Motor Current Waveform Diagnosis for Quantifying Abnormality

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Solution Overview

Problem

Conventional motor abnormality diagnosis techniques only provide a binary determination of abnormality presence, without quantifying the degree of abnormality.

Innovation Solution

An abnormality diagnosis device and method that utilize a processor to extract feature quantities from a motor's current waveform and calculate the degree of abnormality based on stored calculation data, enabling quantitative assessment of motor eccentricity and other abnormalities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If conventional FFT analysis with spectrum peak comparison is used, then abnormality detection is simple and quick, but only binary determination (abnormal/normal) is provided without quantifying the degree of abnormality

Engineering Contradiction:

Improveinformation on degree of abnormalityVSAvoidcomplexity of calculation and data processing

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent pre-calculates and stores feature quantities (such as RMS values, peak values, form factors) for various known abnormality levels in a database during the normal operation phase. When diagnosis is needed, the system only needs to extract current waveform features and compare them against the pre-stored data, avoiding complex real-time calculations and enabling quantitative abnormality assessment.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a database that copies and stores characteristic waveform features associated with different abnormality levels. Instead of performing complex analyses during diagnosis, the system retrieves and compares against these pre-stored copies of abnormality patterns, enabling quantitative assessment without real-time computational complexity.

Inventive Principle:

Principle #26Copying

2Measurement precision

If detailed waveform analysis is performed to determine degree of abnormality, then diagnostic precision is improved, but processing time and computational load increase

Engineering Contradiction:

Improveprecision of abnormality assessmentVSAvoidtime for diagnosis processing

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system pre-computes and stores diagnostic reference data including feature quantities for various abnormality levels before actual diagnosis occurs. During runtime, it only needs to extract current waveform features and perform simple comparisons against the pre-prepared database, achieving both high precision and fast processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the diagnostic process into two distinct phases: an offline phase where comprehensive waveform analysis and database construction are performed, and an online phase where only simple feature extraction and comparison are needed. This segmentation allows detailed analysis to be done in advance without impacting real-time diagnostic speed.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12341450B2Abnormality diagnosis device and abnormality diagnosis method

Publication Date: 2025.06.24 MITSUBISHI ELECTRIC CORP

AI summary

An abnormality diagnosis device includes: a first interface to obtain a value of a driving current for driving a motor; and a processor to access a database including calculation data to be used to calculate a degree of abnormality of the motor, wherein the processor extracts a feature quantity for calculating the degree of abnormality from a current waveform specified by a value of the driving current, and calculates the degree of abnormality of the motor based on the extracted feature quantity and the calculation data.