Battery Capacity Estimation Using OCV-Based SOC Recalculation
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Solution Overview
Problem
Current battery capacity estimation methods fail to accurately predict the state of charge (SOC) when the usable voltage range is reduced, leading to errors in calculating the remaining battery capacity, which can result in unexpected battery discharge in applications like electric vehicles.
Innovation Solution
A battery capacity estimation apparatus and method that uses an Open Circuit Voltage (OCV) table to measure and adjust the SOC based on changes in the voltage range, recalculating the capacity and SOC using specific equations to account for reduced voltage ranges, thereby preventing errors in battery usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the usable voltage range is reduced to extend battery life and improve stability, then battery reliability is improved, but measurement precision of SOC and capacity deteriorates due to unadjusted calculation algorithms
Solution Approach 1:
The patent changes the parameters used in SOC and capacity calculation algorithms to match the reduced voltage range. Specifically, it adjusts the initial capacity estimation and modifies the integration constants in the current integration method to correspond to the new voltage boundaries (e.g., 2.4V-4.0V instead of 2.0V-4.2V), ensuring accurate measurements within the restricted range
Solution Approach 2:
The patent implements dynamic adjustment of calculation parameters based on the actual voltage range being used. The system can adaptively modify the SOC estimation algorithm parameters according to whether the battery is operating in a reduced voltage range or full voltage range, allowing the measurement precision to maintain accuracy under different operational conditions
2Duration of action of stationary object
If the usable voltage range is reduced from 2.0V-4.2V to 2.4V-4.0V, then battery life is extended, but the calculated SOC and capacity show larger errors over time due to unadjusted algorithms
Solution Approach 1:
The patent modifies the calculation parameters including initial capacity estimates and integration constants to match the reduced voltage range of 2.4V-4.0V. This ensures that the SOC and capacity calculations remain accurate despite the reduced operational voltage window, preventing the accumulation of errors over time
Solution Approach 2:
The patent performs preliminary adjustment of the calculation algorithms before deploying them in the reduced voltage range operation. By pre-calibrating the initial capacity and adjustment factors for the specific 2.4V-4.0V range, the system avoids cumulative errors that would otherwise develop during battery cycling
3Device complexity
If standard SOC estimation algorithms are used without adjustment, then device complexity is minimized, but manufacturing precision of capacity estimation deteriorates when voltage range changes
Solution Approach 1:
The patent adjusts the parameters within existing standard algorithms (such as modifying initial capacity values and integration constants) rather than replacing the algorithms themselves. This approach maintains relatively low device complexity while significantly improving capacity estimation precision for the reduced voltage range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate estimation of battery capacity and SOC even when the voltage range is changed, ensuring stable battery performance and preventing unexpected discharges by recalculating the capacity and SOC based on the reduced voltage range, thus enhancing battery management.
Implementation Method 1
a sensing unit connected to the battery to measure an OCV of the battery
Data Source
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AI summary
Provided is a battery capacity estimation apparatus including: a battery; a sensing unit connected to the battery to measure an OCV of the battery; an SOC estimation unit connected to the sensing unit estimate an SOC of the battery using the OCV measured from the sensing unit; a memory unit configured to store data including the SOC and the OCV of the battery and connected to the SOC estimation unit; and an operation unit connected to the SOC estimation unit and the memory unit and configured to calculate an SOC reduction degree according to a use voltage range change and re-calculate a changed SOC according to a changed use capacity.