Efficiency optimized hybrid operation strategy
First Claim
1. A propulsion system comprising:
- a fuel cell system (FCS);
an electric energy storage system (EESS); and
an electric traction system (ETS) that is responsive to power from both the fuel cell system and the electric energy storage system, wherein the electric traction system preferably receives power from the fuel cell system if a power request from the electric traction system is above a determined power limit value and preferably receives power from the electric energy storage system if the power request from the electric traction system is below the determined power limit value.
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Abstract
A propulsion system for a fuel cell hybrid vehicle that includes a fuel cell system and an EESS, where the propulsion system employs an algorithm for increasing system efficiency. A power limit value is defined as the maximum system efficiency times the charge/discharge efficiency of the EESS. If the vehicle operator requests a power greater than the power limit value, then the fuel cell system will preferably provide the power, and if the power request from the vehicle operator is less than the power limit value, then the EESS will preferably provide the power. The algorithm also considers changing operation conditions and parameters that impact the fuel cell system efficiency and the electric energy storage system efficiency, such as the state of charge of the EESS and regenerative braking.
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Citations
20 Claims
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1. A propulsion system comprising:
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a fuel cell system (FCS); an electric energy storage system (EESS); and an electric traction system (ETS) that is responsive to power from both the fuel cell system and the electric energy storage system, wherein the electric traction system preferably receives power from the fuel cell system if a power request from the electric traction system is above a determined power limit value and preferably receives power from the electric energy storage system if the power request from the electric traction system is below the determined power limit value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A propulsion system for a fuel cell hybrid vehicle, said propulsion system comprising:
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a fuel cell system; an electric energy storage system; and an electric traction system that is responsive to power from both the fuel cell system and the electric energy storage system, wherein the electric energy storage system preferably receives power from the fuel cell system if a power request from the electric traction system is above a power limit value and preferably receives power from the electric energy storage system if the power request from the electric traction system is below the power limit value, said power limit value being determined by an efficiency curve of the fuel cell system, a maximum efficiency of the fuel cell system and the charge/discharge efficiency of the electric energy storage system, wherein the power limit value is defined by the location where the maximum efficiency of the fuel cell system times the charge/discharge efficiency of the electric energy storage system crosses the efficiency curve, and wherein power from the fuel cell system is used to charge the electric energy storage system and provide the power request if the electric energy storage system state of charge falls to a predetermined minimum state of charge and the power request is below the power limit value. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification