Permanent magnet synchronous machines particularly, interior magnet type (IPMSM) have been widely used in industries and traction of hybrid and electric vehicle (HEVs, HEVs) applications. Owing to their unique merits due to high efficiency, high power density, fast dynamic response, high torque to inertia ratio and Compactness, they are one of the most competitive candidates for electric vehicle applications. Sensor-less control technique based on observer is one of the most robust and high dynamic performance schemes for IPMSMs. In this study sensor-less vector control back-EMF based method of IPMSMs using observers will be investigated and three popular types of observers, “SMO, LO, EKF”, will be compared to their performance in control system as well as detailed simulation based analyses in terms of high dynamic performance, low and high speed operation, adequate motor parameters variation immunity, power stage distortion immunity, and complexity acceptance by MATLAB/SIMULINK model will be presented.