Series Battery Circuit Bypass for HAPS Short Circuits
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Solution Overview
Problem
Energy storage apparatuses in high-altitude platform stations (HAPS) face challenges in maintaining long-term operation due to unpredictable internal short circuits in lithium-ion batteries with metallic lithium negative electrodes, which can lead to abnormal cell behavior and reduced discharge capacity.
Innovation Solution
The energy storage apparatus includes a series-connected battery circuit configuration with a first and second switch, each with a diode, allowing current to bypass abnormal cells during charge and discharge, preventing short circuits and ensuring continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic lithium is used as the active material of the negative electrode to increase discharge capacity, then the discharge capacity is significantly increased, but internal short circuits may occur due to dendrite formation
Solution Approach 1:
The battery system is divided into multiple independent battery circuits, each with its own protection switches. This segmentation allows the system to isolate and continue operating with healthy circuits even when one circuit experiences internal short circuits, thus maintaining reliability while using high-capacity metallic lithium electrodes.
Solution Approach 2:
Protection switches are introduced as intermediary components between the metallic lithium electrodes and the external circuit. These switches act as mediators that can detect abnormal conditions (internal short circuits) and disconnect the affected battery circuits, preventing the harmful effects from propagating while allowing the system to continue operating.
2Reliability
If protection switches are added to each battery circuit to prevent short circuits, then the system reliability is improved, but the device complexity increases
Solution Approach 1:
The protection switches are designed with universal functionality to handle both charging and discharging operations across multiple battery circuits. Each switch can operate in forward direction for charging and reverse direction for discharging, providing multi-functionality that reduces the need for separate protection mechanisms for different operating modes.
Solution Approach 2:
The protection switches are pre-configured in each battery circuit before operation begins. This preliminary arrangement ensures that protection mechanisms are already in place and can immediately respond to internal short circuits without requiring complex real-time decision-making or additional control logic, thereby improving reliability while keeping the system relatively simple.
3Power
If battery circuits are connected in series to increase voltage output, then the power output is improved, but the risk of system failure increases when cells become abnormal
Solution Approach 1:
The series-connected battery system is segmented into independent circuits with individual protection switches. This segmentation allows the system to maintain high voltage output through series connection while preventing system-wide failure by isolating abnormal circuits. When one circuit becomes abnormal, only that specific circuit is disconnected, while other circuits continue to contribute to the overall voltage output.
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 configuration enables the energy storage apparatus to continue operating even when some cells are abnormal, maintaining high discharge capacity and extending the operational period of HAPS without requiring maintenance.
Implementation Method 1
a first switch including a diode and provided in the first electrical path such that a forward direction of the diode is a charge direction of the energy storage apparatus
Implementation Method 2
a second switch including a diode and provided in the second electrical path such that the forward direction of the diode is a discharge direction of the energy storage apparatus
Implementation Method 3
an energy storage cell connected to an adjacent battery circuit through the first electrical path
Data Source
AI summary
An energy storage apparatus used in a flight vehicle includes battery circuits connected in series, through which current flows during charge and discharge of the energy storage apparatus. Each of the battery circuits includes: a first electrical path; an energy storage cell connected to an adjacent battery circuit through the first electrical path; a first switch that includes a diode and is provided in the first electrical path such that a forward direction of the diode is a charge direction of the energy storage apparatus; a second electrical path connected to the adjacent battery circuit in parallel with the energy storage cell and the first switch; and a second switch that includes a diode and is provided in the second electrical path such that a forward direction of the diode is a discharge direction of the energy storage apparatus, and is turned on when the first switch is turned off.