Battery SOC Calculation Using Threshold-Based Term Grouping
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Solution Overview
Problem
Existing methods for estimating the state of charge (SOC) of secondary batteries, such as lithium ion or nickel hydride batteries, face issues with information loss when the minute increase/decrease amount of SOC and previous integrated quantities differ significantly, leading to operational errors.
Innovation Solution
A battery control device that divides the SOC operation into terms, groups the operation results based on a predetermined threshold, and stores the total operation results for each group, allowing the use of previous values to accurately calculate the SOC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If previous SOC values are directly used in SOC operation, then the operation is simple, but information loss occurs when the size difference between minute SOC change and previous integrated quantities is considerable
Solution Approach 1:
The patent segments the SOC operation into multiple terms (first term, second term, third term) and processes each term separately. By dividing the operation result into multiple groups based on magnitude thresholds, the system prevents information loss that would occur when directly combining values of significantly different sizes, while maintaining manageable operational complexity through structured segmentation.
2Loss of information
If SOC operation is divided into multiple terms and grouped, then information loss is suppressed, but the operation process becomes more complex
Solution Approach 1:
The patent segments the SOC operation into multiple terms (first term, second term, third term) and processes each term separately. By dividing the operation result into multiple groups based on magnitude thresholds, the system prevents information loss that would occur when directly combining values of significantly different sizes, while maintaining manageable operational complexity through structured segmentation.
Solution Approach 2:
The patent changes the parameter of grouping criteria based on the magnitude of operation results. By dynamically adjusting which terms are grouped together based on their size relative to threshold values, the system optimizes the balance between preventing information loss and maintaining operational efficiency, avoiding unnecessary complexity for all term combinations.
3Productivity
If minute SOC change values are combined with large previous integrated quantities, then the operation is efficient, but the minute values are ignored and operational errors occur
Solution Approach 1:
The patent segments the SOC operation into multiple terms (first term, second term, third term) and processes each term separately. By dividing the operation result into multiple groups based on magnitude thresholds, the system prevents information loss that would occur when directly combining values of significantly different sizes, while maintaining manageable operational complexity through structured segmentation.
Solution Approach 2:
The patent introduces threshold-based grouping as an intermediary mechanism between the raw SOC terms and the final operation result. This intermediary step ensures that minute SOC changes are not ignored when combined with large previous integrated quantities, as the grouping process preserves the significance of smaller values before they are incorporated into the final SOC calculation.
Data Source
AI summary
A battery control unit has an SOCv operation unit which calculates a state of charge SOCv based on voltage of a battery, a ΔSOCi operation unit which calculates an amount of change ΔSOCi of the state of charge based on current value of the battery, a weight operation unit which calculates a weight W, and an SOCc operation unit which calculates a final SOC (SOCc) based on the SOCv, the ΔSOCi and the weight W. Terms forming an operational expression of the SOCc are retained, by using a determination threshold, as a sum SOCc_Big of terms of a large value group and a sum SOCc_Small of terms of a small value group, and used in calculating the SOCc of a subsequent operation period. By using the SOCc_Big and the SOCc_Small, it is possible to prevent the accumulation of errors caused by information loss that occurred when repeatedly operating the SOCc.