Fault Detection in Electrical Machines via Circulating Current Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fault detection methods for electrical machines face practical difficulties in acquiring and processing data, particularly in identifying robust fault indicators and interpreting results correctly, especially in machines where sensor integration is challenging, such as low-power units.
Innovation Solution
A method involving frequency analysis of circulating currents between parallel winding branches to determine fault conditions like dynamic and static eccentricity, inter-turn short circuits in rotors and stators, using current sensors and differential measurements to obtain accurate branch current signals, and comparing amplitudes with threshold values to distinguish faults from normal asymmetries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If circulating current measurement is implemented in electrical machines, then fault detection capability is improved, but device complexity increases due to sensor integration requirements
Solution Approach 1:
The patent introduces an intermediary measurement approach by using current sensors positioned in the external circuit to measure branch currents, rather than directly integrating sensors into the winding branches. The circulating current is derived as the difference between two externally measured branch currents, thus avoiding the complexity of internal sensor integration while maintaining fault detection capability
Solution Approach 2:
The patent replaces the mechanical/physical integration of current sensors into the machine windings with an electrical measurement substitution approach. By measuring the branch currents externally and calculating the circulating current through differential measurement, the system eliminates the need for physical sensor integration into the winding structure
2Measurement precision
If multiple measurement locations are used for circulating current, then fault detection accuracy is improved, but ease of operation deteriorates due to difficult sensor arrangement
Solution Approach 1:
The patent uses external circuit measurements as an intermediary to obtain branch current data without requiring direct access to multiple internal measurement locations. This approach maintains measurement precision by using externally accessible points while dramatically improving ease of operation by eliminating the need for complex internal sensor arrangement
3Device complexity
If circulating current analysis is performed without frequency analysis, then measurement simplicity is improved, but measurement precision deteriorates due to inability to identify specific fault indicators
Solution Approach 1:
The patent applies frequency analysis (such as FFT) to the circulating current signal to decompose it into its frequency components. This periodic action of analyzing the signal in the frequency domain enables precise identification of fault indicators at specific frequencies while maintaining relatively simple measurement setup, thus resolving the contradiction between simplicity and precision
Data Source
Figure 1~2b
Figure 3~4
AI summary
A method for identifying a fault condition in an electrical machine in which at least a stator (120) or a rotor (220) has parallel winding branches (30, 40, 50, 60) is disclosed. A measurement (230) is carried out for obtaining a set of circulating current values (240) between two parallel winding branches (30, 40, 50, 60) of which each winding branch (30, 40, 50, 60) comprises a single coil (20). A frequency analysis (250) is applied on the set of circulating current values (250) to obtain at least one frequency component (260). A fault condition (280) of the electrical machine is determined on the basis of the at least one frequency component (260).