The present application relates generally to transformers and, more particularly, to transformer assemblies designed to minimize stray losses.
Transformers are common electrical components used in electrical distribution, transmission, and control systems to transform an input voltage to a desired output voltage. The efficiency of conventional transformers is limited by energy losses associated with joule heating in the transformer windings, core losses (such as hysteresis and eddy current losses in the core), and stray losses. Stray losses result from magnetic flux leaking out of the transformer core and inducing eddy currents in conductive materials within the transformer assembly. These eddy currents are ultimately dissipated through resistive heat generation, which can often contribute to overheating and failure of transformers. Additionally, stray losses (and the resulting eddy currents) are amplified, often significantly, in transformers supplying voltage to a non-linear load, such as electronic equipment. Conventional transformers are not designed to minimize such stray losses.
In one aspect, a transformer is provided. The transformer includes a magnetic core, a first winding assembly, and a second winding assembly. The magnetic core includes a plurality of legs, including a first winding leg. The first winding assembly includes a first conductive conduit helically wound around the first winding leg a first number of turns. The first winding assembly has a first magnetic length. The second winding assembly includes a second conductive conduit wound around one of the plurality of legs a second number of turns. The second winding assembly is inductively coupled to the first winding assembly, and has a second magnetic length substantially equal to said first magnetic length.
In another aspect, a transformer is provided. The transformer includes a magnetic core, a first winding assembly, and a second winding assembly. The magnetic core includes a winding leg. The first winding assembly includes a plurality of first layers, and is inductively coupled to the magnetic core. The second winding assembly is inductively coupled to the first winding assembly. The second winding assembly includes a plurality of second layers. The first and second winding assemblies are concentrically wound around the winding leg in an interleaved configuration such that each second layer is disposed between at least two adjacent first layers.
In yet another aspect, a method of assembling a transformer is described. The method includes providing a magnetic core including a plurality of legs including a first winding leg, providing a first winding assembly including a first conductive conduit, providing a second winding assembly including a second conductive conduit, inductively coupling the first winding assembly to the magnetic core by helically winding the first conductive conduit around the first winding leg a first number of turns such that the first winding assembly has a first magnetic length, and inductively coupling the second winding assembly to the first winding assembly by winding the second conductive conduit around one leg of the plurality of legs a second number of turns such that the second winding assembly has a second magnetic length substantially equal to the first magnetic length.
In yet another aspect, a method of assembling a transformer is described. The method includes providing a magnetic core including a winding leg, providing a first winding assembly including a plurality of first layers, providing a second winding assembly including a plurality of second layers, and concentrically winding the first and second winding assemblies around the winding leg of the magnetic core in an interleaved configuration such that each second layer is disposed between at least two adjacent first layers.
Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing.
Exemplary embodiments of low stray-loss transformers are described herein. In one embodiment, a transformer includes a magnetic core, a first winding assembly, and a second winding assembly. The magnetic core includes a plurality of legs, including a first winding leg. The first winding assembly has a first magnetic length, and includes a first conductive conduit helically wound around the first winding leg a first number of turns. The second winding assembly is inductively coupled to the first winding assembly, and includes a second conductive conduit wound around one of the plurality of legs a second number of turns. The second winding assembly has a second magnetic length substantially equal to the first magnetic length. In another embodiment, a transformer includes a magnetic core, a first winding assembly, and a second winding assembly. The magnetic core includes a winding leg. The first winding assembly includes a plurality of first layers, and is inductively coupled to the magnetic core. The second winding assembly is inductively coupled to the first winding assembly, and includes a plurality of second layers. The first and second winding assemblies are concentrically wound around the winding leg in an interleaved configuration. Each second layer is disposed between at least two adjacent first layers.
Magnetic core 102 includes generally parallel first and second winding legs 108 and 110 coupled together by upper and lower portions 112 and 114 of magnetic core 102. Together, first and second winding legs 108 and 110, and upper and lower portions 112 and 114 form a closed loop for magnetic flux generated by first and/or second winding assemblies 104 and 106. In the embodiment illustrated in
First and second winding assemblies 104 and 106 are inductively coupled to one another by magnetic core 102. More specifically, first winding assembly 104 includes one or more conductive conduits 116 connected in parallel and helically wound around first leg 108, forming a number of turns N104 around first leg 108. Similarly, second winding assembly 106 includes one or more conductive conduits 118 connected in parallel and helically wound around second leg 110, forming a number of turns N106 around second leg 110. The ratio of N104 to N106 is the turns ratio of transformer 100, and can be adjusted to obtain a desired step up or step down between an input voltage and an output voltage.
In the embodiment illustrated in
In the embodiment illustrated in
In operation, first and second terminal ends 120 and 122 of first winding assembly 104 are connected to the positive and negative terminals of a voltage source (not shown), and the first and second terminal ends 124 and 126 of second winding assembly 106 are connected to the input and output terminals of a load (not shown). Current flowing through first winding assembly 104 induces a current in second winding assembly 106, which is delivered to the load at a desired voltage. Alternatively, second winding assembly 106 may be connected to a voltage source, and first winding assembly 104 may be connected to a load.
Each winding assembly 104 and 106 has an axial length L104 and L106. As shown in
Magnetic lengths M104 and M106 of winding assemblies 104 and 106 can be determined based upon axial lengths L104 and L106 of winding assemblies 104 and 106. In particular, magnetic length M104 of first winding assembly 104 is equal to
where L104 is the axial length of first winding assembly 104 and N104 is the number of turns of first winding assembly 104. Similarly, magnetic length M106 of second winding assembly 106 is equal to
where L106 is the axial length of second winding assembly 106 and N106 is the number of turns in second winding assembly 106.
Partially wound sections 128 of transformer 100 account for at least some of the stray losses limiting the efficiency of transformer 100. Stray losses related to partially wound sections 128 are amplified where the magnetic length of one winding assembly is different than the magnetic length of a second winding assembly.
Referring back to
where L104 is the axial length of first winding assembly 104, N106 is the number of turns in second winding assembly 106, and N104 is the number of turns in first winding assembly 104. Alternatively, axial length L104 of first winding assembly 104 may be based upon axial length L106 of second winding assembly 106. As a result, magnetic lengths M104 and M106 of first and second winding assemblies 104 and 106 are substantially equal to one another. Therefore, the structure of transformer 100 improves efficiency over conventional transformers by reducing stray losses.
Although transformer 100 is illustrated as including two winding assemblies and two winding legs, transformer 100 is not limited to the specific embodiment illustrated in
Second winding assembly 302 of transformer 300 is a disk-type winding assembly. More specifically, second winding assembly 302 includes a conductive conduit 304 wound around second leg 110 to form a plurality of disks 306 serially disposed along the axial length of second leg 110. Each disk 306 is formed by one or more concentric layers of conductive conduit 304 extending in a radial direction relative to the longitudinal axis of second leg 110. Each layer corresponds to one turn of second winding assembly 302 around second leg 110. Second winding assembly 302 is wound around second leg 110 a total of N302 turns. Disks 306 are connected in series, and are wound alternately from inside to outside and from outside to inside such that disks 306 are formed from a single conductive conduit.
In the embodiment illustrated in
Similar to transformer 300, in operation, first and second terminal ends 120 and 122 of first winding assembly 104 are connected to the positive and negative terminals of a voltage source (not shown), and the first and second terminal ends 308 and 310 of second winding assembly 302 are connected to the input and output terminals of a load (not shown). Current flowing through first winding assembly 104 induces a current in second winding assembly 302, which is delivered to the load at a desired voltage. Alternatively, second winding assembly 302 may be connected to a voltage source, and first winding assembly 104 may be connected to a load.
Similar to first and second winding assemblies 104 and 106 of transformer 100, second winding assembly 302 has an axial length L302 and a magnetic length M302. Because second winding assembly 302 is a disk-type winding assembly, there are no partially wound sections 128 on second leg 110 of magnetic core 102. As a result, axial length L302 and magnetic length M302 are substantially equal.
Similar to transformer 100, transformer 300 is assembled such that the first and second winding assemblies 104 and 302 have substantially equal magnetic lengths M104 and M302. In particular, axial length L302 of second winding assembly 302 is based upon the magnetic length M104 of first winding assembly 104, which in turn is based upon axial length L104 of first winding assembly 104. Using the above relationships between the axial length of a given winding assembly and the magnetic length of a given winding assembly, axial length L302 of second winding assembly 302 may be selected according to the following equation:
where L104 is the axial length of first winding assembly 104, and N104 is the number of turns in first winding assembly 104. Alternatively, axial length L104 of first winding assembly 104 may be based upon axial length L302 of second winding assembly 302. In such embodiments, axial length L104 of first winding assembly 104 may be selected according to the following equation:
where L302 is the axial length of second winding assembly 302, and N104 is the number of turns in first winding assembly 104. As a result, transformer 300 may be assembled such that magnetic lengths M104 and M302 of first and second winding assemblies 104 and 304 are substantially equal to one another. Therefore, the structure of transformer 300 improves efficiency over conventional transformers by reducing stray losses.
