Abstract:
Embodiments of the present invention pertain to windings and methods thereof. A disclosed winding is for an inductive device, having a winding core and a winding portion. The winding portion has a first winding layer, a connection section, and a second winding layer. The first winding layer comprises a first solenoid wound around the winding core along a step direction. The connection section is on the first winding layer, substantially in parallel to the step direction. The second winding layer comprises a second solenoid wound around the first winding layer along the step direction. The connection section electrically connects the first and second winding layers.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Taiwan Application Series Number 100146082 filed on Dec. 14, 2011, which is incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    The present disclosure relates generally to windings and the formation methods therefore, and more particularly, to windings suitable to be used in transformers. 
         [0003]    Transformers are commonly adapted in electronic and electrical apparatuses. For example, transformers might boost or down-convert operation voltages, transfer electrical power from one stage to another, or perform impedance matching for a load. Transformers generally apply magnetic induction to transfer electrical power from one circuit to another circuit. 
         [0004]    A transformer commonly has several windings, located in close proximity to make the magnetic field of a winding link to the magnetic field of another winding. One of the windings is referred to as a primary winding and another is referred to as a secondary winding. It is possible to increase or decrease the output voltage of a transformer by changing the turn ratio of the primary winding to the secondary winding. As known in the art, each winding has one or more solenoid to generate associated magnetic field. 
         [0005]      FIG. 1  demonstrates winding  10  in the art. Enameled wire  12 , a kind of conductive wire coated with a very thin insulating layer, winds around winding core  14  to form a solenoid, functioning as winding  10 . Winding core  14  could be a winding shaft, inside which could be magnetic material. 
         [0006]      FIGS. 2A to 2C  are side views of winding  10  during different stages when forming winding  10 . Please refer to  FIG. 2A , where enameled wire  12  winds around winding core  14  circle-by-circle along step direction  16   a  from right to left, to form the most inner winding layer  18   a.    FIG. 2B  illustrates how winding layer  18   b  is formed by winding enameled wire  12  around winding core  14  and winding layer  18   a  circle-by-circle along step direction  16   b  from left to right. Enameled wire  12  continues to wind around winding core  14  and winding layer  18   b  circle-by-circle along step direction  18   c  from right to left, forming winding layer  18   c.  It can be found from  FIGS. 2A ,  2 B and  2 C, that step directions  18   a  and  18   c  are the same, but opposite to step direction  18   b.    
       SUMMARY 
       [0007]    Embodiments of the present invention disclose a winding for an inductive device. The winding has a winding core and a winding portion. The winding portion has a first winding layer, a connection section, and a second winding layer. The first winding layer comprises a first solenoid wound around the winding core along a step direction. The connection section is on the first winding layer, substantially in parallel to the step direction. The second winding layer comprises a second solenoid wound around the first winding layer along the step direction. The connection section electrically connects the first and second winding layers. 
         [0008]    Embodiments of the present invention disclose a method for forming a winding in an inductive device. A conductive wire is first provided. The conductive wire winds, along a step direction, around a winding core to form a first solenoid. The conductive wire is extended along a direction parallel to the step direction, to form a connection section on the first solenoid. The conductive wire winds, along the step direction, around first solenoid and the connection section to form a second solenoid. 
         [0009]    Embodiments of the present invention disclose a transformer with a winding core, a primary winding and a secondary winding. The primary winding has a first winding layer, a connection section, and a second winding layer. The first winding layer has a first solenoid wound around the winding core along a step direction. The connection section is on the first winding layer, substantially in parallel to the step direction. The second winding layer comprises a second solenoid wound around the first winding layer and the connection section along the step direction. The secondary winding comprises a secondary solenoid wound around the second solenoid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention can be more fully understood by the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0011]      FIG. 1  demonstrates a winding in the art; 
           [0012]      FIGS. 2A to 2C  are side views of the winding of  FIG. 1  during different stages when forming the winding; 
           [0013]      FIGS. 3A-1  and  3 A- 2  illustrate side and perspective views of a winding, respectively, when a winding layer is formed; 
           [0014]      FIGS. 3B-1  and  3 B- 2  illustrate side and perspective views of the winding, respectively, when a connection section is formed; 
           [0015]      FIGS. 3C-1  and  3 C- 2  illustrate side and perspective views of the winding, respectively, when another winding layer is formed; 
           [0016]      FIGS. 3D-1  and  3 D- 2  illustrate side and perspective views of the winding, respectively, when another connection section is formed; 
           [0017]      FIGS. 3E-1  and  3 E- 2  illustrate side and perspective views of the winding, respectively, when another winding layer is formed; 
           [0018]      FIG. 4A  demonstrates the currents flowing in two winding layers in  FIG. 2C , and the possibly-induced magnetic fields; 
           [0019]      FIG. 4B  shows correlation between two magnetic fields in  FIG. 4A ; 
           [0020]      FIG. 5A  demonstrates the currents flowing in two winding layers in  FIG. 3E-1 , and the possibly-induced magnetic fields; 
           [0021]      FIG. 5B  shows correlation between two magnetic fields in  FIG. 5A ; and 
           [0022]      FIG. 6  demonstrates a transformer according to embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIGS. 3A-1  and  3 A- 2  illustrate side and perspective views of winding  60 , respectively, when winding layer  68   a  is formed. Starting from terminal  70  and ending at terminal  72 , enameled wire  64  winds around winding core  62  circle-by-circle along step direction  66   a  from right to left. Each turn should be as close to a previous one as possible, to reduce induction leakage, if any. As shown in  FIGS. 3A-1  and  3 A- 2 , a solenoid with winding layer  68   a  is formed surrounding winding core  62 , where terminals  70  and  72  seem to be starting and ending terminals of winding layer  68   a,  respectively. 
