Abstract:

Induction motors are the most widely used motors in industry and home applications due to their robust structure, cheapness, low maintenance and high efficiency. The torque-speed characteristic, which is one of the most critical parameters of induction motors, is highly influenced by rotor slot structures. Therefore, slot type and slot sizing should be performed properly to maximize motor performance during the design process of the induction motor. Induction motors have more than 30 rotor slot types, and each of these slot types has different advantages and disadvantages. In the design stage of the induction motor, the choice of rotor slot structure as well as other parameters (external dimensions, winding structure, core material selection, etc.) is of great importance, while effects such as torque ripple, acoustic noise and mechanical vibrations should be taken into consideration topics for motor designers. In this study, the effects of torque ripple in induction motors and the changes of torque ripple in different rotor slot structures are investigated. The analyses are performed using Maxwell RMxprt program. Firstly, static motor models were created and analyzed in RMxprt program. Afterwards, 2-D models of the motors are created and analyzes are carried out to obtain torque ripple changes. 7 different slot geometries are used in rotor slot structure. Other parameters of the motor are kept constant. Rotor slot geometry with minimum torque ripple and the best performance criteria are determined from the motor models. A 90 kW, 3-phase, squirrel cage induction motor is used as the motor model.