Experimental validation of power and torque thruster control

Abstract

Results from laboratory experiments with an electrically driven propeller controlled by three different control systems are presented, showing the advantages of torque and power thruster control over shaft speed control. For fixed pitch propellers, the industrial standard today is shaft speed control based on a static mapping from desired thrust force to desired shaft speed. When the operating conditions change due to vessel motion, waves and current the propeller loading changes. The results are fluctuating thrust production and load torque, which lead to mechanical wear and tear and unpredictable power consumption. This may lead to severe deterioration of the performance of a vessel; the power fluctuations force the operators to have more generators running than necessary, and the mechanical wear and tear lead to vessel down-time due to repairs. Alternatives to shaft speed control are torque and power control, based on static mappings from desired thrust to desired torque and power respectively. This paper demonstrates by experimental results that significant performance improvements can be achieved by changing to torque or power thruster control.

Preliminary Simulation Studies of a New Four-Quadrant Propeller Thrust Controller Applied to Underwater Vehicles

“…The thrust controller performs better that the torque controller because it account for variation in the thrust torque ratio and also it compensates for the shaft moment of inertia. The same conclusion was experimentally found in Smogeli et al (2005) and in Pivano et al (2007). Remark 3.…”

“…Experimental validation of shaft speed and torque control has been presented in Smogeli et al (2005) and in Pivano et al (2007). Both the conventional controllers use the nominal values of the propeller characteristics for J = 0.…”

“…In practice, propeller systems are not usually equipped with thrust and torque sensors therefore thrust losses are not directly measured. As reported in (Smogeli et al 2005), today's industrial standard for fixed pitch propeller is shaft speed control in which the desired shaft speed is computed from the desired thrust through a static mapping. Also torque and power control and combination of those have been developed and implemented (see for example Blanke and Nielsen (1990), Smogeli et al (2005) and Indiveri et al (2006)).…”

A Four-Quadrant Thrust Controller for Marine Propellers with Loss Estimation and Anti-Spin

“…As reported in Smogeli et al [2005], today's industrial standard for fixed pitch propellers is shaft speed control where the desired shaft speed is computed from the desired thrust through a static mapping. Also torque and power control and combination of those have been developed and implemented (see for example Blanke and Nielsen [1990] and Smogeli et al [2005]).…”

“…Also torque and power control and combination of those have been developed and implemented (see for example Blanke and Nielsen [1990] and Smogeli et al [2005]). All the mentioned controllers do not use information about the propeller working condition, i.e.…”