Dual Position Offset Injection Based Multi-Parameter Decoupled Estimation of PMSM Considering Signal Injection Induced Inductance Variation

This paper presents a dual position offset injection based multi-parameter decoupled estimation approach for estimating PM flux linkage and inductances of permanent magnet synchronous machines (PMSMs). Through positive and negative position offset injection, the decoupled estimation models are established to achieve independent estimation of the inductance and PM flux linkage with improved accuracy. Moreover, the position offset injection could cause the slight change of the inductance due to magnetic saturation, which is neglected in existing methods. This paper considers this effect by modeling the slight inductance change using a linear model, which can effectively improve the estimation accuracy. In the proposed approach, PM flux linkage and inductance estimation are decoupled in the estimation model to improve the accuracy of inductance estimation. Moreover, PM flux linkage variation due to saturation can also be estimated, which is modeled as a nonlinear function with respect to the stator currents. The winding resistance and inverter distortion are modeled and cancelled in the estimation model to reduce the influence from winding temperature rise and inverter distortion. The proposed approach is verified on a laboratory motor drive and compared with existing methods under various operating conditions.