Fuel Cell Wet State Inference via Phase Difference Change
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fuel cell systems face challenges in accurately determining inappropriate wet states, such as excessively wet or dry conditions, which disrupt the correlation between phase difference and wet state, leading to inefficient operation and potential damage.
Innovation Solution
A fuel cell system that includes an alternating-current superimposing unit, a phase difference deriving unit, and a first inference unit to detect changes in reactant gas flow rate, stoichiometric ratio, and output current, inferring inappropriate wet states based on phase difference changes and adjusting reactant gas supply and output current to maintain an appropriate wet state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phase difference is used to determine wet state, then measurement simplicity is improved, but measurement precision deteriorates when wet state becomes excessively wet or dry
Solution Approach 1:
The patent introduces an intermediary variable (change amount of phase difference) to mediate between the easily measurable phase difference and the wet state determination. By monitoring the change amount rather than the absolute phase difference value, the system maintains measurement simplicity while achieving accurate detection of inappropriate wet states even when the correlation between phase difference and wet state is disrupted
Solution Approach 2:
The patent changes the parameter used for wet state determination from the absolute phase difference value to the change amount of phase difference. This parameter transformation allows the system to detect inappropriate wet states (excessively wet or dry conditions) by identifying abnormal changes in phase difference, thereby maintaining measurement simplicity while improving measurement precision across all wet state conditions
2Device complexity
If alternating-current signal is applied to determine wet state, then device complexity is reduced, but reliability deteriorates due to inability to detect inappropriate wet states
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the change amount of phase difference and comparing it against predetermined thresholds. This feedback approach enables the system to reliably detect inappropriate wet states (excessively wet or dry conditions) while maintaining the simplicity of the alternating-current signal application method, thereby improving reliability without increasing device complexity
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
Enables accurate detection and correction of inappropriate wet states, preventing damage and ensuring efficient fuel cell operation by distinguishing between excessively wet and dry states and adjusting reactant gas supply and output current accordingly.
Implementation Method 1
an alternating-current superimposing unit that superimposes an alternating-current signal on one of the current and the voltage taken out from the fuel cell by the converter
Implementation Method 2
a phase difference deriving unit that extracts an alternating-current component from an output of the fuel cell and derives a phase difference that is a phase lag of an alternating-current voltage relative to an alternating current in the alternating-current component
Data Source
AI summary
Provided is a fuel cell system including: a fuel cell; a reactant gas supply section; a converter; an alternating-current superimposing unit; a phase difference deriving unit configured to derive a phase difference that is a phase lag of an alternating-current voltage relative to an alternating current in an alternating-current component output from the fuel cell; and a first inference unit. The first inference unit infers that the fuel cell is in an inappropriate wet state, when the absolute value of an amount of change in the phase difference has become equal to or larger than a predetermined criterion value immediately after the magnitude of a change in the value of at least one of parameters that are a flow rate of a reactant gas, a stoichiometric ratio, and an output current has exceeded a predetermined criterion.