Master of Science in Electrical Engineering (MSEE)


Electrical and Computer Engineering

Document Type



Among brushless permanent magnet machines, the torus motors (also called Axial Flux Double-Rotor Permanent Magnet (AFTR PM) motors) are most compact and highly efficient. A cylindrical counterpart of this motor is a newly proposed Radial Flux Double-Rotor Permanent Magnet (RFTR PM) motor. The objectives of this thesis are to optimize the magnetic circuit of both AFTR PM and RFTR PM motors and to compare their electromechanical parameters on the basis of the results obtained from magnetic field simulation using Finite Element Method (FEM). To reach these objectives, FEM models are developed for both the motors, for particular given data. Applying the magnetic field simulation with the help of FEMM 4.0 software package, optimized stator and rotor core dimensions were determined as well as electromechanical parameters such as electromechanical torque, electromotive force, resistance and inductance of the stator windings. Next, the efficiency and torque to volume ratio along with the torque to mass ratio were calculated. Comparing the parameters of both motors, the following conclusions are obtained: • Both slot-less motors developed electromagnetic torque with very low torque ripple contents. • The torque to mass ratio of RFTR PM motor is almost equal to the torque per mass of AFTR PM machine. • AFTR PM motor is more compact than its cylindrical counterpart because its torque to volume ratio is higher. • The efficiency of RFTR PM motor is relatively higher than that of AFTR PM motor, particularly if multi disc motor is considered, mainly due to the smaller percentage of end connection in the entire volume of the winding.



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Committee Chair

Ernest A. Mendrela