Fuel Cell Control Device Air Stoichiometric Ratio Adjustment
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Solution Overview
Problem
During low efficiency power generation in fuel cell systems, the air stoichiometric ratio deviates from its target value, leading to significant fluctuations in fuel cell voltage and actual electric power, causing battery overcharging or overdischarging, which can result in battery deterioration.
Innovation Solution
A fuel cell system with a control device that adjusts the flow rate of oxidizing agent gas to manage heat generation, maintaining a larger air stoichiometric ratio during low efficiency power generation, especially in modes where electric power fluctuation is higher, to minimize deviations in actual and target electric power, thereby preventing battery overcharging or overdischarging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low efficiency power generation is performed to increase self heat generation and rapidly warm up the fuel cell, then the warmup speed is improved, but the battery becomes liable to deteriorate due to overcharging or overdischarging
Solution Approach 1:
The control device dynamically adjusts the air stoichiometric ratio parameter based on the vehicle's operation mode. In first mode (e.g., idle or low load), a smaller air stoichiometric ratio is used to maximize heat generation for rapid warmup. In second mode (e.g., high load or dynamic operation), a larger air stoichiometric ratio is used to stabilize voltage and prevent battery overcharging/overdischarging, thus resolving the contradiction between warmup speed and battery reliability.
2Temperature
If the air stoichiometric ratio is made smaller to increase power generation loss and heat generation, then the heat generation amount is improved, but the voltage fluctuation becomes greater
Solution Approach 1:
The system transitions from a static air stoichiometric ratio to a dynamic one that changes based on operation mode. The control device switches between different air stoichiometric ratio settings (smaller for heat generation, larger for voltage stability) according to real-time vehicle conditions, allowing the system to adaptively balance heat generation and voltage stability requirements.
3Temperature
If the flow rate of oxidizing agent gas is reduced to achieve low efficiency power generation, then the heat generation increases, but the actual electric power deviates greatly from target electric power
Solution Approach 1:
The control strategy applies different air stoichiometric ratio settings to different operation modes. In first mode, the system accepts larger power deviation in exchange for maximum heat generation. In second mode, the system prioritizes power control precision by using a larger air stoichiometric ratio, thus achieving local optimization for each operating condition.
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
This approach reduces power generation loss, stabilizes fuel cell voltage, and prevents battery deterioration by maintaining optimal heat generation levels, ensuring the battery remains within safe charging and discharging limits during rapid warmup operations.
Implementation Method 1
a fuel cell configured to generate electric power by electrochemical reactions between a fuel gas and oxidizing agent gas
Implementation Method 2
performing low efficiency power generation in which the power generation loss becomes greater than normal power generation
Data Source
AI summary
During performance of low efficiency power generation, a control device controls the flow rate of feed of the oxidizing agent gas so that the amount of heat generation of the fuel cell accompanying power generation loss becomes a first amount of heat generation when the state of a mount on which the fuel cell system is mounted is a first mode and controls the flow rate of feed of the oxidizing agent gas so that the amount of heat generation becomes a second amount of heat generation smaller than the first amount of heat generation when the state of the mount is a second mode where the generated electric power of the fuel cell fluctuates more easily compared with the first mode.