magnetic core. The magnetic field generator may be configured to be selectively controlled to switch the electrical switch between a low resistance state, where the magnitude of the magnetic field is relatively small, and a high resistance state, where the magnitude of the magnetic field is relatively large. In the low resistance state, the transport current may be significantly less than the critical current. In the high resistance state, the transport current may be close to, substantially equal to, or greater than the critical current. The superconducting material segment may be arranged to substantially cancel a self-magnetic field generated by the transport current flowing through the superconducting material segment as it approaches the high permeability magnetic core.

[0020] According to another aspect of the present technology, there is provided a rectifier according to any one of the aspects of the present technology, wherein the electrical switch is an electrical switch according to any one of the aspects of the present technology. In another aspect of the present invention, there is provided a use of an electrical switch according to any one of the aspects of the present technology in a rectifier according to any one of the aspects of the present technology.

[0021] Further aspects of the technology, which should be considered in all novel aspects, will become apparent to those skilled in the art upon reading the following description, which provides at least one example of practical application of the technology. One or more embodiments of the present technology will now be described, by way of example only and not by way of limitation, with reference to the following drawings. [Brief description of the drawings]

[0022] [Figure 1] 1 shows an exemplary electric field versus current graph for a high temperature superconductor. [Diagram 2] 1 is a graph of electric field versus current in a superconducting material when three external magnetic fields of different magnitudes are applied. [Diagram 3] FIG. 1 is a schematic diagram of a rectifier in accordance with one form of the present technology. [Figure 4] FIG. 4 is a perspective view of the rectifier shown in FIG. [Figure 4A] FIG. 5 is a diagram of three graphs showing parameters for the rectifier geometry shown in FIGS. 3 and 4. [Diagram 5] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 6] FIG. 6 is a perspective view of the rectifier shown in FIG. 5. [Figure 7] FIG. 7 is a diagram showing the magnitude of parameters that change over time during use of the rectifier shown in FIGS. 5 and 6. [Figure 8] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 9] FIG. 9 is a perspective view of the rectifier shown in FIG. 8. [Figure 10] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 11] FIG. 11 is a perspective view of the rectifier shown in FIG. [Figure 12] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 13] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 14] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 15] FIG. 15 shows the magnitude of a parameter that changes over time during use of the rectifier shown in FIG. 14. [Figure 16] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 17] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 18] FIG. 18 is a diagram showing the magnitude of parameters that change over time during use of the rectifier shown in FIG. 17. [Figure 19] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 20] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 21] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 22] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Diagram 23] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 24] FIG. 24 is a perspective view of the rectifier shown in FIG. 23. [Diagram 25] 25 shows parameter measurements over time during use of the rectifier shown in FIGS. 23 and 24. [Figure 26] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Figure 27] FIG. 27 is a perspective view of the rectifier shown in FIG. 26. [Figure 28] FIG. 28 shows the magnitude of parameters that change over time during use of the rectifier shown in FIGS. 26 and 27. [Figure 29] FIG. 13 is a schematic diagram of a rectifier in accordance with another aspect of the present technique. [Diagram 30] FIG. 30 is a perspective view of the rectifier shown in FIG. 29. [Diagram 31]FIG. 31 shows the magnitude of parameters that change over time during use of the rectifier shown in FIGS. 29 and 30. [Diagram 32] FIG. 1 is a schematic diagram of a transformer in accordance with one form of the present technology. [Diagram 33] FIG. 13 is a schematic diagram of a transformer in accordance with another aspect of the present technique. [Diagram 34] 1 is a perspective view of a rectifier in accordance with another aspect of the present technology; FIG. [Diagram 35] 1 is a perspective view of a rectifier in accordance with another aspect of the present technology; FIG. [Figure 36A] FIG. 1 is a schematic diagram of an electrical switch in accordance with one form of the present technology; [Figure 36B] 1 is a schematic diagram of an electrical switch in accordance with another aspect of the present technology; [Figure 37] 1 illustrates the relationship between critical current of superconducting material segments in an electrical switch in accordance with aspects of the present technology for different applied fields and when the superconducting material segments are in a bifilar and unifilar arrangement; [Figure 38A] 1 illustrates a magnetic field profile of an electrical switch in accordance with an embodiment of the present technology. [Figure 38B] 4 shows the magnetic field profile of an electrical switch according to another form of technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 6.1. Considerations regarding superconductors To aid in understanding the current technology, the reader should become familiar with superconducting terminology such as the critical temperature of a superconductor and the critical current of a superconductor. However, for the reader's benefit, a brief explanation of these concepts is provided below.

[0024] The critical temperature of a superconductor is conventionally defined as the temperature at which the resistivity of the superconductor drops to zero or nearly zero. In other words, a superconductor is said to be in a superconducting state when the temperature of the superconductor is below the critical temperature, and in a non-superconducting state when the temperature is above the critical temperature. Many superconductors have critical temperatures close to absolute zero. For example, the critical temperature of mercury is known to be 4.1 K. However, some materials are also known to have much higher critical temperatures, such as from 30 K to 125 K. For example, the critical temperature of magnesium diboride is about 39 K, while the critical temperature of yttrium barium copper oxide (YBCO) is about 92 K. These superconductors are commonly referred to as high-temperature superconductors.

[0025] The critical current of a high temperature superconducting wire or tape is conventionally defined as the current in the superconducting wire / tape that causes an electric field drop of 100 μV / m (=1 μV / cm) along the wire. It should be understood that the critical current is a function of both the superconducting material used and the physical arrangement of the superconducting material. For example, a wide tape / wire may have a higher critical current than a thin tape / wire composed of the same material. However, it should be understood that throughout this specification, references to the critical current of the superconductor / superconducting material are for ease of discussion.

[0026] In superconductors / superconducting materials, the current I is equal to the critical current I 臨界 When I is approximately equal to the critical current I, the resistance of the superconductor is not zero but is small. 臨界 If the critical temperature is much greater than 0.05, the resistance of the superconductor becomes large enough that heat dissipation occurs and the superconductor may heat up above its critical temperature, causing it to cease to be superconducting (this condition is sometimes called a "quench") and may cause damage to the superconductor itself. An exemplary plot showing the internal electric field versus current curve for a high temperature superconductor is shown in Figure 1. It should be understood that the electric field shown in this plot is related to the resistance by the following equation:

[0027]

number

[0028] Thus, the plot in FIG. 1 relates the resistance per unit length of the superconductor, and because the curve shown is nonlinear, the resulting resistance of the superconductor is nonlinear with respect to current.

[0029] From this figure, the critical current I 臨界 Below we can see that the electric field strength inside the superconductor is practically zero. As the current in the superconductor approaches the critical current, the electric field in the superconductor begins to increase. At the critical current, the electric field in the superconductor is 100 μV / m. If the current in the superconductor is increased further beyond the critical current, the electric field strength in the conductor increases rapidly.

[0030] Throughout this specification, reference is made to the relative resistance of superconducting materials and components that include superconducting materials. More specifically, this specification refers to superconducting materials in a low resistance state or a high resistance state. It should be understood that, since superconducting materials can have zero or substantially zero resistance when in a superconducting state, these resistances are typically represented by the electric field that exists across the superconducting material for a given current. However, throughout this specification, to simplify the foregoing discussion, reference is made to relative resistances such as low and high resistance states of the superconducting material.

[0031] The term "low resistance state" may refer to when a superconducting material has near-zero or substantially zero resistance in a superconducting state, or when the material has low resistance in a partially superconducting state. The term "high resistance state" refers to a state in which a superconducting material has a resistance substantially greater than the low resistance state, e.g., a resistance that is substantially non-zero, or a resistance that is close to zero but substantially greater than the low resistance state. For the avoidance of doubt, unless the context clearly indicates otherwise, the high resistance state referred to herein may include the superconducting state.

[0032] Similarly, where this specification describes a superconductor as being in a high resistance state as a result of the current flowing through it exceeding a critical current, it should be understood that the high resistance state may also be achieved when the current flowing through the superconductor is close to or substantially equal to the critical current, unless expressly indicated otherwise in the context.

[0033] In describing the technology described herein, materials and components that include the materials are referred to as "superconducting." This term is used generally in the art for such materials and is not to be taken to imply that the materials involved are always in a superconducting state. Under certain conditions, materials and components that include the materials may not be in a superconducting state; that is, a material may be described as being superconducting, but is not superconducting.

[0034] 6.2.Superconducting materials Particular forms of the technology may include various types of superconducting materials. For example, forms of the technology may include high temperature superconducting (HTS) materials. Examples of HTS materials suitable for use with forms of the described technology include copper oxide superconductors, e.g., yttrium barium copper oxide, gadolinium barium copper oxide, or rare earth barium copper oxide (ReBCO) superconductors such as bismuth strontium calcium copper oxide (BSCCO), and iron-based superconductors. BSCCO superconductors typically have a strong interdependence between the critical current and the applied magnetic field, and therefore may be particularly suitable for some forms of the current technology. Other types of superconductors may be used for other forms of the technology.

