Battery Safety Device Trigger Detection via Voltage Profile Comparison
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Solution Overview
Problem
Existing safety devices in lithium-ion battery systems, such as Current Interruptive Devices, are ineffective in detecting internal short circuits caused by mechanical deformation or particles, leading to irreversible overheating and damage to monitoring electronics, and are often omitted due to protection costs.
Innovation Solution
A method that records the actual time profile of a battery cell's characteristic and compares it to an expected course using a model, allowing for detection of safety device triggering, even in new types of safety devices that short-circuit or bypass cells, by evaluating existing signals from a battery management unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Current Interruptive Devices are triggered to interrupt current flow, then thermal runaway is prevented, but monitoring electronics are damaged by high negative voltages
Solution Approach 1:
The patent introduces a monitoring circuit as an intermediary that measures voltage signals to detect safety device activation. This intermediary system allows the battery management system to detect CID triggering without being directly exposed to the high negative voltages that occur during actual current interruption, thereby protecting the electronics while maintaining detection capability.
Solution Approach 2:
The patent creates a simplified electrical model that replicates the voltage behavior of the battery system under normal and fault conditions. By comparing actual voltage measurements against this model, the system can detect safety device activation indirectly through voltage profile analysis, avoiding direct exposure to damaging high-voltage transients while maintaining accurate detection.
2Reliability
If protection measures are implemented to protect electronics against high negative voltages, then electronic component reliability is improved, but system cost increases significantly
Solution Approach 1:
The patent uses electrical modeling to create a virtual representation of battery behavior under various conditions. This model allows the system to predict and detect abnormal voltage profiles indicative of safety device activation without requiring expensive hardware protection circuits. The modeling approach provides cost-effective protection by using software-based detection rather than hardware-based protection.
Solution Approach 2:
The patent replaces expensive hardware protection measures with electronic monitoring and signal processing. Instead of using costly voltage clamping circuits, isolation barriers, or other hardware protection mechanisms, the system uses microcontroller-based voltage measurement and comparison against modeled expectations, achieving protection at minimal additional cost.
Data Source
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AI summary
The invention relates to a method for detecting a triggering of a security device (21). Said security device (21) is associated with a battery cell (22) and is triggered if a security-critical situation is present in the battery cell (22). Initially an actual time path of a parameter of the battery cell (23) is detected. At the same time, an expected time path of the parameter is determined, in particular using a model (24). Then, the actual time path is compared to the expected time path of the parameter (25). Finally, based on the comparison, it is determined whether to trigger the security device (21) or not.