Bidirectional Converter Transient Control for Fuel Cell Vehicles
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Solution Overview
Problem
Fuel cell vehicles experience abrupt voltage overshoot/undershoot and component durability issues due to rapid energy conversion in transient states, such as regenerative braking and sudden acceleration, which affect control responsiveness and component longevity.
Innovation Solution
A bidirectional converter is configured to monitor the fuel cell vehicle's state in real time and adjust the current limiting value based on predefined modes, such as regenerative braking and sudden acceleration, by subtracting or increasing the current limiting value by a predetermined ratio when the difference value falls below a certain threshold, typically 5% of the current limiting value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bidirectional converter performs predetermined control based on commands from the fuel cell controller in transient states, then the control system maintains simple hierarchical structure, but voltage overshoot/undershoot occurs and control responsiveness deteriorates
Solution Approach 1:
The control function is segmented between the fuel cell controller (higher-level) and bidirectional converter controller (lower-level). The bidirectional converter controller independently determines transient states and adjusts current limiting values, while the fuel cell controller handles overall energy management. This segmentation enables rapid local response without waiting for higher-level commands.
Solution Approach 2:
The bidirectional converter controller preliminarily identifies transient states (regenerative braking, sudden acceleration) and proactively adjusts current limiting values before voltage fluctuations occur. This preliminary action prevents overshoot/undershoot by anticipating rapid energy conversion needs.
2Speed
If the bidirectional converter adjusts current limiting value rapidly in transient states, then control responsiveness improves, but the system complexity increases
Solution Approach 1:
The bidirectional converter controller continuously monitors battery current and power demand to detect transient states. This feedback mechanism enables automatic adjustment of current limiting values based on real-time conditions, improving responsiveness without requiring complex external control systems.
Solution Approach 2:
The bidirectional converter controller autonomously determines transient states and adjusts current limiting values without requiring complex intervention from the fuel cell controller. This self-service capability simplifies the overall control architecture while maintaining rapid response to transient conditions.
3Reliability
If the current limiting value is adjusted during transient states, then voltage fluctuations are prevented and component durability improves, but energy conversion efficiency may be affected
Solution Approach 1:
The current limiting value is dynamically adjusted based on the detected transient state. During regenerative braking, the limit is reduced to prevent overcharging; during sudden acceleration, it is increased to meet power demand. This dynamic adjustment protects components while optimizing energy conversion for each operating condition.
Solution Approach 2:
The system changes the current limiting parameter in response to transient state detection. By modifying this key parameter, the system prevents voltage overshoot/undershoot and protects components without requiring fundamental changes to the energy conversion process, thus maintaining efficiency.
Data Source
AI summary
A method and system for controlling a fuel cell vehicle are provided in which a bidirectional converter monitors a state of a fuel cell vehicle in real time to improve control responsiveness in a transient state of the fuel cell vehicle. The method includes receiving, by a bidirectional converter, a command for a current limiting value in the high voltage battery from the fuel cell controller while the fuel cell vehicle is driven. In addition, the bidirectional converter is configured to determine whether the fuel cell vehicle is switched to a predetermined mode and change the current limiting value of the high voltage battery. A predetermined control is performed by the bidirectional converter based on the changed current limiting value when the fuel cell vehicle is switched to the predetermined mode.