Low common mode noise transformers and switch-mode dc-dc power converters

Abstract

A switch-mode DC-DC power converter includes one or more input terminals and output terminals, and a transformer coupled between the input and output terminals. The transformer includes a plurality of winding sets. Each winding set includes a primary winding and a secondary winding magnetically coupled with one another. The primary winding and the secondary winding include the same number of turns. The primary windings of the plurality of winding sets are connected in series and the secondary windings of the plurality of winding sets are connected in parallel. The power converter also includes at least one spacer positioned to separate an adjacent pair of the plurality of winding sets. A magnetic coupling between the adjacent pair of the plurality of winding sets is less than the magnetic coupling between the primary winding and the secondary winding within each winding set.

What is claimed is: 
     
         1 . An interleaved LLC power converter, comprising:
 one or more input terminals for receiving an input voltage from a voltage source;   one or more output terminals for supplying an output voltage to a load;   a first LLC converter including a first transformer and a first spacer, the first transformer coupled between the input and output terminals, the first transformer comprising:
 a first plurality of winding sets, each winding set including a primary winding and a secondary winding magnetically coupled with one another; 
 wherein the first spacer is positioned to separate an adjacent pair of the first plurality of winding sets; and 
   a second LLC converter interleaved with the first LLC converter, the second LLC converter comprising:
 a second transformer and a second spacer, the second transformer coupled between the input and output terminals, the second transformer comprising:
 a second plurality of winding sets, each winding set including a primary winding and a secondary winding magnetically coupled with one another; 
 wherein the second spacer is positioned to separate an adjacent pair of the second plurality of winding sets. 
 
   
     
     
         2 . The power converter of  claim 1 , wherein each of the first and second transformers comprises a core;
 wherein each winding set of the first plurality of winding sets of the first transformer is wound about the core; and   wherein each winding set of the second plurality of winding sets of the second transformer is wound about the core.   
     
     
         3 . The power converter of  claim 1 , wherein the primary windings of the first plurality of winding sets are connected in a first coupling relationship, the first coupling relationship comprising a series relationship and a parallel relationship;
 wherein the secondary windings of the first plurality of winding sets are connected in a second coupling relationship, the second coupling relationship comprising a series relationship and a parallel relationship;   wherein the primary windings of the second plurality of winding sets are connected in the first coupling relationship;   wherein the secondary windings of the second plurality of winding sets are connected in the second coupling relationship; and   wherein the first coupling relationship is distinct from the second coupling relationship.   
     
     
         4 . The power converter of  claim 3 , wherein each of the first and second pluralities of winding sets comprises exactly two winding sets; and
 wherein a turns ratio of each of the first and second LLC converters is two to one.   
     
     
         5 . The power converter of  claim 3 , wherein each of the first and second pluralities of winding sets comprises exactly four winding sets; and
 wherein a turns ratio of each of the first and second LLC converters is four to one.   
     
     
         6 . The power converter of  claim 3 , wherein each winding comprises a planar winding including one turn per layer. 
     
     
         7 . The power converter of  claim 3 , wherein each of the first and second LLC converters comprises at least two switches, a capacitor and an inductor;
 wherein the at least two switches, the capacitor, and the inductor are coupled between the one or more input terminals and the transformer of the respective first or second LLC converter.   
     
     
         8 . The power converter of  claim 7  further comprising a controller for controlling switching operation of the switches of the first and second LLC converters to operate the first and second LLC converters with one of a forty-five degree phase shift, a sixty degree phase shift, and a ninety degree phase shift, relative to one another. 
     
     
         9 . The power converter of  claim 1 , wherein the primary windings of the first plurality of winding sets are connected in parallel;
 wherein the secondary windings of the first plurality of winding sets are connected in series;   wherein the primary windings of the second plurality of winding sets are connected in parallel; and   wherein the secondary windings of the second plurality of winding sets are connected in series.   
     
     
         10 . The power converter of  claim 1 , wherein the primary windings of the first plurality of winding sets are connected in series;
 wherein the secondary windings of the first plurality of winding sets are connected in parallel;   wherein the primary windings of the second plurality of winding sets are connected in series; and   wherein the secondary windings of the second plurality of winding sets are connected in parallel.   
     
     
         11 . A transformer, comprising:
 at least one core;   a plurality of winding sets wound about the at least one core, wherein each winding set comprises a primary winding and a secondary winding magnetically coupled with one another; and   at least one spacer positioned to separate an adjacent pair of the plurality of winding sets;   wherein a magnetic coupling between the adjacent pairs of the plurality of winding sets is less than the magnetic coupling between the primary winding and the secondary winding within each winding set.   
     
     
         12 . The transformer of  claim 11 , wherein the primary winding and the secondary winding of each winding set comprise the same number of turns. 
     
     
         13 . The transformer of  claim 12 , wherein the primary windings of the plurality of winding sets are connected in one of a series relationship and a parallel relationship; and
 wherein the secondary windings of the plurality of winding sets are connected in one of a series relationship and a parallel relationship.   
     
     
         14 . The transformer of  claim 13 , wherein the primary windings of the plurality of winding sets are connected in series and the secondary windings of the plurality of winding sets are connected in parallel to define the step-down turns ratio of the transformer. 
     
     
         15 . The transformer of  claim 13 , wherein the primary windings of the plurality of winding sets are connected in parallel and the secondary windings of the plurality of winding sets are connected in series to define the step-up turns ratio of the transformer. 
     
     
         16 . The transformer of  claim 11 , wherein the plurality of winding sets comprises exactly two winding sets and the turns ratio of the transformer is two to one or one to two. 
     
     
         17 . The transformer of  claim 11 , wherein the plurality of winding sets comprises exactly four winding sets and the turns ratio of the power converter is four to one or one to four. 
     
     
         18 . The transformer of  claim 11 , wherein each winding comprises a planar winding including one turn per layer. 
     
     
         19 . The transformer of  claim 11  further comprising a resonant inductor coil integrated with the core. 
     
     
         20 . The transformer of  claim 19 , wherein the resonant inductor coil is positioned adjacently to the plurality of winding sets.