Subjects for PhD thesis

Note, that those are just keynote topics. The final research objectives will depend on qualification of PhD student and research group needs. Please don't hesitate to contact us.

ELECTROMAGNETIC DESIGN OF SYNCHRONOUS RELUCTANCE MOTOR
The main tasks of the thesis are:

Within this thesis, the PhD candidate will learn about the design and optimization of special types of electrical machines. We will provide the necessary software for the numerical analysis of the machine but the candidate will be responsible for developing and implementing the optimization procedure. At the end of the thesis, a prototype machine will be built and the candidate can participate in this process too. The main tasks of the thesis are:

Primary design of the machine without magnets. A synchronous reluctance machine, without permanent magnet, will be designed. The rotor flux barriers and the windings as well as the geometry of the stator will be the starting point
Secondary design with ferrite magnets (power factor). The power factor of synchronous reluctance machines is known to be low. Improving this power factor can be achieved by additional permanent magnet in the rotor of the machine. The design of this so-called pm-assist machine is challenging and need some computations.
Geometrical optimization. After the two machines have been designed, the candidate will have to optimize the machines through numerical analysis and optimization procedure. The optimization targets are the torque, the torque ripple, and the efficiency.
Material optimization. The geometrical optimization does not account for the material and other cost. To make the machine attractive for industry applications, the manufacturing and material cost has to be accounted for in a hypothetical series production process. This optimization can be achieved if materials databases are available and manufacturing details are explicit. The optimization could be carried out as a multi-objective task.

Within the PhD studies, the candidate will present his/her work in international conferences (funded by the project) and publish journal papers required to complete the thesis.
Contact information:
The theses will be carried out under the supervision of Prof. Anouar Belahcen and Dr. Ants Kallaste. The theses are part of a large research project funded by the Estonian Ministry of Education and Research.

DEVELOPMENT OF CONTROL METHODS FOR SYNCHRONOUS RELUCTANCE MOTOR
The main tasks of the thesis are:

Within this thesis, the PhD candidate will learn about the control and application of special types of electrical machines. We will provide the necessary hardware and software for the real-time control of the machine but the candidate will be responsible for developing and implementing the control algorithm. The main tasks of the thesis are:

Design of loss reduction control algorithms for - Usually the optimization concerns only the motor losses, whereas the converter losses are often neglected. Effective loss reduction strategy will require to consider motor and converter losses. Achieving this objective for the novel permanent magnet assisted reluctance machine could help to improve existing control strategies.
Real-time simulation. - Design control algorithms, vision, or plant model in MATLAB/SIMULINK. -Build a real-time application from MATLAB/SIMULINK to the target machine. -Set-up and tune signal parameters from within MATLAB/SIMULINK during real-time execution
Practical tests on the test bench. The test bench, combining advantages of real-time software models and real equipment, contributes to the reduction of the number of test runs and safe maintenance. Test benches cover many different areas like energy management, optimal configuration, combination of different energy sources, etc. Research goals will be achieved by proper verification of the model.

Within the PhD studies, the candidate will present his/her work in international conferences (funded by the project) and publish journal papers required to complete the thesis.

Contact information:
The theses will be carried out under the supervision of Dr. Anton Rassõlkin and Dr. Toomas Vaimann. The theses are part of a large research project funded by the Estonian Ministry of Education and Research.

IMPLEMENTATION POSSIBILITIES FOR INVERSE PROBLEM THEORY IN FAULT DETECTION OF ELECTRICAL MACHINES

possible to detect the faults in such stage, when repairing of the machines is still possible or reasonable.
In the usual diagnosis problems, the emphasis is put on the signal processing in view of extracting useful data from the global quantities, usually the machine current. If more information about the fault is needed, a physical model of the machine is usually constructed and the fault is simulated to extract the local data. This is a forward problem, where the cause is the fault and the consequences are the distortions in the local quantities. The effect of these distortions on the global quantities is usually also sought from these forward simulations through either analytical or experimental procedure.
In the proposed thesis, physical models of the electrical machines based on their numerical analysis (Finite Element Method) are to be develop and then used to derive an inverse problem and solve it. The inverse problem consists of the reconstruction of the local quantities from the global ones. It is however clear that this problem is ill-posed in the sense that it has more than one solution. The essence of the thesis is thus to find out how to deal with this ill-posed problem and find enough global information to solve it.
Within this thesis, the PhD candidate will learn about the diagnostics and fault detection of electrical machines. At the end of the thesis, a novel approach for implementing inverse problem theory in the diagnostics of electrical machines will be developed.

The main tasks of the thesis are:

Inverse problem theory. A comprehensive theoretical background of inverse problem theory and implementation possibilities in fault detection of electrical machines
Physical model of the machine. A number of different fault types and severity levels can be chosen to be used for further analysis. Finite element model of an induction machine that can be used in the solution of the inverse problem will be built
Inverse problem model. Strategies to solve the inverse problem. Finally finding a working strategy to solve the inverse problem even in case it is ill-posed
Signal processing and verification. A signal analysis method altogether with the quantities to be analyzed. Verified reconstruction of the local quantities from the global ones

Within the PhD studies, the candidate will present his/her work in international conferences (funded by the project) and publish journal papers required to complete the thesis.
Contact information:
The theses will be carried out under the supervision of Prof. Anouar Belahcen (anouar.belahcen@aalto.fi) and Dr. Toomas Vaimann. The theses are part of a large research project funded by the Estonian Ministry of Education and Research.