Research On The Radial And Axial Magnetic Feature For Induction Motors Bearing Fault

Induction motors are widely used in various fields in domestic product because of its simple manufacturing process and good working performance According to statistics, bearing fault accounted for about41%of the induction motor fault. So the safety inspection of bearing is extremely important.The paper aims to do research on the radial and axial magnetic feature for induction motors when the bearings are fault. At first, the magnetic feature frequency when the bearings are fault for ideal induction motor, when the motor is with dynamic and static eccentric and when the bearings are fault for induction motor with dynamic and static eccentric are studied. The three conditions above will lead to the change of the air gap length which will make the change of permeability coefficient, then, the magnetic feature frequency related to the three conditions above can be obtained. Similarly, axial magnetic feature when the bearings are fault for ideal induction motor and when the bearings are fault for induction motor with dynamic and static eccentric are studied as well. Then, because the permeability coefficient is closely related to the motor inductance and bearing fault will lead to the change of the permeability coefficient which will make the change of the motor inductance. So the multi loop method is used to do the theoretical derivation of a single coil inductance as well as the three-phase induction motor inductance and the periodic change expression when the bearings are fault for ideal induction motor, when the motor is with dynamic and static eccentric and when the bearings are fault for induction motor with dynamic and static eccentric are obtained, then the specific value of the inductance related to the three conditions above are calculated according to the actual laboratory motor parametersThen the simulation model of the induction motor with bearing fault is set up using the Matlab/Simulink, the simulation when the bearings are fault for ideal induction motor, when the motor is with dynamic and static eccentric and when the bearings are fault for induction motor with dynamic and static eccentric are done By changing the parameters of inductance. Stator current data can be obtained according to the simulation, then the Welch method is used to analyze stator current spectrum which gets the results that magnetic feature frequency is same with the theoretical derivation. At last, a detection platform of induction motor bearing fault is set up which is used to acquire the stator current data of the induction motor when the bearings are fault, then Welch method is used to analyze stator current spectrum. It is concluded that the feature frequency of stator current is consistent with the theoretical derivation and simulation research which verify the correctness of the theoretical derivation and simulation research.