Although transformer 300 is illustrated as including two winding assemblies and two winding legs, transformer 300 is not limited to the specific embodiment illustrated in
Referring now to
In the embodiment illustrated in
First winding assembly 404 and second winding assembly 406 are concentrically wound around second leg 410 of magnetic core 402. First and second winding assemblies 404 and 406 are also coaxially aligned with a longitudinal axis 418 of second leg 410 of magnetic core 402. First and second winding assemblies 404 and 406 are thus inductively coupled to one another by magnetic core 402.
First winding assembly 404 includes a plurality of first layers 420 each formed by a single, continuous piece of conductive material. In the embodiment shown in
In the embodiment illustrated in
Second winding assembly 406 includes a plurality of second layers 422 each formed by a single, continuous piece of conductive material. In the embodiment shown in
Second conductive conduit 504 is wound such that the orientation of each second layer 422 of second winding assembly 406 is substantially opposite the orientation of each first layer 420 of first winding assembly 404. Thus, second winding assembly 406 is wound around second leg 410 of magnetic core 402 in a second orientation that is substantially opposite first orientation of first winding assembly 404. In the embodiment illustrated in
In the embodiment illustrated in
As shown in
Although transformer 400 is illustrated as including two winding assemblies and one winding leg, transformer 400 is not limited to the specific embodiment illustrated in
The direction of current flowing through each conductive conduit 502 and 504 in each first and second layer 420 and 422 is illustrated by an “X,” indicting current flowing into the page, or an “●” indicting current flowing out of the page. As shown in
Referring now to
As shown in
Referring now to
Exemplary embodiments of low stray-loss transformers are described herein. In one embodiment, a transformer includes a magnetic core, a first winding assembly, and a second winding assembly. The magnetic core includes a plurality of legs, including a first winding leg. The first winding assembly has a first magnetic length, and includes a first conductive conduit helically wound around the first winding leg a first number of turns. The second winding assembly is inductively coupled to the first winding assembly, and includes a second conductive conduit wound around one of the plurality of legs a second number of turns. The second winding assembly has a second magnetic length substantially equal to the first magnetic length. In another embodiment, a transformer includes a magnetic core, a first winding assembly, and a second winding assembly. The magnetic core includes a winding leg. The first winding assembly includes a plurality of first layers, and is inductively coupled to the magnetic core. The second winding assembly is inductively coupled to the first winding assembly, and includes a plurality of second layers. The first and second winding assemblies are concentrically wound around the winding leg in an interleaved configuration. Each second layer is disposed between at least two adjacent first layers.
As compared to at least some transformers, in the systems and methods described herein, a transformer utilizes winding assemblies having substantially equal magnetic lengths. Winding assemblies having substantially equal magnetic lengths reduces stray losses associated with the partially wound sections of a magnetic core. As a result, transformers utilizing windings having substantially equal magnetic lengths have lower stray losses and improved efficiency compared to conventional transformers. Additionally, in the systems and methods described herein, a transformer utilizes concentric winding assemblies arranged in an alternating or interleaved configuration. In concentric winding assemblies arranged in an alternating or interleaved configuration, the ampere-turns of one winding assembly counteract the ampere-turns of the other winding assembly, thereby reducing the peak number of cumulative ampere-turns, and correspondingly, stray losses associated with leakage flux within transformer windings. As a result, transformers utilizing concentric winding assemblies arranged in an alternating or interleaved configuration have lower stray losses and improved efficiency compared to conventional transformers.
Additionally, utilizing winding assemblies having substantially equal magnetic lengths and/or concentrically wound winding assemblies arranged in an interleaved configuration facilitates the construction of lighter, more compact transformers. Because these designs reduce stray losses compared to conventional transformers, less heat is generated during operation. As a result, transformers may have a lighter, more compact construction because less heat needs to be dissipated during operation. This is a particularly significant advantage for transformers supplying voltages to non-linear loads, such as electronic equipment, as such transformers are often significantly oversized to prevent overheating.
Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
This application is a continuation application of U.S. patent application Ser. No. 13/893,046, filed May 13, 2013, which is incorporated herein by reference in its entirety.
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Number | Date | Country | |
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20170236637 A1 | Aug 2017 | US |
Number | Date | Country | |
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Parent | 13893046 | May 2013 | US |
Child | 15583653 | US |