Fuel Cell Idling Stop Control for Low-Load Hydrogen Loss
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Solution Overview
Problem
Existing fuel cell systems face inefficiencies and potential deterioration when operating under low loads, particularly due to unnecessary hydrogen consumption and water drainage issues, which are not adequately addressed by existing technologies.
Innovation Solution
A power system with a control device that executes idling stop processes to manage the net output of the fuel cell system, including bypassing oxidant gas to maintain low-load power generation, stopping fuel or oxidant gas supply, and using inert gases to retard deterioration, based on system and battery states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the fuel cell stack continues generating power under a very low load to avoid stopping and restarting, then the restart time is reduced and deterioration is minimized, but hydrogen is consumed unnecessarily and water drainage becomes problematic
Solution Approach 1:
The patent implements periodic idling stop processes where the fuel cell stack alternates between stopping power generation and resuming it. This periodic operation allows the system to avoid continuous low-load operation that wastes hydrogen, while still maintaining readiness to restart quickly when power is needed. The control device determines appropriate timing for these periodic stops and restarts based on system state and battery conditions.
2Reliability
If the fuel cell stack continues generating power under a very low load, then the restartability is maintained, but water drainage efficiency deteriorates and power generation stability is reduced
Solution Approach 1:
By implementing periodic idling stop processes, the system maintains restartability through controlled shutdowns rather than continuous operation. The periodic nature ensures the fuel cell stack is periodically brought to a stopped state and then restarted, maintaining its ability to start while avoiding the stability issues of continuous low-load operation. Water drainage is improved by stopping operation rather than maintaining low-flow conditions.
Solution Approach 2:
The control device changes operational parameters by transitioning between stopped and running states based on system conditions. This parameter change from continuous low-load operation to periodic operation with complete stops resolves the contradiction by allowing the system to maintain restartability while avoiding water drainage and stability problems associated with sustained low-flow operation.
3Loss of energy
If the net output of the fuel cell system is reduced to match low power requirements, then energy efficiency is improved, but the fuel cell stack may require stopping which causes deterioration
Solution Approach 1:
The patent uses periodic idling stop processes where the fuel cell stack is stopped during periods of low power demand and restarted when power is needed. This periodic operation achieves better energy efficiency by completely stopping the fuel cell rather than maintaining low-load operation, while the controlled periodic nature prevents excessive deterioration that would result from frequent or unpredictable stopping.
Solution Approach 2:
The battery serves as a buffer that allows the fuel cell system to stop during low demand periods without affecting vehicle operation. The battery self-services by providing power during these periods, enabling the fuel cell to achieve complete shutdown for efficiency while the battery handles the power supply continuity, thus protecting the fuel cell from deterioration-causing frequent stops.
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 manages net output and reduces deterioration while maintaining energy efficiency and restartability by selectively executing idling stop processes tailored to vehicle and battery conditions, ensuring prompt power resumption and uniform system degradation.
Implementation Method 1
a fuel cell stack that generates power by way of an electrochemical reaction between a fuel gas and an oxidant gas
Data Source
AI summary
The power system includes a fuel cell stack, a system accessory, a battery, and a control device. The control device executes, based on a state of a vehicle and the battery, one of the following processes: a normal power generation process during which the control device makes a net output greater than 0; a first idling stop process during which the control device makes the net output equal to or less than 0 while continuing operation of the system accessory and power generation by the stack; a second idling stop process during which the control device makes the net output less than 0 by stopping the power generation while continuing the operation of the system accessory; and a third idling atop process during which the control device makes the net output equal to 0, by stopping both the operation of the system accessory and the power generation.