Fuel Cell Standby Control via Compressor Minimum Speed
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Solution Overview
Problem
Fuel cell stacks experience high catalyst degradation and performance loss during low power operation, and hybrid fuel cell powertrains face issues with compressor shutdown leading to air starvation and voltage reduction, while existing standby modes do not adequately mitigate these problems.
Innovation Solution
An apparatus comprising a compressor, fuel cell stack, cathode valve, and controller that operates the compressor at a minimum speed and closes the cathode valve to reduce startup time and leakage current, thereby minimizing fuel consumption and preventing high cell voltage, which helps in preserving the platinum catalyst and reducing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the compressor is shut down during standby mode, then fuel consumption is reduced, but air starvation and voltage reduction occur leading to catalyst degradation
Solution Approach 1:
The compressor operates in periodic cycles, running at minimum speed during standby mode rather than being completely shut down. This periodic operation maintains sufficient air supply to prevent catalyst degradation while minimizing fuel consumption during low-power periods
Solution Approach 2:
The compressor speed parameter is changed from complete shutdown to minimum speed operation during standby mode. This parameter adjustment maintains adequate air flow to the fuel cell stack, preventing air starvation and catalyst degradation while still reducing overall energy consumption
2Reliability
If the compressor operates at high speed during standby mode, then air supply is sufficient, but fuel consumption increases
Solution Approach 1:
The compressor speed parameter is optimized to operate at minimum necessary speed during standby mode rather than high speed. This parameter change maintains sufficient air supply for reliability while minimizing fuel consumption by avoiding excessive compressor operation
Solution Approach 2:
The compressor provides partial air supply at minimum speed during standby mode rather than full air supply at high speed. This partial action is sufficient to prevent catalyst degradation and air starvation while significantly reducing fuel consumption compared to high-speed operation
3Loss of time
If the compressor is shut down completely, then startup time is reduced, but air starvation occurs leading to voltage reduction
Solution Approach 1:
The compressor is kept running at minimum speed during standby mode as a preliminary action to maintain readiness. This prevents complete shutdown and subsequent startup delays, ensuring immediate air supply availability when power demand increases, thus maintaining voltage stability without sacrificing startup time
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 reduces catalyst degradation, achieves faster dynamic response, and provides minor fuel savings by maintaining a low cell voltage, thus protecting the fuel cell stack from open circuit voltage and high cell voltages during standby mode.
Implementation Method 1
The compressor pressurizes ambient air to provide a cathode stream
Implementation Method 2
The fuel cell stack receives the cathode stream to provide electrical power to a load
Data Source
AI summary
An apparatus for placing a fuel cell stack in a standby mode is provided. The apparatus comprises a compressor, a fuel cell stack, a cathode valve and a controller. The compressor is operably coupled to an air induction system for providing a cathode stream. The fuel cell stack provides electrical power to a load in response to the cathode stream. The cathode valve is operably coupled to an outlet of the fuel cell stack for controlling a flow of the cathode stream to the fuel cell stack. The controller is configured to receive a power request amount for the load and to compare the power request amount to a predetermined amount. The controller is further configured to control the compressor to operate at a minimum speed and the cathode valve to close in response to determining that the power request amount is similar to the predetermined amount.