Battery Pack Control Apparatus for Accurate SOC Estimation
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Solution Overview
Problem
Existing energy storage systems face challenges in accurately managing and estimating the state of charge (SOC) of battery packs, particularly in large-scale high-power applications, which are critical for efficient use of renewable energy sources and mitigating environmental impact.
Innovation Solution
The proposed solution involves a battery pack control apparatus that calculates a final open circuit voltage (OCV) of battery cells and estimates the initial SOC using an OCV calculation unit and SOC estimation unit, respectively, while considering previous SOC storage times and self-discharge rates, ensuring accurate SOC estimation and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OCV measurement is performed to estimate SOC, then SOC estimation accuracy is improved, but measurement time and system complexity increase
Solution Approach 1:
The system pre-calculates and stores the relationship between OCV and SOC values in a lookup table during battery operation. When SOC estimation is needed, the system simply queries the pre-stored table based on measured OCV values, avoiding complex real-time calculations and significantly reducing measurement time while maintaining high accuracy.
Solution Approach 2:
The patent creates a simplified representation of the complex battery state by storing OCV-SOC correspondence relationships in a table. This copied data structure allows rapid SOC estimation through simple table lookups rather than complex mathematical modeling, reducing computational time while preserving estimation accuracy.
2Measurement precision
If OCV measurement is performed to estimate SOC, then SOC estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent creates a simplified representation of the complex battery state by storing OCV-SOC correspondence relationships in a table. This copied data structure allows rapid SOC estimation through simple table lookups rather than complex mathematical modeling, reducing computational time while preserving estimation accuracy.
Solution Approach 2:
The system uses a simple lookup table approach instead of complex real-time mathematical models. This disposable-like simplification trades off some theoretical precision for practical simplicity and ease of implementation, making the system more suitable for real-world battery management applications.
3Speed
If battery cells are measured at high current, then measurement speed is improved, but measurement accuracy deteriorates due to polarization effects
Solution Approach 1:
The system performs OCV measurements at low currents to ensure accuracy, and pre-processes this data into lookup tables. This preliminary accurate measurement approach compensates for the slower measurement speed by performing calculations offline rather than in real-time.
Data Source
AI summary
An apparatus for controlling a battery pack and an energy storage system including the apparatus are disclosed. In one embodiment, the battery pack includes at least one battery tray each including one or more battery cells. The apparatus may include an open circuit voltage (OCV) calculator and a state of charge (SOC) estimator. The OCV calculator may receive OCV measurement values of the battery cells of each battery tray when the power of the battery pack is turned on, and calculate a final OCV of the battery cells based at least in part on the OCV measurement values. The SOC estimator may extract an SOC value corresponding to the final OCV from an SOC table and estimate the extracted SOC value as an initial SOC.