A Novel Method for Estimating the High Frequency Incremental DQ-Axis and Cross-Coupling Inductances in Interior Permanent Magnet Synchronous Machines

This article proposes a novel method for estimating the high-frequency (HF) incremental dq-axis and cross-coupling inductances of interior permanent magnet synchronous machines based on both the HF rotating and pulsating voltage injection techniques. It mainly includes three HF voltage injection stages, i.e., a HF rotating voltage injection in the stationary reference frame, and a pulsating voltage injection in the d-axis and a pulsating voltage injection in the q-axis of the synchronous rotating reference frame. Compared with conventional estimation methods which either use only rotating voltage injection, or use only pulsating voltage injections in the dq-axes, the proposed method neither requires the closed-loop position estimator to obtain the offset angle caused by the cross-coupling effect nor is sensitive to the delay effects caused by digital filters and voltage synthesis. The estimated results obtained by the proposed method show a good agreement with those by finite element analysis and are also compared with those obtained by the conventional methods.