Marcin Wolkiewicz

On-line neural network-based stator fault diagnosis system of the converter-fed induction motor drive

This paper deals with the incipient stator-winding fault detection of the converter-fed induction motor drive. The fault level is modeled by change of a number of shorted stator-winding turns. The method based on a relative phase shift between the phase voltages and line currents of the converter-fed induction motor is used for the on-line fault monitoring and diagnosis. The fault indicators obtained for different load torque and supply frequency conditions for the drive system are used for neural network training. The on-line diagnosis system based on such neural detector is described and tested. Obtained experimental results show very good efficiency of the neural detector, which enables not only fault level evaluation (number of shorted turns) but also fault localization under drive system operation.

Incipient stator fault detector based on neural networks end symmetrical components analysis for induction motor drives

In this paper a computer system for monitoring and diagnostics of the stator windings of the induction motor fed from the frequencies converter is presented. A possibility of stator faults detection using a neural-network detector, possibly at the early stage of the damage, is checked. The experimental research was carried out for a small power induction motor, with different levels of the stator failures (special motor design allowed to test short circuits in each phase of the motor), load torque and converter frequencies. The measurement of stator phase currents, phase-to-phase voltages and their transformation to symmetrical components are used in stator winding condition monitoring. For diagnostic purposes, the Multi-Layer Perceptron (MLP) neural detectors are developed. Preliminary research of the neural network response (offline) showed that the neural networks with simple internal structure, used for the fault level detection, give satisfactory results, that is very important in practical realization. The designed detector was implemented in LabVIEW and tested during the operation of the machine (online).

Analysis of inter-turn fault symptoms for the converter-fed induction motor based on the phase-shift calculation

In this paper a stator fault detection method based on monitoring of the phase shift between the line currents and phase voltages of the converter-fed induction motor is presented. The phase shift analysis is used as an indicator of the stator-fault-progression level. The mathematical model of induction motor, which includes the stator-winding fault is presented. The fault level is modeled by change of a number of shorted stator-winding turns. Next the new fault indicator is introduced. Comparison of simulation and experimental results of the converter-fed induction motor for different number of shorted turns and different load torque conditions is shown. Proper fault severity is obtained with the proposed fault indicator.

Converter-fed induction motor diagnosis using instantaneous electromagnetic torque and power signals

This paper deals with the problem of the early stator (the short-circuits) and rotor (broken bars) faults detection of the induction motors supplied from the frequency converter. The method basing on the FFT algorithm is used for the spectral analysis of the instantaneous active power, the instantaneous reactive power and the estimated electromagnetic torque. These signals are on-line calculated, basing on the measured currents and voltages of the motor. Computations of the instantaneous active and reactive power use the theory of the electric power for non-sinusoidal power systems. In this paper results of laboratory investigations for low power motor with modeled stator short-circuit and broken rotor bars are demonstrated. Tests were realized for different supply frequencies, what enabled the evaluating of the usefulness of the proposed analysis in the diagnostics of the stator and rotor faults in the converter-fed induction motor drives.

Stator fault monitoring based on internal signals of vector controlled induction motor drives

This paper deals with the stator winding faults monitoring in the vector controlled induction motor drives. Two control methods were taken for analysis, namely the direct field oriented control - DFOC and the direct torque control - DTC. In both control structures the induction motor is supplied form two-level voltage inverter with space vector modulation (SVM). In order to detect the early stage of the stator winding inter-turn short-circuits, the analysis of characteristic components of internal control signals of the DFOC and DTC-SVM structures is used for diagnostic purposes. Experimental results obtained from a specially prepared induction motor working under vector control are presented.

Electrical faults diagnosis in the induction motor drive under the direct field oriented control

This paper deals with the diagnosis of the electrical faults of induction motor operating under the direct field-oriented control. Two different faults are taken into account: stator winding inter-turn short circuit and voltage source inverter transistor damage. The fault diagnostic algorithms are described. Performance of both algorithms is validated in presence of the different kind of damages. The presented methods are examined using the experimental setup with specially prepared induction motor and voltage source inverter.

Stator Faults Monitoring and Detection in Vector Controlled Induction Motor Drives—Comparative Study

This chapter deals with the stator winding faults detection in the induction motor drives working in the closed speed control loops, with the direct field oriented control—DFOC or with the direct torque control—DTC. In order to detect the early stage of stator winding inter-turn short-circuits, the analysis of characteristic components of the stator currents spectra, as well as the control signals of the DFOC structure, are used for diagnostic purposes. Experimental results obtained from a specially prepared induction motor working under vector control are presented.

Monitoring of stator inter-turn short circuits in the direct field oriented controlled induction motor

This paper deals with monitoring and diagnosis of stator windings damages in vector-controlled induction motor (IM) drive. The article proposes a simple method of shorted turns detection using only virtual control and decoupling signals from the classical Direct Field Oriented Control (DFOC) method. The diagnosis of the stator windings faults is based on the analysis of twice the fundamental frequency of mentioned signals. The proposed method is illustrated using experimental test results obtained for 1.5 kW induction motor, especially prepared to allow physical modelling of shorted turns.