Electric Steering Gear Dynamics of Azimuth Thrusters
Tamminen, Teemu (2021)
2021
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2021-04-28
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202104263489
https://urn.fi/URN:NBN:fi:tuni-202104263489
Tiivistelmä
Purpose of this thesis is to compare induction machine and permanent magnet machine performances in azimuth thrusters steering gear. To achieve this purpose, the simulation model of azimuth thruster’s electric steering gear is created in Simulink. Simulink’s usability for steering gear simulation is evaluated. Possible further use for simulation models are considered when evaluation is made.
International regulations and classification societies set limits and performance requirements for azimuth thrusters. In this work, the DNV GL rules are used as a basis for determining the boundary conditions for simulated situations. DNV GL defines minimum permissible turning speed for the azimuth thrusters and requires dimensioning the steering motors be for continuous operation.
The electric steering gear of azimuth thrusters consists of electric motors, frequency converters and mechanical gears between the electric motor and the steering gear of the azimuth thruster. The electric motor in the steering gear of azimuth thruster operates at zero speed while holding the azimuth thruster at the desired angle. The electric motors are mostly accelerating or decelerating when azimuth thruster’s steering angle is altered. Steering motors are rarely operating at steady state with speed close to motor’s nominal speed.
The results of the work show that replacing the induction machine with a permanent magnet machine reduces the power consumption of the steering gear. This is due to the better efficiency of the permanent magnet machine, especially at low speeds, as well as the lower moment of inertia compared to the induction machine. A permanent magnet machine requires better protection against faults than an induction machine because a voltage is induced in the windings of the permanent magnet machine as the motor rotates without current supplied by the frequency converter.
By further developing the simulation model, it is also possible to simulate the most common fault conditions, see their effects, and facilitate the determination of the cause of the fault. This reduces the time required to locate the fault and the cost of repairing it. To achieve proper fault simulation the drive model needs to be developed into a model that can simulate the internal protection of the drive. This is the largest single development target for the further use of the simulation model.
The originality of this thesis has been checked using the Turnitin OriginalityCheck service.
International regulations and classification societies set limits and performance requirements for azimuth thrusters. In this work, the DNV GL rules are used as a basis for determining the boundary conditions for simulated situations. DNV GL defines minimum permissible turning speed for the azimuth thrusters and requires dimensioning the steering motors be for continuous operation.
The electric steering gear of azimuth thrusters consists of electric motors, frequency converters and mechanical gears between the electric motor and the steering gear of the azimuth thruster. The electric motor in the steering gear of azimuth thruster operates at zero speed while holding the azimuth thruster at the desired angle. The electric motors are mostly accelerating or decelerating when azimuth thruster’s steering angle is altered. Steering motors are rarely operating at steady state with speed close to motor’s nominal speed.
The results of the work show that replacing the induction machine with a permanent magnet machine reduces the power consumption of the steering gear. This is due to the better efficiency of the permanent magnet machine, especially at low speeds, as well as the lower moment of inertia compared to the induction machine. A permanent magnet machine requires better protection against faults than an induction machine because a voltage is induced in the windings of the permanent magnet machine as the motor rotates without current supplied by the frequency converter.
By further developing the simulation model, it is also possible to simulate the most common fault conditions, see their effects, and facilitate the determination of the cause of the fault. This reduces the time required to locate the fault and the cost of repairing it. To achieve proper fault simulation the drive model needs to be developed into a model that can simulate the internal protection of the drive. This is the largest single development target for the further use of the simulation model.
The originality of this thesis has been checked using the Turnitin OriginalityCheck service.