Two estimation method of sensorless permanent magnet synchronous wotors

In this paper, two methods are introduced to estimate the position and speed of permanent magnet synchronous motors (PMSM). They are based on EMF and MRAS. The first method estimates the back electromotive force (EMF), then calculates rotor position and speed. In the second method, the model of PMSM is reference model and motor current is adjustable model. The derivation process and the simulation result are given, the result shows both of them have their advantages which can be used separately to obtain the unity of rapidity and stability.