Battery State-of-Charge Estimation Using Voltage Gradient Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the state of charge of electrical energy storage units, especially lithium-ion batteries, face challenges in accuracy and speed due to the need to wait for a steady state, which can take several minutes or hours, and are influenced by measurement inaccuracies.
Innovation Solution
A method that calculates a voltage gradient based on detected voltage values and compares it to a threshold value to determine proximity to a steady state, allowing for quicker and more accurate state of charge assessment without waiting for a predefined period, using mathematical models and considering polarization and quiescent currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the state of charge is ascertained by waiting for a steady state to be achieved, then the accuracy of the state of charge measurement is improved, but the time required for measurement increases significantly
Solution Approach 1:
The patent applies preliminary action by performing gradient formation on voltage values before the steady state is fully achieved. The method calculates voltage gradients and compares them to threshold values to determine when the steady state has been reached, allowing the state of charge to be ascertained without waiting for a predefined time period. This enables early termination of the measurement process while maintaining accuracy.
Solution Approach 2:
The patent implements feedback by continuously monitoring the voltage gradient and comparing it to a threshold value. The method uses the calculated gradient as feedback to determine whether the steady state has been achieved, dynamically adjusting the measurement process based on real-time voltage behavior rather than relying on fixed time intervals.
2Productivity
If the state of charge is ascertained quickly without waiting for steady state, then the measurement speed is improved, but the accuracy of the state of charge decreases
Solution Approach 1:
The patent replaces the traditional mechanical waiting approach with a mathematical analysis system. Instead of physically waiting for the steady state to occur, the method uses gradient formation and threshold comparison to mathematically determine when the steady state has been reached, enabling rapid and accurate state of charge ascertainment without time delays.
Solution Approach 2:
The patent changes the measurement parameter from fixed time-based waiting to dynamic gradient-based detection. By monitoring the rate of change of voltage (gradient) rather than simply waiting for a predetermined time period, the method can quickly identify when the steady state has been achieved, improving both speed and accuracy of the measurement.
Data Source
AI summary
A method for ascertaining the state of charge of an electrical energy storage unit is described. In one example, the method includes ascertaining a voltage gradient at least based on a detected first voltage value of the electrical energy storage unit; comparing the ascertained voltage gradient with a predefined voltage gradient threshold value; and ascertaining the state of charge of the electrical energy storage unit depending on the comparison. A corresponding computer program, a corresponding machine-readable storage medium, a corresponding apparatus and a corresponding electrical energy storage system are also described.