Lithium Battery SOC Display Correction via Voltage Calibration
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Solution Overview
Problem
Lithium iron phosphate batteries in electric vehicles face significant SOC estimation errors due to the wide and unstable platform area during charging and discharging, leading to potential false charging and safety issues, as existing methods rely heavily on current integration and lack accurate voltage calibration.
Innovation Solution
A lithium battery power display method and system that calculates and applies a correction coefficient using a pre-calibrated formula to adjust the SOC value during charging, ensuring the SOC value is displayed accurately within the platform area, thereby eliminating accumulated errors through periodic corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If current integration method is used to estimate SOC in platform area, then charging process is simple, but SOC estimation accuracy deteriorates
Solution Approach 1:
The system implements feedback by periodically comparing the displayed SOC with the actual battery state through voltage calibration. When the battery enters the platform area (30%-97% SOC range), the system uses voltage measurements to correct the SOC estimation, creating a closed-loop feedback mechanism that continuously improves accuracy without complicating the charging process.
Solution Approach 2:
The patent changes the estimation parameter from current integration alone to a hybrid approach that incorporates voltage calibration. By detecting when the battery is in the platform area and switching to voltage-based SOC estimation for that specific parameter range, the system improves accuracy while maintaining simplicity in other operating conditions.
2Measurement precision
If voltage calibration is performed frequently, then SOC accuracy is improved, but system complexity increases
Solution Approach 1:
The system performs voltage calibration periodically rather than continuously. The control unit determines calibration timing based on charging conditions, specifically when the battery enters or exits the platform area. This periodic approach maintains SOC accuracy while avoiding the complexity of continuous calibration operations.
Solution Approach 2:
The system performs preliminary voltage calibration before the battery enters the platform area or when exiting it. By preparing the SOC estimation in advance during transition periods, the system ensures accuracy in the critical platform area without requiring complex real-time calibration operations throughout the entire charging process.
3Ease of operation
If battery is not fully charged for many times, then user convenience is improved, but SOC error increases
Solution Approach 1:
The system provides self-service by automatically detecting and correcting SOC errors without requiring user intervention. The control unit monitors charging conditions, identifies when the battery is in the platform area, and automatically applies voltage calibration to correct SOC estimation. This eliminates the need for users to manually perform calibration or fully charge the battery repeatedly, maintaining both convenience and accuracy.
Data Source
AI summary
A lithium battery power display method and corresponding system, the method includes: during charging process of lithium battery, periodically calculating SOC value charged in this charging through a current integration method (S10); obtaining a sum of the SOC value displayed before charging and the SOC value charged, determining whether it is in a predetermined charging platform area (S11); when determination result is in the predetermined charging platform area and it is determined the correction trigger condition is met, a correction coefficient is calculated according to pre-calibrated formula, the SOC value to be displayed is obtained by correcting the SOC value charged with the correction coefficient, the correction coefficient is positive number less than 1 (S12); displaying the SOC value to be displayed (S13). Solve virtual electricity caused by large SOC error in non-full charge and discharge state of lithium batteries, improve experience of lithium battery electric vehicles.