This thesis deals with the asynchronous engines, describes their structure, principles, properties, use, and briefly describes the design of three-phase asynchronous motor. The first section describes the most common three-phase induction motor, the emergence of the rotating magnetic field and the basic relationships. The second part deals with asynchronous motors for specific applications, their design and features. The next section is an analysis engine borrowed from the electric company ATAS Náchod, and The last section lists ways to improve the basic parameters of induction motors designed and optimized engine.

The aim of this master´s thesis is to introduce methods of diagnostics of vibrations in electrical machines. Describe the various vibration sources located inside and outside of the electric machine. Description of the sources of vibration is then preferably dedicated to vibration of electromagnetic origin. There is a description of the construction of an asynchronous motor and the magnetic circuit, the theory of vibrations and their origin. Described are also vibration sensor enables measurement and mathematical tools for their evaluation. In this work also practical vibration measurements on an asynchronous motor, data processing, their subsequent analysis and computer simulation of electromagnetic vibration origin. The conclusion of this work is devoted to the evaluation of the data obtained.

The doctoral thesis is divided into three main parts with a focus on induction motors. The first part deals with the electromagnetic design and analysis of windings of AC ma-chines. There is introduced the density of conductors, which describes the distribution of the windings in the slots. There is derived general formula for calculation of the total winding factor applicable to any type of winding. The second part of this work deals with the acceleration method of the induction motors torque-speed characteristics measurement. The measured characteristics are used for exact identification of the equivalent circuit parameters of induction motor. The third section is focused on a very precise identification of the equivalent circuit parameters of induction motor in the form of -circuit. The identification is based on mutual comparison of measured and calculated torque-speed and current-speed characteristics.

The main objects of this doctoral thesis are analysis of a small induction motor losses and research of ways how to reduce losses and increase efficiency of this motor. The ways how to reduce losses and increase efficiency under study are as follow: reduction of stator winding’s resistance, lengthening of magnetic circuit, modification of turn number, cooper squirrel cage, slots shape optimization, sheets annealing and use of sheets with lower specific losses. The losses analysis and the research of ways how to reduce losses are done due to laboratory work. For this laboratory work, eleven different samples of the motor with above mentioned modifications were manufactured. Results of their measurements and losses analysis are presented in this thesis. There were also simulations by finite elements method used to help solve objects of this thesis. Due to the simulations, analysis of loses of the induction motor under study was done. Results of this analysis include some details that are not included in the results from measurement, for example separation of core losses between rotor and stator. The simulations were also used for analysis of manufacturing technology impact onto the motor’s performance. During this analysis, following impacts were considered: actual shape of magnetic circuit, stator’s sheets riveting, influence of cutting onto material’s properties and placement of the stator into conductive frame. Results of this analysis are presented in this thesis.

The thesis Diagnostic of induction motor with regard to its maintenance and reliability aims to be a theoretical preparation and application of online diagnostics. It is trying to map correlations between electromechanical system failures driven by induction motor and output information of the diagnostic method. It mainly focuses on spectrum analysis of stator current which carries information on the induction motor status in the form of characteristic signatures in the spectrum (Motor Current Signature Analysis). The theoretical part deals with the concept of diagnostics and mainly with the operational diagnostics, it classifies and characterises types of induction motor failure and it accordingly processes diagnostic methods. This all is done with regard to the application of the maintenance and inspection of machines in a manufacturing company. The practical part develops methodology and measurement procedure. Several measurements demonstrate, validate and apply the MCSA method. It simulates abnormalities and searches for their correlations in the spectrum stream. First, a motor powered from electric distribution network is measured and then the MCSA method is applied to motors powered from frequency converters.

This work deals with the option of substitute aluminum for copper as winding material in induction motor in several variants and compare them. The advantages and disadvantages of these materials for the application are mentioned. The default element is the machine with power 29 kW, 2p = 4, which is the basis for other variants. It is about the verification of the default copper wire machine with cataloging data and then verification of several aluminum wire variants of the machine. Veryfying the machine designs is performed on the basis of three programs - RMxprt, ANSYS Maxwell and Matlab. In all of these programs, the machine calculations were realized for copper and aluminum winding in point close to the nominal. Final results are evaluated. There are also heat and ventilation calculations of the machine.