Sensorless control of IPMSM using rotor flux observer.

Purpose – The aim of this paper is to present a new sensorless control strategy using a flux observer, which is particularly designed for taking into account the rotor saliency and winding inductance variation in an interior permanent magnet synchronous motor (IPMSM). Design/methodology/approach – In a PMSM, the magnets-excited flux-linkage, i.e. the rotor flux-linkage, can be expressed as a vector. Its phase angle stands for the rotor position. Therefore, if this vector is estimated with an observer, the rotor position can be obtained without a position sensor, consequently, sensorless control can be realized. The main object of this paper is to establish and implement a model of rotor flux observer, specifically for IPMSM. Findings – The flux observer model is built on the d-q-0 frame, using unequal values of the d-axis inductance Ld and q-axis inductance Lq to represent the IPMSM rotor saliency. Its digital implementation is proposed, whilst the sensorless control strategy is experimentally verified. Research limitations/implications – Insignificant error exists in the estimated rotor position, probably due to the non-sinusoidal variation of winding inductance. Further improvement of the observer model is preferable. Originality/value – In previous works, the rotor flux observer is only applied to surface-mounted permanent magnet synchronous motors (SPMSM) in which the winding inductance is constant. However, the proposed observer can deal with the rotor saliency and inductance variation in IPMSM, whilst its digital implementation is also new. [ABSTRACT FROM AUTHOR]