[0035] Although aspects of the technology are described with reference to high temperature superconductors, it should be understood that other aspects of the technology may instead use other types of superconductors, for example low temperature superconductors. In certain configurations, the superconducting material may be provided in the form of a tape.

[0036] 6.3.Effect of magnetic field on superconductors The critical current in a superconductor depends on the external magnetic field applied to the superconductor. More specifically, when a higher external magnetic field is applied to the superconductor, the critical current drops to the critical magnetic field value, beyond which the superconductor is no longer in a superconducting (low resistance) state. This relationship is illustrated in Figure 2, which shows a graph of the electric field versus current in a superconducting material when three external magnetic fields of different magnitudes are applied. The maximum magnitude of the external magnetic field B 印加1 is the minimum critical voltage I 臨界1 It becomes.

[0037] 6.4. Electrical Switches A form of the present technology relates to an electrical switch that utilizes the principle that the critical current of a superconducting material decreases when a large external magnetic field is applied to the material. Figures 3 and 4 show an exemplary electrical switch 210. Below, the form of the technology shown in these figures is described in more detail, but for purposes of the present invention, switch 210 will be described.

[0038] The electrical switch 210 includes a high temperature superconducting (HTS) material segment, such as any of the types of HTS materials described above. High temperature superconducting materials have a critical current I 臨界 , and the critical temperature T 臨界 The HTS material has a critical temperature T 臨界 The substrate 700 is disposed within a cryostat 710 (not shown) configured to maintain a temperature below 100° C.

[0039] As shown in Figure 2, the external magnetic field B 印加 When a magnetic field B is applied to the HTS material segment, the critical current decreases. 印加 The HTS material segment can be made to function as a switch by applying a magnetic field B 印加 When the magnitude of the magnetic field B has a particular value, the HTS material goes into a low resistance state when the HTS material passes through a switch current (i.e., a current flowing through the electrical switch 210) that is less than the critical current. 印加 When the magnitude of increases from this value to a relatively large magnitude sufficient to cause the critical current to fall to a value approaching or below the magnitude of the current carried by the HTS material, the HTS material is in a highly resistive state. The low resistance state of the HTS material can be considered to be equivalent to a closed state of switch 210, and the high resistance state can be considered to be equivalent to an open state of switch 210. However, it should be understood that the high resistance state does not represent an electrical open circuit typical of mechanical switches, but rather a highly resistive conductive state. In this highly resistive conductive state, the HTS material remains in a superconducting state, but may have a higher level of resistance or may be rendered non-superconducting.

[0040] The magnetic field B between the low and high resistance states of the switch 印加 The difference in magnitude between the magnetic field B and the magnetic field B may vary in magnitude, including a continuously varying magnitude, and including varying between two magnitudes. 印加 The magnitude of may be zero or non-zero.

[0041] Magnetic field B applied to the HTS material 印加It should be understood that the magnitude of either must be less than the magnitude of the critical field, where the critical field is the magnitude of the external magnetic field that must be applied to the HTS material to transition it to a highly resistive state.

[0042] The energy loss in a superconducting electric switch is roughly proportional to the critical current during switching. Because the electric switch 210 operates by reducing the value of the critical current during switching, the electric switch 210 (and devices including the electric switch 210) has lower losses and therefore is more efficient than conventional superconducting electric switches.

[0043] 6.5. Rectifier Certain forms of the present technology use an electrical switch 210, and in certain forms, multiple electrical switches 210 in the form of a switching assembly 200, to rectify the AC input current. Different forms of the present technology may utilize one or more electrical switches 210 in any configuration to produce the rectifying effect. In the following description, examples of suitable configurations of electrical switches are described, but it should be understood that other configurations may be used in other forms of the present technology.

[0044] A rectifier 100 according to embodiments of the present technology includes a switching assembly 200, a magnetic field generator assembly 300, a control mechanism 400, and a current supply assembly 500. These functional parts are described in more detail below, with an exemplary embodiment of each functional part being described. Also, several specific examples of rectifiers 100 that are combinations of the exemplary embodiments of each functional part are described. It should be understood that other combinations of the exemplary embodiments of each functional part are also provided in some embodiments of the present technology, and the present technology is not limited to the specific examples shown and / or described.

[0045] In a particular form, the current supply assembly 500 is configured to supply an alternating current to the switching assembly 200. The switching assembly 200 includes an array of one or more electrical switches 210 and is configured to rectify the alternating current to generate a direct current output. The direct current output may be transmitted to a load 600. The magnetic field generator assembly 300 includes one or more magnetic field generators 310, each configured to apply a magnetic field to one or more electrical switches 210. The control mechanism 400 controls the magnetic field generator assembly 300 to switch the electrical switches 210 of the switching assembly 200.

[0046] Any portion of the rectifier 100 that contains superconducting materials may be heated to a critical temperature T 臨界 The semiconductor laser 700 is housed within one or more cryostats 710 configured to maintain the semiconductor laser 700 at a temperature below 1000 .mu.m.

[0047] 6.6. Switching Assembly In a particular form of the present technology, the switching assembly 200 includes an arrangement of one or more electrical switches 210 and is configured to rectify AC to produce a DC output. As will be explained through examples below, the arrangement of the electrical switches 210 within the switching assembly 200 determines the type of rectification performed by the rectifier 100.

[0048] In certain forms of the present technology, the rectifier 100 is a half-wave rectifier. A half-wave rectifier allows current to flow in one direction but blocks current to flow in the other direction. In some forms of half-wave rectifiers, the switching assembly includes a single electrical switch 210. In other forms of half-wave rectifiers, the switching assembly includes two electrical switches 210.

[0049] 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, and 19 show example configurations of a switching assembly 200 for a half-wave rectifier 100 that includes a single switch 210. In these configurations, a load 600 is connected in parallel across the electrical switch 210. When the switch 210 is in the "closed" configuration, no voltage is applied across the load 600 and the load current i 負荷 is transferred to the load 600. When the switch 210 is in the “open” configuration, a voltage V 出力 The load current i 負荷 is transferred to the load 600. When the switch 210 is opened, the load current i 負荷 Whether increases or decreases depends on the switch current i スイッチi The voltage V is determined by the direction of the AC input current i1, which is determined by the timing at which the switch 210 opens relative to the phase of the AC input current i1. In some forms, the control mechanism 400 can control the opening and closing of the switch 210 to open the switch 210 when the AC input current i1 flows in one direction and close the switch 210 when the AC input current i1 flows in the opposite direction, i.e., to time the state of each switch 210 based on the phase of the AC input current i1. In this manner, the voltage V 出力 may be generated in only one direction (or polarity) across the load 600, thereby providing a half-wave rectifier. In other forms, the control mechanism 400 may be controlled to open and close the switch 210 at different times in the current cycle. The control mechanism 400 may generate a voltage V across the load 600 in only one direction (or polarity), thereby providing a half-wave rectifier. 出力 is the load current i 負荷 The load current i 負荷 The switch 210 is operable to open and close the switch 210 at selected times in the phase of the AC input current i1 so as to vary the load current i of the load 600 in a desired manner, including increasing and decreasing the load current i 負荷 The gradual change in the amount of energy can be expressed as "pumping."

[0050] Exemplary configurations of a switching assembly 200 for a half-wave rectifier 100 including two switches 210a, 210b are shown in Figs. 14, 20 and 23. In these configurations, the two switches 210a, 210b are connected in series, and a load 600 is connected in parallel across one switch 210. An alternating current i2 is provided to the switching assembly 200. The switching assembly 200 is controlled by a control mechanism 400 configured to control the state of each switch 210 to rectify the alternating current i2. For example, the control mechanism 400 controls each switch 210 such that the state of each switch 210 is based on the flow direction of the alternating current i2. In this configuration, the control mechanism 400 controls the state of each switch 210 in a timed manner based on the phase of the alternating current i2, since the flow direction of the alternating current i2 depends on the phase of the current. For example, when the alternating current i2 flows in a first direction (i.e., current flow is positive), the first switch 210a is placed in its low resistance state and the second switch 210b is placed in its high resistance state. This creates a low resistance path around the outside of the loop through the switch 210a and through the load 600. The control mechanism 400 may transition the switch 210a to a high resistance state and the switch 210b to a low resistance state if the polarity of the current changes (e.g., from positive to negative). The high resistance state of 210a prevents current from the transformer and provides a means to block negative polarity current flow. Meanwhile, the low resistance state of 210b provides a path for the current in the load to continue to flow, albeit exponentially decaying with a time constant L / R (meaning that if the load is superconducting, the load current remains constant). This allows the current flowing through the load 600 to be half-wave rectified. Similarly, the control mechanism 400 may open and close the switches 210a, 210b at the appropriate times to increase or decrease the current in the load 600 as required.

[0051] In some forms of the present technology, the control mechanism 400 may control both switches 210a, 210b to be in a low resistance state simultaneously for a period of the AC cycle. That is, switch 210b may be in a high resistance state only part of the time that i2 is positive, switch 210a may be in a high resistance state only part of the time that i2 is negative, and the rest of the time, both may be in a low resistance state regardless of whether i2 is positive or negative. This may be used as a practical control strategy to ensure that the switches are in an open configuration (i.e., a high resistance state) when the current through them is in a desired direction. The control mechanism 400 may control the switches of the rectifier of any form of technology described herein in this manner, even if not explicitly stated.

