Electrical Storage Device Inspection via Converged Current Measurement
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Solution Overview
Problem
Existing methods for determining the quality of electrical storage devices, such as secondary batteries, are time-consuming and lack accuracy due to variations in circuit resistance and contact resistance during voltage measurement, which affects the measurement of voltage drop and self-discharge properties.
Innovation Solution
An inspection method that uses current measurement instead of voltage measurement, where the circuit resistance is measured and used to predict the convergence timing of the current, allowing for accurate determination of the self-discharge property by acquiring the current value at the predicted convergence time, thereby improving processing time and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurement is used to determine quality of electrical storage device, then quality determination can be performed, but measurement accuracy is poor and processing time is long due to circuit resistance variations and contact resistance
Solution Approach 1:
The patent changes the measurement parameter from voltage to current. By measuring current instead of voltage, the system avoids the problems of contact resistance and circuit resistance variations that affect voltage measurements. The current measurement is performed after convergence, when the current value stabilizes, providing accurate quality determination without requiring long processing times.
2Measurement precision
If leaving time is extended to obtain significant voltage drop amount, then quality determination accuracy improves, but processing time increases
Solution Approach 1:
The patent changes from measuring voltage drop over time to measuring converged current. This parameter change eliminates the need for extended leaving time because the current convergence provides immediate quality information without requiring significant voltage drop accumulation.
Solution Approach 2:
The patent performs resistance measurement in advance to determine the convergence time constant. This preliminary action allows the system to predict when current convergence will occur and schedule the quality measurement accordingly, optimizing the processing time without sacrificing accuracy.
3Productivity
If current measurement is performed immediately after connection, then processing time is reduced, but measurement accuracy is poor due to non-converged current
Solution Approach 1:
The patent performs resistance measurement before current measurement to calculate the expected convergence time. This preliminary action enables the system to wait for the appropriate convergence period without excessive delay, achieving both speed and accuracy in the quality determination process.
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
This method enables quick and accurate quality determination of electrical storage devices by minimizing the influence of circuit and contact resistances, reducing processing time, and preventing false determinations.
Implementation Method 1
a polarity of a voltage of the external power source is reverse to a polarity of a voltage of the charged electrical storage device
Implementation Method 2
A relationship between a circuit resistance of the circuit and a necessary time for convergence of the current in the current measurement is grasped in advance
Data Source
AI summary
A circuit is formed by connecting an external power source to a charged electrical storage device so that a polarity of a voltage of the external power source is reverse to a polarity of a voltage of the charged electrical storage device, and the voltage of the external power source is adjusted so that a current does not flow right after the connection. Then, current measurement to acquire a current value after convergence of the current flowing through the circuit due to a voltage drop of the electrical storage device and quality determination based on the current value after convergence are performed. In the current measurement, resistance measurement to actually measure a circuit resistance and prediction to predict a convergence timing of the current based on the actually measured circuit resistance are performed. The current value is acquired when a predicted convergence timing comes.