Transformer and method for stepping down voltage

Abstract

Transformer and method of stepping down voltage. According to various aspects, transformers are disclosed herein, wherein the primary coil branches into at least two series including a first series and a second series. The first series is interlaced with the secondary coil. The second series is wound separately from the interlaced coil. Methods of making and using these transformers are also disclosed.

Description

Technical Field

[0001] The present disclosure relates to adjustable leakage inductance in a transformer. Background Art

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] Wireless chargers provide users with a convenient way to recharge various types of battery-powered electronic devices and machines. Mobile phones, digital cameras, and game controllers are examples of devices that may have batteries that can be recharged by wireless chargers. In the pulse width modulation (PWM) mode of the power supply for soft switching (e.g., zero voltage and zero current switching) technology, the leakage inductance of the main transformer becomes very important to participate in the resonant action with the capacitor to achieve soft switching.

[0004] Prior art transformers are constructed so that the primary and secondary coils are wound independently or interwound (so-called "sandwich" windings) on the core. The range of leakage inductance modification in these constructions is not flexible. The improved transformer can reduce switching losses from metal oxide semiconductor field effect transistor (MOSFET) diodes at higher frequencies, especially in high voltage and / or high current applications, such as popular on-board charging (OBC) communication stations.

[0005] However, how to achieve accurate and flexible leakage inductance from the transformer winding structure remains a problem. That is, for one transformer winding structure, the adjustable leakage inductance range is very narrow. In addition, AC (alternating current) copper loss increases. Summary of the invention

[0006] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0007] According to various aspects, an exemplary embodiment of a transformer is disclosed, which includes a primary coil, a secondary coil and a core. The primary coil branches into at least two (e.g., three) series. For example, the primary coil may be branched into multiple series (at least two), of which (at least) the first one is wound together with the secondary coil using a sandwich configuration. The second (or more) branches of the primary coil are wound independently. By adjusting the ratio of the number of turns of the first primary coil series, flexible control of the leakage inductance is obtained. In addition, since the second primary coil series is kept at a certain distance from the secondary coil (which can be wound together with the first primary coil series in a "sandwich" manner), the AC loss will remain stable during the adjustment of the leakage inductance.

[0008] In a particular embodiment, a first series of primary coils are interlaced with the secondary coils and a second series of primary coils are not interlaced with the secondary coils. In a particular embodiment, the interlacing is arranged in a sandwich configuration.

[0009] Methods of using these transformers are also disclosed herein. According to various aspects, an exemplary embodiment of a method of stepping down a voltage is disclosed, the method comprising supplying current to a transformer comprising a primary coil, a secondary coil, and a core. The primary coil branches into at least two series comprising a first series and a second series. The first series of the primary coil is interlaced with the secondary coil. The second series of the primary coil is not interlaced with the secondary coil. The sum of the windings of the primary coil series is greater than the secondary coil winding.

[0010] Methods of manufacturing these transformers are also disclosed herein. Additional areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended to be illustrative only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0012] Figure 1 is a perspective view of a transformer according to an exemplary embodiment.

[0013] Figure 2 is a cross-sectional view illustrating a three-dimensional arrangement of components of a transformer according to an exemplary embodiment.

[0014] Figure 3 is a line graph showing the resonant inductance (in microhenries (μH)) of a transformer versus the number of primary turns B (the number of turns in the second series of two series of primary coils) according to an exemplary embodiment.

[0015] Figure 4 is a line graph showing the ratio of AC resistance to DC resistance (ACR / DCR) of a transformer versus frequency (in kilohertz (KHz)) from 0 to 200 KHz according to an exemplary embodiment.

[0016] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0017] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0018] Exemplary embodiments of transformers and methods disclosed herein can alleviate the problems mentioned above in the background. In certain embodiments, exemplary embodiments of transformers disclosed herein can be advantageously used in soft switching techniques for zero voltage switching (ZVS) and zero current switching (ZCS) applications. In particular, these transformers and methods flexibly and accurately control leakage inductance without changing the transformer design and without changing efficiency performance.

