Battery Differential Voltage Curve Measurement With Adaptive Current Rates
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Solution Overview
Problem
Current methods for determining the differential voltage curve of a battery are time-consuming due to the need for low current rates, which prolong the process of charging or discharging the battery, making precise State of Health (SOH) determination inefficient.
Innovation Solution
An apparatus and method that adjust the current rate for charging or discharging based on the battery's state of charge, using different current rates within specific ranges of interest to reduce the time required to determine the differential voltage curve, allowing for more efficient tracking of key feature points and reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low current rate is used to determine the differential voltage curve, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent divides the battery capacity range into multiple segments (first range of interest, second range of interest, and other ranges). Different current rates are applied to different segments: low current rate (0.05C) is used when remaining capacity is within the first range of interest to ensure measurement precision, while high current rate is used when remaining capacity is outside this range to reduce time loss. This segmentation resolves the contradiction by applying appropriate current rates to different portions of the charging/discharging process.
Solution Approach 2:
The patent dynamically adjusts the current rate based on the real-time remaining capacity of the battery. The control unit monitors the remaining capacity and switches between low current rate and high current rate modes accordingly. This dynamic adjustment allows the system to maintain measurement precision when needed (within ranges of interest) while minimizing time loss when precision requirements are lower (outside ranges of interest).
2Productivity
If a high current rate is used for battery charging or discharging, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent applies different current rates to different local regions (ranges of interest) of the battery's capacity profile. Within the first range of interest (where precise SOH determination is critical), a low current rate is maintained to ensure measurement precision. Outside this range, a high current rate is applied to improve productivity. This local quality approach ensures that precision requirements are met only where necessary, while allowing faster operation elsewhere.
Solution Approach 2:
The patent changes the current rate parameter dynamically based on the remaining capacity parameter. When remaining capacity falls within predetermined ranges of interest, the current rate is set to a low value (0.05C) to maintain measurement precision. When remaining capacity is outside these ranges, the current rate is increased to a high value to improve productivity. This parameter change strategy resolves the contradiction by adapting the current rate to the specific operational context.
Data Source
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AI summary
An apparatus for determining a differential voltage curve of a battery includes a constant current unit, a sensing unit outputting a sensing signal indicating a voltage and a current of the battery at each unit time, and a control unit determining a control history indicating the voltage and a remaining capacity of the battery at each unit time based on the sensing signal. The control unit outputs a first request message to the constant current unit based on the remaining capacity when the remaining capacity is outside of a first range of interest, and a second request message to the constant current unit when the remaining capacity is within the first range of interest. The constant current unit discharges the battery with a constant current of a first current rate in response to the first request message, and discharges the battery with a constant current of a second current rate in response to the second request message. The control unit determines the differential voltage curve when the remaining capacity reaches a threshold.