Analysis and force computations of single-phase permanent-capacitor induction motors using FEM at broken bar conditions

Single-phase permanent-capacitor induction motor is studied in this paper using a model based on inductances calculated by finite elements method (FEM). The effects of rotor broken bars on rotor bar currents, motor torque and motor speed are investigated. The radial and tangential forces on the rotor bars are calculated at healthy and broken bar conditions. It is found that the rotor broken bars faults will lead to nonuniform radial and tangential forces. These non-uniform radial forces will increase the mechanical stresses on the rotor shaft which may lead to bearings failure or eccentricity. This paper also introduces a simple method for rotor broken bars faults detection that depends on the trajectory of the main and auxiliary currents of the motor.