Demagnetization Detection in PMSMs Using Search Coils Exploiting Machine’s Symmetry

Magnet demagnetization in permanent magnet synchronous machines (PMSMs) can produce inadmissible performance degradation. Search coils (SCs) have been proven to be a viable option for its detection. Limitations of existing methods using SCs include the low sensitivity and the need of a large number of SCs. This paper proposes two methods for demagnetization detection of PMSMs using SCs which overcome these limitations. Zero-sequence voltage-based method relies on the zero-sequence voltage of three SCs electrically shifted 120 electrical degrees. On the other hand, differential voltage-based method computes the difference between the voltage induced in SCs with the same electrical angle, i.e., both SCs are electrically shifted 360°
^1
1
This work was supported in part by the Research, Technological Development and Innovation Programs of the Spanish Ministry of Science and Innovation, under grant PID2019-106057RB-I00