Traction motors and speed estimation techniques for sensorless control of electric vehicles: A review

Application of electric motor plays an important role in the evolution of electrification transport industry. The electric propulsion system is an integral part of Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs). Desired performance contribution of electric motors are not only limited in different kinds of domestic and industrial automation processes but also has a great deal of importance in the field of electrification of vehicles. This paper presents the major types of traction motors and summarizes the key features with respect to the EV application, since the characteristics of traction motor influences the required control method. Then the discussion on different control techniques which are being applied on traction motor drive to make it much more efficient and reliable. One of the main concerns of this paper is on different speed sensorless control techniques require to achieve better dynamic performance from the drive. These techniques are mainly classified into two major categories based on fundamental machine model and Signal Injection (SI) methods. Performance deterioration and poor observability of the estimator are focused at low speed and zero speed regions. Comparison between both methods is presented with respect to the speed tracking performance of the speed estimator in order to get both better static as well as dynamic performance.