Fuel Cell Deactivation Control for Cathode Oxygen Management
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Solution Overview
Problem
When stopping electric-power generation in a fuel cell system, residual oxygen in the cathode can lead to a high potential state, causing deterioration of the solid polymer electrolyte membrane upon subsequent activation, as existing methods like exhaust-gas recirculation may not effectively manage oxygen concentration.
Innovation Solution
A method involving low electric-power generation to reduce the state of charge in the electricity storage device, followed by oxygen-consumption electric-power generation, which consumes remaining oxygen in the cathode system, ensuring a nitrogen-rich state and preventing high potential states during fuel cell activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If low electric-power generation is performed before oxygen-consumption electric-power generation, then the state of charge in the electricity storage device is reduced appropriately, but the total deactivation time increases
Solution Approach 1:
The patent applies dynamics by making the deactivation process adaptive based on the state of charge level. When the stop switch is operated, the system dynamically selects between two modes: (1) performing low electric-power generation first if the state of charge is high, or (2) proceeding directly to oxygen-consumption electric-power generation if the state of charge is already low. This dynamic adjustment optimizes the total deactivation time while ensuring proper state of charge management.
2Quantity of substance
If exhaust-gas recirculation electric-power generation is used for oxygen consumption, then the oxygen concentration is reduced, but the auxiliary devices operate unnecessarily during the process
Solution Approach 1:
The patent applies parameter changes by modifying the electric-power generation mode based on the operational phase. During low electric-power generation (performed before oxygen-consumption generation), the air supply is reduced to maintain a negative net output, which naturally reduces auxiliary device operation. This parameter change in power generation mode achieves oxygen concentration reduction while minimizing unnecessary auxiliary device operation and energy consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively reduces oxygen concentration in the cathode system, preventing membrane deterioration and ensuring safe fuel cell operation by ensuring the cathode is not in a high potential state during subsequent activations, while optimizing the state of charge and reducing unnecessary auxiliary device operation.
Implementation Method 1
oxygen-consumption electric-power generation in which oxygen remaining in a cathode system of the fuel cell is consumed to reduce oxygen concentration within the cathode system
Implementation Method 2
an electricity storage device provided in the fuel cell system... After the state of charge in the electricity storage device is reduced to the predetermined value by compensating for a negative net output by discharging electricity from the electricity storage device
Data Source
AI summary
In a method for deactivating a fuel cell system, low electric-power generation is performed prior to oxygen-consumption electric-power generation in a case where a state of charge in an electricity storage device provided in the fuel cell system is larger than a predetermined value when a stop switch provided in the fuel cell system is operated. After the state of charge in the electricity storage device is reduced to the predetermined value by compensating for a negative net output by discharging electricity from the electricity storage device, the oxygen-consumption electric-power generation in which oxygen remaining in a cathode system of the fuel cell is consumed to reduce oxygen concentration within the cathode system is performed.