Impact of bridge-saturation on anisotropy-based initial rotor polarity detection of interior permanent-magnet synchronous machines

摘要

Anisotropy-based initial rotor polarity detection of interior permanent-magnet synchronous machines (IPMSM) relies typically on the saturation in the stator iron. The current response to a voltage pulse into the north pole (d+) direction of the magnet should be higher in magnitude than into the opposite direction because of increased stator saturation. However, experiments show sometimes an opposite result. The present paper considers the bridge-saturation in the rotor to explain this phenomenon. Finite element (FE) analyses of six modified PMSM models demonstrate that the bridge-saturation decreases, as the flux linkage begins to increase. That leads to an increase of the differential inductance if the stator iron is not strongly saturated. The impact of the machine geometry parameters on the differential inductance is also studied in this paper by means of a sensitivity analysis.