Fuel Cell Stop Method for Battery Charge and Cathode Concentration
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Solution Overview
Problem
Fuel cell and hybrid vehicle electrical power systems face challenges in completing charge and concentration adjustment processing within a reasonable time frame after a stop operation, leading to user discomfort and potential maintenance delays.
Innovation Solution
A method that calculates a target charge amount and time for charge processing, subtracting concentration adjustment processing time from a predetermined stop processing time, and controls fuel cell output to complete charge processing efficiently while optimizing net efficiency, ensuring both processes are finished within the allowed time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge processing and concentration adjustment processing are performed after stop operation, then the battery is charged and the fuel cell is protected from degradation, but the processing time becomes excessively long causing user discomfort and maintenance delays
Solution Approach 1:
The system performs concentration adjustment processing before the stop operation is completed. By reducing the oxygen concentration in the cathode flow channel while the fuel cell is still operating, the system prepares the fuel cell for subsequent startup and prevents degradation without requiring extended processing time after the stop operation. This preliminary action resolves the time conflict by overlapping the concentration adjustment with the final operational phase.
Solution Approach 2:
The system dynamically adjusts the charge processing time based on the calculated concentration adjustment time. The control unit calculates the required concentration adjustment time and subtracts it from the predetermined stop processing time to determine the charge processing time. This dynamic adjustment allows the system to optimize the balance between charging the battery and performing concentration adjustment within the available time window, preventing user discomfort and maintenance delays.
2Loss of time
If the fuel cell output is increased to complete charge processing faster, then the charge time is reduced, but the net efficiency of the fuel cell decreases
Solution Approach 1:
The system performs concentration adjustment processing in advance while the fuel cell is still operating at high output. By completing the concentration adjustment before the stop operation, the system avoids the need to extend the fuel cell operation solely for concentration adjustment purposes after stopping. This allows the fuel cell to operate at high output during charge processing without compromising overall efficiency, as the concentration adjustment is already completed.
Solution Approach 2:
The control unit calculates the charge processing time by subtracting the concentration adjustment time from the predetermined stop processing time. This parameter change approach allows the system to optimize the charge processing duration based on the actual time available, rather than using a fixed time. By dynamically adjusting the charge processing time parameter, the system can complete charging faster without excessively reducing net efficiency, as the calculation ensures the charge time is appropriate for the available window.
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 allows for the completion of charge and concentration adjustment processing without exceeding the predetermined time, reducing user discomfort and enabling quicker maintenance, while ensuring the fuel cell system is prepared for subsequent startups by maintaining the required energy levels and preventing degradation.
Implementation Method 1
a fuel cell that generates electric power when fuel gas is supplied to an anode flow channel and oxidant gas is supplied to a cathode flow channel
Implementation Method 2
an electrical storage device that stores electric power generated by the fuel cell
Data Source
AI summary
A fuel cell system executes charge processing to charge electric power generated by a stack to a battery, and sealed discharge processing to cause an oxygen concentration inside a cathode flow channel to decrease, after a stop operation has been made on a power switch. The stop method of a fuel cell system includes: a step of calculating a remaining charge time corresponding to a time in which charge processing can be executed, by subtracting a time required in sealed discharge processing from a predetermined stop processing permitted time, after a stop operation has been made on the power switch (Step S52), a step of calculating a remaining target charge amount of the battery (Step S54), a step of executing charge processing while controlling output of the stack based on the remaining charge time and remaining target charge amount (Step S56), and a step of executing sealed discharge processing.