Battery Cell Internal Resistance Detection at Charge Current Change
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Solution Overview
Problem
As battery systems, such as energy storage systems and electrical vehicles, become widely distributed, safety issues arise due to increased internal series resistance in battery cells, leading to heat generation, potential fires, and reduced battery performance.
Innovation Solution
A battery management apparatus and method that monitor changes in internal resistance during battery charging to diagnose cell failures by calculating current and voltage change amounts and determining internal resistance values for each battery cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal resistance monitoring is performed during battery charging to diagnose cell failures, then battery safety and diagnosis accuracy are improved, but device complexity and measurement requirements increase
Solution Approach 1:
The battery management system utilizes the existing charging current and voltage measurements already being performed for normal battery operation to calculate internal resistance. The system serves itself by using operational data for both charging control and safety diagnosis, eliminating the need for separate dedicated measurement hardware.
Solution Approach 2:
The same voltage sensors and current measurements used for standard battery management and charging control are also utilized for internal resistance calculation and cell failure diagnosis. This multi-functional use of existing components improves safety without adding dedicated measurement devices.
2Measurement precision
If internal resistance values are calculated using current and voltage changes during charging, then cell failure diagnosis accuracy is improved, but the difficulty of detecting and measuring increases due to timing and stabilization requirements
Solution Approach 1:
The system waits for the voltage to stabilize after a current change before performing the internal resistance calculation. This preliminary stabilization step ensures that measurements are taken under consistent conditions, improving accuracy while managing the complexity through a clear sequential measurement protocol.
Solution Approach 2:
The system continuously monitors voltage stabilization and uses this feedback to determine the appropriate timing for internal resistance calculation. By incorporating stabilization detection as a feedback mechanism, the system achieves precise measurements without requiring complex external synchronization.
3Productivity
If battery pack charging is continued with high internal resistance cells, then charging capacity is improved, but heat generation increases leading to safety risks
Solution Approach 1:
The system performs internal resistance diagnosis during the charging process to identify cells with abnormally high resistance before they cause dangerous heat generation. By detecting issues preliminarily during normal charging, the system can prevent safety incidents while maintaining charging capacity for healthy cells.
Solution Approach 2:
The system uses the voltage and current data already present during charging to calculate internal resistance, converting the existing charging process data into a safety diagnostic tool. This approach maintains charging productivity while identifying and addressing heat generation risks.
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 approach improves the accuracy of battery cell failure diagnosis by distinguishing between resistance increases due to cell defects and those caused by battery pack deterioration, thereby enhancing safety and performance.
Implementation Method 1
determine an internal resistance value for each of one or more battery cells included in a battery pack by using a current change amount of the battery pack and a voltage change amount of the one or more battery cells
Data Source
AI summary
A battery management apparatus includes a control circuit configured to determine an internal resistance value for each of one or more battery cells included in a battery pack by using a current change amount of the battery pack and a voltage change amount of the one or more battery cells, and diagnose defects in the one or more battery cells by using internal resistance values of the one or more battery cells, in response to charging the battery pack, where the control circuit is configured to determine the current change amount of the battery pack and the voltage change amount of the one or more battery cells based on a current change request time point requiring a charging current change based on a voltage of the battery pack reaching a predetermined voltage during the charge of the battery pack.