Battery SOC Estimation via Adaptive Parameter Extraction
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Solution Overview
Problem
Existing battery management systems face accuracy issues in estimating the state of charge (SOC) of secondary batteries due to measurement errors from current sensors and voltage variations, especially with battery degradation and storage status, leading to reduced SOC accuracy over time.
Innovation Solution
A battery SOC estimating apparatus and method that employs a first SOC calculating unit with a predetermined parameter and multiple second SOC calculating units to identify an optimal parameter close to the actual SOC, using an extended Kalman filter algorithm, and adjusts it in real-time by determining open circuit voltage when current is low, ensuring accurate SOC calculation regardless of storage status and degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current accumulation method is used to estimate SOC, then SOC estimation can be performed in real-time, but measurement errors from current sensors are continuously accumulated causing accuracy to deteriorate over time
Solution Approach 1:
The patent changes the parameters used in SOC estimation by introducing multiple alternative parameters (R0, R1, R2 resistance values and capacitance values) that are selected based on battery state (charge/discharge status, temperature, SOC range). This allows the system to adapt to different operating conditions and maintain accuracy over time by switching parameters rather than continuously accumulating errors with a fixed method.
2Measurement precision
If voltage measurement method is used to estimate SOC, then SOC can be estimated without current sensor accumulation errors, but voltage varies during charging/discharging causing accuracy to deteriorate
Solution Approach 1:
The patent introduces an intermediary approach by using multiple second SOC calculating units that apply different parameters to calculate multiple second SOCs. These are then combined through optimal parameter extraction to produce a final SOC value. This intermediary layer allows the system to compensate for voltage variations during charging/discharging by selecting or combining calculations from different parameter sets, thereby maintaining accuracy without requiring perfectly stable voltage measurements.
3Measurement precision
If fixed parameters are used in SOC estimation algorithm, then initial SOC accuracy is high, but accuracy deteriorates with battery degradation and storage status changes
Solution Approach 1:
The patent implements dynamics by making the parameters adaptive rather than fixed. The system dynamically selects different parameter sets (R0, R1, R2 resistance values and capacitance values) based on real-time battery conditions including charge/discharge status, temperature, and SOC range. This dynamic adaptation allows the SOC estimation to maintain high accuracy even as the battery degrades or undergoes storage, as the parameters are continuously optimized for current battery state rather than remaining fixed from initial calibration.
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AI summary
Provided are battery SOC estimating apparatus and method. The battery SOC estimating apparatus according to the present invention includes a first SOC calculating unit which applies a predetermined parameter to calculate a first state of charging (SOC) of a battery; one or more second SOC calculating units which individually apply different parameters to calculate one or more second SOCs of the battery; and an optimal parameter extracting unit which confirms a second SOC which is the closest to an actual SOC of the battery from one or more second SOCs to extract a parameter which is applied to the second SOC which is the closest to the actual SOC as an optimal parameter, in which the first SOC calculating unit applies the optimal parameter to calculate a final SOC of the battery.