Transformer and coil winding method thereof

Abstract

A transformer includes a core, a primary coil and a secondary coil. The secondary coil is formed by a first right-triangle area, ramp areas and a second right-triangle area. The first right-triangle area is formed by a set of layers providing a slanted surface and outwardly wound by continuous bending. A first layer of the set of layers is wound to be formed with an end wound position. A second layer subsequent to the first layer is wound to be started at a beginning wound position where is bent near the end wound position of the first layer. The rest layers of the set of layers are outwardly formed by repeating the winding sequence of the first and second layers. The ramp areas are wound along the slanted surface, and the second right-triangle area is inwardly wound opposite to the winding sequence of the first right-triangle area.

1 . A transformer comprising:
 a core comprising a first end and a second end; and   a first coil wound around the core by forward winding the first coil from the first end of the core toward the second end of the core as a first layer, backward winding the first coil above the first layer toward the first end of the core from a position near a stop point of the first layer and repeatedly performing the forward and backward winding to form a first right-triangle area; winding the first coil along a slanted surface of the first right-triangle; and winding the first coil by a winding way opposite to that of the first right-triangle area.   
   
   
       2 . The transformer as claimed in  claim 1 , wherein the winding of the first coil along the slanted surface of the first right-triangle area starts from repeatedly forward winding toward the second end of the core and then backward winding toward the first end of the core. 
   
   
       3 . The transformer as claimed in  claim 1 , further comprising a second coil wound outside the first coil. 
   
   
       4 . The transformer as claimed in  claim 3 , wherein the second coil is a primary coil, and the first coil is a secondary coil. 
   
   
       5 . The transformer as claimed in  claim 3 , further comprising a first insulating layer disposed between the first and second coils. 
   
   
       6 . The transformer as claimed in  claim 5 , further comprising a second insulating layer disposed outside the second coil. 
   
   
       7 . The transformer as claimed in  claim 1 , wherein the core comprises a single slot. 
   
   
       8 . A coil winding method for forming a coil on a core with a first end and a second end, comprising the steps of:
 forward winding the first coil from the first end of the core toward the second end of the core as a first layer, backward winding the first coil above the first layer toward the first end of the core from a position near a stop point of the first layer and repeatedly performing the forward and backward winding to form a first right-triangle area;   winding the first coil along a slanted surface of the first right-triangle; and   winding the first coil by a winding way opposite to that of the first right-triangle area.   
   
   
       9 . The coil winding method as claimed in  claim 8 , wherein the winding of the first coil along the slanted surface of the first right-triangle area starts from repeatedly forward winding toward the second end of the core and then backward winding toward the first end of the core. 
   
   
       10 . The coil winding method as claimed in  claim 8 , further comprising winding a second coil outside the first winding. 
   
   
       11 . The coil winding method as claimed in  claim 10 , wherein the second coil is a primary coil, and the first coil is a secondary coil. 
   
   
       12 . The coil winding method as claimed in  claim 10 , further comprising forming a first insulating layer between the first and second coils. 
   
   
       13 . The coil winding method as claimed in  claim 12 , further comprising forming a second insulating layer outside the second coil. 
   
   
       14 . The coil winding method as claimed in  claim 8 , wherein the core comprises a single slot.