Coupled-inductor core for unbalanced phase currents

Abstract

An embodiment of a coupled-inductor core includes first and second members and first and second forms extending between the first and second members. The first form has a parameter (e.g., length) of a first value, and is operable to conduct a first magnetic flux having a first density that depends on the first value of the parameter. The second form is spaced apart from the first form, has the parameter (e.g., length) of a second value different from the first value, and is operable to conduct a second magnetic flux having a second density that depends on the second value of the parameter. Because two or more of the forms of such a core may have different values for the same parameter, the core may be suitable for use in a multiphase power supply where the currents through the phases are unbalanced.

1 .- 21 . (canceled) 
     
     
         22 . A method, comprising:
 driving a magnetizing first current through a first conductor and into an output node during a first period, the first conductor wrapped around a first form of a core, the magnetizing first current having a first magnitude and generating a first magnetic flux through the first form, the first form having a first characteristic of a first value, a density of the first magnetic flux flowing through the form depending on the characteristic; and   directing a first portion of the first magnetic flux through a second form of the core, the first portion of the flux causing an induced second current to flow through a second conductor and into the output node, the second conductor wrapped around the second form of the core, the induced second current having a second magnitude, the second form having the characteristic of a second value that is different from the first value.   
     
     
         23 . The method of  claim 22 , further comprising directing a second portion of the magnetic flux through a third form of the core about which is wrapped no current-carrying conductor. 
     
     
         24 . The method of  claim 22 , further comprising directing a second portion of the magnetic flux through a third form of the core about which is wrapped no current-carrying conductor, the third form having the first characteristic of a third value. 
     
     
         25 . The method of  claim 22 , further comprising directing a second portion of the magnetic flux through a third form of the core about which is wrapped no current-carrying conductor, the third form having a second characteristic of a value that is different than values of the second characteristic for the first and second forms. 
     
     
         26 . The method of  claim 22 , further comprising:
 driving a magnetizing second current through the second conductor and into the output node during a second period, the magnetizing second current having a third magnitude and generating a second magnetic flux through the second form, a density of the second magnetic flux flowing through the second form depending on the characteristic; and   directing a first portion of the second magnetic flux through the first form of the core, the first portion of the second flux causing an induced first current to flow through the first conductor and into the output node, the induced first current having a fourth magnitude.   
     
     
         27 . The method of  claim 26  wherein:
 the third magnitude is substantially equal to the first magnitude; and 
 the fourth magnitude is substantially equal to the second magnitude. 
 
     
     
         28 . A method, comprising:
 driving a magnetizing first current having a first magnitude through a first winding and into an output node during a first period, the first winding having a number of turns; and   driving a magnetizing second current having a second magnitude through a second winding and into the output node during a second period, the second winding having the number of turns and being magnetically coupled to the first winding.   
     
     
         29 . The method of  claim 28  wherein:
 the first winding is wound about a first form of a core, the magnetizing first current generating a first magnetic flux through the first form, the first form having a characteristic of a first value, a density of the magnetic flux flowing through the form depending on the characteristic; and 
 the second winding is wound about a second form of the core, the magnetizing second current generating a second magnetic flux through the second form, the second form having the characteristic of a second value, a density of the magnetic flux flowing through the second form depending on the characteristic. 
 
     
     
         30 . The method of  claim 22  wherein the first characteristic includes a length. 
     
     
         31 . The method of  claim 22  wherein the first characteristic includes a cross-sectional area. 
     
     
         32 . The method of  claim 22  wherein the first characteristic includes a magnetic permeability. 
     
     
         33 . The method of  claim 29  wherein the characteristic includes a length. 
     
     
         34 . The method of  claim 29  wherein the characteristic includes a cross-sectional area. 
     
     
         35 . The method of  claim 29  wherein the characteristic includes a magnetic permeability.