Current Waveform Diagnosis Under Varying Motor Speed

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Solution Overview

Problem

Existing diagnostic systems for determining the degree of abnormality in apparatuses struggle when the rotation speed of the driving device is not maintained constant, leading to reduced accuracy in abnormality diagnosis.

Innovation Solution

A diagnostic system that acquires current waveform data and extracts varying portions corresponding to varying rotation speeds, using short-time Fourier transform to identify and analyze these portions, allowing for accurate abnormality determination even without a constant rotation speed period.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the rotation speed of the driving device is maintained constant for diagnosis, then the measurement precision of abnormality is improved, but the adaptability to varying operation conditions deteriorates

Engineering Contradiction:

Improveabnormality diagnosis accuracyVSAvoiddiagnosis capability under varying rotation speed

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent transforms the static diagnosis approach (requiring constant rotation speed) into a dynamic one by introducing time-frequency analysis. The short-time Fourier transform continuously analyzes the current waveform at different time windows, allowing the diagnosis to adapt to changing rotation speeds while maintaining measurement precision through localized frequency analysis.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the analysis parameter from fixed rotation speed to time-varying frequency characteristics. By analyzing the frequency spectrum of current waveforms at different time points, the system can identify abnormality feature frequencies even when rotation speed varies, thus maintaining diagnosis accuracy under dynamic conditions.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the rotation speed varies during operation, then the adaptability to real-world conditions is improved, but the measurement precision of abnormality deteriorates

Engineering Contradiction:

Improvediagnosis capability under varying rotation speedVSAvoidabnormality diagnosis accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the continuous current waveform into multiple time windows and performs Fourier transform on each segment. This segmentation allows the system to capture frequency characteristics at different moments, identifying abnormality feature frequencies even when the overall rotation speed varies, thus maintaining measurement precision while adapting to real-world conditions.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If constant rotation speed is required for diagnosis, then the measurement precision is improved, but the loss of time for diagnosis increases

Engineering Contradiction:

Improveabnormality diagnosis accuracyVSAvoidtime for maintaining constant rotation speed

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent enables continuous diagnosis by analyzing current waveforms during normal varying operation without requiring the system to maintain constant rotation speed. The short-time Fourier transform continuously processes the current signal, allowing abnormality detection to proceed concurrently with normal operation, thus eliminating time loss while maintaining precision.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS11787057B2Diagnostic system, diagnosing method, and program

Publication Date: 2023.10.17 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A diagnostic system includes an acquirer configured to acquire current waveform data representing a waveform relating to a current supplied to a driving device of an apparatus and a determiner configured to determine a degree of abnormality in the apparatus from a varying portion of the waveform, the varying portion corresponding to a varying time period during which a rotation speed of the driving device increases or decreases.