Battery SOC Prediction Using Temperature and Load Correction
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Solution Overview
Problem
Existing methods for predicting the state of charge (SOC) of high-voltage batteries in electric vehicles (EVs) and Plug-in Hybrid Electric Vehicles (PHEVs) are inaccurate due to the non-proportional relationship between SOC and energy, variations in battery capacity with temperature and load, and complex conversion formulas.
Innovation Solution
A battery SOC prediction apparatus and method that determines battery temperature and electrical load based on driving time to the destination, predicts SOC upon arrival by estimating average voltage and consumption capacity, and corrects the SOC value using open circuit voltage, average load, and polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear comparison method is used to predict SOC based on energy consumed, then calculation is simple, but prediction accuracy deteriorates because SOC and energy are not proportional
Solution Approach 1:
The patent changes the prediction parameters from simple linear energy consumption to a multi-parameter model including temperature-dependent capacity, load-dependent efficiency, and time-based degradation factors. This transforms the prediction from a single-parameter linear calculation to a multi-parameter non-linear model that accurately reflects battery behavior under varying conditions.
2Productivity
If simple proportional equation is applied for SOC prediction, then computation is fast, but error level increases due to temperature and load variations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing temperature-capacity correction factors and load-efficiency relationships in lookup tables before actual SOC prediction. During operation, the system quickly retrieves these pre-computed parameters and applies them to the current state, avoiding real-time complex calculations while maintaining high prediction accuracy.
3Measurement precision
If complex conversion formula is used to convert actual SOC to display SOC, then accuracy is improved, but error propagation increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the difference between predicted SOC and actual measured SOC, then using this error signal to adjust and refine the prediction model parameters. This closed-loop approach compensates for model inaccuracies and prevents error accumulation, maintaining reliable predictions even with complex conversion formulas.
Data Source
AI summary
In a battery SOC prediction apparatus, system, and method, the battery SOC prediction apparatus includes: a processor configured to predict a state of charge (SOC) value of a battery in response to a case where a vehicle arrives at a destination according to energy expected to be consumed while driving to the destination, and in the instant case, to correct the SOC value of the battery upon arrival at the destination according to an electrical load and a battery temperature by predicting the electric load and the battery temperature according to a driving time of the vehicle; and a storage configured to store algorithms and data driven by the processor.