[0052] Exemplary configurations of a switching assembly 200 for a full-wave rectifier 100 including two switches 210a, 210b are shown in Figs. 17, 22 and 26. The two switches 210a, 210b are connected in series, and a load 600 is connected in parallel between the two switches 210a, 210b. An alternating current is supplied to the switching assembly 200. The switching assembly 200 is controlled by a control mechanism 400 configured to control the state of each switch 210 to rectify the alternating current. For example, the control mechanism 400 may control each switch 210 such that the state of each switch 210 is based on the direction of the flow of the alternating current. In this configuration, the control mechanism 400 controls the state of each switch 210 in a timed manner based on the phase of the alternating current, since the direction of the flow of the alternating current depends on the phase of the current. When the current is flowing in a first direction (e.g., when the current is positive), the first switch 210a is in a low resistance state and the second switch 210b is in a high resistance state. This creates a low impedance path around the upper half of the circuit through switch 210a, causing current to flow in a first direction through load 600. When AC is flowing in a second direction (e.g., when the current is negative), first switch 210a is placed in a high resistance state and second switch 210b is placed in a low resistance state. This creates a low impedance path around the lower half of the circuit through switch 210b, causing current to flow in a first direction through load 600. Controlling the opening and closing of the switches in this manner ensures that current always flows in one direction through the load, from the positive terminal to the negative terminal, regardless of the direction of the AC. This causes the voltage V 出力 may be generated in only one direction (or polarity) across the load 600, and the AC is full-wave rectified to DC through the load 600. Similar to the previous example of a half-wave rectifier, the control mechanism 400 may control the timing of the opening and closing of the switch 210 so that the voltage across the load is generated in the desired polarity, and the current through the load 600 increases or decreases accordingly.

[0053] An exemplary embodiment of a switching assembly 200 of a full-wave rectifier 100 including four switches 210a, 210b, 210c, and 210d is shown in Figs. 16, 21, 29, and 30. Two switches 210a, 210b form a first pair of switches and are connected in series with each other. The other two switches 210c, 210d form a second pair of switches and are connected in series with each other. The two pairs of switches are connected in parallel with each other, and each switch is connected in parallel to an AC source. A load 600 is connected from a terminal between the switches 210a, 210b of the first pair of switches to a terminal between the switches 210c, 210d of the second pair of switches. The switching assembly 200 is controlled by a control mechanism 400 configured to control the state of each switch 210 to rectify the AC. For example, the control mechanism 400 may control each switch 210 such that the state of each switch 210 is based on the flow direction of the AC. In this embodiment, the direction of AC flow depends on the phase of the current, so the control mechanism 400 controls the state of each switch 210 in a timed manner based on the phase of the AC. When current is flowing in a first direction (e.g., when the current is positive), the first and fourth switches 210a, 210d are placed in a low resistance state and the second and third switches 210b, 210c are placed in a high resistance state. This creates a low impedance path through the first and fourth switches 210a, 210d, causing current to flow in the first direction through the load 600. When AC is flowing in a second direction (e.g., when the current is negative), the first and fourth switches 210a, 210d are placed in a high resistance state and the second and third switches 210b, 210c are placed in a third low resistance state. This creates a low impedance path through the second and third switches 210b, 210c, causing current to flow in the first direction through the load 600. By controlling the opening and closing of the switch in this way, current always flows through the load in one direction, from the positive terminal to the negative terminal, regardless of the direction of the alternating current. This causes the voltage V 出力may only generate power in one direction (or polarity) across the load 600, and the AC is full-wave rectified to DC through the load 600. Similar to the previous example of a half-wave rectifier, the control mechanism 400 can control the timing of the opening and closing of the switch 210 so that the voltage across the load is generated in the desired polarity, and the current through the load 600 increases or decreases accordingly. Although a particular example arrangement of the switches 210 in the switching assembly 200 has been described, it should be understood that other switching assemblies 200 of other forms of the present technology have other arrangements of the switches 210 for rectifying the alternating current. Other forms of the present technology may have other numbers of switches 210.

[0054] 6.7. Magnetic Field Generator Assembly In a particular form of the present technology, the magnetic field generator assembly 300 includes one or more magnetic field generators 310, each configured to apply a magnetic field to one or more electrical switches 210 of the switching assembly 200.

[0055] Exemplary forms of magnetic field generator assemblies 300 are shown in Figures 3-6, 8-14, 16, 17, 19-24, 26, 27, 29, 30, 34, and 35. In these forms, the magnetic generator assemblies 300 include one or more magnetic field generators 310. Each magnetic field generator 310 may include a magnetic core 320. The core 320 may be a high permeability magnetic core, such as a ferrite core (e.g., iron core) or a laminated steel / ferromagnetic core. In other forms, other types of high relative permeability at the operating frequency may be used, or a non-magnetic core or an air core may be used. An air core may advantageously reduce the size, weight, and cost of the electrical switch 210 and may provide the ability to drive larger currents without saturating the core. In the illustrated forms, the magnetic core 320 is a substantially ring-shaped solid core, such as a square ring with rounded corners.

[0056] In the exemplary embodiment, the magnetic core 320 forms a gap 330. The gap 330 may be a space within the solid magnetic core 320, such as the space on one side of a square link core. Any portion of an air core may also be considered a gap 330.

[0057] In an exemplary form, the conductor is wound around a portion of the magnetic core 320 within the coil 340. For example, the coil 340 formed of the conductor may be wound around a side of a square ring core, e.g., the side opposite the side where the gap 330 is formed. In an air core, the coil 340 defines a volume of space therein, which volume of space is considered to be air core and to include the gap 330. In use, the conductor may carry a generator current. The flow of the generator current through the coil 340 generates a magnetic field within the core 320 and across the gap 330. In a particular form of the present technology, the HTS material segment including the electrical switch 210 is configured to generate a magnetic field across the gap 330 in response to an external magnetic field B applied to the switch 210. 印加 3B. The slits 314 are disposed in the gap 330 such that:

[0058] In certain configurations, the generator current carried by the conductors may be supplied by a current source, e.g., an AC source, such that the generator current is an AC generator current. As will be described in more detail below, in certain configurations, the AC source supplying the current to the conductors may be an AC source that is the same as the AC input current received by the current supply assembly 500 of the rectifier 100, or that varies in magnitude in phase with the AC input current and / or the AC switch current flowing through the switch 210 disposed in the gap 330. In other configurations, the current source supplying the generator current to the conductors of the magnetic field generator 310 may be a separate current source 350. In these configurations, the current source 350 may be a DC source.

[0059] The magnitude of the magnetic field generated by the magnetic field generator 310 may vary continuously. Alternatively, the magnitude of the magnetic field generated by the magnetic field generator 310 may vary between two constant values. In certain configurations, one of the constant values ​​may be zero.

[0060] In a particular embodiment, the magnetic field generator 310 generates a magnetic field B 印加 30, magnetic field generator 310a may be configured to apply a magnetic field to electrical switches 210a, 210d, and magnetic field generator 310b may be configured to apply a magnetic field to electrical switches 210b, 210c. Each magnetic field generator 310a, 310b may include a single magnetic core 320 and one or more gaps 330 in which the HTS material of each electrical switch is disposed. Alternatively, as in the example shown in FIG. 30, each magnetic field generator 310a, 310b may include multiple component magnetic field generators each including a magnetic core 320 and having conductors wound therearound to form coils 340, and the coils 340 of each component magnetic field generator are electrically connected to simultaneously excite the component magnetic field generators.

[0061] Although a particular exemplary arrangement of magnetic field generators 310 in magnetic field generator assembly 300 has been described, it should be understood that other magnetic field generators 310 in other forms of the present technology may take other forms.

[0062] 6.8.Control Mechanism A rectifier 100 in accordance with a particular form of the present technology includes a control mechanism 400 configured to control a magnetic field generator assembly 300 to switch an electrical switch 210 of a switching assembly 200 .

[0063] In a particular form of the present technology, the control mechanism 400 is configured to control the magnetic field generators 310 of the magnetic field generator assembly 300 such that the magnitude of the magnetic field generated by each magnetic field generator 310 is based on the phase of the alternating input current received by the current supply assembly 500. For example, the magnitude of the magnetic field generated by each magnetic field generator 310 may vary with a phase that is a constant phase difference with respect to the phase of the alternating input current. In one example, the constant phase difference may be zero, in which case the magnetic field generated by each magnetic field generator 310 varies in phase with the alternating input current. In a particular example, the magnitude of the magnetic field generated by each magnetic field generator 310 may be a first value for a portion of each cycle of the alternating input current and a second value for another portion of each cycle of the alternating input current. Either the first value or the second value may be zero.

