Fuel Cell Voltage Control for Secondary Cell Overcharge Prevention
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Solution Overview
Problem
In fuel cell systems, voltage feedback control during intermittent operations can lead to overcharging of secondary cells due to improper electric power control, which is not effectively addressed by existing technologies.
Innovation Solution
A fuel cell system with a converter that controls output voltage and includes a high-potential avoidance control mechanism, which corrects the converter command value to prevent the output voltage from exceeding a predetermined threshold, ensuring the deviation between generated power and allowable power equals zero, thereby preventing overcharging of the secondary cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If voltage feedback control is performed during intermittent operation of the fuel cell, then the output voltage can be regulated, but the secondary cell may become overcharged due to improper electric power control
Solution Approach 1:
The patent implements a feedback control mechanism where the control device continuously monitors the output voltage of the fuel cell and adjusts the converter command value based on the detected voltage deviation. When the output voltage approaches the heightened potential avoidance threshold voltage, the feedback control modifies the converter command to reduce the voltage, thereby preventing secondary cell overcharge while maintaining regulated output voltage.
Solution Approach 2:
The patent applies preliminary anti-action by establishing a heightened potential avoidance threshold voltage (lower than the open-circuit voltage) before overcharge can occur. The control device proactively adjusts the converter command value when the output voltage approaches this predetermined threshold, preventing the voltage from reaching levels that would cause secondary cell overcharge, rather than reacting after overcharge has begun.
2Reliability
If the output voltage is restrained from becoming greater than or equal to the heightened potential avoidance threshold voltage, then secondary cell overcharge is prevented, but the electric power control may become improper
Solution Approach 1:
The patent employs dynamic control by continuously adjusting the converter command value based on real-time voltage conditions. The control device dynamically modifies the command during intermittent operation, increasing it when voltage is below the threshold and decreasing it when voltage approaches the threshold, thereby maintaining both overcharge prevention and accurate power control through adaptive regulation.
Solution Approach 2:
The patent changes the converter command value parameter dynamically based on the output voltage level. When the output voltage is below the heightened potential avoidance threshold voltage, the converter command value is increased to allow greater power output. When the voltage approaches the threshold, the command value is decreased to prevent overcharge, thus maintaining proper electric power control while ensuring 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
The system effectively prevents overcharging of the secondary cell during intermittent fuel cell operations by controlling the output voltage, ensuring accurate power management and maintaining the secondary cell within safe charging limits.
Implementation Method 1
a fuel cell system that includes a fuel cell and a secondary cell, and that supplies electric power to a load
Data Source
AI summary
During an intermittent operation of the fuel cell, a demanded FC voltage calculation portion calculates a predetermined voltage that is below a heightened potential avoidance threshold voltage as a demanded FC voltage, and outputs the voltage to a converter. When during the intermittent operation of the fuel cell, a deviation obtained by subtracting a generated power of the fuel cell from a system's allowable power that is allowable in the fuel cell system becomes less than or equal to a value 0, the demanded FC voltage correction portion corrects a command value provided for the converter so that the deviation becomes equal to the value 0.