Propulsion motor vector control based on ILC for dynamic positioning system

Speed sensorless vector control based on ILC of dynamic positioning system propulsion motor for semi-submersible ship is proposed for the problem of speed fluctuation of the semi-submersible ship propulsion motor which is caused by the external sea conditions and the unknown load disturbances. The speed error compensation is introduced in the algorithm, and the periodic torque ripple of the propulsion motor is reduced by utilizing the error trend and the previous error information. The results show that the speed sensorless vector control based on ILC can effectively suppress the torque ripple of the semi-submersible ship propulsion motor and improve the state observation accuracy of the system. It satisfies the steady-state error requirement of the semi-submersible ship propulsion system and the reliability of the system was improved through comparing with the vector control algorithm based on the classical PI control.