The method of elimination bearing currents and leakage current in PWM inverter drives

In the paper are discussed different kinds of parasitic phenomena occurring in PWM inverter driven induction motors. In the article describes methodes for limiting bearing currents and common-mode current in PWM drives. The paper also presents results of experimental researches. Conclusions drawn from laboratory researches are presented in chapter 7

Influence of squirrel cage faults and core saturation on shaft voltage values in induction motors

The paper presents initial results of laboratory investigations. These results emphasize the intensification of the phenomena connected with bearing currents flow at different rotor cage damages. In the section 2 on the figure 5 are presented results of investigations connected with inducing of the third harmonic of the motor EMF. In the section 3 is presented the influence of rotor cage damages on the shaft voltage value. The subject of these studies was a low power induction motor (fig. 6), taking into consideration easiness and low costs of necessary modernization of it. On the figure 7 is presented the diagram of the shaft voltage and current measurement system. The measurements results are presented on the figure 8. Conclusions drawn from laboratory researches are presented in chapter 4

Influence of squirrel cage faults on shaft voltage and currents values in induction motors

The paper presents initial results of laboratory investigations. These results emphasize the intensification of the phenomena connected with bearing currents flow at different rotor cage damages. In the section 3 is presented the influence of rotor cage damages on the shaft voltage value. The subject of these studies was a low power induction motor (fig. 3), taking into consideration easiness and low costs of necessary modernization of it. On the figure 4 is presented the diagram of the shaft voltage and current measurement system. The measurements results are presented on the figures 10, 11, 12. Conclusions drawn from laboratory researches are presented in chapter 4

Shaft voltage in high power induction motor with insulated rotor cage

Initial results of shaft voltage tests in high power induction motor with insulated rotor cage are presented in the paper. Different types of bearing faults occurring in tested motor are shown in Figs. 3,4 and 5 in section 1. Descriptions of lab test stand and rotor modernization of tested motor are given in section 2. Figs. 8 to 15 show the modernized rotor. The results of lab tests are given in section 3. The test measurement scheme is shown in Fig.16. The wavecourses and their Fourier transforms are presented in Figs. 17 and 18. Conclusions drawn from lab tests are stated in section 4.W artykule przedstawiono wstępne pomiary napięć wałowych w silniku indukcyjnym dużej mocy z izolowaną klatką uzwojenia wirnika. W rozdziale 1 na rysunkach 3, 4 i 5 przedstawiono różne rodzaje uszkodzeń łożysk badanego silnika. Rozdział 2 zawiera opis stanowiska laboratoryjnego i modernizacji wirnika badanego silnika. Na rysunkach od 8 do 15 przedstawiono zmodernizowany wirnik silnika. Wyniki badań laboratoryjnych zawarto w rozdziale 3. Na rysunku 16 przedstawiono schemat układu pomiarowego. Przebiegi czasowe napięć i prądów i ich transformaty Fouriera przedstawiono na rysunkach 17 i 18. Wnioski z badań laboratoryjnych zawarto w rozdziale 4

Reconstruction of magnetic fluxes and rotational speed of induction motor using MRAS-type estimator with Luenberger observer as an adaptive model

The paper presents the principle of operation and block diagrams of different, modified MRAS-type estimators of the induction motor rotational speed. A Luenberger observer with additional integrators is used for reconstruction of magnetic fluxes in the adaptive model of the considered estimators. In the presented estimators the measurable currents of the stator winding are applied to generation of a speed tuning signal. For stator winding current reconstruction in the adaptive model there are used the Luenberger observer output signals. Moreover, in the paper there are presented the results of simulations and laboratory investigations of the described estimators operating in a multiscalar control system. For comparison, the results of similar investigations performed for a MRAS-type estimator designed basing on the so-called current model of magnetic flux estimator are given as well

Bearing currents in large power induction motors supplied from line voltage - experimental research

The paper presents results of scientific reasearches of large power induction motors. In chapter 2 are presented the causes of bearing currents forming supplied from line voltage. The figure 2 are presented influence rotational speed on the bearings resistance. The figure 3 are presented bearing current density versus life curve. The figure 5 are presented equivalent measurement system. In the chapter 4.2 are presented laboratory results. Figures 8 and 9 show characteristics determining influence of avarage bearing temeperature, shaft voltage and rotational speed on bearing current. Conclusions drawn from laboratory researches are presented in chapter 5

PI observer stability and application in an induction motor control system

The paper discusses the problem of stability of a proportional-integral Luenberger observer, designated for the state variables reconstruction of a linear, time-invariant dynamical system. It is proven, that there exists such a class of observed systems, for which the observer is always unstable, independently of its gains. Stability can be provided in every possible case after application of proposed modifications to the structure of the observer. It is proven, that stability of the modified observer depends only on its gains. It is shown, that an induction motor is the exemplary observed system, for which application of the unmodified observer is impossible due to its lack of stability, while the modified observer provides proper operation of the control system. Finally, some experimental results are presented, obtained in the multiscalar control system of the induction motor, equipped with the modified proportional-integral observer

Bearings faults of induction motors for mining elements of heading machine

The paper presents research results dealing with bearing faults of high power induction motors.In the chapter 2 are presented simulation results, as an introduction to laboratory measurements. The harmonic analysis of the stator winding phase currents are shown In charter 3. In charter 4 are presented the causes of bearing currents forming during motor direct startup. The figure 3 shows the graphical presentation of the bearing currents forming issue. In charter 5 measurement results are discussed. Waveforms of shaft currents and voltages, and their Fourier transforms are shown in Fig. 5, 6 and 7. Equivalent circuit diagram for bearing current flow is presented in chapter 6, Fig. 9. Equivalent circuit diagram for bearing current flow is presented in chapter 6, Fig. 9. Conclusions drawn from laboratory researches are presented in chapter 8

Shaft voltage calculations in a cage induction motor by the finite element method

In the paper results of finite-element calculations of the shaft voltage in a squirrel-cage induction motor were presented. A two-dimensional field-circuit model of the 300 kW induction motor was developed taking into account supplying the stator winding from the voltage source and the rotary motion of the rotor. Calculations of transient waveforms of the shaft voltage and other electromagnetic and electromechanical quantities were performed during starting under no-load and rated load conditions. An influence of static and dynamic air-gap eccentricity was examined. Ways of the improvement in the accuracy of calculations were discussed

Application of the proportional observer with additional integrators to reconstruction of induction motor state variables

In the paper there are presented some problems connected with reconstruction of induction motor state variables with use of a proportional observer with additional integrators. The considered Luenberger observer with additional integrators has high resistance to disturbances overlapping its input signals. In the paper the mathematical model and error equation of the observer are given. There is also described the application of the considered observer as an adaptive model in the structure of a MRAS-type estimator for reconstruction of rotational speed and magnetic fluxes of an induction motor. The quality of the observer operation is evaluated based on the quality of operation of a multiscalar control system using the values reconstructed by the observer as feedback signals