[0064] Additionally, in certain embodiments, the control mechanism 400 is configured to supply the magnetic field generator 310 with an alternating current (i.e., an alternating current generator current) having a phase (i.e., an alternating current switch current) based on the phase of the alternating current through the electrical switch 210 to which the magnetic field is supplied via the magnetic field generator 310. Thus, the magnitude of the magnetic field generated by the magnetic field generator 310 varies in phase with the magnitude of the alternating current switch current. For example, the magnitude of the alternating current generator current may vary in phase with a constant phase difference from the phase of the alternating current switch current. In one example, the constant phase difference may be zero, in which case the magnetic field generated by each magnetic field generator 310 varies in phase with the alternating current switch current. In certain examples, the magnitude of the magnetic field generated by each magnetic field generator 310 may be a first value for a portion of each cycle of the alternating current switch current and a second value for another portion of each cycle of the alternating current switch current. Either the first value or the second value may be zero.

[0065] In certain forms of the present technology, the AC input current may be supplied directly to the magnetic field generator 310 as an AC generator current. In examples where the magnetic field generator 310 includes a conductor wound into a coil 340, the AC input current may be supplied directly to the conductor / coil 340.

[0066] In a particular embodiment of the above technique, an AC input current or an AC based on the AC input current (including, for example, an AC split from the AC input current at a shunt, or an AC generated on the secondary side of a transformer from an AC input current on the primary side of a transformer) is provided to a magnetic field generator 310, where 1) the magnetic field generator 310 applies a magnetic field to the electrical switch 210, and 2) the electrical switch 210 passes an AC switch current based on the AC input current (also including, for example, an AC split from the AC input current at a shunt, or an AC generated on the secondary side of a transformer from an AC input current on the primary side of a transformer). In this embodiment of such technique, an external magnetic field B applied to the electrical switch 210 p may be considered to include one or more "auto-synchronizing" electrical switches 210 because the timing of the change in magnitude of is automatically synchronized to the phase of the AC input current by the relationship between the currents. In these forms, the control mechanism 400 may be considered to be the electrical components and / or connections that facilitate a predetermined relationship between the AC input current and the AC generator and AC switch currents.

[0067] In a particular embodiment, an external magnetic field B applied to the electrical switch 210 p may be automatically synchronized with the phase of the AC input current in the manner described, and the magnetic field generator 310 generates the external magnetic field B p may include a generator portion configured to generate other portions of by other means. A specific example of an automatic synchronizing electrical switch 210 provided within a rectifier 100 in accordance with aspects of the present technique will now be described.

[0068] In the form of rectifier 100 shown in Figures 3 and 4, magnetic field generator 310 receives an AC input current i1 from AC source 900. Magnetic field generator 310 generates a magnetic field B p4, the magnetic field generator includes a coil 340 wound around a magnetic core 320 through which an alternating input current i1 flows. The coil 340 is configured as part of the electrical switch 210 and is electrically connected to an HTS material segment disposed within the gap 330 of the magnetic core 320. Thus, as the alternating input current i1 changes, the applied magnetic field B p changes and the two are synchronized.

[0069] In the form of rectifier 100 shown in FIGS. 5, 6, 12, and 19, an AC source 900 provides an AC input current i1 to a magnetic field generator 310, which generates a magnetic field B p 6, the magnetic field generator includes a coil 340 wound around a magnetic core 320, with an alternating current input current i1 flowing through the coil 340. The coil 340 is electrically connected to a primary coil 520 on the primary side of a transformer 510. The transformer 510 generates an alternating current i2 in a secondary coil 530 on the secondary side of the transformer 510. The secondary coil 530 is configured as part of the electrical switch 210 and is electrically connected to an HTS material segment disposed within a gap 330 in the magnetic core 320. The alternating current i2 in the secondary coil 530 is synchronous with the alternating current input current i1 in the primary coil 520, such that a change in the alternating current input current i1 changes the applied magnetic field B. p This leads to a change in the two, and they become synchronized.

[0070] In the configuration of the rectifier 100 shown in Figures 14, 16, 17, 20, 21 and 22, the magnetic field generator assembly 300 is on the primary side of the transformer 510, similar to the configurations shown in Figures 5, 6 and 19. In the configurations shown in Figures 14, 16, 17, 20, 21 and 22, the magnetic field generator assembly 300 includes multiple magnetic field generators 310, e.g., two magnetic field generators 310a, 310b, each of which generates a magnetic field B 印加1 and B. 印加2to electrical switches 210a, 210b (or, in the case of the configurations shown in FIGS. 16 and 21, electrical switches 210a, 210d and 210b, 210c), respectively.

[0071] In the form of rectifier 100 shown in Figures 8, 9 and 13, an AC source 900 provides an AC input current i1 to a primary coil 520 on the primary side of a transformer 510. The transformer 510 generates an AC current i2 in a secondary coil 530 on the secondary side of the transformer 510. The secondary coil 530 generates a magnetic field B p 9, the magnetic field generator 310 is configured to generate an alternating current i2 and apply the magnetic field to the electrical switch 210. As shown in FIG. 9, the magnetic field generator includes a coil 340 wound around a magnetic core 320 and is supplied with an alternating current i2 provided by a secondary coil 530. The coil 340 is configured as part of the electrical switch 210 and is electrically connected to an HTS material segment disposed within a gap 330 in the magnetic core 320. The alternating current i2 in the secondary coil 530 is synchronous, i.e., in phase, with the alternating current i1 in the secondary coil 520 such that a change in the alternating current i1 causes a change in the applied magnetic field B. p changes and the two are synchronized.

[0072] In the configuration of rectifier 100 shown in FIGS. 10 and 11, an AC source 900 provides an AC input current i1 to a primary coil 520 on the primary side of a transformer 510. The transformer 510 generates an AC current i2 in a secondary coil 530 on the secondary side of the transformer 510. In this configuration, the transformer 510 and the magnetic field generator 310 are constructed from the same part, i.e., the magnetic core 320 of the magnetic field generator 310 also functions as the magnetic core 540 of the transformer 510. The magnetic core 320 / 540 includes a gap 330 in which an HTS material segment, constructed as part of an electrical switch 210, is disposed, the HTS material segment being electrically connected to the secondary coil 530 of the transformer 510. The AC current i2 in the secondary coil 530 is synchronous, i.e., in phase, with the AC input current i1 in the primary coil 520, so that changes in the AC input current i1 result in a change in the applied magnetic field B. pand the two are synchronized. Rectifier 100 of this form of the present technology can be more compact than the rectifiers shown in Figures 5, 6, 8 and 9 because it uses only a single magnetic core 320 / 540.

[0073] In some forms of the present technology, the control mechanism 400 includes one or more current flow control devices configured to control the AC generator current through any one or more of the magnetic field generators 310.

[0074] In some forms of the present technology, each current flow control device includes a diode 410 connected in parallel across one of the magnetic field generators 310. In certain forms, the diode 410 may be of a diode type configured to allow current in one direction to flow through the diode 410, but block current in another opposite direction from flowing through the diode 410. Forms of rectifier 100 including this type of diode are shown in Figures 12, 13, 14, 16 and 17. In these forms, when current flows in a direction that the diode 410 allows current to flow, the magnetic field generator 310 shorts out and is consequently turned off. When current flows in a direction that the diode 410 blocks current, current flows through the magnetic field generator 310 and the magnetic field generator 310 is turned on. This is due to the magnetic field B applied by the magnetic field generator 310. 印加 This means that the electrical switch 210 controlled by the diode 410 can only be activated (i.e., in a high resistance state or open) during half of the AC cycle. One advantage of the form of rectifier 100 including the diode 410, compared to the other types of rectifiers 100 described herein, is that because the magnetic field generator 310 causes resistive losses of energy when current flows through the windings of the coil 340, the diode 410 means that substantially no resistive losses occur during the half of the cycle when the diode 410 passes current and no current flows through the magnetic field generator 310.

[0075] In the forms of the present technology shown in Figures 14, 16, and 17, the rectifier 100 includes a plurality of current flow control devices, and in these forms, each of the plurality of current flow control devices includes a diode, such that the current flow control device includes a plurality of diodes 410a, 410b. Each diode 410a, 410b is connected in parallel across each of the magnetic field generators 310a, 310b. The diodes 410a, 410b are oriented in opposite directions such that when the AC input current i1 flows in one direction, the diode 410a allows the current to flow and the diode 410b blocks the current to flow, and when the AC input current i1 flows in the other opposite direction, the diode 410a blocks the current to flow and the diode 410b allows the current to flow. As a result of this arrangement, when the AC input current i1 flows in one direction, the magnetic field generator 310b is activated but the magnetic field generator 310a is deactivated, and when the AC input current i1 flows in the opposite direction, the magnetic field generator 310a is activated and the magnetic field generator 310b is deactivated. This means that when the AC input current i1 flows in two directions, the electrical switches 310a, 310b (magnetic field generators 310a, 310b each apply a magnetic field) can be switched.

