A BEMF Harmonic-Extended State γδ-Axes Observer for PMSM Sensorless Control Reducing Structural Redundancy

Abstract

The drive system of permanent magnet synchronous motors (PMSMs) is sensitive to harmonic disturbance, thereby degrading the control precision of the sensorless control system. However, conventional observers face difficulties in properly reducing harmonics due to their restricted controllability. To alleviate this problem, this article proposes a back-electromotive force (BEMF) harmonic-extended state observer. First, compared to the αβ-axes-based observer, the investigated observer is built based on the estimated dq-axes to attain greater harmonic attenuation in terms of total low-pass characteristic. Then, different BEMF harmonic components are extended as state variables in the γδ-axes model. The reduced-order generalized integrator (ROGI) is added to the studied observer to achieve the separation of estimated BEMF harmonic components and dc components. With the local linearization technique, the position estimation closed-loop system is derived, which is used in stability analysis as well as the derivation of parameter tuning rules. The proposed algorithm is validated by the experiments conducted on a 2.2-kW PMSM platform.