[0019] Disclosed herein are exemplary embodiments of a transformer in which the primary coil is branched into multiple series (at least two), one (or more) of which is wound together with the secondary coil. In a specific embodiment, the first primary coil branch is wound with the secondary coil in a "sandwich" configuration. The remaining primary coil branches are wound around the core independently. By adjusting the number of turns in the branches of the primary series that are wound together with the secondary series, flexible control of the leakage inductance can be obtained. In addition, the independent coils of the primary branches are arranged at any given desired distance from the secondary coil. By adjusting this distance, the AC losses can be kept or maintained stable regardless of the leakage inductance modification.

[0020] Now referring to the accompanying drawings, Figure 1 An exemplary embodiment of a transformer (100) embodying one or more aspects of the present disclosure is shown. Figure 1 As shown, the transformer (100) includes coils (103, 104, 105) wound around a core (102). Figure 1 The core (102) shown is an E-shaped core, but aspects of the invention disclosed herein may work equally well with other core shapes (e.g., I-shaped, C-shaped, L-shaped, O-shaped, etc.). In certain embodiments, the core may have a shell structure. The core may be a single-phase or multi-phase structure. Similarly, Figure 1 The core (102) is shown as a solid body. However, in other embodiments, the core may be composed of multiple thin layers (eg, insulating iron or ferrite, etc.).

[0021] In this exemplary embodiment, the primary coils (103, 105) are branched into two series. In other embodiments, the primary coils may be divided into more than two (e.g., 3, 4, 5, 6, 7, 8, 9, 10 or more) branches. One primary coil branch (103) is interwoven with the secondary coil (104). The other primary coil branch (105) is wound around the core at a distance from the interwoven series (103 / 104). Figure 2 An exemplary embodiment of such interlaced windings is shown in , which shows a two-dimensional cross-section of an exemplary embodiment of a transformer as disclosed herein. The two windings of the secondary coil are sandwiched between the three windings of the first primary coil branch. The second branch of the primary coil is wound separately.

[0022] The inventors of the present invention unexpectedly discovered that ( Figure 3 ), when the windings are arranged as disclosed herein, the resonant inductance is proportional to the number of turns of the interlaced coils. In a particularly surprising discovery, the inventors of the present invention have found that the rate of increase in resonant inductance increases dramatically at 6 turns. See, for example, Figure 3, which shows a line graph showing the resonant inductance (in microhenries (μH)) of a transformer according to an exemplary embodiment versus the number of primary turns B (the number of turns in the second series of two series of primary coils).

[0023] However, although the leakage inductance can be controlled by adjusting the number of coil turns as shown above, the resulting AC losses ( Figure 4 ). See, for example, Figure 4 , which shows a graph showing the ratio of AC resistance to DC resistance (ACR / DCR) of a transformer according to an exemplary embodiment versus frequency (in kilohertz (KHz)) from 0 to 200 KHz. Figure 4 As shown, ACR / DCR increases slightly from about 1 to about 1.1 in the frequency range of about 0 to 200 KHz.

[0024] return Figure 1 , the AC loss can be stabilized by adjusting the distance between 103 / 104 and 105. In a specific embodiment, the gap between 103 / 104 and 105 is no wider than the coil width of 105, such as no wider than half the coil width of 105, no wider than one-third the coil width of 105, or no wider than one-quarter the coil width of 105. In a specific embodiment, the gap between 103 / 104 and 105 is at least one-quarter the width of the coil of 105, such as at least one-third the width of the coil of 105, at least one-half the width of the coil of 105, at least as wide as the width of the coil of 105, at least one and a half times (1.5x) the width of the coil of 105, or at least twice the width of the coil of 105. In particular embodiments, the gap between 103 / 104 and 105 is between about one quarter and twice the width of the coil of 105, for example, between about one third and one and a half (1.5x) the width of the coil of 105, or between about half and about the same width.

[0025] The exemplary embodiments of the transformers described above can improve ZVS and ZCS applications. The transformer structures disclosed herein are very advantageous compared to conventional coil winding structures. For example, by adjusting the gap width as disclosed herein, the leakage inductance can be precisely controlled at the initial design stage, thus avoiding the need to repeatedly adjust the coil packaging in an already constructed transformer.

