Aircraft Battery String Isolation Under Fault and Load Limits
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Solution Overview
Problem
Existing aircraft electrical distribution systems lack effective methods for isolating faulty battery strings and managing electrical loading to prevent overloading of remaining battery strings, which can lead to thermal and electrical limits being exceeded.
Innovation Solution
A control system is implemented to detect faults in battery strings, isolate faulted strings, and maintain unfaulted strings in a closed position, while managing electrical loading and thermal conditions through a thermal management system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery string experiences a fault, then the faulty string should be isolated to prevent further damage, but the remaining battery strings may become overloaded and exceed thermal and electrical limits
Solution Approach 1:
The battery system is divided into multiple independently controllable battery strings, each with its own contactor. This segmentation allows individual faulty strings to be isolated while maintaining operation of healthy strings, preventing complete system failure while managing load distribution across remaining strings
Solution Approach 2:
The control system dynamically adjusts the operational state of battery strings based on real-time fault detection and load conditions. When a fault is detected, the system dynamically reconfigures the electrical architecture by opening the faulty string's contactor while maintaining closed contactors for healthy strings, adapting to changing system conditions to prevent overloading
2Reliability
If all battery strings are kept in closed position to ensure continuous power supply, then power availability is maintained, but a fault in one string can propagate and cause system-wide failure
Solution Approach 1:
Each battery string has an independent contactor that can be individually controlled, creating electrical isolation between strings when needed. This segmentation enables the system to maintain power supply from healthy strings while isolating faulty ones, preventing fault propagation throughout the entire battery system
Solution Approach 2:
The contactors serve as intermediary devices between the battery strings and the electrical distribution bus. They mediate the electrical connection, allowing the control system to selectively connect or disconnect individual strings based on their operational status, thus preventing fault propagation while maintaining power supply from healthy strings
3Reliability
If the control system isolates a faulty battery string, then fault propagation is prevented, but the electrical loading on remaining strings increases potentially exceeding safe limits
Solution Approach 1:
The control system continuously monitors the electrical loading conditions of remaining battery strings after fault isolation. This feedback mechanism allows the system to detect when load distribution approaches unsafe limits and take corrective actions, such as adjusting the operational state of contactors or alerting operators to prevent exceeding thermal and electrical limits
Data Source
AI summary
An assembly for an aircraft includes an aircraft electrical distribution bus, a battery, and a control system. The battery includes a plurality of battery strings. Each battery string includes a string contactor. The control system is in signal communication with the string contactor of each battery string. The control system is configured to control a position of the string contactor of each battery string in a closed string position or an open string position. The control system is configured to: detect a fault in a faulted first battery string of the plurality of battery strings and position the string contactor of the faulted first battery string in the open string position, in response to the detected fault in the faulted first battery string and maintain the string contactor of at least one unfaulted second battery string of the plurality of battery strings in the closed string position.