Hybrid Observer for Sensorless Permanent Magnet Synchronous Machine Control for Wind Energy Generation

This paper presents the design of a disturbance observer used for estimating the electromotive force of a surface mount permanent magnet synchronous machine. The proposed observer combines the linear advantages of a Luenberger observer and the non-linear advantages of a sliding mode observer. In addition, the use of low-pass filters is avoided since the discontinuous function of the observer is replaced by the continuous sigmoid function without affecting its performance. Because the internal electromotive force contains the information on the position and speed of the motor used, its estimation is digitally process in order to obtain the position and speed of the motor. These position and speed estimates are used in a vector control scheme, where the need for the mechanical position/ speed sensor is eliminated. However, the electromotive force is Iinearly dependent on the speed of the motor, making it difficult to detect at zero and low speeds. Therefore, the proposed observer is useful only at medium and high speeds. Various simulations are carried out in MATLAB/ Simulink where the correct performance of the proposed observer is shown. Finally, the results obtained are analyzed and discussed.