Abstract: A method of delivering an optimized power level from a backup energy system to a load connected to a primary energy supply via a DC link and an inverter is provided. The method has the steps of: sensing a voltage of the DC link connected to the load; connecting a converter between the backup energy supply and the DC link; evaluating a rate of change of the voltage of the DC link; determining an estimate of the average load current using the rate of change of the DC link voltage; and controlling the converter using the average load current to switch the optimized power output from the backup energy supply to the load. In an embodiment, the step of determining an estimate of the average load current using the rate of change of the DC link voltage is performed in accordance with a formula I.sub.load =C.sub.DC link (dV.sub.DC link /dt).

Abstract: Improved superconducting thin films are provided having very high T.sub.c (zero) and J.sub.c values, on the order of greater than or equal to 120K and 10.sup.5 A/cm.sup.2 or greater, respectively. The films of the invention are adapted for deposit and support on a compatible substrate, and include a superconductive material, most preferably Tl.sub.2 Ba.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10, with up to about 10% elemental gold admixed with the superconductive material. The preferred method for fabricating the thin film superconductors comprises first forming a non-superconducting precursor film on a compatible substrate which is placed in contact with an unsintered bulk body containing thallium; the substrate with precursor film are sintered with the bulk body to form the desired superconductor material.

Abstract: High T.sub.c superconducting magnetic shields are provided, together with a method of fabricating such shields, wherein the shields exhibit very high critical applied magnetic field values of at least about 50 Gauss at 77 K. In fabrication procedures, a particulate superconducting ceramic oxide (24) (e.g., thallium 2223) is placed within an uniaxial die assembly (10) and subjected to compression while the die is heated via an external heating jacket (26). After formation of a self-sustaining body (24a), the die (10) is additionally heated via the jacket (26). External heating of the die (10) with the superconducting material therein reduces internal stresses within the shield body.

Abstract: A superconducting voltage stabilizer is set forth which utilizes a superconducting coil for storing and releasing electrical energy. A first semiconductor switch is disposed to conduct current from the superconducting coil therethrough when the superconducting coil is to be charged or is to store energy and to inhibit current flow therethrough when the superconducting coil is to release energy. A crowbar circuit including a second semiconductor switch and a dump load are also employed. A third semiconductor switch is connected in parallel with the dump load and is disposed in series between the superconducting coil and the crowbar circuit. Quench detection and control circuits are employed for detecting a quench condition of the superconducting coil.

Abstract: Improved superconducting oxides are provided having the general formula (Hg.sub.1-x Tl.sub.x)Ba.sub.2 Ca.sub.n-1 Cu.sub.n O.sub.2n+2+.alpha. where x is from about 0.05-0.5 and n is 1, 2, 3 or 4, and .alpha. is an oxygen enrichment factor. The Tl-doped oxides exhibit very high T.sub.c and J.sub.c values.

Abstract: A shunt connected energy stabilizing system with isolation switching for providing stored energy to loads or to a utility or industrial electrical distribution system or source of electrical power. An energy backup and recovery system stores energy in a superconducting magnet and releases the energy to a real power/reactive power (VARs) generator which in turn delivers energy to either the loads or to both the loads and the source of electrical power. During periods of voltage sag or power outage, an isolation switch provide a means for isolating the loads from the source of power so that energy can be supplied to the loads only to provide "ride-thru". In effect, the isolation of the load sheds this load from the power system, thereby boosting the rest of the electrical distribution to a level so that other loads on the power system are not disturbed by the voltage sags. By supplying energy to the loads only, small superconducting magnets can be used thereby providing economic and size advantages.

Abstract: Composite bulk superconducting materials having desirable physical, measured transport current density and high T.sub.c superconducting characteristics are provided which comprise a first matrix of superconducting ceramic oxide crystalline grains with a second matrix of elemental metal (gold, silver, palladium and tin) situated within the interstices between the crystalline grains. Preferably, each matrix is a continuous phase within the composite material, with the ceramic oxide preferably being present at a level of at least about 80% by weight, whereas the elemental metal is present at a level of up to about 20% by weight. In fabrication procedures, a precursor superconducting ceramic oxide is first prepared and reduced to a fine powder size; this is mixed with powdered elemental metal, and the mixture is compressed using high compaction pressures on the order of 14 tons/cm.sup.2 or greater to form a body, which is then sintered to yield the composite.

Abstract: A shunt connected energy stabilizing system with isolation switching for providing stored energy to loads or to a utility or industrial electrical distribution system or source of electrical power. An energy backup and recovery system stores energy in a superconducting magnet and releases the energy to a real power/reactive power (VARs) generator which in turn delivers energy to either the loads or to both the loads and the source of electrical power. During periods of voltage sag or power outage, an isolation switch provides a way for isolating the loads from the source of power so that energy can be supplied to the loads only to provide "ride-thru". In effect, the isolation of the load sheds this load from the power system, thereby boosting the rest of the electrical distribution to a level so that other loads on the power system are not disturbed by the voltage sags. By supplying energy to the loads only, small superconducting magnets can be used thereby providing economic and size advantages.

Abstract: An improved technique for the fabrication of thallium-based superconducting oxides, and particularly Tl:Ba:Ca:Cu:O 2223 oxides, is described which allows production of very pure superconductors (>95% 2223 phase) having excellent structural characteristics. The method of the invention involves first forming a self-sustaining body of starting oxides and subjecting this body to a sintering technique wherein the temperature of the body is gradually raised to a maximum level of about 850.degree.-930.degree. C., followed by maintaining the body at this temperature for a period of about 48 hours. The body is then slowly cooled to avoid distortion and loss of superconducting character. Most preferably, the sintering is a two-stage operation, wherein the body is first heated a relatively low rate (e.g., 1.degree.-10.degree. C./min.) to a temperature of about 650.degree.-750.degree. C., followed by faster heating at a higher rate to achieve the maximum sintering temperature.

Abstract: A selectively controllable, direction-, amplitude- and/or frequency-specific superconducting shield (10) is provided which includes a multiply-connected superconducting shield (12) adapted to shield a zone (13) from external magnetic, electric and/or electromagnetic fields and signals. Controlled gating of the shield (12) is provided by means (16) serving to selectively lower the critical shielding current density of a portion (26) of the shield (12) to a level permitting entrance of external fields through the portion (26), while leaving the critical shielding current densities of other portions of the shield (12) at higher, field-shielding levels. The means (16) preferably includes respective, selectively energizable coil pairs (CP.sub.1, CP.sub.2 . . . CP.sub.n) disposed about the shield (12). A highly sensitive magnetic detector (30) would include the shielding device (10) as well as a SQUID assembly (18) situated within the zone (13) defined by shield (12).

Abstract: A superconductive voltage stabilizer employs an improved current switch. The improved current switch controls the release of current stored in an energy storage device or superconducting inductive energy storage coil for selective delivery of the current to a load or an electric utility system. A transformer employed in the current switch provides isolation of the energy storage components from the load, thereby making a local ground possible. The amount of energy which can be recovered from the energy storage device is also increased.

Abstract: A superconducting energy stabilizer having multiple load connections employs DC-DC conversion. A discharging DC-DC converter removes stored energy from a superconducting inductive energy storage device or superconducting magnet and delivers the energy to an energy storage cell for use by a load or a utility or industrial electrical distribution system. Regenerated energy can also be retrieved from regenerative type devices and stored in the superconducting magnet for later use. A charging DC-DC converter provides this function. The charging DC-DC converter and the discharging DC-DC converter as well as an off-the-line power supply which provides energy for storage in the superconducting magnet can operate simultaneously under the control of a control system.

Abstract: A superconductive voltage stabilizer comprises an AC/DC converter, a voltage regulator, an energy storage cell and a superconducting energy storage coil. Alternating current is converted to direct current and stored in a superconducting coil. The stored direct current is selectively delivered to an energy storage cell to satisfy the energy requirements of a load. A voltage regulator senses the energy drawn from the energy storage cell and when appropriate releases stored energy from the superconducting coil to maintain a constant supply of energy to the load.