Sensorless Control of Underwater Propulsion PMSM Based on Parameter Identification

In the operation of an underwater propeller, parameters of the permanent magnet synchronous motor(PMSM), such as stator resistance and inductance, are changed based on the temperature and current, resulting in a large error of the rotor position and speed, which are estimated by a sensorless control algorithm. In this paper, a sensorless control method is proposed to control an underwater propeller based on the Luenberger observer combined with parameter identification. In this method, based on a double closed-loop vector control strategy, recurrence least square(RLS) combined with a forgetting factor is adopted as an online parameter identification algorithm to evaluate the stator resistance and motor inductance. The initial resistance and inductance parameters in the Luenberger observer model are thereafter replaced using the same algorithm. The back electromotive force estimated through the Luenberger observer is used as the input of the phase-locked loop. Finally, the position and speed of the rotor are obtained from the output of the phase-locked loop. The simulation results show that the rotor position and speed can be rapidly and accurately identified by Luenberger observer when this parameter identification technique, which reduces the sensitivity of motor parameters on sensorless control system, is used.