Improving a model of the induction traction motor operation involving non-symmetric stator windings

Abstract

The analysis of operating conditions of induction traction motors as part of traction electric drives of electric locomotives reported here has revealed that they are powered by autonomous voltage inverters with asymmetric non-sinusoidal voltage. It was established that the induction motor operation may be accompanied by defects caused by the asymmetrical modes of the motor stator. A model of the induction motor has been proposed that takes into consideration changes in the values of mutual inductance of phases and complete inductance of the magnetization circuit due to changes in the geometric dimensions of the winding caused by a certain defect. An algorithm that considers the saturation of the magnetic circuit of the electric motor has been proposed. This approach to modeling an induction motor is important because if one of the stator's windings is damaged, its geometry changes. This leads to a change in the mutual inductance of phases and the complete inductance of the magnetization circuit. Existing approaches to modeling an induction motor do not make it possible to fully take into consideration these changes. The result of modeling is the determined starting characteristics for an intact and damaged engine. The comparison of modeling results for an intact engine with specifications has shown that the error in determining the controlled parameters did not exceed 5 %. The modeling results for the damaged engine demonstrated that the nature of change in the controlled parameters did not contradict the results reported by other authors. The discrepancy in determining the degree of change in the controlled parameters did not exceed 10 %. That indicates a high reliability of the modeling results. The proposed model of an induction electric motor could be used to investigate electromagnetic processes occurring in an electric motor during its operation as part of the traction drive of electric locomotives

Method for Determining the Degree of Damage to the Stator Windings of an Induction Electric Motor with an Asymmetric Power System

“…The studies were carried out for a squirrel-cage induction motor for a simulation model made in the MATLab software environment, the principles of which are given in [32], and the implementation is in [33]. The choice of the model is due to the establishment of the adequacy of its operation both for asymmetric modes of the stator windings as a result of damage, and for the asymmetry of the supply voltage system.…”

“…On the basis of works [35][36][37], the simulation of the Park transform block was performed. The simulation model of an induction motor [33] was supplemented with a Park transformation block.…”

“…The technical characteristics of the AIR132M4 electric motor are given in Table 1 [23]. The values of the remaining parameters required for the organization of asymmetric regimes were obtained automatically using a simulation model [33]. In a real induction machine, phase currents and voltages are described in three-phase ABC coordinates.…”

“…The values of the remaining parameters required for the organization of asymmetri regimes were obtained automatically using a simulation model [33].…”

“…For research, the original simulation model of an induction motor [33] was supplemented with "Block for determining the coordinates of the Park vector" (Figure 2).…”