[0026] Also disclosed herein are methods of making exemplary embodiments of the above-described transformers. As described above, these transformers can be made by winding a coil around a core. The transformers described herein have two coils: a primary coil and a secondary coil. In the case where the transformer is intended to "step up" the output voltage relative to the input voltage, the secondary coil has more windings than the primary coil. In the case where the transformer is intended to "step down" the output voltage relative to the input voltage, the primary coil has more windings than the secondary coil. Figure 2 The transformer shown is a "step-down" transformer, but in Figure 2 The number of coil windings can be varied in the illustrated embodiment to create a "step-up" transformer. Regardless of whether the transformer is a "step-up" transformer or a "step-down" transformer, the exemplary transformers disclosed herein can be manufactured by dividing the primary coil into at least two branches, then winding one of those branches around the core by itself while the other branch is wound around the core in an interlaced configuration with the secondary coil.

[0027] Also disclosed herein is a method for stepping down a voltage. In a specific embodiment, the method includes supplying a current to a transformer, wherein the transformer includes a primary coil, a secondary coil, and a core. The primary coil branches into at least two series. The first series of the primary coil is interlaced with the secondary coil. The second series of the primary coil is not interlaced with the secondary coil. The sum of the windings of the primary coil series is greater than the secondary coil winding. In a specific embodiment of the method, the interlacing is arranged in a sandwich configuration. In a specific embodiment, the primary coil branches into at least three series, such as at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10 series, etc. The space between the first and second primary coil series defines a gap. In a specific embodiment, the gap between the first and second primary coil series is not wider than the coil width of the second primary coil series, such as not wider than half of the width of the second primary coil series, not wider than about one-third of the width of the second primary coil series, or not wider than about one-quarter of the width of the second primary coil series.

[0028] Example embodiments are provided so that the present disclosure is thorough and the scope is fully conveyed to those skilled in the art. Many specific details such as examples of specific components, devices, and methods are stated to provide a thorough understanding of the embodiments of the present disclosure. It is obvious to those skilled in the art that specific details need not be adopted, the example embodiments can be implemented in many different forms, and the example embodiments should not be interpreted as limiting the scope of the disclosure. In certain exemplary embodiments, known processes, known device structures, and known technologies are not described in detail. In addition, the advantages and improvements that can be achieved by means of one or more exemplary embodiments of the present disclosure are provided only for illustrative purposes and do not limit the scope of the present disclosure, because the exemplary embodiments disclosed herein can provide all of the above advantages and improvements or none of them, and still fall within the scope of the present disclosure.

[0029] The specific size, specific material and / or specific shape disclosed herein are substantially exemplary, and do not limit the scope of the present disclosure. The specific value of a given parameter disclosed herein and the specific range of value do not exclude other values ​​and the range of value that can be used in one or more examples disclosed herein. Moreover, it is conceivable that any two specific values ​​of a specific parameter described herein can limit the endpoints of the range of the value that can be suitable for a given parameter (that is, the first value and the second value of a given parameter disclosed herein can be interpreted as the disclosure of a given value and can also adopt any value between the first value and the second value). For example, if parameter X is illustrated as having value A and is also illustrated as having value Z herein, it is conceivable that parameter X can have a value range from about A to about Z. Similarly, it is conceivable that two or more value ranges of a disclosed parameter (whether these ranges are nested, overlapped or different) contain all possible combinations of the value ranges that can utilize the endpoints of the disclosed range to advocate. For example, if parameter X is illustrated herein as having a value in the range of 1-10 or 2-9 or 3-8, it is also contemplated that parameter X may have other value ranges including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, and 3-9.

[0030] The terms used herein are only for describing specific example embodiments and are not intended to be limiting. As used herein, unless clearly indicated in the context, the singular forms "one", "an" are also intended to include plural forms. The terms "include", "comprise" and "have" can be used interchangeably, so the features, wholes, steps, operations, elements and / or parts are specified to exist, but one or more other features, wholes, steps, operations, elements, parts and / or groups thereof are not excluded from existence or addition. The method steps, processing and operations described herein should not be interpreted as requiring them to be performed in the specific order discussed or shown, unless the execution order is clearly identified. It should also be understood that additional or alternative steps can be adopted.

