Sensorless operation of SRM drives from starting to steady state

It is known that control strategies for most electrical machines are derived based on machine parameters, which are constant for most of the excitation range. However, due to the salient pole nature of Switched Reluctance Motor (SRM), the machine inductance is not only a function of the rotor angle but also is a function of the excitation current. This complicates the development of control strategies for such drive systems. The position information requirement is a limitation of SRM. The shaft position sensors are normally used for this purpose. These sensors reduce the reliability of the drive. Efforts are on to replace the position sensor with suitable estimation technique. In this paper, an overview of the different existing sensorless starting methods and their shortcomings are explained and finally, a starting method is proposed. Also this paper presents a method of position estimation for SRM. The method is suitable from starting to full speed. It ensures smooth starting without initial hesitation.