Mid-Point Battery Disconnect for Multi-String Short-Circuit Isolation
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Solution Overview
Problem
Aircraft battery packs face challenges in protecting against high-voltage and high-current short circuits, requiring innovative architectures that ensure safety without exceeding weight or volume constraints, and existing solutions lack standardization and effective redundancy for critical events like overcharge, over-discharge, and thermal runaway.
Innovation Solution
A modular, scalable battery pack protection system with a smart mid-point disconnect and centralized management, utilizing redundant and dissimilar technologies to safely disconnect high-voltage batteries without high-voltage fuses or contactors, and implementing differential protection and fault detection to minimize energy release and structural stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage fuses or contactors are used for battery protection, then protection reliability is improved, but device weight and complexity increase
Solution Approach 1:
The patent removes high-voltage fuses and contactors from the battery protection system, extracting these heavy and complex components while maintaining protection functionality through alternative means (low-voltage control circuits and solid-state switches), thereby reducing device complexity and weight while preserving reliability
Solution Approach 2:
The patent replaces mechanical protection devices (fuses and contactors) with electronic control systems including low-voltage control circuits and solid-state switches, substituting mechanical systems with electronic ones to reduce complexity and weight while maintaining or improving protection reliability
2Reliability
If redundant protection systems are implemented for critical events, then safety is improved, but device complexity increases
Solution Approach 1:
The patent implements a multi-functional control system where a single integrated control unit performs multiple protection functions (overcharge protection, over-discharge protection, short-circuit protection, thermal runaway detection) rather than requiring separate dedicated systems for each function, thereby achieving redundancy without proportionally increasing complexity
Solution Approach 2:
The patent combines multiple protection functions and monitoring capabilities into an integrated control system that manages overcharge, over-discharge, short-circuit, and thermal events through unified logic and control circuits, reducing overall system complexity while maintaining comprehensive safety coverage
3Power
If high-capacity high-voltage battery packs are used to provide sufficient power, then power output is improved, but the risk of thermal runaway and short-circuit damage increases
Solution Approach 1:
The patent implements preliminary protection measures including pre-configured control circuits that continuously monitor battery parameters and automatically activate protection mechanisms before thermal runaway or short-circuit damage can occur, enabling preventive action rather than reactive response
Solution Approach 2:
The patent applies preliminary anti-action by implementing control systems that anticipate and counteract potential harmful events (overcharge, over-discharge, short-circuits) before they can cause thermal runaway, using monitoring and control logic that actively prevents dangerous conditions from developing
4Reliability
If protection systems are designed for high-voltage (>1000 V DC) and high-current (3,500 A DC/string) conditions, then protection capability is improved, but device complexity and weight increase
Solution Approach 1:
The patent introduces low-voltage control circuits as intermediary devices that manage high-voltage battery protection indirectly through control signals and solid-state switches, allowing the system to handle high-voltage/high-current conditions without requiring heavy high-voltage protection hardware
Solution Approach 2:
The patent segments the battery system into multiple independent strings with individual control circuits for each string, allowing distributed protection that reduces the complexity burden on any single protection component while maintaining overall system capability to handle high-voltage and high-current conditions
Data Source
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AI summary
Methods and systems for protection/disconnect of high-power/energy high-voltage modular multi-string battery packs, such as battery packs for electric propulsion systems in all-electric or hybrid-electric aircraft. The methods and systems use a smart mid-point battery disconnect (14), comprising a current sensor (46) and a mid-point disconnect contactor (48), in conjunction with centralized battery management system (22). The resulting battery disconnect/protection system is configured to detect bus faults, load faults and string faults and then take appropriate action to isolate the detected fault. For example, in response to a short circuit in one battery string, the faulty battery string may be disconnected from the positive and negative busbars while the remaining battery strings continue to provide power.