Aircraft Battery Pack Switching for High-Altitude Arc Prevention
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Solution Overview
Problem
Battery packs in aircraft and other platforms face challenges with arcing or shorting between terminals and enclosures due to depressurization events at high altitudes, where low air pressure increases electrical conductivity, exceeding the clearance's protective capabilities.
Innovation Solution
A battery assembly with an intermediate switch between battery cells that opens in response to falling air pressure below a threshold, dividing the series connection into disconnected groups to reduce voltage and prevent arcing or shorting, using sensors to monitor air pressure and altitude for control signal activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If battery cells are connected in series to provide high voltage, then power output is improved, but the risk of arcing and shorting increases at high altitudes due to low air pressure increasing electrical conductivity
Solution Approach 1:
The battery pack is divided into multiple series strings of battery cells, with each string containing multiple cells connected in series. Switches are placed between strings to enable reconfiguration. This segmentation allows the system to maintain high voltage operation during normal conditions while providing a pathway to reduce voltage during depressurization events by disconnecting or reconfiguring individual strings.
Solution Approach 2:
The battery pack incorporates switches that can dynamically reconfigure the series connection of battery cell strings based on ambient pressure conditions. During normal pressure, all strings are connected in series for maximum power output. When depressurization is detected, the switches reconfigure the connection to reduce the number of active series connections, thereby reducing voltage and the associated arcing risk.
2Reliability
If air pressure decreases at high altitude, then electrical conductivity of air increases, but the clearance between terminals and enclosure becomes insufficient for protection
Solution Approach 1:
Pressure sensors continuously monitor ambient air pressure and detect depressurization conditions before they become critical. The control system is pre-programmed with threshold values and response protocols. When pressure drops below the threshold, the system automatically activates switches to reconfigure the battery connections, reducing voltage before arcing can occur. This preliminary detection and response prevents the harmful effect rather than merely reacting to it.
3Object-affected harmful factors
If switches are added to reconfigure battery cells, then protection against arcing is improved, but device complexity increases
Solution Approach 1:
The battery pack system incorporates pressure sensors that continuously monitor ambient air pressure and provide feedback to the control system. The control system processes this feedback and automatically actuates switches to reconfigure the battery cell connections when depressurization is detected. This closed-loop feedback mechanism enables automatic protection without requiring complex manual intervention or overly sophisticated control logic, balancing safety with manageable system complexity.
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 solution effectively reduces the risk of arcing and shorting by dividing the battery cells into lower voltage groups, thereby minimizing electrical hazards during depressurization events at high altitudes.
Implementation Method 1
A first end switch, the first one or more battery cells, the intermediate switch, the second one or more battery cells, and the second end switch are connected in series to the load
Data Source
AI summary
A battery assembly includes a first plurality of battery cells, a second plurality of battery cells, and a switch between the first plurality of battery cells and the second plurality of battery cells. In an example, the first plurality of battery cells, the switch, and the second plurality of battery cells are connected in series to a load. In an example, the first plurality of battery cells, the second plurality of battery cells, and the switch are within an enclosure, which is within a pressure regulated section of an aircraft. The load may be external to the enclosure. The battery assembly further includes a controller configured to open the switch and the disconnect the first plurality of battery cells from the second plurality of battery cells, in response to an air pressure proximal to the first and second pluralities of battery cells falling below a threshold level.