Parallel Battery Cell Fault Detection Using Voltage and DCIR
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Solution Overview
Problem
In parallel connected battery systems, disconnection of a specific cell due to an open parallel connection line or CID operation leads to overcurrent flow in remaining cells, causing cell deterioration and performance degradation, necessitating a method to detect such disconnections effectively.
Innovation Solution
A method involving reference data acquisition, monitoring actual discharge data, and applying machine learning techniques to identify changes in discharge voltage, combined with DCIR measurement to confirm cell connection failures, and generating abnormality signals for notification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If parallel connection of battery cells is implemented to increase power and capacity, then the battery can meet high power requirements of medium and large devices, but disconnection of specific cells due to open parallel connection lines or CID operation causes overcurrent in remaining cells leading to cell deterioration and performance degradation
Solution Approach 1:
The system performs preliminary detection of cell disconnection by monitoring discharge voltage changes and comparing them against reference data obtained under known disconnection conditions. This preliminary detection enables early identification of connection failures before they cause overcurrent damage to cells, resolving the reliability issue while maintaining the high power capability of parallel connections
2Reliability
If CID operation is performed to prevent overcharging and ensure safety, then battery protection is improved, but disconnection of the specific cell causes overcurrent flow in remaining parallel connected cells resulting in cell deterioration
Solution Approach 1:
The system implements feedback monitoring by continuously measuring discharge voltage during battery operation and comparing it against reference data that characterizes voltage changes under CID operation. When a match is detected, the system identifies the specific cell that has disconnected due to CID operation and can trigger appropriate protective actions to prevent overcurrent damage to remaining cells, thus resolving the harmful effects while maintaining safety protection
3Difficulty of detecting and measuring
If monitoring of discharge voltage is performed to detect cell disconnection, then detection capability is improved, but accurate identification of disconnection causes requires complex analysis of voltage change patterns
Solution Approach 1:
The system performs preliminary work by obtaining reference data under controlled conditions of known disconnection causes (open parallel connection line or CID operation). This reference data characterizes the discharge voltage change patterns for each type of disconnection. During actual operation, the system simply needs to monitor discharge voltage and compare it against the pre-established reference data, significantly simplifying the detection process while maintaining high accuracy in identifying disconnection causes
Data Source
AI summary
Disclosed is a method and system for detecting connection failure of a parallel connected cell that provides improved accuracy by first detecting the cell connection failure due to the current interruption device (CID) operation of the battery or opening the parallel connection line for a battery that is being discharged by the operation of an external device, and confirming the first detection result through Direct Current Internal Resistance (DCIR) measurement for the battery.