Analysis and diagnosis of broken rotor bars in induction motors based on maxwell

In this paper, a complete mathematical analysis of broken rotor bars based on the revolving-field theory is presented in the first place. Particularly, rotor speed oscillation, neglected by many previous researches, is underlined which can largely change the fault characteristics in torque, speed and stator currents. Next, a faulty model is established in Ansoft Maxwell 2D software using finite element analysis method. Comparing the simulation results of a fixed-speed model with the ones at a changeable speed, the effects of speed oscillation is evidenced. In the end, a few more simulations are carried out to study the fault characteristics under different fault degrees. As expected, fault characteristics become more obvious with the increase of adjacent broken number. Furthermore, several new characteristics such as the reduction of average rotor speed are found in the simulation results, which can be seen as new bases for fault diagnosis.