Electric Motor Fault Detection via Harmonic Phase Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Detecting partial discharge in electric motors is challenging due to it being buried in noise from normal operation, necessitating a method to distinguish it from background noise.
Innovation Solution
A control device with a fault detector performs frequency analysis on voltage and current signals to identify odd-order harmonics and their phase angles, distinguishing partial discharge from noise by analyzing phase relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis is performed to detect partial discharge, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by analyzing specific frequency parameters (odd-order harmonics at 3ω, 5ω, 7ω) and their phase angles relative to the fundamental frequency. The fault detector transforms the time-domain signal into frequency-domain parameters, detecting partial discharge through changes in harmonic presence and phase relationships rather than analyzing the entire signal spectrum, thus improving detection precision while managing complexity.
2Measurement precision
If signal processing is enhanced to distinguish partial discharge from noise, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent implements preliminary action by pre-defining the characteristic parameters of partial discharge (odd-order harmonics with specific phase angles) before actual detection. The system is prepared with knowledge of what to look for (3ω, 5ω, 7ω harmonics with phase angles of ±90° or more relative to fundamental frequency), allowing rapid identification during operation without requiring complex real-time signal processing or extensive data accumulation.
3Reliability
If comprehensive frequency analysis is performed on voltage and current signals, then reliability of fault detection is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the frequency spectrum into specific segments of interest (odd-order harmonics at 3ω, 5ω, 7ω) rather than analyzing the entire frequency spectrum. The fault detector segments the analysis to focus only on these specific frequency components and their phase relationships, reducing the complexity of comprehensive frequency analysis while maintaining high detection reliability through targeted parameter monitoring.
Data Source
AI summary
According to an embodiment, a control device includes a controller and a fault detector. The controller controls an electric motor. The fault detector detects a fault of the electric motor. The fault detector performs a frequency analysis of a voltage signal and a current signal that drive the electric motor. The fault detector determines, based on a result of the frequency analysis, whether or not the current signal includes an odd-order harmonic having a frequency that is odd multiples of a fundamental wave of the voltage signal. The fault detector determines, based on the result of the frequency analysis, whether or not the odd-order harmonic has a first phase angle that is a phase angle of an opposite phase with respect to a phase angle of the fundamental wave.