Fuel Cell Power Assembly Control for On-Off Degradation Tradeoffs
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Solution Overview
Problem
Fuel cell systems face degradation and energy wastage due to frequent on-off cycles, and existing control strategies fail to balance fuel consumption and durability when power demand is low, leading to inefficient operation.
Innovation Solution
A method for controlling a power assembly comprising a fuel cell unit and an electric energy storage system that predicts power demand and calculates costs for different control scenarios, balancing fuel consumption and degradation by selecting the most beneficial scenario, allowing independent control of multiple fuel cell units to optimize power delivery and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fuel cell unit is turned off to save fuel consumption, then fuel efficiency is improved, but fuel cell degradation increases due to frequent on-off cycles
Solution Approach 1:
The control method performs preliminary actions by predicting future power demand and calculating costs for different control scenarios before making the on-off decision. This allows the system to anticipate whether turning off the fuel cell now will lead to costly restarts or excessive fuel consumption later, thereby making more informed decisions that balance both fuel efficiency and degradation concerns
Solution Approach 2:
The system dynamically adjusts the control strategy by continuously evaluating multiple scenarios with different on-off decisions based on real-time conditions and predictions. The control approach transitions from static on-off thresholds to dynamic scenario-based optimization, allowing flexible adaptation to changing power demands while minimizing both fuel consumption and degradation costs
2Reliability
If the fuel cell unit is turned on to meet power demand, then power delivery reliability is improved, but fuel consumption increases
Solution Approach 1:
The control method incorporates feedback mechanisms by continuously monitoring the state of charge of the electric energy storage system, predicting future power demand, and evaluating the costs of different control scenarios. This feedback loop enables the system to make optimized decisions about when to keep the fuel cell on or off, balancing power delivery reliability with fuel consumption minimization
3Reliability
If the fuel cell system operates at higher power to avoid low current density degradation, then fuel cell durability is improved, but excess power must be stored or dissipated increasing energy wastage
Solution Approach 1:
The system changes the operational parameters by considering the state of charge of the electric energy storage system as a key factor in the cost calculation. This allows the fuel cell to operate at higher powers when the battery can absorb the excess energy, thereby maintaining durability without wasting energy through dissipation. The parameter change transforms the degradation avoidance strategy from fixed power thresholds to dynamic power levels based on storage availability
Data Source
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Figure 3
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AI summary
The invention relates to a method for controlling a power assembly comprising a fuel cell unit and an electric energy storage system. The method comprises: - predicting (S1) a power demand for power delivery from the power assembly over a prediction horizon, - calculating (S2) costs associated with controlling the power assembly according to at least two different control scenarios during the prediction horizon, wherein the at least two different control scenarios include a first control scenario in which the fuel cell unit is turned off, and a second control scenario in which the fuel cell unit is turned on. For each of said control scenarios, the associated cost includes at least a cost associated with an expected ability or non-ability of the power assembly to deliver power according to the predicted power demand, a cost associated with fuel consumption, and a cost associated with fuel cell degradation, - comparing (S3) the calculated costs of the respective at least two control scenarios to obtain a comparison result, - selecting (S4) one of the at least two control scenarios based on the comparison result, and - controlling (S5) the power assembly according to the selected control scenario.