Jae-seung Yoon, “영구자석 동기전동기의 향상된 센서리스 제어 알고리즘 연구,” 아주대학교 공학박사 학위 논문, 2017. > Paper

This thesis proposes an improved sensorless control method to estimate the rotor position of an permanent magnet synchronous

motor. The rotor position can be estimated using a phase-locked loop (PLL) based on extended electromotive force(EEMF) because 

the EEMF contains information of rotor position. In order to operate the permanent magnet synchronous motor, a current controller 

can be used for the initial operation and after that, the controlling method of the permanent magnet synchronous motor is changed 

to a method for using a speed controller for the sensorless control. At the time of changing the controlling method, the rotor speed 

overshoot is generated due to a rapid change of the controlling method and increased calculation amount of the speed controller. 

The proposed. The proposed algorithm is able to reduce the overshoot of a rotor speed by compensating the estimated feedforward 

value to the current component of the speed controller. Additionally, this thesis proposes the full-dimensional flux observer algorithm 

which shows improved performance in both low and high velocity regions. The existing full-dimensional flux observer tends to show 

decrease in estimation performance due to the angular speed value included in the denominator of the gaining numerical formula of 

the observer. The proposed full-dimensional flux observer makes the angular speed value of the denominator to a constant value, 

applies it as the optimal value according to the velocity region and therefore improves the weakness of the existing full-dimensional 

flux observer. The optimal constant value is the constant value in which the difference between the estimated angle and the actual 

angle is minimized, and this value is accurately verified through simulation and experimental procedures. The performance of the 

proposed algorithm, its excellence and validity shall be verified through the simulation and experiment results.