Method and apparatus for controlling and integrated fuel cell system

Abstract

A control algorithm for operating an integrated fuel cell system includes the following steps: determining whether a power output of a fuel cell is within a first predetermined range of an electrical load coupled to the fuel cell; lowering a reactant flow to the fuel cell when the power output is within the first predetermined range; detecting an increase of the electrical load; determining whether the increase exceeds a second predetermined range; and increasing a reactant flow to the fuel cell when the increase exceeds the second predetermined range.

What is claimed is:  
     
         1 . A control network for an integrated fuel cell system, comprising: 
 a fuel cell having an output power, the fuel cell having a voltage and an output current;    a controller adapted to vary a reactant flow to the fuel cell;    an electrical load connected to the fuel cell such that the fuel cell output power is supplied to the electrical load;    an electrical load sensor adapted to communicate a measurement of the electrical load to the controller;    wherein the controller is adapted to monitor a change in the electrical load, and wherein the controller is further adapted to vary the reactant flow when the change in the electrical load exceeds a first predetermined level; and    wherein the controller is further adapted to delay varying the reactant flow for a first predetermined period.    
     
     
         2 . The control network of  claim 1 , wherein the fuel cell is a PEM fuel cell.  
     
     
         3 . The control network of  claim 1 , wherein the reactant flow comprises hydrogen.  
     
     
         4 . The control network of  claim 1 , wherein the electrical load comprises a residential appliance.  
     
     
         5 . The control network of  claim 1 , wherein the predetermined level is 110 percent of the fuel cell output power.  
     
     
         6 . The control network of  claim 1 , wherein the first predetermined period is less than 1 second.  
     
     
         7 . The control network of  claim 1 , further comprising a fuel cell voltage sensor adapted to communicate a voltage of the fuel cell to the controller; and 
 wherein the controller is adapted to increase the reactant flow when the voltage of the fuel cell is below a second predetermined level.    
     
     
         8 . The control network of  claim 7 , wherein the controller is further adapted to lower the reactant flow until the voltage of the fuel cell is at least as low as the second the predetermined level.  
     
     
         9 . The control network of  claim 1 , wherein the controller comprises a computer readable memory, and the controller is adapted to store a reactant flow instruction referenced to a fuel cell electrical output parameter.  
     
     
         10 . The control network of  claim 1 , further comprising a supplemental power source, wherein the controller is adapted to supply power to the electrical load from the supplemental power source when the electrical load exceeds a third predetermined level.  
     
     
         11 . The control network of  claim 1 , further comprising a supplemental power source, wherein the controller is adapted to supply power to the electrical load from the supplemental power source during the predetermined period.  
     
     
         12 . A method of controlling an integrated fuel cell system, comprising: 
 determining whether a power output of a fuel cell is within a first predetermined range of an electrical load coupled to the fuel cell;    lowering a reactant flow to the fuel cell when the power output is within the first predetermined range;    detecting an increase of the electrical load;    determining whether the increase exceeds a second predetermined range; and    increasing a reactant flow to the fuel cell when the increase exceeds the second predetermined range.    
     
     
         13 . The method of  claim 12 , further comprising: 
 measuring a voltage of the fuel cell and communicating the voltage to the controller;    increasing the reactant flow when the voltage of the fuel cell is below a second predetermined level.    
     
     
         14 . The method of  claim 13 , further comprising: 
 decreasing the reactant flow until the voltage of the fuel cell is at least as low as the second the predetermined level.    
     
     
         15 . The method of  claim 12 , further comprising: 
 storing a reactant flow instruction referenced to a fuel cell electrical output parameter in a computer readable memory.    
     
     
         16 . The method of  claim 12 , further comprising: 
 supplying power to the electrical load from a supplemental power source when the electrical load exceeds a third predetermined level.    
     
     
         17 . The method of  claim 12 , further comprising: 
 supplying power to the electrical load from a supplemental power source during a predetermined period when the electrical load exceeds a third predetermined level.    
     
     
         18 . A method of controlling an integrated fuel cell system, comprising: 
 determining whether a power output of a fuel cell is within a first predetermined range of an electrical load coupled to the fuel cell;    executing a steady state algorithm when the power output is within the predetermined range;    executing an up-transient algorithm when the power output is lower than the predetermined range;    executing a down transient algorithm when the power output is greater than the predetermined range;    wherein the steady state algorithm comprises maintaining a reactant flow above a predetermined level;    wherein the up-transient algorithm comprises increasing the reactant flow; and    wherein the down-transient algorithm comprises decreasing the reactant flow.    
     
     
         19 . The method of  claim 18 , further comprising: 
 measuring a voltage of the fuel cell and communicating the voltage to the controller;    increasing the reactant flow when the voltage of the fuel cell is below a second predetermined level.    
     
     
         20 . The method of  claim 19 , further comprising: 
 decreasing the reactant flow until the voltage of the fuel cell is at least as low as the second the predetermined level.    
     
     
         21 . The method of  claim 18 , further comprising: 
 storing a reactant flow instruction referenced to a fuel cell electrical output parameter in a computer readable memory.    
     
     
         22 . The method of  claim 18 , further comprising: 
 supplying power to the electrical load from a supplemental power source when the electrical load exceeds a third predetermined level.    
     
     
         23 . The method of  claim 18 , further comprising: 
 supplying power to the electrical load from a supplemental power source during a predetermined period when the electrical load exceeds a third predetermined level.