Torque Ripple Investigation in Squirrel Cage Induction Machines

Low torque ripple of electrical machines is an important requirement for many different applications. The causes of torque fluctuations in squirrel cage asynchronous induction motors might be a challenging task due to the complex phenomena raised by the whole set of rotor bars. This paper proposes an accurate analysis of the torque contributions distinguishing in time-varying, synchronous and asynchronous components. The investigation is performed by adopting a general analytical approach based on a circuital modelling technique for electromagnetic devices. The analysis aims to identify spatial harmonic interactions between stator and rotor magneto-motive forces which generate torque components. The most interesting effects obtained from the analytical investigation are compared and validated against finite element results for the most significant operating points.