[0076] FIG. 15 illustrates a diagram of an AC input current i1, a secondary current i2, a magnetic field B generated by the magnetic field generator 310a, and a secondary current i3 generated by the magnetic field generator 310a during use of the example half-wave rectifier 100 of FIG. 14, in accordance with one form of the technology. 印加1 , the magnetic field B generated by the magnetic field generator 310b 印加2 , and an exemplary change over time in the magnitude of the output voltage across the load 600. The magnitude of the AC input current i1 may be controlled by the current supply assembly 500 (not shown) to have the illustrated waveform profile that is reflected in the magnitude profile of the secondary current i2. The diode 410a is connected to the magnetic field B generated by the magnetic field generator 310a during the positive portion of the AC input current i1 cycle. 印加1 The diode 410b activates the magnetic field B generated by the magnetic field generator 310b during the positive part of the secondary current i2 cycle and deactivates it otherwise. 印加21 and off the rest of the time. Rectifier 100 produces a voltage across load 600 during only the positive part of the AC input current i1 cycle, which has the effect of half-wave rectifying the AC input current i1.

[0077] FIG. 18 illustrates a graph of the AC input current i1, the magnetic field B generated by the magnetic field generator 310a, and the frequency response of the example full-wave rectifier 100 of FIGS. 16 and 17 in accordance with an embodiment of the present technology. 印加1 , the magnetic field B generated by the magnetic field generator 310b 印加2 5 shows an example time variation of the magnitude of the output voltage across the load 600, and the AC input current i1. The magnitude of the AC input current i1 may be controlled by the current supply assembly 500 to have the illustrated waveform profile. This profile is reflected in the magnitude of the secondary current in the secondary coil 530 (not shown). The diode 410a reduces the magnetic field B generated by the magnetic field generator 310a during the positive portion of the AC input current i1 cycle. 印加1 The diode 410b activates the magnetic field B generated by the magnetic field generator 310b during the positive part of the secondary current i2 cycle and deactivates it otherwise. 印加2 and off elsewhere. Rectifier 100 has the effect of producing a positive voltage across load 600 whenever the AC input current i1 is non-zero (negative or positive), and acting to full-wave rectify the AC input current i1.

[0078] The forms of rectifier 100 shown in Figures 14, 16 and 17 include multiple diodes 410 and multiple electrical switches 210. These rectifiers may operate with only one current source 900 and the control mechanism 400 may be driven by the AC input current i1, i.e., no external control mechanism is required. In some forms, they may be more efficient and have less cryogenic losses than the forms of rectifier 100 shown in Figures 5, 6, 8, 9, 10, 11, 12 and / or 13. Additionally, the forms of rectifier 100 shown in FIGS. 14, 16 and 17 may operate with a symmetrical AC input current i1 (i.e., may not need to control the input current to have an asymmetrical waveform profile as required for the forms of rectifier 100 shown in FIGS. 5, 6, 8, 9, 10, 11, 12 and / or 13) and may therefore generate an output voltage across load 600 for a significant portion of the cycle, resulting in increased output voltage and power compared to those other forms of rectifier. However, in some forms, rectifier 100 of FIGS. 14, 16 and 17 may be physically larger than rectifier 100 disclosed herein that includes only a single electrical switch 210, and the timing of activation / deactivation of switch 210 may be less effective compared to rectifier forms in which the control mechanism 400 that controls the timing of activation / deactivation of switch 210 is a separate part of the rectifier (i.e., non-autosynchronous forms).

[0079] In certain forms of the present technology, the control mechanism 400 includes one or more current flow control devices in the form of generator control switches 420 connected in parallel across the magnetic field generators 310. In certain forms, the generator control switches 420 may be switches in the form of transistors such as MOSFETs or IGBTs. Forms of the rectifier 100 including the generator control switches 420 are shown in Figs. 19-22. In these forms, the control mechanism 400 includes a switch control mechanism (not shown) configured to selectively open and close the generator control switches 420 to activate / deactivate the magnetic field generators 310 by respectively passing or shorting current to the magnetic field generators 310 connected in parallel to each generator control switch 420. Although such a switch control mechanism introduces additional complexity to the rectifier 100 compared to a rectifier in which the current flow control devices include one or more diodes, the switch control mechanism allows for active control of the electrical switches 210, thereby providing greater flexibility and enabling greater efficiency to be achieved in some forms of the present technology. Furthermore, only a single current source 900 may be required.

[0080] The example of the rectifier 100 shown in Figures 19 and 20 is a half-wave rectifier. The form of the rectifier 100 in Figure 19 includes a single generator control switch 420 connected in parallel to the magnetic field generator 310. The control mechanism 400 is configured to selectively open and close the switch 420 based on the phase of the AC input current i1 to perform half-wave rectification in a similar manner as described above. In the form of the half-wave rectifier 100 shown in Figure 20 and the exemplary form of the full-wave rectifier 100 shown in Figures 21 and 22, the control mechanism 400 includes a first switch 420a connected in parallel across one of the magnetic field generators 310a and a second switch 420b connected in parallel across the other of the magnetic field generators 310b. The control mechanism 400 is configured to selectively open and close the switches 420a, 420b to perform rectification based on the phase of the AC input current i1.

[0081] An exemplary form of the rectifier described above is one in which the magnetic field generator assembly 300 is energized by an AC input current or a current based on the AC input current (including, for example, AC split from the AC input current at a shunt, or AC generated on a transformer secondary from the AC input current on a transformer primary). In other forms of the present technology, the magnetic field generator assembly 300 includes one or more separate current / power sources 350. Figures 23, 24, 26, 27, 29, and 30 show exemplary such forms of the present technology.

[0082] In the exemplary form of rectifier 100 shown in FIGS. 23 and 24, a magnetic field B applied to electrical switch 210 印加1 and B. 印加2 are generated by magnetic field generators 310a, 310b, respectively, and coils 340a, 340b carry currents provided by current sources 350a, 350b, respectively. A control mechanism 400 (not shown) is configured to control the current supply from current sources 350a, 350b to coils 340a, 340b to activate and deactivate magnetic field generators 310a, 310b in a desired manner.

[0083] FIG. 25 illustrates a cross-sectional view of an AC input current i1 in a primary coil 520 of a transformer 510, an AC input current i2 in a secondary coil 530 of the transformer 510, and a magnetic field B generated by a magnetic field generator 310b during use of the example half-wave rectifier 100 of FIGS. 23 and 24 in accordance with one form of the present technology. 印加2 , the magnetic field B generated by the magnetic field generator 310a 印加16 shows measurements of the output voltage across the load 600 and the change in current in the load 600 over time. The magnitude of the AC input current i1 is controlled by the current supply assembly 500 (not shown) to have the illustrated waveform profile, i.e., extended periods of constant voltage at the current peaks, extended periods of dead time at the zero crossings where the AC input current i1 is zero, and constant slope transitions between current levels. The control mechanism 400 may be configured to control the magnetic field generator 310b to apply a constant non-zero magnetic field to the electrical switch 210b when the current i1 is positive and a zero magnetic field when the current i1 is negative. The control mechanism 400 may be configured to control the magnetic field generator 310a to apply a constant non-zero magnetic field to the electrical switch 210a when the current i1 is negative and a zero magnetic field to the electrical switch 210a when the current i1 is positive, i.e., opposite to the activation / deactivation of the magnetic field generator 310b. With these inputs, the output voltage across load 600 may be as shown in Figure 25, i.e., as a non-zero voltage across load 600 when the alternating current i2 in secondary coil 530 exceeds a critical current. If load 600 includes a superconducting material segment maintained in its superconducting state (e.g., in a cryostat below its critical temperature), the current in load 600 may be increased stepwise (which may be described as a "pump") with each output voltage pulse across load 600, as shown in Figure 25.

[0084] The control mechanism 400 may control both switches 210a and 210b to be in a low resistance state simultaneously for a period of an AC cycle, similar to that described in the different embodiments of the technology above, to ensure that the switches are in an open configuration (i.e., a high resistance state) when the current through the switches is in the desired direction.

[0085] 28 and 31 show example magnitudes of the same variables as shown in FIG. 25 (except for AC i2 in the secondary coil 530 of the transformer 510) during simulated use of the example full-wave rectifier 100 of FIGS. 26 and 27 (for FIG. 28) and 29 and 30 (for FIG. 31) in accordance with certain forms of the present technology. The effect of the example full-wave rectifier 100 is similar to that described above for the half-wave rectifier with respect to FIGS. 23 and 24, in that a non-zero voltage is only generated across the load 600 during two stages of the cycle, i.e., when AC i2 in the secondary coil 530 exceeds a critical current. This causes the current in the superconducting load 600 to be pumped twice per cycle. Again, the control mechanism 400 may control two sets of switches to be in a low resistance state simultaneously for a period during the AC cycle, such that the switches are in an open configuration (i.e., a high resistance state) when the current through them is in the desired direction.

[0086] The rectifier 100 shown in Figures 23, 24, 26, 27, 29, and 30 may operate more efficiently than the rectifiers shown in the previous figures, since the timing of the switches may be controlled to improve efficiency. This may allow the rectifier to operate at a lower cold load to cool the superconducting material and / or increase output power. The timing of the switches may be controlled to achieve other purposes. On the other hand, the need for additional power sources and more complex control mechanisms may increase costs and physical dimensions compared to the rectifiers described above.

[0087] 6.9. Current Supply Assembly A rectifier 100 according to certain forms of the present technology includes a current supply assembly 500 configured to supply alternating current to HTS material segments in a switching assembly 200. The current supply assembly 500 may include an alternating current source 900. Alternatively or additionally, the current supply assembly 500 may receive an alternating current supply from an external current source.

