Battery Pack Impedance Detection for Loose Connection Faults
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Solution Overview
Problem
The existing battery pack systems face reliability issues due to aged or abnormally loose connection components between battery modules or cells, leading to increased impedance, overheating, and potential thermal runaway or fire.
Innovation Solution
A battery pack system equipped with voltage and current detection circuits and a battery management system (BMS) that calculates the impedance of each to-be-detected assembly, determining if the connection component is abnormally connected by comparing it to a preset impedance threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connection components are used to connect battery modules or cells, then the battery pack can be assembled and function, but the connection components may age and decay leading to increased impedance and overheating
Solution Approach 1:
The patent implements preliminary detection of connection components by measuring impedance values and comparing them against threshold values. The BMS proactively identifies abnormal connections before they cause overheating or thermal runaway, allowing preventive action to be taken. This resolves the contradiction by detecting potential failures before they manifest as harmful effects.
Solution Approach 2:
The patent establishes a feedback mechanism where the BMS continuously monitors connection components through impedance measurement, compares results against thresholds, and triggers warnings or protective actions. This closed-loop feedback system enables real-time detection and response to connection degradation, preventing the progression from normal aging to harmful overheating conditions.
2Measurement precision
If impedance detection is implemented to detect abnormal connections, then connection safety can be monitored, but detection accuracy may be insufficient without proper threshold comparison
Solution Approach 1:
The patent transforms the detection approach by measuring impedance (a electrical parameter) instead of directly measuring physical connection status. By converting the detection target into a measurable electrical parameter and comparing it against threshold values, the system achieves accurate detection of connection abnormalities without requiring complex mechanical or visual inspection systems.
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 solution effectively detects abnormal connections in battery subpacks, enhancing the safety and reliability of the battery pack by preventing overheating and thermal runaway.
Implementation Method 1
the voltage detection circuit is configured to detect voltages at two ends of the corresponding to-be-detected assembly
Implementation Method 2
The current detection circuit is configured to detect a current of the charge/discharge loop of the battery pack
Implementation Method 3
separately calculate an impedance of each to-be-detected assembly based on the current sequence and the first voltage sequence
Implementation Method 4
the increased impedance causes the connection component to heat up abnormally when a current flows through the connection component
Data Source
AI summary
A battery pack includes a plurality of battery subpacks and voltage detection circuits, a current detection circuit, and a BMS. Each battery subpack and one connection component connected to the battery subpack form one to-be-detected assembly. The current detection circuit is configured to detect a current of the charge/discharge loop. The voltage detection circuit is configured to detect voltages at two ends of the to-be-detected assembly. The BMS is configured to: obtain the current of the charge/discharge loop and voltages at two ends of each to-be-detected assembly based on a preset period, generate a current sequence and a first voltage sequence of each to-be-detected assembly, calculate an impedance of each to-be-detected assembly based on the current sequence and the first voltage sequence, and when the impedance is greater than or equal to an impedance threshold, determine that the connection component in the to-be-detected assembly is abnormally connected.