[0031] When an element or layer is referred to as being "on," "engaged to," "connected to," or "bound to" another element or layer, it may be directly on, engaged to, connected to, or bound to another element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly bound to" another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] The term "about" when applied to a value indicates that the calculation or measurement allows for some slight imprecision in the value (some proximity to the exact value of the value; approximately or reasonably close to the value; about the same). If for some reason the imprecision provided by "about" cannot be understood in this ordinary sense in the art, then "about" as used herein at least indicates variations that may occur due to ordinary measurement methods or use of these parameters. For example, the terms "usually", "about" and "roughly" may be used herein to indicate within manufacturing tolerances. Or, for example, the term "about" as used or employed herein to modify the amount of an ingredient or reactant of the present invention refers to variations in quantity that may occur due to typical measurement and processing procedures used, for example, in the preparation of concentrates or solutions in the real world; due to differences in the manufacture, source or purity of ingredients used to prepare the composition or perform the method; and so on. The term "about" also encompasses quantities that differ due to different equilibrium conditions of the composition obtained from a particular initial mixture. Whether or not modified by the term "about", the claims include equivalents of the amounts.

[0033] Although the term first, second, third etc. can be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or part from another region, layer or part. Terms such as "first", "second" and other numerical terms used herein do not imply order or sequence, unless the context clearly indicates. Therefore, without departing from the teaching of the example embodiments, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part.

[0034] For ease of description, spatially relative terms such as "inside", "outside", "below", "below", "down", "above", "upper", etc. may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figure. Spatially relative terms may be intended to cover different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, the elements described as being "below" or "below" other elements or features will be oriented to be "above" other elements or features. Therefore, the example term "below" may cover both the above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly.

[0035] The above description of the embodiments is provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. The independent elements, intended or described uses or features of a specific embodiment are generally not limited to the specific embodiment, but are interchangeable where applicable and can be used in the selected embodiment (even if not specifically shown or described). The embodiments can also be changed in many ways. Such variations are not considered to deviate from the disclosure, and all such modifications are intended to be included in the scope of the disclosure.

Claims

1. A transformer comprising a primary coil, a secondary coil and a core, wherein: The primary coil is branched into at least two series including a first series and a second series, the space gap between the first series and the second series is not wider than the coil width of the second series, and by adjusting the space gap between the first series and the second series, the AC loss of the coil winding of the transformer is maintained stable.

2. The transformer according to claim 1, wherein: The first series of the primary coils are interwoven with the secondary coils, and wherein the second series of the primary coils are not interwoven with the secondary coils.

3. The transformer according to claim 2, wherein: The interlaces are arranged in a sandwich configuration.

4. The transformer according to claim 2, wherein: The primary coil is branched into at least three series.

5. The transformer according to claim 4, wherein: The primary coil is branched into at least four series.

6. The transformer according to claim 1, wherein: The spatial gap is no wider than one-half the width of the coils of the second series.

7. The transformer according to claim 6, wherein: The spatial gap is no wider than one third of the width of the coils of the second series.

8. The transformer according to claim 7, wherein: The spatial gap is no wider than one quarter of the width of the coils of the second series.

9. The transformer according to claim 1, wherein: The transformer is a step-down transformer.

10. A method of stepping down a voltage, the method comprising supplying a current to a transformer, wherein: The transformer comprises a primary coil, a secondary coil and a core; The primary coil is branched into at least two series including a first series and a second series; said first series of said primary coils being interlaced with said secondary coils; said second series of said primary coils are not interlaced with said secondary coils; The sum of the windings of the primary coil series is greater than the secondary coil windings; and The space gap between the first series and the second series is not wider than the coil width of the second series, and by adjusting the space gap between the first series and the second series, the AC loss of the coil winding of the transformer is maintained stable.

11. The method according to claim 10, wherein: The interlaces are arranged in a sandwich configuration.

12. The method according to claim 11, wherein: The primary coil is branched into at least three series.

13. The method according to claim 12, wherein: The primary coil is branched into at least four series.

14. The method according to claim 10, wherein: The spatial gap is no wider than one-half the width of the coils of the second series.

15. The method according to claim 14, wherein: The spatial gap is no wider than one third of the width of the coils of the second series.

16. The method according to claim 15, wherein: The spatial gap is no wider than one quarter of the width of the coils of the second series.

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