[0088] In the form of the technology shown in Figures 3, 4, 5, 6, 8, 9, 10, 11, 12, and 13, the rectifier 100 includes a current control mechanism configured to control an alternating current (i.e., the AC switch current) flowing through the HTS material segments of one or more of the electrical switches 210 such that, in each cycle of the current, there is a first peak of the current when the current flows in one direction (e.g., the positive direction) and a second peak of the current when the current flows in the other opposite direction (e.g., the negative direction), and the magnitude of the current at the first peak is greater than the magnitude of the current at the second peak. In other words, the AC switch current is controlled to be asymmetric over its entire cycle. Furthermore, the current control mechanism is configured to control the magnitude of the current at the first peak to be greater than the critical current I of the HTS material segments in the electrical switches 210 when the magnitude of the magnetic field applied by the magnetic field generator 310 is relatively large. 臨界 and the magnitude of the magnetic field applied by the magnetic field generator 310 is relatively small, the magnitude of the current at the second peak is greater than the critical current I of the HTS material segment in the electrical switch 210. 臨界 It is configured to be smaller than

[0089] In certain forms of the present technology, the current supply assembly 500 (represented in the figures by AC source 900, but as noted above, in other forms the current supply assembly 500 does not include a current source) includes a current control mechanism and is configured to control the AC input current i1 such that the AC flowing through the switch 210 is asymmetric as described above. In other forms of the present technology, the current supply assembly 500 may provide a symmetric AC input current i1, with the current control mechanism receiving the symmetric AC input current i1 and providing the described asymmetric current to the switch 210. FIG. 4A shows three graphs for the configuration of rectifier 100 shown in FIGS. 1) AC input current i1 and magnetic field B applied to the high temperature superconducting material segment of switch 210 by magnetic field generator 310 p Changes over time, 2) the critical current I of the HTS material segment of the electrical switch 210 臨界is the magnetic field B applied to the HTS material segment of switch 210 by magnetic field generator 310. p and how it varies with 3) The change in voltage over time across load 600 when an AC input current i1 is applied. During a current cycle, as the current through the magnetic field generator 310 (and the current through the switch 210) increases, the magnetic field B applied to the switch 210 p The magnitude of the critical current I of the HTS material segment of the electrical switch 210 also increases. 臨界 The switch current reduces the critical current I 臨界 4A, the electrical switch 210 is in a high resistance state. 臨界 The current is equal to i th Therefore, the switch current is i th 4A, the voltage across the load 600 is not zero, and in the example of FIG. 4A, the AC input current i1 has a positive peak value greater than the critical current i th This occurs during the positive portion of the cycle since the input current i1 is controlled to exceed 1. In Figure 4A, this current is shown as the AC input current i1 because it is assumed that all of the input current flows through the electrical switch 210 when the switch is "closed", i.e., in a low resistance state.

[0090] The current is i th If the HTS material segment is in a low resistance state, no current will flow through the load 600. Furthermore, if the negative peak value is less than the critical current i th Since the AC input current i1 is controlled so as not to exceed (magnitude), the HTS material segments are maintained in a low resistance state for the entire negative portion of the cycle, meaning that negligible current flows through the load 600. When repeated over multiple cycles, a periodic positive voltage is generated across the load 600, thereby half-wave rectifying the AC input current i1.

[0091] FIG. 7 shows four graphs illustrating the magnitude of the following parameters over time during use of the rectifier 100 shown in FIGS. 1) the AC input current i1 supplied to the magnetic field generator 310 and to the primary coil 520 of the transformer 510; 2) AC current i2 generated in the secondary coil 530 of the transformer 510; 3) the voltage across the load 600, and 4) Current in load 600 (load 600 comprises a piece of superconducting material maintained in its superconducting state, such as in a cryostat below its critical temperature).

[0092] In this example, the critical current I of the HTS material segment of the electrical switch 210 臨界 is 200 A when no external magnetic field is applied. The alternating current i2 conducted by electrical switch 210 does not exceed 200 A at any point in its cycle, which is insufficient to place switch 210 in a high resistance state. By applying a magnetic field of 0.25 T generated by magnetic field generator 310, the critical current I 臨界 is reduced to about 50 A. In this case, when the AC current i2 flowing through the electrical switch 210 exceeds 50 A, the electrical switch 210 switches to a high resistance state, and a voltage is generated across the load 600. Since the AC current i2, according to the AC input current i1, is asymmetric, the switch 210 switches to a high resistance state only during the positive part of the current cycle, and is half-wave rectified. As a result, the current flowing through the load 600 is pumped.

[0093] One advantage of the rectifier 100 in the form of technology shown in Figures 3-6 is that the current required to switch the rectifier's switch 210 is significantly lower than the current required in the absence of an external magnetic field applied to the switch 210. This reduces the input current requirements, reduces losses in the rectifier 100, and improves efficiency when producing the same levels of current and voltage across the load 600. For example, for the parameters shown in Figure 7, losses are reduced by 75%.

[0094] As discussed above, in certain forms of the present technology, the current control mechanism is configured to asymmetrically control the alternating current flowing through one or more electrical switches 210 to have a required peak magnitude relative to the critical current of the HTS material segments. The current control mechanism may achieve such control of the current in any suitable manner. In certain forms, the current control mechanism may include a programmable signal generator in which a digital signal representing a desired waveform is provided to a digital-to-analog converter to generate an analog voltage signal having a suitable asymmetric waveform. This analog voltage signal may be provided to a power amplifier to generate the asymmetric alternating input current.

[0095] In certain forms of the present technology, the current supply assembly 500 may include a transformer 510, as has been described for many examples. The transformer may include a primary coil 520 connected to the current source 900 and a secondary coil 530 connected to the switching assembly 200. The transformer 510 may include a magnetic core 540 around which the primary coil 520 and the secondary coil 530 are wound. In the rectifiers 100 of Figures 23, 24, 26, 27, 29, and 30, the AC input current i1 is supplied to the primary coil 520 of the transformer 510, and the secondary coil 530 is connected to the switching assembly 200. In the rectifiers 100 of Figures 5, 6, 12, 14, 16, 17, 19, 20, 21, and 22, the magnetic field generator 310 (particularly the coil 340 forming a conductor) is connected to the primary coil 520 of the transformer 510. In the rectifiers 100 of Figures 8, 9 and 13, the magnetic field generator 310 (particularly the coil 340 forming the conductor) is connected to a secondary coil 530 of a transformer 510. In the rectifiers 100 of Figures 10 and 11, the transformer 510 and the magnetic field generator 310 are constructed from the same component, as described in more detail above. In certain configurations, the primary coil 520 may be formed from a normal conductor material and the secondary coil 530 may be formed from a superconducting material, e.g., an HTS material.

[0096] Rectifiers 100 including transformers 510 according to certain forms of the present technology may be applied to a variety of applications including, for example, superconducting magnets, superconducting motors / generators, space propulsion systems, fusion reactors, research magnets, NMR, MRI, levitation, water purification, and induction heating. The use of a transformer 510 in the rectifier allows the two parts of the rectifier to be physically separated, meaning that the rectifier can be used as or within a flux pump. The appropriate rectifier form for an application depends on a variety of factors, such as physical size limitations, cryogenic heat load, output power, efficiency, cost, and controllability. In certain forms, the rectifiers 100 of Figures 5, 6, 8, 9, 10, 11, 12, and 13 may be considered suitable for compact, simple, and / or low-cost applications where the requirements for factors such as efficiency, cryogenic heat load, and output power are not particularly stringent, such as some superconducting motor / generator or laboratory superconducting power supply applications. In certain configurations, the rectifiers 100 of Figures 23, 24, 26, 27, 29, and 30 may be considered suitable for applications requiring high efficiency, cryogenic heat loads, and / or high power output, such as space propulsion or large magnets with fast ramping speeds. For example, the rectifiers of the other figures may be applied to other applications.

[0097] 6.10.Thermal Break In certain forms of technology, the electrical switch 210 and the rectifier 100 include components made from superconducting materials, such as HTS materials. The superconducting materials must be maintained in an environment having a temperature below the critical temperature of the superconducting materials in order for the superconducting materials to become in a low resistance ("superconducting") state. The rectifier 100 according to forms of technology may include a cryostat 700 configured to maintain the rectifier 100, or a portion thereof, in a suitable cryogenic environment at a temperature below the critical temperature of one or more superconducting materials of the rectifier 100.

[0098] Maintaining certain portions of the rectifier 100 at low temperatures within the cryostat 700 can be costly in terms of energy if not necessary for operation of the rectifier 100. However, maintaining some portions of the rectifier 100 at low temperatures and other portions at higher temperatures can result in heat losses from the cryostat 700 and increased energy costs. Therefore, certain forms of the present technology include one or more thermal breaks 710 that insulate one or more portions of the rectifier 100 from one or more other portions of the rectifier 100 to reduce the flow of thermal energy when different portions need to be maintained at different temperatures.

