Fuel Cell Control Device for Low Load Degradation
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Solution Overview
Problem
Fuel cell vehicles experience high degradation when operating at open circuit voltage or neighboring values, leading to inefficient power generation and increased fuel cell degradation during low load conditions.
Innovation Solution
Implementing extremely low current control with a control device that sets target output voltage limits for the fuel cell, maintaining the output voltage within specific upper and lower limits below the open circuit voltage, and using an energy storage device to manage regenerative power, thereby reducing fuel cell degradation and improving power generation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If operation of the fuel cell is stopped during low load conditions, then power generation efficiency is improved, but fuel cell degradation increases due to open circuit voltage
Solution Approach 1:
The patent applies parameter changes by controlling the fuel cell to operate at extremely low current levels (below normal lower limit) during low load conditions, rather than completely stopping operation. This maintains the voltage below open circuit voltage, preventing degradation while still achieving energy efficiency goals through coordinated battery usage.
Solution Approach 2:
The patent implements partial action by maintaining minimal fuel cell operation at extremely low current levels instead of complete shutdown. This partial operation prevents the harmful open circuit voltage condition while consuming minimal energy, striking a balance between efficiency and degradation prevention.
2Reliability
If the fuel cell operates at extremely low current below normal lower limit, then degradation is suppressed, but control complexity increases
Solution Approach 1:
The patent employs feedback control mechanisms where the control device continuously monitors fuel cell operating conditions and adjusts the converter control to maintain voltage within safe ranges. This feedback system automatically manages the complexity of extreme low current control without requiring manual intervention.
Solution Approach 2:
The patent introduces a control device as an intermediary between the fuel cell and the load/battery system. This intermediary manages the complex control logic for extreme low current operation, isolating the complexity from the fuel cell itself and providing a unified control interface.
3Reliability
If the converter controls target voltage within upper and lower limits, then fuel cell degradation is reduced, but power output flexibility is constrained
Solution Approach 1:
The patent applies multi-functionality by combining the fuel cell with a battery system that can handle variable power demands. The fuel cell operates in a protected voltage range while the battery compensates for power fluctuations, allowing the overall system to maintain flexibility and adaptability despite the voltage constraints on the fuel cell.
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 effectively suppresses fuel cell degradation and enhances power generation efficiency by accurately controlling current and voltage, even at low loads, and allows for stable energy management during extremely low current conditions.
Implementation Method 1
a fuel cell stack that generates electric power
Implementation Method 2
a converter that controls an output voltage of the fuel cell
Implementation Method 3
an energy storage device to which the output of the fuel cell is connected
Data Source
AI summary
In a case where a load amount of a load is a predetermined value or less, a control device of an FC vehicle implements extremely low current control for performing power generation at an extremely low current below a lower limit current of an FC for normal operation. At the time of implementing the extremely low current control, upper and lower limit values of a target output voltage of the converter are set in correspondence with the extremely low current, and the output voltage of the FC is controlled to be within a range between the upper and lower limit values.