Transformer having fractional turn windings

• US 6,348,848 B1
• Filed: 05/03/2001
• Issued: 02/19/2002
• Est. Priority Date: 05/04/2000
• Status: Expired due to Fees

• Current Assignee: Herbert, Edward
• Original Assignee: Herbert, Edward
• Inventors: Herbert, Edward
• Primary Examiner(s): Donovan, Lincoln
• Assistant Examiner(s): NGUYEN, TUYEN T
• Application Number:
  US09/848,671
• Time in Patent Office: 292 Days
• Field of Search: 323/362, 323/331-334, 323/308, 323/249, 335/209-306, 363/45, 363/91, 363/126, 336/178, 336/212
• US Class Current: 336/178
• CPC Class Codes: H01F 29/14 with variable magnetic bias amplitude modulation by means of variable impedance element H03C1/08 ; magnetic amplifiers H03F; circuits for automatic telephonic communication H04M3/00
• CPC Class Codes: H01F 3/12 Magnetic shunt paths
• CPC Class Codes: H01F 30/10 Single-phase transformers H01F30/16 takes precedence

Abstract

In a transformer wound on a core having three or more legs (N legs), N−1 of the legs can have a flux distribution winding on them comprising flux distribution coils on each of the N−1 legs. The flux distribution coils are all connected together, usually in phase, so all of the coils see the same voltage. If the several coils have different numbers of turns, then the volt per turn will differ inversely, and so too will the flux in the N−1 legs. The flux in the Nth leg is the algebraic sum of the flux in the N−1 legs, and is usually the “Main” flux path. A winding around one of the legs would have a terminal voltage proportional to the number of turns and the flux in the leg. A winding may make several turns around the main leg of the transformer, then make one or more turns around a side leg having a different flux, usually some fraction of the flux in the main leg. The extra turns, having a fractional flux, are the equivalent of a fractional turn. The ampere-turns are reconciled by a circulating current in the flux distribution windings.

Claims

1. A transformer having fractional equivalent turns on at least one winding, comprising

at least a first magnetic core,

the at least a first magnetic core comprising a magnetic circuit having at least three flux paths,

a source of magnetomotive force to generate magnetic flux in the at least three flux paths,

the source of magnetomotive force having a phase defined by the timing and the direction of the flux

which it generates in the at least three flux paths, and

a flux distribution winding to determine the distribution of the flux in the at least three flux paths comprising

a first flux distribution coil wound around one of the at least three flux paths, and

at least a second flux distribution coil wound around

at least a second of the at least three flux paths,

the at least a first flux distribution coil having a number n turns where n is a positive or negative integer, the sign of the number n indicating its phase with respect to the phase of the source of magnetomotive force,

the at least a second flux distribution coil having a number m turns where m is a positive or negative integer, the sign of the number m indicating its phase with respect to the phase of the source of magnetomotive force,

the first flux distribution coil and at least the at least a second flux distribution coil further being connected together so that the first flux distribution coil and at least the at least a second flux distribution coil have a common terminal voltage Vt induced in the first flux distribution coil and at least the at least a second flux distribution coil by the flux through the first flux distribution coil and the flux through at least the at least a second flux distribution coil,

whereby through flux through the first flux distribution coil is proportional to Vt divided by n and whereby the flux through the at least a second flux distribution coil is proportional to Vt divided by m.

2. The transformer of claim 1 wherein a total number of flux paths comprising the at least three flux paths is a number x and a total number of flux distributing coils comprising the first flux distributing coil and the at least a second flux distributing coil is a number equal to x minus one.

3. The transformer of claim 1 wherein the input of the transformer is connected to the flux distribution winding.

4. The transformer of claim 1 wherein an output of the transformer is connected from the flux distribution winding.

5. The transformer of claim 1 wherein the first flux distribution coil and the at least a second flux distribution coil are connected with the same phase.

6. The transformer of claim 1 wherein the first flux distribution coil and the at least a second flux distribution coil are connected with opposite phase.

7. The transformer of claim 1 further comprising at least a first additional winding wound around at least one of the at least three flux paths.

8. The transformer of claim 7 wherein the at least additional winding is wound around one of the at least three flux paths.

9. The transformer of claim 7 wherein the at least one additional winding is wound first around a first flux path of the at least three flux paths with a number of turns equal a number u and then around at least a second flux path of the at least three flux paths with a number of turns equal the number v where u and v are negative or positive integers and where the sign of the integer indicates its phase with respect to the phase of the source of electromotive force whereby a voltage induced in the at least a first additional winding will be proportional to u times the flux through the first flux path plus v times the flux through the second flux path.

10. The transformer of claim 7 wherein the input to the transformer is connected to the at least one additional winding.

11. The transformer of claim 8 wherein an output from the transformer is connected to the at least one additional winding.

12. The transformer of claim 1 wherein at least one of the first flux distribution coil and the at least a second flux distribution coil is a tapped coil.

13. The transformer of claim 2 wherein the total number of flux paths is five, comprising a main flux path and first, second, third and fourth return flux paths, and wherein the total number of flux distribution coils is at least four, comprising at least first, second, third and fourth flux distribution coils.

14. The transformer of claim 13 wherein the first flux distribution coil is on the first return flux path, the second flux distribution coil is on the second return flux path, the third flux distribution coil is on the third return flux path and the fourth flux distribution coil is on the fourth return flux path.

15. The transformer of claim 14 wherein the respective first, second, third and fourth flux distribution coils have a ratio of three to four to six to twelve, whereby the magnitude of the flux in the respective first, second, third and fourth return flux paths will have a ratio with respect to each other of 4 to 3 to 2 to 1 and the magnitude of the flux in the respective first, second, third and fourth return flux paths is respectively 0.4, 0.3, 0.2 and 0.1 times the flux in the main flux path.

16. The transformer of claim 14 wherein the first flux distribution coil is connected to the second flux distribution coil and the third flux distribution coil is connected to the fourth flux distribution coil, and further comprising a fifth flux distribution coil wound around both of the first return flux path and the second return flux path and a sixth flux distribution coil wound around both the third return flux path and the fourth return flux path.

17. The transformer of claim 16 wherein the first flux distribution coil has one times x turn, the second flux distribution coil has four times x turns, the third flux distribution coil has two times y turns, the fourth flux distribution coil as three times y turns, the fifth flux distribution coil has one times z turns and the sixth flux distribution coil has one times z turns, where x, y and z are integers, whereby the magnitude of the flux in the respective first, second, third and fourth return flux paths is respectively 0.4, 0.1, 0.3 and 0.2 times the flux in the main flux path.