[0099] Aspects of the present technology are not limited by the form or structure of the thermal break 710. In certain aspects, the thermal break 710 includes one or more elements formed of an insulating material. Additionally or alternatively, the thermal break 710 may include a vacuum region. Additionally or alternatively, the thermal break 710 may include one or more radiation shields.

[0100] 32 is a schematic diagram of a transformer 510 in accordance with a particular form of the present technology. The transformer 510 may include any one or more of the following different types of thermal breaks 710: 1) The thermal breaker 710a may be located between the primary coil 520 and the magnetic core 540. 2) Thermal break 710b may be located between a first portion of magnetic core 540a and a second portion of magnetic core 540b. In a particular embodiment, primary coil 520 may be wound around first core portion 540a and secondary coil 530 may be wound around second core portion 540b. 3) The thermal breaker 710c may be located between the secondary coil 530 and the magnetic core 540.

[0101] 33 is a schematic diagram of a transformer 510 in accordance with a particular form of the present technology having a coaxial geometry with a primary coil 520 and a secondary coil 530 wound together, one coil wound closer to the axis than the other coil. Such a transformer 510 may include a thermal break 710d between the primary coil 520 and the secondary coil 530. Similarly, any one or more of the magnetic field generators 310 of the rectifier 100 may include one or more thermal breaks 710, such as, for example, a thermal break 710 between a first portion of the magnetic core 320a and a second portion of the magnetic core 320b, a thermal break between the magnetic core 320 and the conductor coil 340 wound around the magnetic core 320, etc.

[0102] In accordance with the present technology, it is contemplated that the rectifier 100 may be configured to include thermal breaks 710 in any number of locations as needed to provide thermal isolation between the “cold” and “warm” environments to achieve superconducting behavior.

[0103] FIG. 34 shows an example of a rectifier 100 including a thermal break 710. In FIG. 34, the magnetic core of each of the transformer 510, the first and second magnetic field generators 310 is split into two core parts, with one core part located inside the cryostat 700 and the other core part located outside the cryostat 700. The two parts of each magnetic core are magnetically coupled. The interior of the cryostat 700 is maintained at a sufficiently low temperature so that the superconducting material segments located inside the cryostat 700, including the superconducting material segments forming the electrical switch 210, can operate in a low resistance or superconducting state. This causes the walls of the cryostat 700 to form the thermal break 710. The layout of the rectifier 100 of FIG. 34 is otherwise similar to the layout of the rectifier 100 shown in FIGS. 26 and 27.

[0104] FIG. 35 shows another example of a rectifier 100 including a thermal break 710. This configuration again shows a rectifier 100 with a similar layout as the rectifier 100 shown in FIGS. 26 and 27. In this configuration, all of the magnetic cores 320, 540 of the magnetic field generator 310 and the transformer 510 are located inside the cryostat 700. The magnetic cores of the transformer 510, the first and second magnetic field generators 310 are split into two core parts, and the two core parts of each magnetic core are separated by a thermal breaker 710. The two parts of each magnetic core are magnetically coupled. Conductors connected to the primary coil 520 of the transformer and the coil 340 of the magnetic field generator 310 pass through the wall of the cryostat 700.

[0105] 6.11. Bifilar arrangement A technical form has been described for an electrical switch 210 that utilizes the principle that the critical current of a superconducting material is reduced when a high external magnetic field is applied to the material. Figure 24 shows an example of an electrical switch 210a. The electrical switch 210a of Figure 24 includes superconducting material segments arranged in a bifilar arrangement. Figure 36 shows another electrical switch 210 including superconducting material segments arranged in a bifilar arrangement. This aspect of the technology will now be described in more detail.

[0106] Although a bifilar arrangement of superconducting material segments is described with respect to the configuration of the electrical switch 210 shown in Figures 24, 36A, and 36B, it should be understood that the bifilar arrangement is applicable to other configurations of the present technology. In particular, any of the electrical switches 210 described herein may include superconducting material segments arranged in a bifilar arrangement in alternative configurations of the present technology. Furthermore, according to configurations of the present technology, any of the electrical switches 210 incorporated in any of the rectifiers 100 may include one superconducting material segment arranged in a bifilar arrangement.

[0107] In the context of this specification, unless otherwise stated, a "bifilar arrangement" should be understood to mean an arrangement of two strands of conductor such that the two strands are substantially parallel and electrically connected, with current flowing in opposite directions through the strands. The strands may be closely adjacent to each other. The strands may be two portions of a superconducting material segment folded over each other. Alternatively, the two strands may be separate segments of superconducting material that are electrically connected to each other, for example, by soldering, diffusion bonding, or other suitable form of electrical connection.

[0108] It should also be understood that in certain embodiments of the present technology, multiple bifilar lands may be used, and thus, unless the context clearly requires otherwise, other embodiments of the present technology, when describing a bifilar arrangement, may also include similar arrangements having multiple bifilar lands.

[0109] More specifically, in the form of technology shown, for example, with reference to FIG. 36A, the electrical switch 210 includes a superconducting material segment 800 in one form of bifilar arrangement. The superconducting material segment 800 includes two strands (i.e., sub-segments) 810a, 810b of superconducting material. The two strands 810a, 810b are connected in series with each other. The superconducting material segment 800 is arranged to fold back on itself, with the two strands 810a, 810b arranged approximately parallel in space. In such an arrangement, when the superconducting material segment 800 carries a transport current, the current in the first strand 810a flows in the opposite direction to the current in the second strand 810b. A folded region 820 (which may take the form of a loop) of the superconducting material segment 800 may separate the two strands 810a, 810b along the length of the superconducting material segment 800. In an alternative form of the technique shown in FIG. 36B, the electrical switch 210 includes two separate strands 810a, 810b of superconducting material. One end of each of the two strands 810a, 810b is electrically connected at an electrical junction 820b, and the two strands are arranged in a bifilar configuration. Similarly, in this configuration, when the superconducting material segment 800 carries a transport current, the current in the first strand 810a flows in the opposite direction to the current in the second strand 810b. The electrical junction 820b may be a solder joint, a diffusion joint, or any suitable electrical joint.

[0110] In the technical form shown in Figures 36A and 36B, the two strands 810a, 810b may be placed close to each other. One or both of the strands 810a, 810b may be provided with an insulating coating, and the insulating coatings of the strands may be in contact with each other. Alternatively, an insulating layer may be placed between the two strands 810a, 810b in contact with one or both strands. The insulating layer may be formed of an insulating tape, such as Kapton or Nomex tape.

[0111] In a particular form of the present technology, the superconducting material segment 800 may take the form of a tape, which is a length of material having a length that is clearly greater than its width and depth, and a width that is clearly greater than its depth. The tape may have two opposing faces that are substantially parallel, the two faces being separated by the depth of the tape. The strands may be arranged such that the opposing faces of one strand 810a are parallel to the opposing faces of the other strand 810b. In the form of technology shown in FIG. 36B, each of the two strands 810a, 810b may take the form of a band. The two separated strands may be electrically connected (e.g. soldered) face to face at one end to form an electrically continuous junction 820b. Such an arrangement may reduce the inductance of the electrical switch 210, but such advantage may be achieved at the expense of a small increase in resistance in the low resistance state. Alternatively, a single superconducting material segment (eg, a tape) may be arranged such that the two strands 10a, 810b are connected end-to-end for adjacent portions of its length.

[0112] In certain forms of the present technology, the superconducting material segment 800 may be a high temperature superconducting (HTS) material segment as previously described.

[0113] As shown in the technical forms of Figures 24, 36A, and 36B, the electrical switch 210 of a particular form of the present technology may be arranged to activate a magnetic field generator 310 to apply a magnetic field to two strands 810a, 810b of superconducting material. The magnetic field generator 310 may take the form of any of the magnetic field generators previously described herein. The magnetic field generator 310 may be selectively controlled to selectively generate a magnetic field to move the electrical switch 210 between a low resistance state and a high resistance state as previously described.

[0114] In a particular embodiment, the magnetic field generator 310 includes a magnetic core 320. The core 320 may be a ferromagnetic core, such as a ferrite core (e.g., iron core), or a high permeability magnetic core, such as a laminated steel / iron core. In an exemplary embodiment shown in FIG. 24, the magnetic core 320a is a substantially ring-shaped solid core, e.g., a circular ring. In other embodiments, the core may have a different shape, e.g., a square ring with rounded corners. In an exemplary embodiment, the magnetic core 320 includes a first end and a second end separated by a gap 330. The gap 330 may be a space within the solid magnetic core 320, e.g., a space on one side of a ring core.

[0115] In a particular embodiment, the electrical switch 210 is positioned such that the magnetic field generated by the magnetic field generator 310 is substantially perpendicular to the opposing faces of the strands 810a, 801b, i.e., the magnetic flux lines of the magnetic field are substantially perpendicular to the faces of the strands 810a, 801b where the magnetic flux lines intersect the strands.

[0116] In certain forms of the present technology, the width of the gap 330 is similar to the combined depth of the two strands 810a, 810b, i.e., the space separating each of the strands 810a, 810b from the respective ends of the core 330 closest to the strands is relatively small.

