Battery State-of-Charge Correction Using Accumulative Capacity
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Solution Overview
Problem
Current state of charge (SOC) calculation methods, such as the open circuit voltage method, are inaccurate for batteries with hysteresis characteristics due to historical operating conditions, leading to errors in SOC estimation.
Innovation Solution
A method and apparatus that determine the operating state of a battery cell and correct its SOC by using the acquired current open circuit voltage, accumulative capacity, and an accumulative capacity correspondence relationship, which accounts for historical operating conditions, thereby improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the open circuit voltage method is used to calculate SOC, then the calculation is simple and fast, but the accuracy deteriorates when the battery has hysteresis characteristics
Solution Approach 1:
The patent introduces an accumulative capacity parameter as an intermediary to bridge the gap between simple voltage-based SOC calculation and accurate hysteresis compensation. By using accumulative capacity to identify and select appropriate OCV curves corresponding to different historical operating conditions, the system maintains calculation simplicity while achieving accurate SOC estimation for batteries with hysteresis characteristics
Solution Approach 2:
The patent changes the parameter selection strategy by dynamically selecting different OCV curves based on the battery's historical operating conditions (charging or discharging state) and accumulative capacity. This parameter change approach allows the system to adapt to hysteresis effects without complicating the overall calculation framework, thus maintaining both speed and accuracy
2Device complexity
If the open circuit voltage method is used for batteries with hysteresis characteristics, then the calculation process remains simple, but the SOC error increases due to historical operating conditions
Solution Approach 1:
The patent performs preliminary classification of the battery's operating state (charging or discharging) and determines the appropriate OCV curve in advance based on accumulative capacity. This preliminary action eliminates the need for complex real-time hysteresis calculations, maintaining simplicity in the SOC calculation process while significantly improving accuracy by pre-selecting the correct voltage-SOC relationship
Solution Approach 2:
The patent segments the OCV-SOC relationship into multiple distinct curves based on historical operating conditions (charging vs. discharging states). By dividing the single OCV curve into multiple condition-specific curves, the system accurately captures hysteresis effects without increasing overall system complexity, as each segment can be selected and applied independently
Data Source
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AI summary
The present application provides a method and apparatus for correcting a state of charge, and relates to the technical field of batteries. The method for correcting a state of charge comprises: determining an operating state of a battery cell, wherein the operating state comprises a discharging state or a charging state; and determining a corrected state of charge of the battery cell according to an acquired current open circuit voltage of the battery cell, an acquired current accumulative capacity of the battery cell, an accumulative capacity correspondence relationship corresponding to the operating state of the battery cell, and an open circuit voltage curve corresponding to a limit initial state of charge, wherein the accumulative capacity correspondence relationship comprises a correspondence relationship between a pre-measured open circuit voltage and an accumulative capacity threshold. A technical solution of the present application can be used to improve the accuracy of calculation of a state of charge.