Aircraft Battery String Charging for Voltage Equalization
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Solution Overview
Problem
Existing aircraft battery charging systems struggle to efficiently and uniformly charge multiple battery strings connected in parallel, leading to voltage disparities that can cause electrical issues and reduce system reliability.
Innovation Solution
A battery monitoring system with sensors and a processor is used to determine the voltage of each battery string, identify the highest and lower-voltage strings, and sequentially charge the lower-voltage strings to a target voltage, then all strings to a final target voltage, ensuring uniform charging and minimizing voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple battery strings are charged simultaneously in parallel, then charging time is reduced, but voltage disparities occur among battery strings leading to electrical issues
Solution Approach 1:
The charging process is segmented into two distinct phases: a first charging phase where battery strings are charged individually to a first target voltage, and a second charging phase where all battery strings are charged together to a final target voltage. This segmentation allows voltage equalization in the first phase while maintaining charging efficiency in the second phase, resolving the contradiction between charging speed and voltage uniformity.
2Reliability
If battery strings are charged sequentially one at a time, then voltage uniformity is improved, but total charging time increases significantly
Solution Approach 1:
The system performs preliminary voltage measurement and identification of the highest-voltage battery string before charging begins. Based on this preliminary information, it determines a first target voltage that is higher than the highest-voltage string's current voltage, ensuring all strings will be equalized by the end of the first charging phase. This preliminary action prevents overcharging while achieving voltage uniformity.
3Ease of operation
If a single target voltage is used for all battery strings, then charging simplicity is maintained, but voltage disparities persist among strings
Solution Approach 1:
The charging system dynamically changes the target voltage parameter through two distinct charging phases. In the first phase, a first target voltage (higher than any individual string's current voltage) is applied to equalize all strings. In the second phase, a final target voltage is applied to complete charging. This parameter change approach maintains operational simplicity while achieving voltage balance, as the control system automatically manages the phase transitions based on voltage measurements.
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 method ensures uniform charging of aircraft battery strings, reducing the risk of electrical issues and maximizing available battery power for aircraft propulsion.
Implementation Method 1
Each sensor is configured to measure a battery string voltage of a respective one of the plurality of battery strings
Implementation Method 2
The charger is configured to selectively direct an electrical charging current to the battery to charge the plurality of battery strings
Data Source
AI summary
An assembly for an aircraft includes a battery, a charger, and a battery monitoring system. The battery includes a plurality of battery strings. The charger is configured to charge the plurality of battery strings. The battery monitoring system further includes a processor in communication with a non-transitory memory storing instructions, which instructions when executed by the processor, cause the processor to determine the battery string voltage for each battery string of the plurality of battery strings, identify a highest-voltage battery string of the plurality of battery strings and a lower-voltage subset of the plurality of battery strings, and sequentially charge each battery string of the lower-voltage subset of the plurality of battery strings with the charger to a first target string voltage.