US3675176A - Electrical transformers - Google Patents

Electrical transformers Download PDF

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Publication number
US3675176A
US3675176A US142567A US3675176DA US3675176A US 3675176 A US3675176 A US 3675176A US 142567 A US142567 A US 142567A US 3675176D A US3675176D A US 3675176DA US 3675176 A US3675176 A US 3675176A
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United States
Prior art keywords
core
conductors
band
transformer
electrically connected
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Expired - Lifetime
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US142567A
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English (en)
Inventor
Anthony R Brown
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Racal Mobilcal Ltd
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Racal Mobilcal Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/346—Preventing or reducing leakage fields

Definitions

  • the trans- [30] Apphuhoh Data former has a toroidal core mounted between first and second. May 12, 1970 Great Britain “22827/70 electrically conductive, apertured disks. A conductive band encircles the outer periphery of the core.
  • the single-layer pri- 52 user. "336/182, 336/183, 336/192, Seven paral'el-wnneced windings each 336/229 having two bi-filar turns one of which is connected to one of [51] Int. Cl.
  • the secondary, also single-layer, comprises several parallel-connected windings each having a number of turns, UNITED STATES PATENTS the ends of the secondary windings passing through the apertures of the conductive disks and terminating on further, insue 3,008,108 11/1961 Baker et a1 ..336/229 X lated conductive washem 3,179,908 4/1965 Peabody ..336/229 X 3,453,574 7/1969 De Parry ..336/229 X 8 Claims, 2 Drawing Figures 16 28 m 70 s ay, 5
  • the invention relates to electrical transformers, such as 'wideband transformers particularly suitable for use in transistor high-frequency amplifiers for example.
  • Transformers have been previously proposed with a magnetic core providing a closed magnetic circuit and carrying multiple windings arranged in parallel. With such transformers operating at very low impedances, a problem is to reduce the coupling inductance.
  • an electrical transformer comprising a magnetic core providing a closed magnetic circuit around an aperture, first and second conductors providing relatively large electrically conductive areas and arranged to extend across the aperture with the core between them, a plurality of primary windings wound on the core all in a single-layer and extending through the core aperture and terminating on the conductors so as to be connected in parallel thereby, third and fourth conductors providing relatively large electrically conductive areas and respectively arranged adjacent to but insulated from the first and second conductors, and a plurality of secondary windings wound on the core all in a single-layer and extending through the core aperture and terminating on the third and fourth conductors so as to be connected in parallel thereby.
  • FIG. 1 is a plan view of the transformer
  • FIG. 2 is a section on the line II-ll of FIG. 1.
  • the transformer comprises a ferrite toroid 5 on which are mounted upper and lower stepped insulating rings 6 and 8.
  • a conductive washer or centrally apertured disk 10, 12, made of copper for example, is mounted on each insulating ring 6, 8.
  • the primary of the transformer consists of 20 (in this example) parallel-connected center-tapped windings 14 (only some being referenced on the drawing), each winding having two bifilar turns.
  • FIG. 2 shows one of the windings 14 in greater detail. This winding consists of two turns 14A and 148.
  • the turn 14A is soldered to the conductive disk at a point 16 and is led therefrom down the outside surface of the toroid 5, then round the toroid in an anti-clockwise direction as viewed in F IG. 2 so as to pass down the outside surface of the toroid 5 again until it is finally curved round the lowest edge of a copper band 19 and soldered thereto at a point 20.
  • the other turn 14B of the winding in question is soldered to the band 18 at a point 22, then looped round the top edge of the band and passes down the outer surface of the toroid 5, around the toroid in an anti-clockwise direction and is finally terminated by soldering to the lower conductive disk 12 at a point 24.
  • the other primary windings are arranged similarly and each consists of two wires.
  • the band 18 completely encircles the outside of the toroid 5 and is insulated from the windings thereon by a liner 25 of p.t.f.e. or similar material.
  • the two ends of the band are bent outwardly of the toroid 5, as shown in FIG. 1, to form the primary winding center-tap terminal 26.
  • the secondary of the transformer has a higher impedance and consists of four (in this example) windings 32 to 38.
  • Each winding comprises five turns, made of p.t.f.e. insulated wire for example, interwound with the primary windings.
  • winding 32 has five turns 32A to 32E (FIGJ). As shown in FIG. 2, one end of the winding 32 passes through an aperture in the upper conductive disk 28,'where it is electrically connected in parallel with the corresponding end of the other three secondary windings, and the other end of the winding 32 passes through an aperture in the lower conductive disk 30 where it is connected in parallel with the other ends of 'the secondary windings. The two ends of the secondary windings are connected to respective conductive washers or centrally apertured disks 40, 42 (omitted from FIG.
  • the terminal 26 is a center-tap terminal of the primary.
  • the transformer described has very low leakage inductance, and yet maintains a reasonable value of coupling inductance between the primary and secondary windings. Furthermore, the circumferential band 18 and the single-layer and unifonn nature of the windings minimize problems caused by heating.
  • the described transformer is particularly suitable for use in transistor h.f. power amplifiers.
  • the disks 28 and 30 can be formed with integral and projecting connecting tags.
  • a U- shapedband may be arranged to partially encompass the circular band 18 and to be in electrical contact therewith to provide a center-tap temiination to replace the terminal 26 of FIG. 1.
  • Such modified arrangement is particularly suitable for printed circuit board mounting.
  • An electrical transformer comprising a magnetic core providing a closed magnetic circuit extending around and defining an aperture
  • first and second electrical conductors each providing relatively large electrically conductive area
  • third and fourth conductors each providing relatively large electrically conductive area
  • each of the first and second conductors defines a through hole, in which the third and fourth conductors are respectively mounted outside of the first and second conductors, and in which the ends of the secondary windings extend with electrically insulating clearance through the holes in the first and second conductors to the third and fourth conductors.
  • each of the primary and secondary windings comprises a plurality of turns and the turns of the primary windings are arranged in bi-filar form.
  • a transformer according to claim 1 including an electrically conductive band at least partially encircling the outer periphery of the core, and in which each primary winding comprises a first turn connected at one end to the first conductor and wound round the core and terminating at an electrical connection on the said band, and a second turn electrically connected to the said band and wound round the core and terminating at an electrical connection on the second conductor.
  • a high frequency, wideband electrical transformer comprising a toroidal core, first and second planar, apertured electrical conductors mounted on opposite sides of the core with their apertures coaxial with the core, an electrically conductive band encircling the outer periphery of the core, a plurality of primary windings wound on the core all in single-layer form, each primary winding having two bi-filar turns one of which is electrically connected at one end to the first conductor and winds round the core and is electrically connected at the other end to the said band, and the other of which is electrically connected at one end to the said band and winds round the core and is electrically connected at the other end to the second conductor, such that the said band provides a center-tap terminal for the transformer,
  • third and fourth planar electrical conductors respectively arranged outside of and adjacent to but electrically insulated from the first and second conductors
  • each winding comprising a plurality of turns round the core with one end of each winding extending with electrically insulating clearance through the aperture in the first conductor to an electrical connection on the third conductor and the other end of each winding extending with electrically insulating clearance through the aperture in the second conductor to an electrical connection on the fourth conductor.
  • each turn of the secondary winding is made of p.t.f.e. insulated wire
  • a transformer according to claim 6, including respective terminal means on each of the first, second, third and fourth conductors and on the said conductive band, for making external connections to the transformer.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Coils Or Transformers For Communication (AREA)
US142567A 1970-05-12 1971-05-12 Electrical transformers Expired - Lifetime US3675176A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2282770 1970-05-12

