Design and Optimization of an IE44-pole 7.5 kW Induction Motor

Abstract: In this thesis, a High Efficiency (IE2), 7.5 kW, 4-pole, induction motor (IM) is studied and redesigned using finite element method (FEM) software with the purpose of increasing its efficiency to the new Super Premium Efficiency (IE4) level. First, a pre-existing model of the motor is analyzed and improved. Then, different methods to improve the efficiency of the motor are investigated and the performance of the machine is studied after each modification. Thirdly, a complete optimization of the design is carried out with the goal of developing an IE4 IM compatible with IEC standard frames. Finally, a similar optimization of the motor is performed substituting the aluminum squirrel cage by a copper one. The pros and cons of this change are studied. The results show the feasibility of reaching the IE4 efficiency level by this type of IM with a standard shaft height. Preserving the original cross-section design of the stator, this efficiency level is only reached if a copper squirrel cage is used and if the rotor cross-section is redesigned. However, if the external diameter of the stator is increased and the rotor and stator cross-sections are redesigned, aluminum rotor bars and short-circuit rings can be used to reach the IE4 efficiency level.