Interturn Fault Severity Monitoring in Symmetrical Six-Phase PMSMs Using Subspace Negative-Sequence High-Frequency Current Residuals

This article proposes a fault severity monitoring method for interturn short-circuit fault (ISCF) based on the
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subspace negative-sequence high-frequency (HF) current residuals in symmetrical six-phase permanent magnet synchronous machines. For six-phase machines, both the fundamental frequency and HF behaviors in the
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subspace can be used to design fault indicators. However, another fault type, high-resistance connection faults (HRCFs) can cause similar
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subspace fundamental current symptoms to ISCF. To avoid incorrectly identifying HRCF as ISCF, the proposed method uses the
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subspace negative-sequence HF current residuals to reduce the sensitivity to the HRCF. Moreover, the proposed method has high robustness for different work conditions and does not need additional sensors. Experimental results show the effectiveness of the proposed method for different fault severities and operations.