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US3675176A true US3675176A (en) 1972-07-04

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US (1) US3675176A (enrdf_load_stackoverflow)
GB (1) GB1297423A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4524342A (en) * 1981-12-28 1985-06-18 Allied Corporation Toroidal core electromagnetic device
US4536733A (en) * 1982-09-30 1985-08-20 Sperry Corporation High frequency inverter transformer for power supplies
US5083101A (en) * 1990-01-03 1992-01-21 Integrated Power Components Integrated electromagnetic interference filter
EP0532360A1 (en) * 1991-09-13 1993-03-17 Vlt Corporation Transformer with controlled interwinding coupling and controlled leakage inductances and circuit using such transformer
US6143157A (en) * 1995-11-27 2000-11-07 Vlt Corporation Plating permeable cores
US20030006874A1 (en) * 2001-07-06 2003-01-09 Chin-Kuo Chou Winding structure of inductor used in power factor correction circuit
US12033783B2 (en) * 2021-02-18 2024-07-09 Global Hises Co.,Ltd Power saving device

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3008108A (en) * 1956-11-13 1961-11-07 Burroughs Corp Toroidal coils
US3179908A (en) * 1960-08-25 1965-04-20 Emp Electronics Inc Heat exchange means for electromagnetic devices
FR1552259A (enrdf_load_stackoverflow) * 1967-11-24 1969-01-03
US3453574A (en) * 1968-03-22 1969-07-01 Atomic Energy Commission High-frequency,wide-band transformer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3008108A (en) * 1956-11-13 1961-11-07 Burroughs Corp Toroidal coils
US3179908A (en) * 1960-08-25 1965-04-20 Emp Electronics Inc Heat exchange means for electromagnetic devices
FR1552259A (enrdf_load_stackoverflow) * 1967-11-24 1969-01-03
US3453574A (en) * 1968-03-22 1969-07-01 Atomic Energy Commission High-frequency,wide-band transformer

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4524342A (en) * 1981-12-28 1985-06-18 Allied Corporation Toroidal core electromagnetic device
US4536733A (en) * 1982-09-30 1985-08-20 Sperry Corporation High frequency inverter transformer for power supplies
US5083101A (en) * 1990-01-03 1992-01-21 Integrated Power Components Integrated electromagnetic interference filter
EP0532360A1 (en) * 1991-09-13 1993-03-17 Vlt Corporation Transformer with controlled interwinding coupling and controlled leakage inductances and circuit using such transformer
US5546065A (en) * 1991-09-13 1996-08-13 Vlt Corporation High frequency circuit having a transformer with controlled interwinding coupling and controlled leakage inductances
US6653924B2 (en) 1991-09-13 2003-11-25 Vlt Corporation Transformer with controlled interwinding coupling and controlled leakage inductances and circuit using such transformer
US6143157A (en) * 1995-11-27 2000-11-07 Vlt Corporation Plating permeable cores
US6165340A (en) * 1995-11-27 2000-12-26 Vlt Corporation Plating permeable cores
US20030006874A1 (en) * 2001-07-06 2003-01-09 Chin-Kuo Chou Winding structure of inductor used in power factor correction circuit
US7113068B2 (en) * 2001-07-06 2006-09-26 Chin-Kuo Chou Winding structure of inductor used in power factor correction circuit
US12033783B2 (en) * 2021-02-18 2024-07-09 Global Hises Co.,Ltd Power saving device

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Publication number Publication date
GB1297423A (enrdf_load_stackoverflow) 1972-11-22

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