Inverter Current-Vector Diagnosis for Early Rotating Machine Faults
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Solution Overview
Problem
Existing power conversion devices, such as general-purpose inverters, are unable to provide accurate failure symptom diagnosis for rotating machines due to limited calculator capacity, making them expensive and only feasible for a few sites, and existing low-cost abnormality detection methods struggle to maintain sensitivity when removing output frequency components.
Innovation Solution
A power conversion device with a current measurement unit, current vector calculation unit, amount-to-be-analyzed calculation unit, feature amount waveform extraction unit, and abnormality degree calculation unit that performs 3-phase to 2-phase conversion, extracts waveforms in specific frequency ranges, and calculates abnormality degrees without extensive frequency analysis, allowing for early and cost-effective failure symptom detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis is performed to diagnose rotating machine abnormalities, then diagnosis accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The invention extracts only the necessary frequency components related to bearing defects from the current signal, rather than performing complete frequency analysis. By using bandpass filters to isolate specific frequency bands containing bearing defect information, the system achieves effective diagnosis without the computational burden of full spectrum analysis, thus maintaining diagnosis accuracy while reducing device complexity and cost
Solution Approach 2:
The frequency spectrum is segmented into multiple bands, with bandpass filters targeting specific frequency ranges where bearing defect signatures appear. This segmentation approach allows the system to focus computational resources only on relevant frequency components, avoiding the need for expensive industrial PCs while maintaining effective abnormality detection
2Measurement precision
If output frequency component is removed using bandpass filter, then abnormality detection sensitivity is improved, but output frequency component cannot be completely removed
Solution Approach 1:
Instead of attempting to remove the output frequency component uniformly across all signal processing stages, the invention applies bandpass filters with specific frequency characteristics tailored to each bearing defect type. Each filter is designed with local quality parameters (center frequency, bandwidth) optimized for detecting specific bearing faults, allowing effective sensitivity enhancement while managing the challenge of complete output frequency removal through targeted frequency band isolation
Data Source
AI summary
This power conversion device has: a current measurement unit for measuring phase current; a current vector calculation unit for calculating a current vector by performing 3-phase to 2-phase conversion on the phase current; an amount-to-be-analyzed calculation unit for calculating, on the basis of the current vector, an amount to be analyzed; and a feature amount waveform extraction unit for extracting a waveform in a specific frequency range on the basis of the amount to be analyzed.