Fuel Cell Operating Point Cycling for Temperature-Limited Power Output
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Solution Overview
Problem
Fuel cell stacks face reduced service life due to high operating temperatures, voltage cycles, and fuel contaminants, necessitating a solution that optimizes performance, durability, and robustness while achieving electric power targets.
Innovation Solution
A torque generating system that includes fuel cell power devices, high-voltage batteries, and an electric drive unit, with a controller managing the operation to alternate between different power-temperature operating points to maintain average temperatures below target levels, thereby extending the service life and achieving responsive torque output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the fuel cell operates at higher electric power levels to meet power targets, then the electric power output is improved, but the operating temperature increases which reduces service life
Solution Approach 1:
The fuel cell is operated in a cyclic manner, alternating between a first operating point (lower power, lower temperature) and a second operating point (higher power, higher temperature). This periodic operation allows the fuel cell to meet power targets while reducing the average temperature exposure, thereby extending service life.
Solution Approach 2:
The operating parameters of the fuel cell (power level and temperature) are dynamically changed by switching between two distinct operating points. This parameter variation enables the system to achieve required power output while controlling the thermal stress that degrades durability.
2Duration of action of stationary object
If the fuel cell operates at lower temperatures to extend service life, then durability is improved, but the electric power output decreases
Solution Approach 1:
The system uses periodic switching between operating points to ensure that the fuel cell spends sufficient time at lower temperatures for durability while periodically operating at higher power levels to meet demand. This temporal distribution resolves the contradiction between power output and service life.
Solution Approach 2:
The operating point of the fuel cell is made dynamic rather than static, allowing real-time adjustment between two operating states. This dynamic operation enables the system to adapt to varying power demands while maintaining favorable average temperature conditions for extended service life.
3Device complexity
If the fuel cell operates continuously at a fixed power level to simplify control, then device complexity is reduced, but the ability to optimize both power output and temperature management is limited
Solution Approach 1:
The control system implements a relatively simple periodic switching strategy between two predetermined operating points. This approach maintains acceptable control system complexity while achieving superior performance optimization compared to continuous fixed-power operation, as it enables temperature management without requiring complex real-time control algorithms.
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 fuel cell temperature to improve durability and performance, ensuring the fuel cell stack operates within optimal conditions, enhancing service life and maintaining electric power targets.
Implementation Method 1
A fuel cell is an electro-chemical device that converts chemical energy of a fuel, e.g., hydrogen, into electrical power by an electro-chemical reaction.
Implementation Method 2
The fuel cell power device has a non-linear power-temperature relationship that has a local temperature maxima at a first electric power level and a local temperature minima at a second electric power level.
Data Source
AI summary
A torque generating system is described, and includes a fuel cell power device, a high-voltage battery, an electric drive unit, and a controller. The fuel cell power device has a non-linear power-temperature relationship that has a local temperature maxima at a first electric power level and a local temperature minima at a second electric power level. A first operating point of the fuel cell power device is less than the first electric power level, and a second operating point of the fuel cell power device is set at a third electric power level that is greater than the first electric power level, wherein the third electric power level generates a fuel cell temperature that is less than the local temperature maxima. The fuel cell power device is controlled to one of the first operating point or the second operating point to transfer electric power to the electric drive unit.