Rotor speed and position sensorless control of a switched reluctance motor using the binary observer

The rotor speed and position control of a switched reluctance motor (SRM) need an encoder or resolver to obtain information about the rotor position because rotation of the SRM is achieved by switching on the phases of the SRM in sequence, which depends on the direction of rotation. These position sensors can be affected by EMI (electromagnetic interference), dust and high temperature surroundings. Several approaches have been proposed to achieve sensorless speed and position control of the SRM. A binary observer of the SRM which has two feedback loops to estimate the rotor speed of the SRM is proposed. One reduces the estimation error directly like the sliding mode observer, and the other indirectly removes the chattering of the estimation error in the rotor speed and position which occurs in the sliding mode observer. The proposed observer is constructed on the basis of variable structure control theory and has inertial terms to exclude chattering. It has good estimation performance without the chattering of the estimation error in the rotor speed and position. The proposed observer also shows the robustness of the parameter variations and disturbances. The advantages of the proposed method are verified experimentally