Since accurate rotor position information is essential for proper switching operation, an expensive position sensor is required. In general, encoders and resolvers, which are rotor position sensors, are used to generate rotational force by exciting the appropriate stator winding according to the rotor position. However, for high-resolution position detection, the cost of the motor and system including the position sensor may be increased, and the reliability of the motor may be reduced in a poor environment. Accordingly, the application as an industrial motor has been limited in terms of price. Therefore, in order to reduce the cost of motors and systems, low-cost encoders or sensorless techniques are adopted. As a result, in order to drive the SRM, control according to the rotor position information must be basically performed, so it is important to design the SRM driving system according to the environment in consideration of the applied fi eld. Therefore, in this paper, we study a method of obtaining rotor position information by applying low-cost cost, moving away from the general control system using the conventional encoder and resolver. We propose a method to determine the excitation point of each phase by attaching an optical sensor with a light-emitting part and a light-receiving part to the periphery of the stator and using the protrusion of the rotor. Unlike the aforementioned high resolution encoders and resolvers, this method cannot accurately control speed, but it can be easily applied to fi elds requiring low performance and system cost to drive and control SRM.