[0117] One advantage of the electrical switch 210 including a bifilar arrangement of superconducting material segments is that the inductance of the switch is reduced compared to a similar switch having a single superconducting material segment. One such advantage is that the coil 340 of the magnetic field generator 310 that applies the magnetic field to the electrical switch 210 can have fewer turns than would otherwise be the case.

[0118] Another advantage of the electrical switch 210 including a bifilar arrangement of superconducting material segments is that it helps reduce the suppression of the critical current of the superconducting material segments when a low (e.g., zero) magnetic field is applied to the segments, resulting in a higher critical current for the low resistance state of the switch 210. This effect is described in more detail below.

[0119] The forms of technology described above include an electrical switch 210 in which a magnetic field is applied to a superconducting material segment to suppress a critical current in the superconducting material segment. This effect is used in some forms of technology to transition a superconducting material segment between a low resistance state and a high resistance state. A magnetic field generator 310 that generates the magnetic field may include a high permeability magnetic core 320, such as a ferromagnetic core, that can be used to focus the magnetic field on the superconducting material segment.

[0120] It has been observed that the placement of a single superconducting material segment carrying a transport current in the vicinity of a ferromagnetic core further suppresses the critical current even when the strength of the magnetic field is very low, including zero. In fact, the relative additional suppression of the critical current due to this effect is greater when the strength of the applied magnetic field is low. This is due to the effect of self-field amplification due to the proximity of the ferromagnetic body in the core 320 to the superconducting material when a current flows through it. More specifically, it has been confirmed through experiments and finite element analysis that the presence of a low reluctance return path through the ferromagnetic core 320 amplifies the self-field of the single superconducting material segment, and when the single superconducting material segment is in the form of a tape, it is oriented perpendicular to the tape and extends across its width. This suppresses the critical current density at each point across the width of the tape, and therefore the overall critical current, compared to the absence of a ferromagnetic core.

[0121] Moreover, it has been confirmed that the electrical switch 210 in which the superconducting material segments are arranged in a bifilar arrangement significantly mitigates such effects, i.e., reduces the suppression of the critical current described. In other words, when approaching the ferromagnetic core 320, the bifilar arrangement substantially cancels the self-magnetic field generated by the current flowing through the superconducting material segments. FIG. 37 shows the critical current at different applied fields of one superconducting material segment of the electrical switch 210 according to the present technology when the superconducting material segments are arranged in a bifilar (blue, top line) and unifilar (orange, bottom line) arrangement, i.e., when arranged in a single layer of superconducting material segments. These experimental results are compared with the reference value of the superconducting material from the database (green dotted line, center line). This shows that the suppression of the critical current at low applied magnetic fields is much lower in the bifilar arrangement compared to the unifilar arrangement. At higher applied magnetic fields, where the applied magnetic field is significantly larger than the self-magnetic field effect, the difference is less noticeable. The relatively small difference in critical current at higher applied fields is believed to be due to the increased shielding capability of the two-layer bifilar configuration compared to the single-layer unifilar configuration. It should be understood that in certain forms of the present technology, the superconducting material segments may be maintained in a superconducting state at all times.

[0122] The larger difference in critical current for low applied magnetic fields compared to high applied magnetic fields means that an electrical switch 210 comprising a length of superconducting material in a bifilar configuration may have improved switching performance compared to, for example, a unifilar configuration switch. The switching performance may be given by the switching factor k, which can be calculated as the ratio of the critical current when the magnetic field is zero to the critical current when the magnetic field is applied, i.e., Ic(0) / Ic,b(Ba). From FIG. 37, it can be seen that k is larger for the bifilar configuration than for the unifilar configuration. The higher the switching factor k, the higher the efficiency of the switch, as long as the transport current is lower than Ic(0). Also, the higher critical current in the low resistance state allows the electrical switch 210 to output a higher maximum current.

[0123] 38A and 38B show magnetic field profiles in the gap between the ends of a ferromagnetic core 320 for an electrical switch 210 according to a particular form of the present technology. The electrical switch 210 includes a superconducting material segment 810 in the form of a tape located between the ends of the ferromagnetic core 320. The magnetic field profiles are generated by finite element analysis. In FIG. 38A, the tape is placed in the gap 330 between the ends of the core 320 in a unifilar arrangement, i.e., a single tape segment passes through the gap 330. In FIG. 38A, the tape is modeled to have a current of 195A passing through it, and the magnetic field applied to the tape is modeled to have a field strength of 250mT. In FIG. 38B, the tape is placed in the gap 330 between the ends of the core 320 in a bifilar arrangement, i.e., two strands of tape are placed in the gap 330 parallel and close to each other. In FIG. 38B, the tape is modeled as having a current of 375 A passing through it, and the magnetic field applied to the tape is modeled as having a field strength of 70 mT.

[0124] Figures 38A and 38B show that the magnitude of the average magnetic field in the form of the technique in which the superconducting material segments are arranged in a unifilar arrangement (Figure 38A) is significantly larger than that in the form of the technique in which the superconducting material segments are arranged in a bifilar arrangement (Figure 38B). In fact, the bifilar arrangement almost eliminates the self-inductance of the magnetic tape, and the magnetic field remaining in the magnetic tape is mainly oriented parallel to the magnetic tape surface. This explains why the critical current of the bifilar arrangement under zero applied magnetic field is obviously larger than that of the unifilar magnetic tape (see Figure 37).

[0125] It has also been determined that the larger the gap 330 between the ends of the core 320, the lower the magnetic field strength of the applied magnetic field. This means that as the gap 330 increases, a larger current source must be provided to the magnetic field generator to maintain the same magnetic field strength. This requires additional drive power and dissipates additional heat, which may be undesirable. Therefore, in certain forms of the present technology, the dimensions of the gap 330 may be as small as possible, for example, the width of the gap 330 is similar to the combined depth of the two strands of the superconducting material segment 810.

[0126] 6.12.Other Notes Unless the context clearly requires otherwise, throughout the description and claims, the terms "comprise," "comprising," and the like, are to be construed in their inclusive sense, i.e., "including but not limited to," rather than in their exclusive or exhaustive sense.

[0127] The entire disclosures of all applications, patents and publications, cited above and below, if any, are hereby incorporated by reference.

[0128] The citation of any prior art in this specification is not, and should not be, considered as an acknowledgment or implication that the prior art forms part of the public knowledge of any country in the world.

[0129] The technology may also be broadly described as consisting of the parts, elements and features individually or collectively referred to or indicated in the specification of this application, and any and all combinations of two or more of said parts, elements or features.

[0130] Where in the foregoing description reference has been made to components having integers or known equivalents, those integers are incorporated herein as if set forth individually.

[0131] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the technology and without losing its attendant advantages. Therefore, such changes and modifications are intended to be included in the technology. [Explanation of symbols]

[0132] 100 rectifier 200 Switching Assembly 210 Switch 300 Magnetic Field Generator Assembly 310 Magnetic Field Generator 400 Control Mechanism 600 Load 900 current source

Claims

1. An electrical switch, a first strand of superconducting material and a second strand of superconducting material each configured to carry a transport current and having a critical current; a magnetic field generator constructed and arranged to apply a magnetic field to the first strand of superconducting material and the second strand of superconducting material, the magnetic field generator including a high permeability magnetic core; the magnetic field generator is configured to be selectively controlled to electrically switch between a low resistance state when the magnitude of the magnetic field is relatively small and a high resistance state when the magnitude of the magnetic field is relatively large, wherein in the low resistance state, the transport current is substantially less than the critical current and in the high resistance state, the transport current is close to, substantially equal to, or greater than the critical current; the first and second superconducting material strands being spatially arranged substantially parallel to one another within the region of the magnetic field and electrically connected such that the transport current flows in opposite directions through the first and second superconducting material strands within the region of the magnetic field.

2. 2. The electrical switch of claim 1, wherein the high permeability magnetic core includes a first end and a second end separated by a gap, the first strand of superconducting material and the second strand of superconducting material being located within the gap.

3. An electrical switch according to any one of claims 1 to 2, wherein the first strand of superconducting material and the second strand of superconducting material are each in the form of a tape having two opposing faces.

4. 4. The electrical switch of claim 3, wherein the tape is oriented such that opposing faces of the first strands of superconducting material are parallel to opposing faces of the second strands of superconducting material.

5. 5. The electrical switch of claim 4, wherein the tape is oriented such that a magnetic field applied to the first strand of superconducting material and the second strand of superconducting material is substantially perpendicular to each of the two opposing faces.

6. 6. The electrical switch of claim 1, wherein the electrical switch comprises a single superconducting material segment including a first strand of superconducting material and a second strand of superconducting material connected together end-to-end.

7. 6. The electrical switch of claim 1, wherein the first strand of superconducting material and the second strand of superconducting material are electrically connected by connecting one side of the first strand to one side of the second strand.

8. An electrical switch according to any one of claims 1 to 7, wherein the superconducting material is a high temperature superconducting (HTS) material.

9. A rectifier configured to rectify an AC input current, the rectifier including an electrical switch as described in any one of claims 1 to 8, the electrical switch being arranged to rectify the AC input current to produce a DC output.

Images