Battery Pack Abnormal Cell Detection During Rest and Balancing

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Solution Overview

Problem

Existing battery packs face safety issues due to overheating caused by internal foreign materials or short circuits, necessitating early detection of abnormal cells to prevent thermal runaway and ignition.

Innovation Solution

A method and device for detecting abnormal cells in a battery pack that involves obtaining discharge rates during rest periods with and without cell balancing, using threshold values to identify and block abnormal cells, thereby preventing further charging and discharging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If cell balancing is performed during rest periods, then battery pack efficiency is improved, but abnormal cells may be missed due to discharge rate changes

Engineering Contradiction:

Improvebattery pack efficiencyVSAvoidabnormal cell detection accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system dynamically adjusts the cell balancing operation based on detected abnormal cells. When an abnormal cell is detected through discharge rate analysis, the cell balancing operation is automatically adjusted or prohibited for that specific cell, preventing false normalization of abnormal cells while maintaining efficient balancing for normal cells during rest periods

Inventive Principle:

Principle #15Dynamics

2Reliability

If discharge rate threshold is set low, then more abnormal cells are detected, but false positives increase

Engineering Contradiction:

Improveabnormal cell detection coverageVSAvoiddetection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system uses two different threshold values for discharge rate detection: a first threshold during cell balancing operation and a second (higher) threshold during rest periods. This parameter change approach allows sensitive detection during balancing while reducing false positives during rest, optimizing detection accuracy across different operational states

Inventive Principle:

Principle #35Parameter changes

3Reliability

If continuous monitoring is performed, then early detection is achieved, but energy consumption increases

Engineering Contradiction:

Improveearly detection capabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs discharge rate analysis periodically during rest periods rather than continuously. By utilizing the natural rest periods that occur during battery operation, the system achieves early detection of abnormal cells without requiring continuous active monitoring, thus minimizing additional energy consumption while maintaining detection effectiveness

Inventive Principle:

Principle #19Periodic action

Data Source

PatentEP4376252A1Abnormal cell detection method, abnormal cell detection device, and battery pack

Publication Date: 2024.05.29 SAMSUNG SDI CO LTD

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AI summary

An abnormal cell detection method of a battery pack including a plurality of cells according to the present disclosure includes: obtaining a first discharge rate for each cell during a first rest period in a state where cell balancing is allowed; prohibiting the cell balancing of the plurality of cells when a cell having the first discharge rate greater than or equal to a first threshold value is detected; obtaining a second discharge rate during a second rest period for each cell in a state where the cell balancing is prohibited; and detecting a cell having a second discharge rate greater than or equal to a second threshold value among the plurality of cells as an abnormal cell.