Battery Cell Pressure Monitoring for Swelling-Triggered Fire Isolation
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Solution Overview
Problem
Conventional battery management systems fail to effectively monitor and mitigate internal pressure changes in battery cells, which can lead to swelling and potential fires, as they primarily focus on voltage and temperature monitoring rather than the internal state of the cells.
Innovation Solution
Incorporating swelling/pressure sensors into battery modules to detect abnormal swelling, triggering alarms and automatically halting charging and discharging, and integrating high-frequency AC power for cell balancing with isolation transformers, along with a water-based fire suppression system and exhaust ducting to manage and prevent fires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional battery management systems only monitor voltage and temperature, then the system complexity is low, but the ability to detect internal pressure changes and swelling is insufficient
Solution Approach 1:
The pressure sensor is integrated within the battery cell structure itself, with the sensor positioned inside the cell to directly measure internal pressure. This nested configuration allows the sensing function to be embedded within the existing battery architecture, improving detection capability while minimizing additional system complexity.
Solution Approach 2:
The battery management system is enhanced to perform multiple functions: voltage monitoring, temperature monitoring, and pressure monitoring. By making the BMS multi-functional, the system can detect various failure modes including swelling and internal pressure changes, thereby improving measurement precision without requiring entirely separate monitoring systems.
2Reliability
If pressure sensors are integrated into battery cells to detect swelling, then fire prevention capability is improved, but the device complexity increases
Solution Approach 1:
The pressure sensor continuously monitors internal cell pressure before swelling becomes severe or thermal runaway occurs. By detecting pressure changes in advance, the system can trigger early warnings or protective actions, preventing fire hazards before they develop. This preliminary detection significantly improves reliability by catching issues in their incipient stages.
Solution Approach 2:
The sensor and control circuitry are integrated within the battery module structure, with the pressure sensing function nested within the cell assembly. This integration approach improves fire prevention capability while minimizing the increase in device complexity by utilizing existing structural elements.
3Reliability
If high frequency AC power is used for cell balancing with isolation transformers, then safety is improved, but the device complexity increases
Solution Approach 1:
An isolation transformer is introduced as an intermediary component in the cell balancing circuit. The transformer provides galvanic isolation between the high-frequency AC power source and the battery cells, improving safety by preventing direct electrical contact and reducing the risk of short circuits or electrical shocks. While this adds a component, it significantly enhances system safety.
Solution Approach 2:
The system uses high-frequency AC power instead of conventional low-frequency AC or DC for cell balancing. This parameter change enables the use of isolation transformers and improves safety through frequency-based isolation, while the high frequency also allows for more efficient power transfer and smaller component sizes, partially offsetting the complexity increase.
4Reliability
If water fire suppression systems are implemented, then fire control capability is improved, but the device complexity and water usage increase
Solution Approach 1:
The water-based fire suppression system is pre-positioned within the battery rack structure, with water reservoirs and delivery mechanisms in place before a fire event occurs. When thermal runaway or fire is detected, the system immediately activates to suppress the fire, preventing its spread. This preliminary preparation ensures rapid response while controlling water usage to only what is necessary for suppression.
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 prevents battery cell fires by detecting swelling, halting operations, and using advanced cooling and suppression systems to manage and control fire risks within battery systems.
Implementation Method 1
a sensor that detects changes in an internal pressure of the battery cell
Implementation Method 2
high frequency AC power is used as a power source for balancing the battery module cells. Using high frequency AC power permits the use of isolation transformers as a part of the cell balancing circuit
Implementation Method 3
a water fire suppression system having a cascading water flow among the battery modules, which provides cooling in the event of a battery cell fire
Implementation Method 4
cascading water flow among the battery modules
Implementation Method 5
an exhaust duct to remove gases and/or heat and direct these gases and/or heat outside of the room, container, building, etc. that houses the battery rack
Data Source
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AI summary
Sensors and circuits for batteries are provided that prevent battery fires. The sensors and circuits are part of a battery management system that detects battery cell swelling and changes in the internal pressure of battery cells and removes the battery cells from service before they vent and catch on fire or explode. The sensors and circuits continually monitor every battery cell for swelling/increases in internal pressure that are indicative of the formation of flammable and explosive gases within the battery cells, and a battery management system that includes one or more of the sensors and circuits removes battery cells with issues from service before they vent and catch on fire or explode.