SOC Estimation Device Deterioration Mode Adaptation
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Solution Overview
Problem
Existing energy storage devices, such as lithium ion batteries, face challenges in accurately estimating State of Charge (SOC) across different usage periods and situations, particularly when repurposed from automotive use to other applications, due to varying deterioration modes affecting their capacity retention and internal resistance.
Innovation Solution
An SOC estimation device that determines the deterioration mode of the energy storage device based on internal resistance changes and selects appropriate correlation data between SOC and Open Circuit Voltage (OCV) to improve estimation accuracy, using a storage unit and data processing unit to manage correlation maps and capacity retention ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single correlation map between SOC and OCV is used for all deterioration modes, then the device complexity is reduced, but the SOC estimation precision deteriorates due to varying deterioration modes affecting capacity retention and internal resistance
Solution Approach 1:
The patent segments the correlation data between SOC and OCV into multiple distinct correlation maps, each corresponding to a specific deterioration mode. The SOC estimation device determines the current deterioration mode and selects the appropriate correlation map for estimation. This segmentation allows precise SOC estimation adapted to the actual battery condition while managing complexity through systematic organization of multiple correlation maps based on deterioration stage.
2Measurement precision
If multiple correlation maps are stored for different deterioration modes, then the SOC estimation precision is improved, but the storage unit size and data processing complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-establishing multiple correlation maps corresponding to different deterioration modes before actual SOC estimation is needed. The SOC estimation device determines the current deterioration mode and selects the appropriate pre-prepared correlation map. This approach avoids the need for real-time generation or adaptation of correlation data, reducing computational burden and storage requirements while maintaining high estimation precision.
3Reliability
If the correlation data is not updated according to deterioration mode, then the ease of operation is improved, but the reliability of SOC estimation deteriorates in secondary uses or after long usage periods
Solution Approach 1:
The patent implements dynamics by making the correlation data selection adaptive to the actual deterioration state of the energy storage device. The SOC estimation device determines the current deterioration mode and dynamically selects the corresponding correlation map from multiple pre-established maps. This dynamic adaptation ensures reliable SOC estimation throughout the battery's lifecycle, including secondary uses and long usage periods, while maintaining operational simplicity through automated mode determination and map selection.
Data Source
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AI summary
An SOC estimation device 50 of an energy storage device includes a storage unit 73 and a data processing unit 71. The energy storage device 100 has a characteristic including a first deterioration mode in which a capacity drop with respect to time indicates a first transition, and a second deterioration mode in which a capacity drop indicates a second transition. The storage unit 73 holds first correlation data M1 indicating a correlation between SOC and OCV of the energy storage device in the first deterioration mode, and second correlation data M2 indicating a correlation between SOC and OCV of the energy storage device in the second deterioration mode. The data processing unit 71 executes a mode determination process of determining a deterioration mode of the energy storage device, and an estimation process of selecting correlation data corresponding to the deterioration mode from the storage unit, to estimate SOC of the energy storage device.