Battery Cell Pressure Sensing Circuits for Pre-Venting Fire Prevention
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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 only monitor voltages and temperatures without indicating internal cell conditions.
Innovation Solution
Incorporating sensors to detect swelling or pressure changes in battery cells, which trigger alarms and automatically halt charging and discharging, combined with high-frequency AC power for cell balancing and a water-based fire suppression system to prevent and control fires within battery racks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional battery management systems only monitor voltages and temperatures, then the monitoring system remains simple, but the system cannot detect internal pressure changes that lead to battery fires
Solution Approach 1:
The patent introduces pressure sensors as intermediary devices that detect internal pressure changes in battery cells. These sensors act as mediators between the battery cell's internal state and the monitoring system, providing early warning of potential fire hazards before temperatures rise or voltages become abnormal. This resolves the contradiction by adding a specific detection mechanism that enhances reliability without requiring complete system redesign.
Solution Approach 2:
The system performs preliminary detection of pressure changes before actual fire conditions develop. By monitoring pressure as an early indicator, the system can trigger alarms and halt charging/discharging operations before the battery cell reaches critical temperature or voltage levels that would cause fire. This preliminary action approach improves reliability by preventing fires rather than just responding to them.
2Reliability
If pressure sensors are added to detect swelling, then battery fire prevention is improved, but the device complexity increases
Solution Approach 1:
The pressure sensors are designed to serve multiple functions: detecting cell swelling, monitoring internal pressure changes, and providing early warning for both thermal and mechanical failure modes. This multi-functionality improves reliability by covering multiple failure mechanisms with a single sensor type, rather than requiring separate sensors for each parameter, thus limiting the increase in device complexity.
Solution Approach 2:
The sensor system is designed to be self-diagnosing and self-reporting, with integrated circuitry that automatically processes sensor signals and generates alarms without requiring complex external processing systems. This self-service capability improves reliability while minimizing the added complexity by making the sensor system autonomous rather than dependent on elaborate external monitoring infrastructure.
3Reliability
If high frequency AC power is used for cell balancing, then isolation transformers can be used, but the power system becomes more complex
Solution Approach 1:
The patent replaces conventional low-frequency AC power systems with high-frequency AC power for cell balancing operations. This substitution enables the use of smaller, more efficient isolation transformers and reduces electromagnetic interference. The high-frequency operation allows for miniaturized magnetic components while maintaining galvanic isolation, improving safety without requiring large, complex power transformation equipment.
Solution Approach 2:
The system changes the frequency parameter of the AC power from conventional 50/60 Hz to high frequency (kHz range). This parameter change fundamentally alters the characteristics of the power system, enabling the use of smaller transformers and reducing ripple effects in the cell balancing process. The frequency change improves safety through better isolation while keeping the power system manageable in size and complexity.
4Reliability
If water fire suppression systems are implemented, then fire control is improved, but the risk of water damage to electronics increases
Solution Approach 1:
The water fire suppression system is designed to activate only after pressure sensors detect swelling and confirm a fire hazard, and only after the battery module has been electrically isolated. This preliminary action sequence ensures that water is applied only when necessary and when electrical hazards have been mitigated, improving fire suppression effectiveness while minimizing unnecessary water exposure to electronics.
Solution Approach 2:
The system extracts and removes electrical power and connections from the battery module before applying water suppression. By taking out the electrical component first through isolation transformers and circuit breakers, the system eliminates the harmful interaction between water and electronics, allowing water to be used safely for fire suppression without risking damage to sensitive electronic components.
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
Prevents battery cell fires by detecting swelling before it leads to venting or combustion, ensuring safe operation by disconnecting faulty cells and using high-frequency AC power and water-based suppression to manage and extinguish potential fires.
Implementation Method 1
a battery module having a sensor that detects swelling of a battery cell
Implementation Method 2
high frequency AC power is used as a power source for balancing the battery module cells
Implementation Method 3
a top cover that collects water and directs this water to plates of the battery module to cool the battery
Implementation Method 4
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
Data Source
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.