Transient Analysis Of Induction Motor Based On Time-stepping Finite Element Method Coupled With The Circuit Equations

The transient process of motor is quite complex associated with electromagnetic andmechanical motion. The problem of movement eddy field coupled with electromagnetic isa difficult issue in engineering electromagnetic field at home and abroad. Accuratecalculation of the electrical transient process will be difficult because of the non-linear offerromagnetic material, cogging effect, eddy current set of the skin effect, all kinds ofcurrent harmonic factors. Traditional method based on circuit is too much dependent on thecircuit parameters and its accuracy is not high enough. With the finite element method iswidely used in the electrical field, it has the absolute advantage in terms of the transientcalculation. More in-depth research has been done in this paper against related theory andnumerical algorithms based on the systematic summary of the existing literature.Four key points dealing with the moving transient analysis are elaborated using timestepping finite element method coupled with circuit equations. They are the selection ofcoordinate of moving eddy field, grid sliding coordination algorithms caused by rotorrotation, the establishment of field equations coupled with circuit and the solution methodof the equations of motion on the rotor. Our approach is stator and rotor using differentcoordinate systems respectively just coupling connection through the interpolation movingboundary method on air gap centerline and appropriate loading voltage through field modelcoupled with circuit coupling rotor motion equations indirectly.Then this article gives the two-dimensional field model coupled with circuit equationstaking example for an induction motor. The modeling process is description in detail. Wehave implemented harmonic field calculation through loading rated voltage on the motorand obtained the realistic situation results also verified the validity of the field-circuitcoupling model. The transient simulation of starting from no-load to the stability isimplemented based on a simplified model. Flux density and current density distributionand the stator and rotor current, electromagnetic torque and speed curves versus time canbe obtained. We analyze a variety of phenomenon in the transient startup process. Theseresults will be analyzed and compared with non-sinusoidal supply case. The influencegenerated by voltage source harmonic will be presented. Advantages from controlling withinverter power supply can be effectively utilized for those problems. Therefore somehazards can be reduced.