Hydrogen-producing fuel cell systems with load-responsive feedstock delivery systems

A method for controlling the flow rate of feedstock delivered to a hydrogen-producing region of a hydrogen-producing fuel cell system containing a hydrogen generation assembly with the hydrogen-producing region that produces hydrogen gas from at least one feedstock, a feedstock delivery system that delivers a feed stream containing the at least one feedstock to the hydrogen-generation assembly, and a fuel cell stack that receives hydrogen gas produced by the hydrogen-generation assembly and produces an electrical output therefrom to satisfy at least a portion of an applied load, the method comprising:

• regulating, with a control system having a feed-forward control portion and a feedback control portion, the flow rate of feedstock to the hydrogen-producing region of the hydrogen generation assembly responsive at least in part to a demand for hydrogen gas by the fuel cell stack to satisfy the portion of the applied load, wherein the regulating includes cooperatively:
• estimating, by the feed-forward control portion, the flow rate of hydrogen gas required by the fuel cell stack to produce an electrical output to satisfy the applied load that is applied to the fuel cell stack, wherein the estimating is based at least in part upon determining a portion of the applied load that is not being satisfied by the fuel cell stack using hydrogen gas produced by the hydrogen generation assembly;
• and
• adjusting, by the feedback control portion, the estimated flow rate of hydrogen gas responsive to the rate at which the hydrogen gas produced by the hydrogen generation assembly is consumed by the fuel cell stack.