A Whole Speed Range Sensorless Method for SPMSM Drive

In order to achieve sensorless control of Surface Permanent Magnet Synchronous Motor (SPMSM) in the whole speed range, a hybrid observer that can accurately obtain rotor speed and position information in the whole speed range proposed. In the zero-low speed range, a pulsating high-frequency (HF) signal injection algorithm is used to obtain more accurate rotor information; in the medium-high speed range, an improved sliding mode observer (ISMO) based on a new sliding mode reaching law is proposed to estimate the back electro-motive force (EMF), and an improved phase-locked loop (PLL) based on the extended state observer (ESO) to estimate the motor rotor speed and position. Both the position and speed estimation is greatly improved compared with the traditional SMO and the PLL. At the same time, in order to achieve smooth switching between medium-high speed and zero-low speed, this paper adopts a weighted algorithm control strategy to eliminate the chattering caused by direct switching. The simulation results demonstrate the reliability and effectiveness of sensorless control strategy raised in this paper in the whole speed range.