Fuel Cell and Traction Battery Power Coordination for Durability
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Solution Overview
Problem
Fuel cell electric vehicles face challenges in efficiently managing power demand fluctuations, leading to durability issues and suboptimal fuel economy due to the fuel cell system's inability to handle rapid power changes without degradation.
Innovation Solution
A controller is implemented to maintain the fuel cell system at a near constant power output, while the traction battery dynamically adjusts to meet transient power demands, optimizing fuel cell operation at a steady state and utilizing historical data for power predictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fuel cell system dynamically adjusts power output to meet varying power demands, then the vehicle can respond to power needs, but the fuel cell system experiences degradation due to rapid power changes
Solution Approach 1:
The power delivery function is segmented between the fuel cell system and traction battery. The fuel cell system handles steady-state base power demand, while the traction battery handles transient power fluctuations. This segmentation allows the fuel cell to operate at stable power levels, avoiding degradation from rapid power changes while still meeting overall vehicle power needs.
Solution Approach 2:
The traction battery acts as an intermediary between the fuel cell system and the vehicle's power demand. It absorbs transient power demands and releases stored energy during high-demand periods, shielding the fuel cell system from direct exposure to rapid power changes that cause degradation.
2Productivity
If the fuel cell system operates at variable power levels to match demand, then power efficiency may improve, but fuel economy deteriorates due to frequent startup and shutdown cycles
Solution Approach 1:
The traction battery is pre-charged during low-demand periods when the fuel cell operates at optimal steady-state power levels. This preliminary energy storage allows the battery to supply power during transient high-demand periods, eliminating the need for the fuel cell to frequently adjust power levels or shut down, thereby improving fuel economy.
Solution Approach 2:
The fuel cell system maintains continuous operation at steady-state power levels, avoiding frequent startup and shutdown cycles. The traction battery bridges periods of varying demand, ensuring the fuel cell's useful action continues uninterrupted, which improves fuel economy by maintaining efficient operating conditions.
3Device complexity
If the fuel cell system handles transient power demands directly, then system complexity is reduced, but the fuel cell system experiences increased wear and degradation
Solution Approach 1:
The system is segmented into two distinct power sources with specialized roles: the fuel cell system provides steady base power, while the traction battery handles transient demands. This functional segmentation protects the fuel cell from wear-causing transient operations while maintaining overall system capability.
Solution Approach 2:
The traction battery serves as a protective intermediary that absorbs transient power demands before they reach the fuel cell system. This intermediary role reduces wear and degradation on the fuel cell components while maintaining the simplicity of the overall dual-powertrain architecture.
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 enhances the durability and fuel economy of the fuel cell system by reducing power cycling and maintaining efficient operation at optimal power points, leveraging the traction battery to handle dynamic power needs.
Implementation Method 1
The FCS converts chemical energy of a fuel, e.g., hydrogen, and an oxidizing agent, e.g., oxygen, into electrical energy
Implementation Method 2
The traction battery stores electrical energy
Data Source
AI summary
A vehicle includes a fuel cell system (FCS), a traction battery, and a controller. The controller controls the FCS to output a constant amount of power throughout a vehicle trip. Responsive to a demanded power greater than the constant amount, the controller controls the traction battery to output an amount of power commensurate with a difference between the demanded power and the constant amount.