STACK CATHODE INLET RH (RELATIVE HUMIDITY) CONTROL WITHOUT RH SENSING DEVICE FEEDBACK
First Claim
1. A method for controlling relative humidity (RH) of a fuel cell stack in a fuel cell system, said method comprising:
- providing an RH sensor on a cathode inlet line that measures the RH of cathode inlet air;
determining if the RH sensor is providing a valid RH signal at fuel cell system start-up;
determining if the RH sensor is providing a valid RH signal during a run mode of the fuel cell system;
calculating an average of the RH signal over a predetermined time period, which is determined by the sensing signal characteristics of the RH sensor, if the RH sensor is providing a valid RH signal during the run mode of the fuel cell system;
using the calculated average of the RH signal if the RH sensor becomes invalid during the run mode to enable the fuel cell stack to operate utilizing closed-loop cathode inlet RH control;
operating the fuel cell stack at a predetermined optimized stack power level for a predetermined period of time if the RH signal is invalid at system start-up, wherein the optimized stack power level provides a highest stack relative humidity without liquid water occurring inside the stack; and
operating the fuel cell stack with closed-loop cathode inlet RH control using the highest stack relative humidity after the predetermined period of time has expired.
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Accused Products
Abstract
A method for controlling relative humidity (RH) of a cathode side of a fuel cell stack in a fuel cell system that includes an RH sensor on a cathode inlet line for providing an RH signal indicative of the RH of cathode inlet air. If the RH sensor is providing a valid RH signal, the RH signal is calculated as an RH average of the cathode inlet air. When the RH sensor is not providing a valid RH signal, the calculated RH average is utilized to control the cathode inlet air RH. If the RH sensor is not providing a valid signal during start-up, then the stack power is temporarily set at an optimum level for a known cathode inlet air RH.
5 Citations
20 Claims
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1. A method for controlling relative humidity (RH) of a fuel cell stack in a fuel cell system, said method comprising:
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providing an RH sensor on a cathode inlet line that measures the RH of cathode inlet air; determining if the RH sensor is providing a valid RH signal at fuel cell system start-up; determining if the RH sensor is providing a valid RH signal during a run mode of the fuel cell system; calculating an average of the RH signal over a predetermined time period, which is determined by the sensing signal characteristics of the RH sensor, if the RH sensor is providing a valid RH signal during the run mode of the fuel cell system; using the calculated average of the RH signal if the RH sensor becomes invalid during the run mode to enable the fuel cell stack to operate utilizing closed-loop cathode inlet RH control; operating the fuel cell stack at a predetermined optimized stack power level for a predetermined period of time if the RH signal is invalid at system start-up, wherein the optimized stack power level provides a highest stack relative humidity without liquid water occurring inside the stack; and operating the fuel cell stack with closed-loop cathode inlet RH control using the highest stack relative humidity after the predetermined period of time has expired. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for controlling relative humidity (RH) of a fuel cell stack in a fuel cell system, said method comprising:
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providing an RH sensor on a cathode inlet line to measure the RH of the cathode inlet air; determining if the RH sensor is providing a valid RH signal during a run mode of the fuel cell system; calculating an average of the RH signal for each consecutive predetermined time period if the RH sensor is providing a valid RH signal during the run mode of the fuel cell system; and using the calculated average of the RH signal if the RH signal becomes invalid during the run mode of the fuel cell system to prevent the fuel cell stack from being improperly humidified. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for controlling relative humidity (RH) of a fuel cell stack in a fuel cell system, said method comprising:
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providing an RH sensor on a cathode inlet line that measures the RH of the cathode inlet air; determining if the RH sensor is providing a valid RH signal at fuel cell system start-up; and operating the fuel cell stack at a predetermined optimized power level for a predetermined period of time if the RH signal is invalid at system start-up, wherein the optimized stack power level provides a known cathode inlet RH. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification