Feeder conductors for a high-temperature superconductive rotor coil winding and electric machine

Description of the invention

The present invention relates to a power supply line for an electrical system and a cooling system for a high-temperature superconducting rotor coil winding. More specifically, the present invention relates to a power lead for high temperature superconducting field windings in a rotor of a synchronous machine.

Synchronous electrical machines having field windings include, but are not limited to, generators, motors and linear motors. These machines generally include a stator and rotor that are electromagnetically coupled. The rotor may include a multi-pole rotor core and coil windings mounted on the rotor core. The rotor core may contain a magnetically permeable solid material, as in the case of a ferromagnetic core rotor.

Traditional copper windings are commonly used in the rotors of synchronous machines. However, the electrical resistance of the copper windings (albeit low for other applications) is high enough to induce significant heating of the rotor and reduce the energy efficiency of the machine. Recently, superconducting windings have been developed for rotors that have essentially no resistance and are of great benefit to the rotor coil windings.

Typical superconducting rotor windings are saddle-shaped coils mounted around cylindrical bodies that form a structural support. Saddle-shaped coils are complex winding designs that are cooled on direct contact with cryogenic fluids. Power Cables! they are also cooled by cryogenic fluids in the parallel flow paths of the flow path, which presents problems with flow rate control and temperature stability under high centrifugal forces.

The power line for the electrical system and the cooling system of the high-temperature superconducting rotor coil winding, including a heat exchange block that can be attached to the return line bulkhead, an insulator mounted between the heat exchange block and the return line partition, and thermally optimized power lines as per The invention is characterized in that the insulator comprises ceramic material and the heat exchange block comprises two half-blocks, with dimensions where the partition of the return line is surrounded by them and the thermally optimized current leads contain two thermally optimized current leads connected to the respective half-blocks.

The half-blocks are attached to each other with electrically insulated screws.

The ceramic insulator is made of beryllium or sapphire.

The ceramic insulator is plated on both sides except the edges.

The invention is illustrated in an embodiment in the drawing, in which Fig. 1 shows an assembly diagram of the power cables for the HTS rotor firing coil; Figure 2 shows the feed lines of Figure 1 and a thermally insulated supporting tube; Figure 3 shows a power line connected to the rotor of the HTS; fig. 4 depicts thermally optimized current leads coupled to braided copper leads that connect to ceramic vacuum conduits; Figs. 5-8 are mechanical drawings showing the feed lines for an HTS rotor and the rotor of the invention, and Fig. 9 is an enlarged assembly drawing of the power lines of the invention.

The drawings show the power cables for the HTS coil winding! rotor. The HTS coil start and end leads (not shown) are preferably soldered to copper terminals 14 which are proximate the rotor axis so that they are subjected to low centrifugal loads. The return line 20 transports the cryogenic fluid from the HTS coil heat exchanger coolant tube adjacent the copper ends 14 to the end of the rotor shaft (shown in Fig. 8), wherein a fluid transport connection supplies the cryogenic fluid to an external source of cryogenic coolant. Short braided copper leads 12 connect the ends of the coil 14 to the copper heat transfer blocks 16. The heat exchange blocks 16 are formed of two half-blocks that are dimensioned such that the partition 18 of the return pipeline 20 is enclosed therewith. As shown in Fig. 9 the heat exchange half blocks 16 are connected to one another by electrically insulated bolts 24 which withstand the centrifugal load.

The clad ceramic insulators 22 are brazed on one side to the heat exchange blocks 16 and on the other side to the partition 18 of the return line 20, such that the feed lines are cooled by conduction of heat to remove heat into the return line 20 of the rotor coolant. The heat exchange blocks 16 are electrically insulated from the flow line 20

Through the ceramic insulators 22, but remove heat efficiently with a low temperature difference because the ceramic insulators 22 are designed to have high thermal conductivity at cryogenic temperatures. Ceramic insulators 22 are typically made of thin beryllium (beryllium oxide) or sapphire plates that are plated on both sides beyond the edges to provide adequate electrical insulation for the HTS coil. Typical insulator thickness ranges from 0.040 to 0.125 inch. Thicker insulators improve the electrical insulation and increase the breakdown voltage of the HTS coil at the cost of worsening the cooling capacity of the heat exchanger.

The thermally optimized current leads 26 are soldered with one end to the heat transfer blocks 16 and the other end to the braided copper lugs 28 which connect to ceramic vacuum openings (vacuum sealed, ceramic, insulated copper lugs). The conductors 26 are optimized to transmit the highest current with the lowest thermal load for the heat exchanger. The cross-section, length, and electrical resistance of the thermally optimized current leads 26 are adapted to transmit the rotor current with sufficient headroom for transients and minimize transport to the cold end of the heat generated by resistive heating and thermal conduction. The thermally optimized portions of the feed lines are supported by a thin-walled thermally separated fiberglass tube 30 which is attached with one end to the impeller bore and with the other end supporting the heat exchange blocks 16 and the baffle 18 of the return pipeline 20.

In the design of the HTS rotor feed lines according to the invention, the feed line heat exchange blocks are electrically coupled to the rotor of the electrical machine, electrically insulated from the return flow line, and at the same time thermally coupled to the return flow line through the ceramic insulator provided therebetween. The ceramic insulator provides heat conduction between the heat exchange blocks and the return line. Thermally optimized power cables are designed to transmit transients while minimizing heat transport.

While the invention has been described in conjunction with the presently believed to be the most practical and preferred embodiments, it should be understood that the invention is not limited to the described embodiments but should, on the contrary, encompass various modifications and equivalent solutions falling within the spirit and letter of the appended claims.