Battery Pack Cell Degradation Detection via Voltage Disparity
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Solution Overview
Problem
Conventional battery management systems for electric vehicles fail to accurately determine the degradation degree of secondary cells within a battery pack, leading to inefficient SOC estimation and balancing, which can result in unpredictable vehicle performance and safety issues.
Innovation Solution
An apparatus and method that utilize voltage sensing and monitoring units to calculate disparate voltage values between secondary cells, identifying and updating information on degraded cells, and adjusting SOC estimation and balancing processes accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional battery management systems use average voltage values for SOC estimation, then the system complexity is reduced, but the measurement precision of cell degradation and SOC estimation deteriorates
Solution Approach 1:
The patent divides the battery pack into individual secondary cells and monitors each cell's voltage separately throughout the charging cycle. By segmenting the monitoring approach, the system can identify degradation in specific cells rather than relying on average values, thereby improving measurement precision without significantly increasing overall system complexity.
Solution Approach 2:
The patent performs preliminary monitoring of voltage values during the charging cycle to detect degradation patterns before they significantly impact battery performance. By detecting degradation early through continuous voltage tracking, the system can take preventive actions and maintain accurate SOC estimation without requiring complex real-time intervention systems.
2Ease of operation
If conventional battery management systems ignore individual cell degradation, then the ease of operation is maintained, but the reliability of vehicle performance prediction deteriorates
Solution Approach 1:
The battery management system automatically monitors and identifies degraded cells through voltage tracking during charging cycles, without requiring manual intervention or complex user operations. The system self-diagnoses degradation patterns and adjusts SOC estimation accordingly, maintaining ease of operation while improving reliability of performance predictions.
Solution Approach 2:
The patent implements a feedback mechanism where voltage monitoring data from individual cells is continuously fed back to the control unit. This feedback enables automatic adjustment of SOC estimation and degradation assessment, improving vehicle performance prediction reliability while keeping the system easy to operate through automated processes.
3Measurement precision
If battery management systems monitor all voltage values continuously, then the measurement precision of degradation detection is improved, but the loss of energy increases
Solution Approach 1:
The patent monitors voltage values at specific intervals during the charging cycle rather than continuously throughout operation. By performing periodic monitoring at key points in the charging process, the system achieves sufficient degradation detection precision while minimizing energy consumption associated with continuous monitoring.
Data Source
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AI summary
The present invention discloses an apparatus for managing a battery pack by reflecting a degradation degree of secondary cells, the apparatus comprising: a voltage sensing unit for measuring the voltages of a plurality of secondary cells constituting the battery pack; a first monitoring unit for storing a first voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when all voltages of the plurality of secondary cells are not lower than a minimum reference voltage value in a charging cycle; a second monitoring unit for storing a second voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when the voltage of one cell among the plurality of secondary cells is not lower than a maximum reference voltage value in the charging cycle; and a controlling unit for calculating a disparate voltage value being the difference between the first voltage value and the second voltage value, selecting the secondary cell having a maximum disparate voltage value among the calculated disparate voltage values as a degraded cell in the current charging cycle, and updating the information on the degraded cell.