Multiphase Machine Winding Fault Detection by Current Ratio Comparison
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Solution Overview
Problem
Existing methods for detecting winding faults in multiphase electrical machines, such as those used in urban air mobility and electric vertical take-off and landing aircraft, are inefficient due to large computational data requirements, inaccuracy in threshold setting, and operational constraints, often failing to detect incipient turn-to-turn short circuits before they lead to catastrophic failures.
Innovation Solution
A method involving the calculation of ratios from harmonic and DC components of DC link and stator currents in two electrically isolated multiphase machines to determine if the ratios fall outside a predetermined range, indicating a winding fault, without requiring additional sensors or historical data, and applicable to all winding types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods for detecting winding faults are used, then fault detection capability is provided, but computational data requirements are large and computational effort is high
Solution Approach 1:
The patent extracts only the essential features needed for fault detection by comparing fundamental quantities (DC link currents and stator currents) between two machines, rather than analyzing complete operational datasets. This extraction approach reduces computational data requirements while maintaining detection accuracy.
Solution Approach 2:
The patent segments the fault detection process into distinct current component comparisons (DC link current comparison and stator current comparison), allowing each segment to be analyzed independently with reduced data requirements.
2Measurement precision
If existing fault detection methods are implemented, then winding faults can be detected, but threshold setting inaccuracy occurs
Solution Approach 1:
The system uses itself for calibration by utilizing the second healthy machine as a reference standard. The healthy machine's current characteristics automatically define the expected range, eliminating the need for external threshold calibration and improving threshold setting accuracy.
Solution Approach 2:
The comparison between two machines provides continuous feedback on system health. When one machine deviates from the other's characteristics, the system automatically identifies this as a fault condition, creating a self-regulating detection mechanism with accurate threshold determination.
3Reliability
If existing monitoring methods are used, then fault detection is provided, but operational constraints limit applicability
Solution Approach 1:
The patent creates a universal monitoring solution that works across different operating conditions by comparing relative differences between two machines rather than relying on absolute threshold values. This approach eliminates operational constraints and improves ease of operation while maintaining detection reliability.
4Measurement precision
If traditional fault detection approaches are applied, then winding faults can be identified, but additional sensors and historical data are required
Solution Approach 1:
The patent uses the second machine as a copy or reference model of the first machine. By comparing the operational characteristics of this reference copy against the monitored machine, the system can detect faults without requiring additional sensors or historical data, as the reference machine provides the necessary baseline information.
Data Source
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AI summary
The disclosure relates to monitoring of multiphase electrical machines, in particular to determine the presence or absence of a winding fault. A method of monitoring first and second multiphase electrical machines (1011, 1012) driven by respective first and second power electronics modules (1021, 1022) from respective first and second DC electrical supplies (1031, 1032) comprises: measuring first and second DC link currents (Idc1, Idc2) from the respective first and second DC electrical supplies (1031, 1032) to the respective first and second power electronics modules (1021, 1022); measuring stator currents (Ia1, Ib1, Ia2, Ib2) through phases of the first and second electrical machines (1011, 1012); calculating a first ratio from a harmonic component of the first DC link current (Idc1) divided by a harmonic component of the second DC link current (Idc2); calculating a second ratio from a harmonic component of a positive sequence stator current through the first electrical machine (1011) divided by a harmonic component of a positive sequence stator current through the second electrical machine (1012); calculating a third ratio from a DC component of a combined sequence stator current through the first electrical machine (1011) divided by a DC component of a combined sequence stator current through the second electrical machine (1012); and determining a winding fault in the first or second electrical machine (1011, 1012) if one or more of the first, second and third ratios is outside of a predetermined range.