Fuel Cell Cathode Air Cutoff Valve Control for Airtight Shutdown
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Solution Overview
Problem
Fuel cell systems face challenges in maintaining airtightness after shutdown, leading to hydrogen exhaust and air inflow, which deteriorates the stack and affects durability, due to inadequate control of the air cutoff valve's pressurization time and torque.
Innovation Solution
A fuel cell system with a stack pressure sensor and air cutoff valve, controlled by a controller that determines and adjusts pressurization time and torque based on measured pressures to maintain airtightness within the cathode, even after the fuel cell stops, by using a bypass line connecting the air supply and discharge lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant pressurization time and torque are used for the air cutoff valve, then airtightness may be maintained under specific conditions, but the system cannot adapt to changing atmospheric pressure and hydrogen supply pressure, leading to airtightness failure
Solution Approach 1:
The patent implements dynamic control of the air cutoff valve by continuously adjusting pressurization time and torque based on real-time atmospheric pressure and hydrogen supply pressure measurements. The controller modifies valve operation parameters dynamically rather than using fixed constant values, enabling the system to adapt to varying pressure conditions and maintain reliable airtightness across different operating environments.
2Reliability
If excessive pressurization time and torque are applied to the air cutoff valve, then airtightness is maintained, but battery discharge occurs due to dark current
Solution Approach 1:
The patent optimizes pressurization parameters by adjusting time and torque values based on actual pressure conditions. The controller calculates appropriate pressurization duration and force levels that are sufficient to maintain airtightness while avoiding excessive values that would cause prolonged valve operation and battery discharge. This parameter optimization reduces energy consumption while ensuring reliable sealing.
3Use of energy by moving object
If insufficient pressurization time and torque are used, then battery energy is conserved, but airtightness is not maintained, causing hydrogen exhaust and air inflow that deteriorate the stack
Solution Approach 1:
The patent employs a feedback control mechanism where the controller continuously monitors atmospheric pressure and hydrogen supply pressure, then adjusts pressurization time and torque accordingly. This closed-loop control ensures that the minimum necessary pressurization is applied to maintain airtightness without waste, preventing both insufficient sealing (which causes stack deterioration) and excessive pressurization (which wastes battery energy).
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 solution effectively maintains airtightness, prevents stack deterioration, and improves initial output responsiveness by actively controlling the air cutoff valve's pressurization time and torque in response to changing atmospheric and hydrogen supply pressures.
Implementation Method 1
a stack pressure sensor provided in the air supply line to measure pressure of air at an inlet side of the stack supplied to a cathode side of the fuel cell stack
Implementation Method 2
an air cutoff valve provided with a bypass line connecting the air supply line and the air discharge line in the air cutoff valve
Implementation Method 3
a fuel cell stack in which a plurality of fuel cells used as power sources are stacked... generates electricity through an electrochemical reaction that takes place inside a fuel cell stack
Implementation Method 4
the air supply system operates an air compressor to supply the introduced external air to a cathode (air electrode) of the fuel cell stack
Data Source
AI summary
A fuel cell system and a control method thereof include an air supply line supplying air to a fuel cell stack and an air discharge line discharging post-reaction air, a stack pressure sensor provided in the air supply line to measure pressure of air at an inlet side of the stack supplied to a cathode side of the fuel cell stack, an air cutoff valve provided with a bypass line connecting the air supply line and the air discharge line in the air cutoff valve, and a controller electrically connected to the stack pressure sensor and the air cutoff valve and configured to determine pressurization time and pressurization torque for the air cutoff valve when the controller concludes that it is necessary to shut off air inside a cathode and control the stack pressure sensor and the air cutoff valve according to the determined pressurization time and the determined pressurization torque so that inside of the cathode is airtight even after stopping of a fuel cell in the fuel cell stack is completed.