Development And Design Of PMSM Control Systems For Autonomous Underwater Vehicles

Underwater vehicle propulsion is usually performed exploiting hydraulic or electrically operated propellers and hydraulic or electrically operated ducted jet propulsors. Electrical motor propulsion is in general the most flexible solution and it is growing in popularity because of its high efficiency both at high and low advance speed, quick and simple deployment, low costs and encumbrance. In the present work, the advantages of Permanent Magnet Synchronous Motors (PMSM) for underwater propulsion are highlighted. In particular sensorless control of PMSM permits reduced costs high reliability and performances. As a test case, the development of the MARTA AUV propulsion system has been developed. It is an Observation Class AUV for subsea archeology purposes. Several motor control techniques are presented with the relative test results. In particular, the author focused the research in the development of a technique able to perform a reliable rotational speed and torque estimation. This indeed would permit the exploitation of a vehicle dynamic model for the navigation algorithm. Pool and field tests for the identification of the dynamic parameters of the vehicle and of the propellers are presented. Finally, an off-line preliminary validation of a navigation algorithms based on a dynamic model is presented with encouraging results. In particular, the possibility to operate a position estimation of the vehicle less dependent on the on board sensors was highlighted. This involves obvious benefits in terms of cost reduction and reliability of the system.