SOC Estimation Using Region-Based Noise Adaptation
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Solution Overview
Problem
Existing methods for estimating the State of Charge (SOC) of batteries, such as the ampere-counting method and extended Kalman filter using equivalent circuit models, face accuracy issues due to current measurement discrepancies and difficulty in simulating non-linear battery operations, especially as batteries degrade.
Innovation Solution
An SOC estimating apparatus and method that generates and filters noise based on preset voltage regions, using a measuring unit to collect voltage, current, and temperature data, and an SOC estimating unit that employs a Kalman filter to improve accuracy by adjusting noise magnitude according to voltage regions and battery degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the extended Kalman filter uses an equivalent circuit model to estimate SOC, then the estimation can account for battery electrochemical properties, but the accuracy decreases as the battery degrades due to difficulty in updating model parameters
Solution Approach 1:
The patent applies dynamics by making the noise magnitude adjustable based on battery degradation state. The system dynamically adapts the process noise magnitude in the Kalman filter according to the actual degradation level of the battery, allowing the estimation algorithm to remain accurate despite changing battery characteristics over time.
Solution Approach 2:
The patent changes the parameter of noise magnitude based on battery degradation. By adjusting the process noise magnitude according to degradation indicators, the system maintains accurate SOC estimation without requiring complete re-calibration of the equivalent circuit model parameters.
2Device complexity
If the equivalent circuit model simulates linear operational characteristics of the battery, then the model structure remains simple, but it becomes very difficult to accurately simulate non-linear operational characteristics
Solution Approach 1:
The patent changes the noise magnitude parameter based on battery operating conditions and degradation state. This allows the simple linear equivalent circuit model to effectively handle non-linear characteristics by adapting the noise characteristics to match actual battery behavior under different conditions.
3Device complexity
If the ampere-counting method integrates charging and discharge currents over time to determine SOC, then the calculation is simple, but the accuracy degrades over time due to differences between measured current and actual current
Solution Approach 1:
The patent introduces process noise as an intermediary element that bridges the gap between measured current and actual current. The Kalman filter uses this noise component to compensate for measurement discrepancies and accumulate errors, maintaining accuracy without increasing calculation complexity.
4Measurement precision
If noise is generated based on preset voltage regions to improve SOC estimation accuracy, then the estimation accuracy enhances, but the system complexity increases due to additional noise generation and filtering processes
Solution Approach 1:
The patent segments the voltage range into multiple preset voltage regions, each with its own noise magnitude settings. This segmentation allows the system to apply appropriate noise levels for different operating conditions without requiring a completely complex adaptive model.
Solution Approach 2:
The patent changes the noise magnitude parameter according to the preset voltage regions. By pre-defining noise magnitudes for different voltage regions, the system achieves adaptive noise generation without real-time complex calculations, balancing accuracy and complexity.
Data Source
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AI summary
A SOC estimating apparatus according to an embodiment of the present disclosure includes: a measuring unit configured to measure at least one of voltage, current and temperature of a battery; a noise generating unit configured to generate noise corresponding to the voltage of the battery based on a plurality of preset voltage regions; a filtering unit configured to receive the noise generated by the noise generating unit and filter the generated noise to correspond to the voltage of the battery based on the plurality of preset voltage regions; and a SOC estimating unit configured to estimate a SOC of the battery based on at least one of voltage, current and temperature of the battery and the noise filtered by the filtering unit.