Rechargeable Battery SOC Range Reset Using Voltage Error Detection
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Solution Overview
Problem
Existing methods for controlling the charging and discharging of rechargeable batteries, particularly in vehicles, fail to accurately correct the usable State of Charge (SOC) range due to errors in SOC estimation and the need for complex procedures.
Innovation Solution
A method that acquires measured current, voltage, and temperature data from the rechargeable battery, estimates the SOC based on voltage measurements, collects samples to calculate SOC estimation errors, and resets the SOC range limits accordingly to ensure safe and efficient charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current integrated value is used as the true value of SOC estimation, then SOC estimation can be obtained, but it requires a relatively large amount of time and is affected by accumulation of measurement errors
Solution Approach 1:
The patent pre-calculates and stores the relationship between voltage differences and SOC estimation errors in a lookup table during battery characterization. During operation, the controller directly queries this pre-prepared table using the measured voltage difference, eliminating the need for real-time integration and error calculation, thus resolving the time consumption issue while maintaining accuracy
Solution Approach 2:
The patent replaces the continuous integration process (mechanical accumulation of current measurements) with a direct voltage-based lookup method. By substituting the integration mechanism with a voltage difference query to a pre-computed table, the system achieves faster SOC error estimation without accumulating measurement errors over time
2Reliability
If the battery model is repeatedly updated each time the difference between output value and actual measurement value is obtained, then the battery model can be optimized, but the control on the SOC range cannot be separated from the battery model
Solution Approach 1:
The patent separates the SOC estimation function from the battery model by introducing an independent voltage difference-based error calculation mechanism. The SOC estimator uses a fixed lookup table approach that does not require repeated battery model updates, thereby decoupling SOC control from battery model complexity while maintaining reliability through accurate error compensation
Solution Approach 2:
The patent introduces a voltage difference lookup table as an intermediary between the battery model and SOC estimation. This intermediary layer provides accurate SOC error correction without requiring direct coupling to the battery model, allowing the SOC control to remain independent while still benefiting from model-optimized accuracy
3Reliability
If a fixed SOC range is controlled to avoid overcharging and overdischarging, then battery safety is maintained, but the usable range is limited and cannot adapt to SOC estimation errors
Solution Approach 1:
The patent makes the SOC range limits dynamic by adjusting them based on the estimated SOC error. The controller calculates the voltage difference, queries the lookup table for the corresponding error value, and then dynamically shifts the charge and discharge threshold values. This allows the system to adapt to estimation errors while maintaining safety margins, resolving the contradiction between fixed safety limits and adaptive usability
Data Source
AI summary
A method for controlling charging and discharging of a rechargeable battery with a controller includes acquiring a measured current, a measured voltage, and a measured temperature; estimating an estimated voltage based on the measured current and the measured temperature; collecting samples each indicating a difference between the measured voltage and the estimated voltage; classifying the samples into an upper limit side determination sample and a lower limit side determination sample with reference to a reference value; calculating an upper limit error based on at least a predetermined quantity of the upper limit side determination sample, and calculating a lower limit error based on at least a predetermined quantity of the lower limit side determination sample; and resetting an upper limit of a usable SOC range in accordance with the upper limit error, and resetting a lower limit of the usable SOC range in accordance with the lower limit error.