         [0024]      FIGS. 3B-1  and  3 B- 2  illustrate side and perspective views of winding  60 , respectively, when connection section  74  is formed. When winding layer  68   a  is completed, fastening object  76   a,  which is a piece of Mylar tape in one embodiment, is then used to substantially fasten the position of terminal  72 . Enameled wire  64  is then bent and extended along a direction opposite to step direction  66   a  to form connection section  74 . Fastening object  76   b,  which could be another piece of Mylar tape, substantially fastens the position of terminal  78 , where enameled wire  64  is slightly bent to form another turning. 
         [0025]    As shown in  FIGS. 3B-1  and  3 B- 2 , connection section  74  is substantially in parallel to the axis of the solenoid of winding layer  68   a  and crosses over most of the turns in winding layer  68   a.  In another embodiment, fastening objects  76   a  and  76   b  are two protruding portions of winding core  62  around which enameled wire  64  are bent and fixed, roughly defining the positions of terminals  72  and  78 . 
         [0026]      FIGS. 3C-1  and  3 C- 2  illustrate side and perspective views of winding  60 , respectively, when winding layer  68   b  is formed. Similar to the formation of winding layer  68   a,  enameled wire  64 , from terminal  78  and to terminal  80 , winds around winding core  62  circle-by-circle along step direction  66   b  from right to left. Another solenoid with winding layer  68   b  is now formed around and over winding layer  68   a.  As shown in  FIG. 3C-2 , connection section  74  and fastening objects  76   a,    76   b  as well are sandwiched between winding layers  68   a  and  68   b.  Terminals  78  and  80  seem to be a starting terminal and an ending terminal of winding layer  68   b,  respectively. Accordingly, connection section  74  electrically connects the ending terminal of winding layer  68   a  to the starting terminal of winding layer  68   b.  Step direction  66   a  is the same with step direction  66   b , as can be derived from  FIGS. 3B-1  and  3 C- 1 . Each circle in winding layer  68   b,  as a result, is substantially in parallel to every circuit in winding layer  68   a.    
         [0027]      FIGS. 3D-1  and  3 D- 2  illustrate side and perspective views of winding  60 , respectively, when connection section  82  is formed. Similar to the formation of connection section  74 , connection section  82 , electrically connecting terminals  80  and  84 , is formed by extending enameled wire  64  along a direction opposite to step direction  66   b,  and fastened on winding layer  68   b  by fastening objects  76   c  and  76   d.  In one embodiment, connection sections  82  and  74  are on substantially the same location at the circumference of winding core  62 , such that both form a stacked structure at one side of winding core  62 . In another embodiment, connection sections  82  and  74  are on two different locations at the circumference of winding core  62 . For example, winding core  62  is between connection sections  82  and  74 . 
         [0028]      FIGS. 3E-1  and  3 E- 2  illustrate side and perspective views of winding  60 , respectively, when winding layer  68   c  is formed. Similar to the formation of winding layers  68   a  and  68   b,  enameled wire  64 , from terminal  84  to terminal  86 , winds around winding core  62  circle-by-circle along step direction  66   c  from right to left. Another solenoid with winding layer  68   c  is now formed over and around winding layer  68   b  and connection section  82 . Because step directions  66   a,    66   b,  and  66   c  are substantially all the same, each circle in winding layer  68   c  is substantially in parallel to every circuit in winding layer  68   a  or  68   b.    
