Battery Cell OCV Deviation Inspection for Internal Short Detection
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Solution Overview
Problem
Conventional methods for diagnosing internal short circuits in battery cells are inefficient, particularly when the short circuit occurs in a fully charged state, as the difference in open circuit voltage (OCV) drop is minimal, making it difficult to timely detect such faults.
Innovation Solution
A battery inspection method and apparatus that determines the deviation of open circuit voltage (OCV) and state of charge (SOC) of each cell after full charging, using reference values and time intervals to accurately diagnose internal short circuits by comparing cell deviations and drops, enhancing the diagnosis with error correction mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OCV drop method is used to diagnose internal short circuit, then the diagnosis can be performed, but the diagnosis time becomes excessively long when battery is fully charged
Solution Approach 1:
The patent changes the diagnostic parameter from simple OCV drop to OCV deviation after preset time delay. By measuring OCV at a specific time point after charging completion rather than immediately, the method captures polarization voltage effects that differentiate normal from short-circuited cells, improving diagnosis accuracy while maintaining reasonable timing
Solution Approach 2:
The patent applies preliminary action by waiting for a preset time delay after charging completion before performing the OCV measurement. This time delay allows polarization voltage to manifest in normal cells while short-circuited cells show different behavior, enabling accurate diagnosis without requiring excessively long measurement periods
2Loss of time
If OCV measurement is performed immediately after charging completion, then the measurement is quick, but the OCV difference between normal and short-circuited cells is insignificant
Solution Approach 1:
The patent changes the measurement parameter from immediate OCV to OCV at a specific time delay after charging. This temporal parameter change allows the system to capture the polarization voltage characteristics that create measurable differences between normal and short-circuited cells, significantly improving measurement precision
Data Source
AI summary
A battery inspection method comprises charging a battery to a fully charged state, determining, when the charging is finished while the battery is in a fully charged state, deviation of an open circuit voltage (OCV) value of each of a plurality of cells included in the battery at a first time point after a preset first reference time has elapsed from a time point of finishing the charging while considering polarization voltage, and determining, according to a result of comparing the determined deviation with a preset first reference value, whether an internal short circuit has occurred in the battery on the basis of the open circuit voltage (OCV) value of each of the plurality of cells or a state of charge (SOC) of each of the plurality of cells.