Battery Overvoltage Evaluation via Differential Voltage Analysis
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Solution Overview
Problem
Existing Differential Voltage Analysis (DVA) methods face difficulties in accurately obtaining overvoltage characteristics of batteries due to polarization-induced noise, which affects battery degradation assessment and safety performance.
Innovation Solution
An apparatus and method that measure current and voltage during a discharge event after polarization-inducing pretreatment, determining overvoltage characteristics by comparing differential voltage curves and calculating a concentrated overvoltage range and area, allowing for precise evaluation of overvoltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low current discharge/charge rate is used to suppress polarization, then overvoltage noise is reduced, but measurement precision of overvoltage characteristics deteriorates
Solution Approach 1:
The patent applies preliminary action by conducting polarization-inducing pretreatment before the actual measurement. The battery is first subjected to high-current discharge/charge cycles to establish polarization conditions, then measured at low current rates. This preliminary preparation enables the system to capture overvoltage characteristics that would otherwise be masked, resolving the contradiction between measurement precision and evaluation efficiency.
Solution Approach 2:
The patent implements continuity of useful action through multi-step measurement processes. Instead of a single measurement, the system performs multiple discharge/charge cycles with varying current rates, continuously collecting data to build a comprehensive profile of overvoltage characteristics. This continuous measurement approach ensures precise characterization while maintaining evaluation thoroughness.
2Reliability
If DVA is used to determine degradation parameters, then battery performance prediction is improved, but overvoltage characteristics are lost due to polarization noise
Solution Approach 1:
The patent applies segmentation by dividing the measurement process into distinct phases: polarization-inducing pretreatment, low-current measurement, and data processing. This segmentation allows the system to separate the polarization effect from the underlying battery characteristics, enabling simultaneous determination of degradation parameters and overvoltage characteristics without information loss.
Solution Approach 2:
The patent uses an intermediary approach by introducing a reference battery that has undergone the same polarization-inducing pretreatment. The reference battery serves as a mediator to compensate for polarization effects during measurement, allowing the system to extract accurate overvoltage characteristics and degradation parameters by comparing test battery data with the reference data.
3Productivity
If high current rate is used for rapid charging/discharging, then productivity is improved, but polarization-induced overvoltage noise increases
Solution Approach 1:
The patent implements periodic action through cyclic measurement protocols. The system alternates between high-current polarization induction phases and low-current measurement phases, repeating this cycle multiple times. This periodic alternation allows the battery to experience high-current conditions for productivity while capturing voltage data at low current rates for precision, resolving the contradiction between speed and accuracy.
Data Source
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AI summary
An overvoltage characteristics evaluation apparatus for a battery includes a sensing unit to measure a current and a voltage of the battery, and a control unit to determine a measured capacity history and a measured voltage history of the battery during a discharge event executed subsequent to polarization-inducing pretreatment for the battery. The control unit determines a first measured voltage curve indicating a correlation between the measured capacity history and the measured voltage history, and a second measured voltage curve indicating a correlation between a depth of discharge history obtained by normalizing the measured capacity history to a total discharge capacity of the measured capacity history and the measured voltage history. The control unit determines a differential voltage curve by differentiating the measured voltage history. The control unit determines overvoltage characteristics information associated with the polarization-inducing pretreatment by comparing the differential voltage curve with a reference differential voltage curve.