Multi-Phase AC Machine Fault Detection Without Rotor Rotation
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Solution Overview
Problem
Existing methods for off-line testing of multi-phase alternating current machines are inefficient, require complex calculations, and can be affected by rotor position asymmetry, making it difficult to reliably detect faults without rotating the rotor.
Innovation Solution
A method that determines a joint physical stator quantity by summing physical stator quantities of each winding, independent of rotor position, allowing for quick and reliable fault detection without rotor rotation, using electronic circuitry to apply test signals and compare reference values with current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor is rotated in fixed steps or at constant rate to obtain reliable measuring data, then measurement reliability is improved, but device complexity and ease of operation deteriorate due to the difficulty of obtaining perfect rotation
Solution Approach 1:
The invention extracts the rotor position dependency from the measurement process by summing physical stator quantities across all phases. This eliminates the need to control rotor position or rotation, as the summation operation inherently removes the position-dependent components, leaving only fault-related asymmetries.
Solution Approach 2:
The invention replaces the mechanical requirement for precise rotor rotation with an electrical/mathematical operation (summing physical quantities). Instead of mechanically controlling rotor position to ensure measurement reliability, the solution uses mathematical processing of electrical measurements to achieve the same goal without mechanical constraints.
2Measurement precision
If powerful surge voltage with high energy content is supplied to the motor for off-line testing, then fault detection capability is improved, but harmful factors increase due to initiation or acceleration of incipient insulation failures
Solution Approach 1:
The invention changes the test signal parameters from powerful surge voltage to low-voltage sinusoidal test signals. This parameter change maintains fault detection capability through phase asymmetry analysis while eliminating the harmful high-energy effects that could damage insulation or accelerate degradation.
Solution Approach 2:
The invention converts the previously harmful surge voltage method into a beneficial low-voltage measurement approach. By using phase asymmetry analysis of physical quantities instead of high-energy surge testing, the method transforms a potentially damaging test into a safe diagnostic procedure that detects faults without causing harm.
3Measurement precision
If time-consuming and complex calculations are performed to analyze the exponentially decaying response, then fault detection accuracy is improved, but productivity deteriorates
Solution Approach 1:
The invention extracts only the essential information needed for fault detection by directly comparing phase asymmetries in physical quantities. This eliminates the need for complex calculations and analysis of entire decay curves, retaining only the critical asymmetry information that indicates faults.
Solution Approach 2:
The invention uses partial action by measuring physical quantities at only two specific instants (before and after the test signal) rather than continuously analyzing the entire exponentially decaying response. This partial measurement approach achieves sufficient fault detection accuracy while dramatically reducing calculation complexity and testing time.
4Measurement precision
If bulky and heavy equipment is used for surge voltage testing, then fault detection capability is improved, but ease of operation deteriorates due to transport and installation problems
Solution Approach 1:
The invention replaces the mechanical surge voltage testing equipment with electronic measurement circuitry that uses low-voltage sinusoidal signals. This substitution eliminates bulky and heavy equipment, making the testing system portable and easy to install while maintaining fault detection capability through electronic analysis of physical quantities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables convenient, time-efficient, and accurate fault detection in multi-phase alternating current machines, reducing the need for complex calculations and eliminating rotor position-related asymmetry issues, thus simplifying the testing process and improving reliability.
Implementation Method 1
determining a physical stator quantity of each stator winding by applying a test signal to each stator winding
Data Source
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AI summary
According to the present invention, there is provided a method and apparatus for off-line testing of a multi-phase alternating current machine. The method comprises determining, at a first rotor position, a physical stator quantity of each stator winding by applying a test signal to each stator winding, and determining a first joint physical stator quantity by summing the determined physical stator quantities of the stator windings. There is also provided a method and apparatus for off-line testing of a multi-phase alternating current machine. The method comprises determining, at a second rotor position, a physical stator quantity of each stator winding by applying a test signal to each stator winding, determining a second joint physical stator quantity by summing the determined physical stator quantities of the stator windings, comparing the second joint physical stator quantity with a previously determined first joint physical stator quantity, and determining a fault condition of said multi-phase alternating current machine if the first joint physical stator quantity differs from the second joint physical stator quantity.