Phase-shifting transformer with a six-phase core

• US 5,003,277 A
• Filed: 08/08/1989
• Issued: 03/26/1991
• Est. Priority Date: 08/15/1988
• Status: Expired due to Term

• Current Assignee: ABB Power T&D Co Inc (ABB Limited)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ishii, Koichi, Sokai, Katsuji
• Primary Examiner(s): Kozma, Thomas J.
• Application Number:
  US07/390,821
• Time in Patent Office: 595 Days
• Field of Search: 323/215, 323/361, 336/5, 336/10, 336/12, 336/180, 336/181, 336/182, 336/212, 336/215, 363/64, 363/160, 363/171
• US Class Current: 336/10
• CPC Class Codes: H01F 30/12 Two-phase, three-phase or polyphase transformers

Abstract

A phase-shifting transformer including main and series transformer units comprises a six-phase core including six independent magnetic circuits, numbered first through sixth from right to left. The combined U-, V-, and W-phase windings of the main transformer unit link with the fifth, third, and first magnetic circuits, respectively. The combined a-, b-, and c-phase windings of the series transformer unit link with the sixth, fourth, and second magnetic circuits. The winding directions of the V- and b-phase windings are reversed with respect to those of other phase windings. Thus, if three-phase voltages 120 degrees apart are input to the main transformer unit, then the phase angles between the main magnetic fluxes generated in any two adjacent magnetic circuits are equal to 30 degrees. Consequently, the magnitudes of the differential magnetic fluxes passing through the interphase portions between two adjacent magnetic circuits are reduced to about one half of the magnitudes of the main magnetic fluxes, with the result that the cross-sectional area of the interphase portions of the core can be reduced to about one half of that of its main leg portions.

Claims

1. A phase-shifting transformer comprising:

a six-phase magnetic core including six mutually independent magnetic circuits, first through sixth, through which six mutually independent magnetic fluxes may pass, any two adjacent numbered circuits being geometrically adjacent to each other, wherein any two adjacent magnetic circuits each comprises an interphase portion that is common to both magnetic circuits;

three-phase main transformer windings wound on said six-phase magnetic core and including a three-phase primary winding having three inputs for receiving three-phase input voltages wherein respective phase-windings of said three-phase main transformer windings link with the first, third, and fifth, respectively, of the six magnetic circuits of said six-phase magnetic core, and wherein the windings of the third magnetic circuit are reversed in winding direction with respect to the first and fifth magnetic circuits, whereby, when three-phase input voltages whose phases are displaced by 120 degrees from each other are applied to the three inputs, three magnetic fluxes whose phases are separated from each other by 60 degrees are generated in the first, third, and fifth magnetic circuits; and

three-phase series transformer windings wound on said six-phase magnetic core and electrically coupled to said main three-phase transformer windings, the respective phase-windings of the three-phase series transformer windings linking with the second, fourth, and sixth of the six magnetic circuits of said six-phase magnetic core whereby when the three-phase input voltages are applied to the three inputs, three magnetic fluxes are generated in the second, fourth, and sixth magnetic circuits, respectively, whose phases are separated by 60 degrees from each other and by 30 degrees from the phases of the magnetic fluxes generated in adjacent magnetic circuits, whereby the differential magnetic fluxes passing through said interphase portions of said six-phase magnetic core each consist of a vector difference between two magnetic fluxes whose phases are separated by 30 degrees from each other.

2. A phase-shifting transformer comprising:

a six-phase magnetic core including six mutually independent magnetic circuits, first through sixth, through which six mutually independent magnetic fluxes may pass, any two adjacent numbered circuits being geometrically adjacent to each other, wherein any two adjacent magnetic circuits comprises an interphase portion that is common to both magnetic circuits;

a three-phase primary winding having three phase-windings linking with the first, third, and fifth, respectively, of the six magnetic circuits of the six-phase magnetic core and having three inputs for receiving three-phase input voltages, the third magnetic circuit including a phase-winding having a winding direction reversed with respect to winding directions of phase-windings linking with the first and fifth magnetic circuits whereby when three-phase input voltages whose phases are displaced by 120 degrees from each other are applied to the three inputs, three magnetic fluxes whose phases are separated by 60 degrees from each other are generated in the first, third, and fifth magnetic circuits;

a three-phase secondary winding having three phase-windings linking with the first, third, and fifth, respectively, of the six magnetic circuits of the six-phase magnetic core and having three output terminals;

a three-phase tertiary winding having three phase-windings linking with the first, third, and fifth, respectively, of the six magnetic circuits of the six-phase magnetic core, the three phase-windings being electrically coupled in a delta configuration;

a three-phase excitation winding having three phase-windings linking with the second, fourth, and six, respectively, of the six magnetic circuits of the six-phase magnetic core, said three-phase excitation winding being wound on the magnetic core, electrically coupled in a Y configuration, and electrically coupled to said three-phase tertiary winding, whereby when three-phase input voltages whose phases are displaced by 120 degrees from each other are applied to the three inputs, three magnetic fluxes are generated in the second, fourth, and sixth magnetic circuits, respectively, which are separated by 60 degrees from each other and by 30 degrees from the phases of the magnetic fluxes generated by the three phase-windings of said three-phase primary winding in adjacent magnetic circuits, whereby the differential magnetic fluxes passing through said interphase portions of said six-phase magnetic core each consists of a vector difference between two magnetic fluxes of the magnetic circuits to which the interphase portions are common whose phases are separated by 30 degrees from each other; and

a three-phase phase-regulating winding having three phase-windings linking with second, fourth, and sixth, respectively, of the six magnetic circuits of the six-phase magnetic core and magnetically coupled with the respective three phase-windings of said three-phase excitation winding via the second, fourth, and sixth magnetic circuits, respectively, wherein the three phase-windings of said three-phase phase-regulating winding are electrically coupled in series with the three phase-windings of said three-phase secondary winding.

3. A phase-shifting transformer as claimed in claim 2 wherein said three-phase phase-regulating winding includes tap means for changing lengths of the three phase-windings of the phase-regulating winding, whereby phase angles of three-phase output voltages supplied at three terminals of said three-phase secondary winding are varied and adjusted arbitrarily by changing the lengths of the three-phase windings that are electrically coupled in series with the three phase-windings of the three-phase secondary winding.

4. A phase-shifting transformer as claimed in claim 2, further comprising a three-phase stabilizing winding having three phase windings linking with the second, fourth, and sixth, respectively, of the six magnetic circuits of the six-phase magnetic core.

5. A phase-shifting transformer as claimed in claim 2, wherein the three phase-windings of said three-phase primary and secondary windings and those of said three-phase excitation winding and of the three-phase phase-regulating winding are Y-connected, while the three phase-windings of said three-phase tertiary winding are Δ

-connected.