Battery Depth-of-Charge Calculation via Inner Resistance
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Solution Overview
Problem
Existing methods for calculating battery depth-of-charge are inconsistent and require manufacturing three electrodes, leading to inaccuracies and inefficiencies in determining the inner resistance value of battery cells.
Innovation Solution
A battery depth-of-charge calculation apparatus and method that calculates inner resistance based on open circuit voltage and voltage values during charge, allowing for the determination of negative electrode depth-of-charge without requiring three electrodes, using a resistance calculating unit to derive the inner resistance value and a depth-of-charge calculating unit to determine the SoC based on this resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing depth-of-charge check method using differential curve is used, then the charge profile can be analyzed, but different values are read depending on individual interpretation leading to measurement inaccuracy
Solution Approach 1:
The patent replaces the manual visual interpretation method with an automated calculation system that computes inner resistance values and determines depth-of-charge objectively. The controller automatically calculates inner resistance based on voltage and current measurements, eliminating subjective human interpretation and providing consistent, accurate results.
Solution Approach 2:
The system performs self-measurement by automatically calculating its own depth-of-charge status through inner resistance computation. The battery management system autonomously determines charge levels without requiring external manual analysis, enabling the system to self-monitor and report its state accurately.
2Manufacturing precision
If three electrodes are manufactured to identify depth of charging, then charge protocol can be derived, but the process requires additional manufacturing complexity and time
Solution Approach 1:
The patent extracts the depth-of-charge measurement function from the complex three-electrode manufacturing process. By using the existing two electrodes and calculating inner resistance through voltage and current measurements, the system removes the need for the third reference electrode while maintaining measurement capability.
Solution Approach 2:
Instead of physically creating a three-electrode reference battery, the system creates a computational model that replicates the depth-of-charge identification function. The controller calculates depth-of-charge based on measured parameters, providing the same information without the physical complexity of three electrodes.
3Measurement precision
If negative electrode profile is derived from three electrodes, then depth of charging can be identified, but change depending on time occurs requiring reference battery cell manufacturing
Solution Approach 1:
The patent replaces the time-dependent physical reference battery with an automated calculation system. The controller continuously computes inner resistance and depth-of-charge in real-time, eliminating the need for pre-manufactured reference cells and providing consistent results regardless of time elapsed.
Solution Approach 2:
The system performs preliminary calculations by continuously monitoring voltage and current to maintain up-to-date inner resistance values. This preliminary action ensures that depth-of-charge identification is always based on current battery state rather than historical reference data, preventing time-dependent drift.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate calculation of battery depth-of-charge for each C-rate, allowing for efficient charge protocols without the need for additional electrodes, and provides a guide for charge termination based on ion precipitation.
Implementation Method 1
calculate the internal resistance value of the battery cell during charge by dividing the calculated over-voltage value with respect to the SoC of the battery cell by a current value flowing through the battery cell
Data Source
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AI summary
A battery depth-of-charge calculation apparatus according to an embodiment disclosed herein includes an information obtaining unit configured to obtain an open circuit voltage (OCV) value with respect to a state of charge (SoC) of a battery cell and information about a voltage value with respect to an SoC of the battery cell during charge, a resistance calculating unit configured to calculate an inner resistance value with respect to the SoC of the battery cell during charge, based on the information about the voltage value with respect to the SoC of the battery cell during charge and the open circuit voltage value with respect to the SoC of the battery cell, and a depth-of-charge calculating unit configured to calculate a negative electrode depth-of-charge of the battery cell based on the inner resistance value.