METHOD AND APPARATUS FOR MULTIPLE MODE CONTROL OF VOLTAGE FROM A FUEL CELL SYSTEM
First Claim
1. A fuel cell system, comprising:
- a fuel cell stack;
a battery;
a series pass element electrically coupled between at least a portion of the fuel cell stack and a portion of the battery; and
a regulating circuit for regulating current through the series pass element in response to a greater of a battery charging current error, a battery voltage error and a stack current error.
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Accused Products
Abstract
A fuel cell system determines each of a battery charging current error, a battery voltage error, and a stack current error. The fuel cell system regulates current through a series pass element in response to a greater of the determined errors. Thus, the fuel cell system operates in three modes: battery voltage limiting mode, stack current limiting mode and battery charging current limiting mode. Additionally, there can be a fourth “saturation” mode where the stack voltage VS drops below the battery voltage VB as the load pulls even more current. Individual fuel cell systems can be combined in series and/or parallel to produce a combined fuel cell system having a desired output voltage and current.
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Citations
21 Claims
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1. A fuel cell system, comprising:
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a fuel cell stack;
a battery;
a series pass element electrically coupled between at least a portion of the fuel cell stack and a portion of the battery; and
a regulating circuit for regulating current through the series pass element in response to a greater of a battery charging current error, a battery voltage error and a stack current error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A fuel cell system, comprising:
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a number of fuel cells forming a fuel cell stack;
a number of battery cells forming a battery;
a series pass element;
a blocking diode electrically coupled between the fuel cell stack and the series pass element; and
a regulating circuit for regulating current through the series pass element in proportion to at least a greater of a difference between a battery charging current and a battery charging current limit, a difference between a battery voltage and a battery voltage limit, and a difference between a stack current and a stack current limit. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A fuel cell system, comprising:
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a voltage bus;
a first fuel cell stack electrically couplable across the voltage bus;
a first battery electrically couplable across the voltage bus;
a first series pass element electrically coupled in series on the voltage bus between at least a portion of the first fuel cell stack and a portion of the first battery;
a first regulating circuit for regulating current through the first series pass element in response to a greater of a battery charging current error, a battery voltage error and a stack current error;
a second fuel cell stack electrically couplable across the voltage bus;
a second battery electrically couplable across the voltage bus;
a second series pass element electrically coupled in series on the voltage bus between at least a portion of the second fuel cell stack and a portion of the second battery; and
a second regulating circuit for regulating current through the second series pass element in response to a greater of a battery charging current error, a battery voltage error and a stack current error. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification