Multi-phase transformer

Abstract

A multi-phase transformer includes a centrally-disposed first core, a plurality of second cores each provided outside the first core so as to constitute a loop-shaped magnetic path with respect to the first core, and a primary winding and a secondary winding wound on each of the second cores.

What is claimed is: 
     
         1 . A multi-phase transformer comprising:
 a centrally-disposed first core;   a plurality of second cores each provided outside the first core so as to constitute a loop-shaped magnetic path with respect to the first core; and   a primary winding and a secondary winding wound on each of the second cores.   
     
     
         2 . The multi-phase transformer according to  claim 1 , wherein the second cores have the same shape. 
     
     
         3 . The multi-phase transformer according to  claim 1 , wherein the second cores are disposed around the first core rotationally symmetrically with respect to the center of the first core. 
     
     
         4 . The multi-phase transformer according to  claim 1 , wherein a spacer constituting a magnetic path is provided between the exterior of the first core and each of the second cores. 
     
     
         5 . The multi-phase transformer according to  claim 1 , wherein each of the second cores integrally includes:
 two radial leg portions each facing the exterior of the first core at one end and extending radially; and   an outer peripheral portion connecting the other ends of the two radial leg portions, wherein   the primary winding and the secondary winding are wound on the corresponding radial leg portions.   
     
     
         6 . The multi-phase transformer according to  claim 5 , wherein the exterior of the first core is round in shape corresponding to the shape of the one end of the radial leg portions of the second cores. 
     
     
         7 . The multi-phase transformer according to  claim 5 , wherein the exterior of the first core is polygonal in shape corresponding to the shape of the one end of the radial leg portions of the second cores. 
     
     
         8 . The multi-phase transformer according to claim  6 , further comprising a non-magnetic core fixation member provided between the outer peripheral portions of the adjoining second cores. 
     
     
         9 . The multi-phase transformer according to  claim 8 , wherein only a part of the core fixation member is made of a non-magnetic material. 
     
     
         10 . The multi-phase transformer according to  claim 8 , wherein a round cylindrical structure is formed onto the core fixation member and the outer peripheral portions of the second cores. 
     
     
         11 . The multi-phase transformer according to  claim 8 , wherein the core fixation member is used to assemble or secure the multi-phase transformer. 
     
     
         12 . The multi-phase transformer according to  claim 10 , wherein the cylindrical structure made of a non-magnetic material is integrally and fixedly fitted onto the core fixation member and the outer peripheral portions of the second cores. 
     
     
         13 . The multi-phase transformer according to  claim 10 , wherein the core fixation member or the cylindrical structure has predetermined holes. 
     
     
         14 . The multi-phase transformer according to  claim 1 , wherein the multi-phase transformer is a three-phase transformer to which three-phase alternating current (AC) voltage is applied. 
     
     
         15 . The multi-phase transformer according to  claim 14 , wherein the first windings of the three-phase transformer are connected by delta connection. 
     
     
         16 . The multi-phase transformer according to  claim 14 , wherein
 the number of the second cores is an integral multiple of 3, and   the windings wound on the second cores are grouped into three.