Sensorless control of a stand-alone Doubly fed induction machine for ship shaft generator systems

This paper presents a position sensorless control strategy of stand-alone doubly fed induction machine (DFIM) used for ship shaft generation systems. Direct voltage control method is used to generate constant frequency and voltage with variable load and main engine speed. The strategy does not need any signal from speed, so the position encoder or estimators are unnecessary. The space vector pulse width modulation (SVPWM) technique is used to reduce the rotor current harmonics and the modification of the reference stator vector angle is applied to achieving the reference stator voltage quickly and successfully. Simulation results are given to illustrate the efficacy of the proposed method.