Efficient Electromagnetic-Field and Electric-Circuit Coupled Time-Stepping Finite Element Analysis for Modelling of Solid-Rotor Induction Machines

The accurate modelling of solid-rotor induction machines by electromagnetic-field and electric-circuit coupled finite element analysis (FEA) is a very time-consuming task, because induced eddy currents on the rotor surface will create strong magnetic fields to oppose the stator flux further penetrating into the rotor, which finally cause a long electromagnetic transient during the FEA. The aim of this paper is to reduce the simulation time in order to numerically reach the steady state more quickly in FEA for solid-rotor induction machines. To implement the efficient algorithm, an in-house dedicated electromagnetic-field and electric-circuit coupled time-stepping transient solver has been developed. The solver is further integrated with the flux linkage maintaining and locked-rotor methods. The former method is performed by injecting additional voltage signals in the voltage supply estimated from the flux linkage feedbacks during the transient, which can help to significantly eliminate the transient flux linkage during the simulation. The latter approach helps to further mitigate the transient in the rotor circuit. Finally, the steady state is achieved within one and a half electrical time period. The proposed efficient computation method proves to have the advantages of easy implementation, high accuracy, and significant speed boost.