         [0029]    In summary, if electric current flows into winding layer  68   a  through terminal  70 , it spires toward to the left via winding layer  68   a,  goes back to the right through connection section  74  from terminal  72  to terminal  78 , spires again toward to the left via winding layer  68   b,  goes back to the right through connection section  82  from terminal  80  to terminal  84 , and so on. 
         [0030]    Winding  60  of  FIG. 3E-1  should induce a magnetic field with higher intensity than winding  10  of  FIG. 2C  does if they both have substantially the same size, the same number of turns, the same number of winding layers, and the same electric current flow. 
         [0031]      FIG. 4A  demonstrates the currents flowing in winding layers  18   a  and  18   b  in  FIG. 2C , and the possibly-induced magnetic fields, where solid line  34   a  with an arrow represents the current flowing through the front half of winding layer  18   a,  dashed line  32   a  with an arrow the current flowing through the rear half of winding layer  18   a,  and arrow  33   a  the magnetic field induced by winding layer  18   a . The front half of winding layer  18  is substantially in front of winding core  14  and the rear half is behind winding core  14 , in view of  FIG. 2C . Similarly, solid line  34   b  and dashed line  32   b,  each having an arrow, represent the currents respectively flowing through the front and the rear halves of winding layer  18   b,  and arrow  33   b  represents the magnetic field induced by winding layer  18   b.    FIG. 4B  shows correlation between magnetic fields  33   a  and  33   b.  As step directions  16   a  and  16   b  are in opposite, vectors of magnetic fields  33   a  and  33   b  will be slightly different in angle, and form a folded line if the end of one vector is attached to the beginning of the other, as shown in  FIG. 4B . 
         [0032]      FIG. 5A  demonstrates the currents flowing in winding layers  68   a  and  68   b  in  FIG. 3E-1 , and the possibly-induced magnetic fields, where solid lines  36   a  and  36   b  with arrows represent the currents flowing through the front halves of winding layers  68   a  and  68   b,  dashed lines  38   a  and  38   b  with arrows the currents flowing through the rear halves of winding layers  68   a  and  68   b,  and arrows  37   a  and  37   b  the magnetic fields induced by winding layers  18   a  and  18   b , respectively.  FIG. 5B  shows correlation between magnetic fields  37   a  and  37   b.  As step directions  66   a  and  66   b  are the same in direction, turns in winding layers  18   a  and  18   b  are almost in parallel to one another, such that magnetic field  37   a  shall have a direction the same with magnetic field  37   b.  A straight line may be formed if the end of the vector representing magnetic field  37   b  is attached to the beginning of the vector representing magnetic field  37   a,  as shown in  FIG. 5B . If magnetic fields  33   a  and  37   a  have the same magnitude, and magnetic fields  33   b  and  37   b  do as well, the vector summation of magnetic fields  37   a  and  37   b  will be larger than the summation of magnetic fields  33   a  and  33   b  simply because magnetic fields  37   a  and  37   b  are in line to each other and magnetic fields  33   a  and  33   b  are not. Therefore, winding  60  of  FIG. 3E-1  could induce an overall magnetic field with higher magnitude than winding  10  of  FIG. 2C . 
         [0033]      FIG. 6  demonstrates transformer  100  according to embodiments of the invention. In transformer  100  are winding core  96 , a primary winding with inner portion  97  and outer portion  99 , and secondary winding  98 . Secondary winding  98  is located between inner portion  97  and outer portion  99 . Inner portion  97  has winding layers  90   a,    90   b,    90   c,  and  90   d;  secondary winding  98  has winding layers  92   a  and  92   b;  and outer portion  99  has winding layers  94   a  and  94   b . In one embodiment, similar with winding  60  of  FIG. 3E-1 , winding layers  90   a,    90   b,    90   c,    90   d,    94   a  and  94   b  in the primary winding all have the same step direction and the primary winding has connection sections (not shown), each connecting two neighboring winding layers, and sandwiched therebetween. For example, between winding layers  90   a  and  90   b  might exist a connection section (not shown) formed by extending an enameled wire along a direction opposite to the step direction commonly shared by winding layers  90   a  and  90   b.  It is preferred, but not limited, that both winding layers  92   a  and  92   b  of secondary winding  98  have the same step direction as the winding layers of the primary winding have. As analyzed, the primary winding in transformer  100  of  FIG. 6  should induce a stronger magnetic field, in comparison with a conventional one. 
         [0034]    While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.