Battery Resistance State Estimation Across Temperature Variations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery technologies struggle to accurately estimate internal resistance and resistance state of batteries, particularly due to variations in temperature, which can lead to inaccurate estimation of battery health and performance.
Innovation Solution
A battery apparatus and method that utilize an adaptive filter, such as a recursive least squares (RLS) filter, to estimate internal resistance at a reference temperature by correcting measured resistance values based on temperature-dependent correction ratios, thereby enabling accurate estimation of resistance state regardless of temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance estimation is performed at specific temperature and SOC conditions, then resistance state can be quantified for battery health assessment, but accuracy deteriorates when applied to different temperatures
Solution Approach 1:
The patent transforms the resistance estimation from being condition-specific to condition-independent by changing the parameter representation. Instead of estimating resistance at specific temperature and SOC points, the system estimates resistance at reference conditions (0°C, 45°C, 85°C, 100% SOC) and uses temperature coefficients to adjust for actual operating conditions. This parameter transformation approach resolves the contradiction by maintaining measurement precision while achieving temperature adaptability.
Solution Approach 2:
The patent introduces temperature coefficients as intermediary parameters that mediate between the reference temperature resistance values and the actual operating temperature resistance values. These coefficients act as translators that convert resistance measurements from standard conditions to real-world conditions, enabling accurate resistance estimation across varying temperatures without requiring direct measurements at each temperature point.
2Device complexity
If resistance values from specific conditions are applied to all conditions, then estimation process is simplified, but estimation accuracy deteriorates due to temperature variations
Solution Approach 1:
The system changes the parameter framework from direct resistance values at operating conditions to reference resistance values with temperature coefficients. This parameter transformation maintains relatively simple estimation processes while significantly improving accuracy by accounting for temperature effects through the coefficient-based adjustment mechanism.
Solution Approach 2:
The patent performs preliminary estimation of resistance at reference conditions (0°C, 45°C, 85°C, 100% SOC) and stores temperature coefficients in advance. This preliminary action allows the system to quickly adjust resistance estimates for actual operating conditions without performing complex real-time calculations, thus maintaining process simplicity while improving accuracy.
3Ease of operation
If temperature correction is not applied, then estimation process remains simple, but resistance state estimation becomes inaccurate under varying temperature conditions
Solution Approach 1:
The patent introduces temperature coefficients as intermediary elements that enable temperature correction without significantly complicating the operation. These coefficients serve as pre-calculated correction factors that can be applied through simple multiplication, maintaining operational ease while dramatically improving estimation accuracy under varying temperature conditions.
Solution Approach 2:
The system changes the operational approach from direct resistance measurement to reference resistance measurement with temperature-based adjustment. This parameter change allows the estimation process to remain operationally simple while achieving high accuracy by separating the reference measurement phase from the temperature-adjustment phase.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A processor of a battery apparatus estimates an internal resistance of a battery at a reference temperature based on a measured voltage of the battery, a measured current of the battery, an open circuit voltage of the battery, and a measured temperature of the battery, and estimates a resistance state of the battery based on the estimated internal resistance and a BOL resistance at the reference temperature when the battery is in a BOL state.