Proposal of Q-axis Inductance-Free Position Estimator and Its Application to Position Sensorless Control

Generally, position sensorless control in the medium-to-high speed region is achieved by estimating the phase of the Electromotive Force (EMF) or the Flux. However, these methods are significantly affected by variations in the q-axis inductance, and we have been studying countermeasures to address this issue to date. In this paper, we propose an alternative position estimation method that relies on d-axis inductance and magnetic flux, without depending on q-axis inductance, to achieve robust position sensorless control. The proposed method estimates the d- and q-axes without dependence on q-axis inductance, which distinguishes it from conventional approaches. Finally, the experimental results demonstrate the effectiveness of the proposed method in achieving the position sensorless control under variations in torque, speed, and q-axis inductance.