Romashykhina Z. Diagnostic of the induction motor rotor bar breaks on the basis of the electromotive force analysis

The object of research - the electromagnetic processes in the induction motor with damaged rotor bars; The aim is to improve the efficiency of diagnosis damage rotor bars of induction motors by analyzing the signal of the electromotive force in the stator windings in the coasting mode, using wavelet-transform and decomposition of signals on the basis of the theory of the inverse z-transform; research methods are based on the theory of electrical machines, methods of numerical solution of the equations of the electromagnetic field using finite element method, spectral analysis, wavelet transform theory of inverse z-transform, approximation methods, mathematical modeling and experimental investigations; Theoretical results: first developed methods for diagnosis of rotor bars induction motors based on analysis of the signal of the electromotive force in the stator windings suggestive damped currents in the rotor coasting mode, which, unlike other methods, the influence of quality devoid supply voltage fluctuations and load level and allows to determine the damage to rotor bars without removing the engine from the process, dismantling and incorporation in the design of an induction motor of additional sensors; method first developed by the decomposition of the signal phase of the electromotive force of the stator winding of the asynchronous motor signals electromotive forces active side winding coils using the theory of inverse z-transform, which in contrast to the method of analysis of the electromotive force of the winding phase, improves the reliability of rotor bars fault diagnosis of induction motors by allocation information features present in the signal of the electromotive force of one active coil side; further developed diagnostic methods damage rotor bars of induction motors in the parameters of the electromagnetic field, which, in contrast to the methods based on spectral analysis allows, by use of wavelet transform to determine the number and positioning of the damaged rotor bars. Practical results - proposed method of calculation of the electromagnetic field in a cross section of an induction motor using a mathematical model based on the finite element method, which allows you to assess the impact of damage to the rotor bars signal electromotive force of one active side of the coil, the coil, the coil group and phase stator winding in coasting mode engine, which may be used as a software of previous studies the diagnostic object; developed a software module for the automated calculation of the electromagnetic field in a cross section of the induction motor in coasting mode, which is used in the study of the work of induction motors damaged rotor bars in static and dynamic operation modes; The software for the implementation of the measurement of the instantaneous values of voltage and current; developed industrial design of the measuring system and the laboratory stand for research of methods of diagnosis of induction motors.