Analysis of Position Control Stability Affected by Non-ideal Characteristics of IPMSM in Signal-Injection Sensorless Control

Abstract

In this paper, the stability of position control loop under signal-injection sensorless control (SISC) considering the non-ideal characteristics of IPMSMs has been analyzed. To take into account the effects of the torque ripple and the inductance variation due to the non-ideal characteristics in frequency-domain analysis, they are linearized using Taylor series at each rotor position and operating current. Using the small signal model, it is revealed that the non-ideal characteristics make the system unstable and cause oscillation under position control with SISC. It is also revealed that the stability varies according to the rotor position and load torque even if the same controller gains are used. The validity of the proposed analysis is verified through simulations and experiments.