Fuel cell system utilizing control of operating current to adjust moisture content within fuel cell
AssigneeDenso Corporation
InventorsTomonori Imamura, Hideshi Izuhara
Life of this patent
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Abstract
In a fuel cell system utilizing fuel cells which generate electric power by a reaction between oxygen and hydrogen, the moisture content within a fuel cell is adjusted to be brought within an appropriate range by adjusting the operating current of the fuel cell. The total amount of electric power generated by the system is maintained at a required value by supplying/obtaining electric power to/from a secondary battery as required, or by utilizing a plurality of separately controlled fuel cells (or fuel cell stacks) and increasing or decreasing the electric power generated by another fuel cell or stack that is currently operating with an appropriate moisture content.
Claims23
A fuel cell system having a fuel cell generating section comprising at least one fuel cell for generating electric power by an electrochemical reaction between a fuel gas containing hydrogen and an oxidizing gas containing oxygen, fuel gas supply means for supplying a flow of fuel gas to said fuel cell generating section and oxidizing gas supply means for supplying a flow of oxidizing gas to said fuel cell generating section, wherein
- said system further comprises a controllable electric power source, and
- control means for
- controlling a moisture content condition within said fuel cell generating section by adjusting said value of electric current generated by said fuel cell generating section,
- detecting a first condition whereby a value of total electric power generated by said system exceeds a required value and a second condition whereby said total value of electric power is less than said required value, and
- reducing an amount of electric power generated by said controllable electric power source when said first condition is detected and for increasing said amount of electric power generated by said controllable electric power source when said second condition is detected.
A fuel cell system having a fuel cell generating section comprising at least one fuel cell for generating electric power by an electrochemical reaction between a fuel gas containing hydrogen and an oxidizing gas containing oxygen, control means for controlling a value of electric current generated by said fuel cell generating section, fuel gas supply means for supplying a flow of fuel gas to said fuel cell generating section and oxidizing gas supply means for supplying a flow of oxidizing gas to said fuel cell generating section, wherein
- said system comprises electrical energy storage means, and
- said control means comprises
- means for controlling a moisture content condition within said fuel cell generating section by adjusting said value of electric current generated by said fuel cell generating section,
- means for detecting a first condition whereby said electric power generated by said fuel cell generating section exceeds a required value of electric power and a second condition whereby said electric power generated by said fuel cell generating section is less than said required value of electric power, and
- means for applying a part of said electric power generated by said fuel cell generating section to be stored in said electrical energy storage means when said first condition is detected and for obtaining electric power from said electrical energy storage means to supplement said electric power generated by said fuel cell generating section when said second condition is detected.
A fuel cell system having a plurality of fuel cell generating sections each comprising at least one fuel cell for generating electric power by an electrochemical reaction between a fuel gas containing hydrogen and an oxidizing gas containing oxygen, control means for mutually separately controlling respective values of electric current generated by said fuel cell generating sections, fuel gas supply means for supplying a flow of fuel gas to said fuel cell generating sections, oxidizing gas supply means for supplying a flow of oxidizing gas to said fuel cell generating sections,
- wherein said system comprises moisture diagnosis means for diagnosing respective moisture content conditions of said fuel cell generating sections, and
- said control means comprises
- means for judging results obtained by said moisture diagnosis means to determine a one of said fuel cell generating sections having a lowest value of moisture content, judging whether said lowest value of moisture content is below a predetermined lower limit value, and when said moisture content value is found to be below said lower limit value, applying control to increase a value of electric current generated by said fuel cell generating section having the lowest value of moisture content, until said moisture content value is within a predetermined range of values,
- judging results obtained by said moisture diagnosis means, to determine a one of said fuel cell generating sections having a highest value of moisture content, judging whether said highest value of moisture content exceeds a predetermined upper limit value, and when said moisture content value is found to exceed said upper limit value, applying control to decrease a value of electric current generated by said fuel cell generating section having the highest value of moisture content, until said moisture content value is within said predetermined range of values, and
- when said control is applied to increase or decrease a value of electric current generated by one of said fuel call generating sections, altering a value of electric current generated by at least one other of said fuel cell generating sections in a direction such as to adjust a total value of electric power generated by said plurality of fuel cell generating sections towards a required value.
A fuel cell system having a plurality of fuel cell generating sections each comprising at least one fuel cell for generating electric power by an electrochemical reaction between a fuel gas containing hydrogen and an oxidizing gas containing oxygen, control means for mutually separately controlling respective values of electric current generated by said fuel cell generating sections, fuel gas supply means for supplying a flow of fuel gas to s said fuel cell generating sections along a hydrogen flow path, oxidizing gas supply means for supplying a flow of oxidizing gas to said fuel cell generating sections along an air flow path, and moisture diagnosis means for diagnosing respective moisture content conditions of said fuel cell generating sections;
- wherein said plurality of fuel cell generating sections are disposed in series along at least one of said air flow path and said hydrogen flow path, and wherein said control means controls a value of electric current produced by a first one of said fuel cell generating sections in accordance with results obtained by said moisture diagnosis means for a second one of said fuel cell generating sections, said first one of the fuel cell generating sections being located upstream with respect to said second one of the fuel cell generating sections along said at least one of the air flow path and hydrogen flow path.
Dependencies are inferred from the claim text.