Yung J Cha

US Patent:

6751075, Jun 15, 2004

Filed:

Dec 12, 2001

Appl. No.:

10/015373

Inventors:

Yung S. Cha - Darien IL

Assignee:

The University of Chicago - Chicago IL

International Classification:

H02H 700

US Classification:

361 19, 361141

Abstract:

A superconducting fault current controller/current controller employs a superconducting-shielded core reactor (SSCR) with a variable impedance in a secondary circuit to control current in a primary circuit such as an electrical distribution system. In a second embodiment, a variable current source is employed in a secondary circuit of an SSCR to control current in the primary circuit. In a third embodiment, both a variable impedance in one secondary circuit and a variable current source in a second circuit of an SSCR are employed for separate and independent control of current in the primary circuit.

US Patent:

7023673, Apr 4, 2006

Filed:

Dec 23, 2002

Appl. No.:

10/328324

Inventors:

Yung S. Cha - Darien IL, US
John R. Hull - Downers Grove IL, US

Assignee:

The University of Chicago - Chicago IL

International Classification:

H01H 47/00

US Classification:

361 19, 361141

Abstract:

A superconducting shielded core reactor (SSCR) operates as a passive device for limiting excessive AC current in a circuit operating at a high power level under a fault condition such as shorting. The SSCR includes a ferromagnetic core which may be either closed or open (with an air gap) and extends into and through a superconducting tube or superconducting rings arranged in a stacked array. First and second series connected copper coils each disposed about a portion of the iron core are connected to the circuit to be protected and are respectively wound inside and outside of the superconducting tube or rings. A large impedance is inserted into the circuit by the core when the shielding capability of the superconducting arrangement is exceeded by the applied magnetic field generated by the two coils under a fault condition to limit the AC current in the circuit. The proposed SSCR also affords reduced AC loss compared to conventional SSCRs under continuous normal operation.

US Patent:

7073513, Jul 11, 2006

Filed:

May 27, 2003

Appl. No.:

10/445681

Inventors:

Yung Sheng Cha - Darien IL, US
John R. Hull - Downers Grove IL, US
Thomas R. Askew - Kalamazoo MI, US

Assignee:

The University of Chicago - Chicago IL

International Classification:

A61B 19/00
H01H 47/00

US Classification:

128899, 361141, 361143, 361149

Abstract:

A system and method of controlling movement of magnetic material with at least first and second high temperature superconductors at spaced locations. A plurality of solenoids are associated with the superconductors to induce a persistent currents in preselected high temperature superconductors establishing a plurality of magnetic fields in response to pulsed currents introduced to one or more of the solenoids. Control mechanism in communication with said solenoids and/or said high temperature superconductors are used to demagnetize selected ones of the high temperature superconductors to reduce the magnetic fields substantially to zero. Magnetic material is moved between magnetic fields by establishing the presence thereof and thereafter reducing magnetic fields substantially to zero and establishing magnetic fields in other superconductors arranged in a predetermined configuration.

US Patent:

58926445, Apr 6, 1999

Filed:

Nov 20, 1997

Appl. No.:

8/975431

Inventors:

Daniel J. Evans - Wheeling IL
Yung S. Cha - Darien IL

Assignee:

The University of Chicago - Chicago IL

International Classification:

H02H 700

US Classification:

361 19

Abstract:

A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment.