Sensorless Speed and Position Identification of Rim Electromagnetic Direct-Driven Propeller Based on Sliding-Mode Observer

Rim electromagnetic direct-driven propeller (REDP) is a propeller used in the underwater vehicle. It has many merits compared with the traditional propeller. It is difficult to utilize the sensor to get the rotor position and speed that are important to control REDP. An observer based on sliding mode method was proposed to estimate the rotor position and speed in the paper. Its stability was proved and some parameters were obtained. The influence of the switching function on the observation performance was analyzed and the sigmoid function was chosen as the switching function of the sliding mode observer. Then the observation position and speed were analyzed under different parameters to get the better observation performance. Finally, the experiment verified the feasibility of sliding mode observer.