Eliminating Interferences Based on Common-Mode Rejection for Inductive Debris Detections

As inductive debris detection has several unique advantages such as simple structure, usability for metallic flow channel and non-sensitivity to the quality of lubricant, it has been more and more applied in the mechanical fault diagnosis and condition-based maintenance. However, the inductive principle is easily interfered by electromagnetic variations and mechanical vibrations in the actual working condition, which limits the detection resolution and the early mechanical wear prediction. Although some signal processing methods have been proposed to improve the signal-to-noise ratio (SNR), the fundamental denoising idea for sensor designs is still absent. This paper proposes using common-mode rejection to eliminate interferences for inductive debris detections. The mathematic model is built to discuss the rejection effect, and the magnetic distribution is simulated to analyze the sensor structure. Finally, a debris sensor is designed to validate the performance through conducting actual debris detections and external interference experiments. The results indicate that the sensor can effectively eliminate the multiple interferences such as alternating power, oil pulsation, electromagnetic variation and mechanical vibration. Especially, the SNR has been improved about 7.5 times in the actual debris detection, which demonstrates a good potential for applications.

Automated summary

This study proposes a method using common-mode rejection to eliminate interferences for inductive debris detections. Experimental results show that the sensor effectively eliminates multiple interferences and improves the SNR by about 7.5 times in actual debris detection.