Battery Aging Estimation via Non-Hysteresis Voltage Segmentation
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Solution Overview
Problem
Existing battery systems face challenges in accurately estimating aging deterioration, particularly in lithium-ion batteries with significant hysteresis in the open-circuit voltage values, which complicates the identification of the battery's state of charge and full charge capacity.
Innovation Solution
A battery system and method that detect voltage and current values in the non-hysteresis region to estimate aging deterioration, using an electronic control unit to calculate open-circuit voltage values and integrated current values, allowing for precise estimation of battery health without hysteresis influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If open-circuit voltage values are used to estimate state of charge and full charge capacity, then battery aging deterioration can be estimated, but significant hysteresis in lithium-ion batteries causes inaccuracies in identification of battery state
Solution Approach 1:
The patent divides the battery charge-discharge process into distinct segments: a charge process, a rest period, and a discharge process. By segmenting the measurement timing, the system captures open-circuit voltage values at specific stages (after charging and after discharging) to calculate full charge capacity while accounting for hysteresis effects. This segmentation allows accurate battery state identification without requiring complex continuous monitoring systems.
2Reliability
If full charge capacity is estimated using conventional methods, then battery aging deterioration can be monitored, but hysteresis region causes significant difference in open-circuit voltage values between charging and discharging
Solution Approach 1:
The patent implements a rest period between charging and discharging processes, during which the battery is allowed to stabilize. This preliminary action (resting) before discharge measurement ensures that the open-circuit voltage values are taken when the battery is in a stable state, reducing the impact of hysteresis. The system calculates full charge capacity using voltage values obtained after this preliminary stabilization period, thereby improving reliability of aging deterioration estimation.
3Measurement precision
If battery management system continuously monitors all parameters, then accurate charge level estimation is achieved, but system complexity and computational load increase
Solution Approach 1:
Instead of continuously monitoring all battery parameters, the patent applies partial action by measuring open-circuit voltage values only at specific critical moments: after the charge process and after the discharge process. This selective measurement approach captures sufficient information to estimate charge level and monitor aging deterioration without requiring complex continuous monitoring systems, thereby reducing device complexity while maintaining adequate precision.
Data Source
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AI summary
A battery system (10) includes: a battery (12); a voltage detector (22) that detects a voltage of the battery (12) as a detected voltage value (Vb); a current detector (20) that detects a current flowing through the battery (12) as a detected current value (Ib); and an electronic control unit (14). The electronic control unit (14) is configured to estimate an aging deterioration of the battery (12) based on an open circuit voltage value (Vo; Vo1, Vo2) that is calculated from the detected voltage value and an integrated current value (ΔAh ; ΔAh12) that is calculated from the detected current value, and estimate the aging deterioration of the battery (12) based on the open circuit voltage value (Vo; Vol, Vo2) and the integrated current value (ΔAh ; ΔAh12) that are calculated when a charge level of the battery (12) is in the non-hysteresis region.