Reactance-Based Electrical Connection Deterioration Diagnosis
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Solution Overview
Problem
Existing methods for diagnosing the deterioration degree of electrical connection portions between metal members, such as those in connectors, face challenges due to non-monotonic increases in contact resistance values over time, making it difficult to accurately assess the deterioration state, especially when metal members are plated with base metals like copper alloys.
Innovation Solution
A deterioration degree diagnosis device and method that measures impedance using an AC signal of a predetermined frequency (500 kHz to 2 MHz) to determine the reactance component value, which correlates strongly with the deterioration degree, allowing for accurate diagnosis by tracking deviations from initial values, even in noisy environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If DC signal measurement method is used to diagnose deterioration degree, then the measurement process is simple, but the diagnosis accuracy is low due to non-monotonic increase in contact resistance
Solution Approach 1:
The patent changes the measurement parameter from DC contact resistance to AC impedance (specifically reactance component) at frequencies of 500 kHz to 2 MHz. This parameter change transforms the non-monotonic resistance increase into a monotonic reactance increase, enabling accurate deterioration diagnosis while maintaining measurement simplicity.
2Measurement precision
If AC signal measurement method is used to diagnose deterioration degree, then the diagnosis accuracy is improved through reactance component measurement, but the device complexity increases
Solution Approach 1:
The patent replaces the simple DC resistance measurement system with an AC impedance measurement system that utilizes electromagnetic induction and capacitive coupling effects. The measurement unit applies AC signals and measures the resulting voltage and current to calculate impedance, substituting direct resistance measurement with a more sophisticated but accurate electromagnetic-based measurement approach.
3Reliability
If high frequency AC signal is used for measurement, then noise interference is reduced and measurement range is expanded, but the measurement system becomes more complex
Solution Approach 1:
The patent employs periodic AC signals at specific high frequencies (500 kHz to 2 MHz) for measurement. This periodic action at optimized frequencies provides immunity from low-frequency noise and interference, while the frequency range is carefully selected to balance measurement reliability with system complexity constraints.
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 approach enables accurate diagnosis of the deterioration degree of electrical connection portions by leveraging the monotonic increase in reactance component values with oxidation, providing a large measurement range and reducing noise interference, thus ensuring reliable assessment of the connection's state.
Implementation Method 1
a measurement unit that is configured to measure an impedance related to a contact resistance of the electrical connection portion by measuring an AC voltage between metal members and an AC current flowing between the metal members
Implementation Method 2
a contact resistance of the electrical connection portion (more specifically, an electrical resistance value measured using a DC signal) generally increases with passage of time (and accordingly, with progress of an oxidation reaction in a vicinity of the electrical connection portion)
Data Source
AI summary
A deterioration degree diagnosis device includes a measurement unit and a diagnosis unit. The measurement unit measures an impedance related to a contact resistance of an electrical connection portion by measuring an AC voltage between metal members and an AC current flowing between the metal members in a state where an AC signal of a predetermined frequency is applied to an electric circuit that connects two metal members in contact via the electrical connection portion. The diagnosis unit diagnoses a deterioration degree of the electrical connection portion based on a reactance component value in the impedance measured by the measurement unit.