Integral stack columns

Abstract

Systems and methods for power conversion are illustrated. Power conversion architecture for fuel cell systems in particular are described that use dual bus architectures having stack segment pairs and a center-tapped neutral line, and/or an architecture employing integer multiple of three DC/DC converter branches.

What is claimed is: 
     
         1 . A fuel cell circuit, comprising:
 a first fuel cell segment having positive and negative terminals;   a second fuel cell segment having positive and negative terminals;   a neutral line; and   wherein the negative terminal of the first fuel cell segment is electrically connected to both the positive terminal of the second fuel cell segment and the neutral line.   
     
     
         2 . The apparatus of  claim 1 , further comprising a first DC/DC converter electrically connected to the positive terminal of the first fuel cell segment. 
     
     
         3 . The apparatus of  claim 2 , further comprising a second DC/DC converter electrically connected to the negative terminal of the second fuel cell segment. 
     
     
         4 . The apparatus of  claim 3 , wherein an output of the first DC/DC converter is electrically connected to a first input of an inverter. 
     
     
         5 . The apparatus of  claim 4 , wherein an output of the second DC/DC converter is electrically connected to a second input of the inverter. 
     
     
         6 . The apparatus of  claim 2 , wherein the first fuel cell segment comprises a plurality of fuel cell stacks individually wired to be connected in series. 
     
     
         7 . The apparatus of  claim 5 , further comprising first and second capacitors, the first capacitor connected between the output of the first DC/DC converter and the neutral line; the second capacitor connected between the output of the second DC/DC converter and the neutral line. 
     
     
         8 . A power conversion module, comprising:
 a plurality of DC/DC converter branches, each branch comprising a DC/DC converter; and   a plurality of series connections comprising two fuel cell segments;   wherein each DC/DC converter branch is connected to at most one series connection comprising two fuel cell segments; and   wherein the total number of DC/DC converter branches is an integer multiple of three.   
     
     
         9 . The power conversion module of  claim 8 , wherein the total number of DC/DC converter branches is an integer multiple of six. 
     
     
         10 . The power conversion module of  claim 8 , wherein each DC/DC converter branch comprises an output bus, and wherein each of the DC/DC converter branch output busses is electrically connected to another DC/DC converter branch output bus. 
     
     
         11 . The power conversion module of  claim 8 , wherein each DC/DC converter branch comprises an output bus, and wherein each of the DC/DC converter branch output busses is electrically connected to an inverter input. 
     
     
         12 . The power conversion module of  claim 10 , wherein each DC/DC converter branch comprises an output bus, and wherein each of the DC/DC converter branch output busses is electrically connected to an inverter input. 
     
     
         13 . The power conversion module of  claim 12 , wherein the DC/DC converter branches are divided into groups of two, the groups of two being defined in that each DC/DC converter branch in the group is connected to the same series connection of two fuel cell segments. 
     
     
         14 . A fuel cell power conversion system comprising a plurality of power conversion modules of  claim 13 . 
     
     
         15 . The power conversion module of  claim 8 , wherein one half of the fuel cell segments are located on a positive side of a neutral line and a remaining one half of the fuel cell segments are located on a negative side of the neutral line. 
     
     
         16 . A method for converting DC to AC, comprising:
 accepting a first output of a first series connection comprising two fuel cell segments at an input of a first DC/DC converter;   accepting a second output of the first series connection comprising two fuel cell segments at an input of a second DC/DC converter;   accepting a first output of the first DC/DC converter at a first input of a first inverter;   accepting a first output of the second DC/DC converter at a second input of the first inverter; and   generating a first AC output from the first and second inputs of the first inverter relative to a neutral line connected to a reference potential.   
     
     
         17 . The method of  claim 16 , further comprising:
 accepting a first output of a second series connection comprising two fuel cell segments at an input of a third DC/DC converter;   accepting a first output of the third DC/DC converter at a first input of a second inverter;   accepting a second output of the second series connection at a second input of the second inverter;   generating a second AC output from the first and second inputs of the second inverter relative to the neutral line;   accepting a first output of a third series connection comprising two fuel cell segments at an input of a fourth DC/DC converter;   accepting a first output of the fourth DC/DC converter at a first input of a third inverter;   accepting a second output of the third series connection at a second input of the third inverter; and   generating a third AC output from the first and second inputs of the third inverter relative to the neutral line.