Fuel Cell State Estimation Using Impedance Segmentation
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Solution Overview
Problem
Conventional state estimation methods for fuel cells struggle to accurately differentiate between hydrogen starvation and oxygen concentration reductions based on internal impedance measurements, as both conditions can result in increased arc size, leading to ambiguous state estimation.
Innovation Solution
A state estimation device and method that measures internal impedance using alternating-current signals, calculates preliminary estimation values for reaction resistance and electrical double layer capacitance from both imaginary and real components, and determines final estimation values by selecting the larger reaction resistance and smaller capacitance, employing an equivalent circuit model to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If internal impedance measurement is used for state estimation, then measurement capability is provided, but measurement precision deteriorates due to inability to differentiate between hydrogen starvation and oxygen concentration reduction
Solution Approach 1:
The patent segments the internal impedance measurement into two distinct components: real component (resistive part) and imaginary component (reactive part). By analyzing these components separately through equivalent circuit modeling, the system can differentiate between hydrogen starvation and oxygen concentration reduction effects, thereby resolving the measurement precision issue while maintaining state estimation capability.
Solution Approach 2:
The patent transitions from scalar impedance magnitude analysis to complex impedance plane analysis by introducing the real and imaginary components as separate dimensions. This dimensional expansion allows the system to distinguish between different failure modes that previously appeared identical in terms of arc size alone, improving measurement precision without sacrificing detection capability.
2Difficulty of detecting and measuring
If arc size of internal impedance is used for hydrogen starvation detection, then detection capability is provided, but reliability deteriorates due to false positives from oxygen concentration reduction
Solution Approach 1:
The patent segments the impedance analysis into real and imaginary components, allowing separate evaluation of resistive and reactive effects. Hydrogen starvation primarily affects the real component while oxygen concentration reduction affects the imaginary component, enabling reliable differentiation and eliminating false positives.
Solution Approach 2:
The patent introduces equivalent circuit model parameters (resistance and reactance) as intermediaries between the raw impedance measurement and the physical state interpretation. These intermediaries provide a structured framework for understanding the distinct effects of hydrogen and oxygen concentration changes, improving detection reliability.
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 enables precise state estimation of fuel cells, allowing for timely detection of abnormalities and optimal operation control by providing accurate final estimation values for reaction resistance and capacitance, thereby ensuring reliable power generation.
Implementation Method 1
an internal impedance measurement unit configured to measure an internal impedance of the fuel cell on the basis of an alternating-current signal of a predetermined frequency output from the fuel cell
Implementation Method 2
an equation for an imaginary component of the internal impedance determined by an equivalent circuit model of the fuel cell, and a second preliminary estimation value of the reaction resistance value and/or the electrical double layer capacitance of the electrode from a real component of the measurement value of the internal impedance on the basis of an equation for a real component of the internal impedance determined by the equivalent circuit model
Data Source
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AI summary
A state estimation device for a fuel cell for generating power upon receiving the supply of anode gas and cathode gas, comprising: an internal impedance measurement unit configured to measure an internal impedance of the fuel cell on the basis of an alternating-current signal of a predetermined frequency output from the fuel cell; a state quantity preliminary estimation value calculation unit configured to calculate a first preliminary estimation value for a state quantity of an electrode obtained from a real component of a measurement value of the internal impedance and a second preliminary estimation value for the state quantity of the electrode obtained from an imaginary component of the measurement value of the internal impedance; and a state quantity final estimation value determination unit configured to determine a final estimation value of the state quantity of the electrode on the basis of the calculated first and second preliminary estimation values.