Electrical Storage Device Inspection via Self-Discharge Current
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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 prone to inaccuracies due to contact resistance variations and environmental conditions, especially when relying on voltage measurements.
Innovation Solution
An inspection method that sets a pseudo parasitic resistance value based on the power storage capacity of the device, using current measurement to determine quality by measuring the self-discharge current after convergence, thereby reducing measurement time and improving 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 measurement time is long due to contact resistance variations and voltage drop in current path
Solution Approach 1:
The patent replaces voltage measurement with current measurement. Specifically, it measures the self-discharge current of the electrical storage device directly using a current meter, substituting the voltage measurement system that was affected by contact resistance and voltage drops. This substitution eliminates the harmful effects of contact resistance variations and internal voltage drops, achieving both higher measurement accuracy and shorter measurement time.
Solution Approach 2:
The patent introduces a current measurement system as an intermediary to indirectly determine the quality of the electrical storage device. Instead of measuring voltage directly at the device terminals (which is affected by contact resistance), the system measures the self-discharge current flowing through the device, providing an accurate representation of device quality without being influenced by contact resistance or voltage drops in the measurement path.
2Measurement precision
If leaving time is extended to obtain significant voltage drop amount, then quality determination becomes possible, but inspection time increases significantly
Solution Approach 1:
The patent substitutes the voltage-based measurement system with a current-based measurement system. By measuring self-discharge current directly, the system obtains significant measurement values immediately without requiring extended leaving time to accumulate measurable voltage drops. This substitution enables both accurate quality determination and high inspection speed simultaneously.
Solution Approach 2:
The patent performs current measurement directly on the charged electrical storage device without requiring a preliminary leaving period. The self-discharge current can be measured immediately after charging, eliminating the need to wait for voltage drops to develop. This preliminary action approach enables rapid quality inspection while maintaining measurement accuracy.
3Measurement precision
If contact resistance is reduced for accurate voltage measurement, then measurement accuracy improves, but contact resistance varies every time terminals are connected making consistent measurement difficult
Solution Approach 1:
The patent replaces the voltage measurement system with a current measurement system. The current measurement is performed by connecting the current meter in series with the electrical storage device, measuring the self-discharge current directly. This substitution eliminates the problem of variable contact resistance at terminal connections, as the current measurement path does not depend on contact resistance at the device terminals in the same way voltage measurement does. The measurement consistency is significantly improved.
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 allows for quick and accurate quality determination of electrical storage devices regardless of varying conditions, with shorter processing times and higher accuracy compared to traditional voltage-based methods.
Implementation Method 1
a state where a pseudo parasitic resistance value is set, a current value after convergence of a current flowing through a circuit is acquired in which the circuit is formed by connecting an external power source to the electrical storage device in a direction where a voltage of the external power source is applied to the electrical storage device
Implementation Method 2
acquiring a current value after convergence of a current flowing through the circuit such that the circuit is formed by connecting the external power source to the electrical storage device
Data Source
AI summary
An inspection method of an electrical storage device includes: setting a pseudo parasitic resistance value to be small in a case where a power storage capacity of the electrical storage device is large, while setting the pseudo parasitic resistance value to be large in the case where the power storage capacity is small; in a state where the pseudo parasitic resistance value is set, acquiring a current value after convergence of a current flowing through a circuit such that the circuit is formed by connecting an external power source to the charged electrical storage device in a direction where a voltage is applied thereto; and determining quality of the electrical storage device based on the current value.