Contact Resistance Measurement Using Multi-Frequency Synchronous Detection
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Solution Overview
Problem
Impedance measurement devices suffer from contact check errors due to noise interference at specific frequencies, leading to unreliable measurements.
Innovation Solution
A contact resistance measurement device that supplies AC currents at multiple frequencies, synchronously detects corresponding voltages, and processes the results to accurately determine contact quality, even in noisy environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronous detection is performed at a specific frequency to detect contact resistance, then contact resistance can be detected, but noise at the same frequency causes detection errors and reduces reliability
Solution Approach 1:
The patent applies periodic action by using multiple AC currents with different frequencies (first through fourth frequencies) to periodically excite the measurement target. Each frequency component allows synchronous detection at its specific frequency, enabling the system to periodically sample contact resistance information across multiple frequency domains. This periodic multi-frequency excitation ensures that noise at any single frequency does not continuously interfere with measurements, as other frequency components remain unaffected.
Solution Approach 2:
The patent changes the frequency parameter of the AC current used for contact resistance measurement. By using AC currents at four different frequencies (f1, f2, f3, f4) and performing synchronous detection at each corresponding frequency, the system can detect contact resistance while avoiding noise interference. The processing unit integrates results from all four frequencies, and since noise typically affects only one frequency band, the overall measurement reliability is maintained through parameter diversity.
2Reliability
If multiple AC currents at different frequencies are supplied to perform contact checks, then noise interference is reduced, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the AC current source to perform multiple functions: it generates both the measurement AC current (for impedance measurement) and the contact determination AC current (for contact resistance measurement) using the same hardware components. The processing unit also serves dual purposes by performing both impedance calculation and contact resistance detection algorithms. This multi-functionality reduces the need for separate dedicated hardware for each measurement type, thereby reducing overall device complexity despite using multiple frequencies.
Solution Approach 2:
The patent merges the contact resistance measurement function with the impedance measurement function. Both measurements are performed simultaneously using the same AC current source, synchronous detection unit, and processing unit. The measurement AC current and contact determination AC current are generated and detected through shared hardware pathways, consolidating what could have been separate measurement systems into a unified device, thus reducing complexity.
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
The device ensures accurate contact checks and enhances impedance measurement reliability by minimizing noise interference effects.
Implementation Method 1
a synchronous detection unit configured to synchronously detect an AC voltage corresponding to a frequency of the contact determination AC current and generated at the determination target contact part
Data Source
AI summary
A contact resistance measurement device including an AC current source SS for supplying a plurality of determination currents Ij defined at different frequencies to a current path including a determination target contact part, a synchronous detection unit for synchronously detecting a detection voltage corresponding to a frequency of the determination current and generated at the determination target contact part when the determination current is supplied from the AC current source with synchronization signals; having the same frequencies as the frequencies of the detection voltage and outputting a voltage whose voltage value changes according to the voltage value of each detection target corresponding to the different frequencies, and a processing unit for executing a quality determination process for the determination target contact part for each of the different frequencies.