Aleksander Kilk

• Doctor of Engineering
• Tallinn University of Technology

The paper is about the design and prototyping of directly driven outer rotor permanent magnet generator for small scale wind turbine. In the paper, the initial design of the generator is given. Main issues and phenomena affecting the generator design, such as cogging torque and its reduction possibilities, selection and demagnetization risk assessm...

The paper discusses problems concerning the influence of permanent magnet material characteristics on the low-speed permanent magnet generator losses and output characteristics. The variability of the magnet material and its effect on the output parameters of the machine has been quantified. The characteristics of six different grades of neodymium...

This paper discusses the problems concerned to thermal analysis of brushless PM synchronous generator for small-scale wind power applications. Thermal analysis is one of the most important processes that needs to be discussed, because of increasing interest in high efficiency and low weight of electrical machines. In this paper, analytical analysis...

This paper presents the PM electrical machine with the Gramme's winding, which is intended for a small unmanned aircraft. The PM machine is a part of a hybrid drive operating in conjunction with an internal combustion engine. The main study involves operations in the motor mode, where the PM electric machine performs as the main propulsion system,...

This paper presents a study of the application of the exterior-rotor permanent magnet synchronous motor for a single pilot paraglider as the main propulsion device. The results based on analytical calculations are compared with those obtained by SPEED modeling software. The primary magnetic field distribution is simulated with the SPEED sub-module...

The paper represents the study of electric output parameters of a multi-pole exterior-rotor permanent magnet (PM) synchronous machine, which is a part of a hybrid drive for a small unmanned aircraft. The PM synchronous machine's constructional feature is a toroidal or Gramme's type of stator winding. The studied machine is designed to operate as a...

This paper presents a comparative analysis between the energy efficiency of two wind generator designs. A hypothesis is presented that generators for wind applications should be designed based on their energy efficiency instead of rated efficiency. As wind generators are working with variable rotational speeds and power levels, resulting in changes...

This paper represents the study of the multimode permanent magnet synchronous machine constructed for a small-sized unmanned aircraft. An overview of commonly used electrical machine types for unmanned aircrafts is also given within this paper. The main objective of the research was to create an electrical machine that could be used in addition to...

This paper considers the study of methods for reduction of the cogging torque in permanent magnet machines. Cogging torque has been analyzed to be reduced by slot skewing, width of slot opening, magnet pole radius and also by mounting of the magnets. Electromagnetic simulations of the PM generator were performed by using finite element analysis. Vi...

This paper presents the experimental study of three-phase squirrel cage induction motor broken rotor bars diagnostics. Tests have been performed with two different machines, one through a frequency converter and the other supplied directly from grid. This comparison has been presented, as the use of frequency converters changes the traditional curr...

This paper describes the procedure of lifecycle-based design and optimization of electrical motor-drives as well as related methodologies to be developed. As the electric motor-drives are the most electrical energy consuming apparatuses, thorough and in depth optimization of the drives during their design process is essential to support energy effi...

This paper describes the magnetic properties of different permanent magnet materials and their industrial usage as crucial components of permanent magnet electric machines. As the prices of rare earth materials, especially neodymium-iron-boron (NdFeB), has been rising rapidly during the last few years and has been quite unstable during the past dec...

This paper presents the possibilities of using Clarke vector approach for stator current and voltage analysis for induction motors with broken rotor bars. The equations for performing Clarke transformation on three-phase stator current and voltage are presented. Since this method is generally used for transforming current signals, benefits for usin...

Many companies engaged in wind generator development are investigating permanent magnet generators (PMG) mainly because of higher efficiency over a broad range of wind speed and reduced costs of maintenance. One important parameter of PM generators is the primary magnetic flux that has certain influence to no load voltage of the machine. Thus, need...

This paper considers the study of a directly driven low-speed permanent magnet synchronous generator specially constructed for a vertical axis wind turbine. The studied PM generator with outer rotor construction offers an alternative to fix the wind turbine directly to the end-disk of rotor. As an advantage of the outer rotor PM generator construct...

This paper presents the analytical analysis of different eccentricities in the rotor of a novel slotless wind power generator. The analytical expressions for the air gap eccentricity have been derived and the effects of these eccentricities on the air gap flux density, the resultant unbalanced magnetic pull and the induced emf are investigated. The...

This paper presents the experimental study of induction motor broken rotor bars diagnostics. Fault tests are performed on a machine with 3 broken bars, driven through a frequency converter. Park's vector approach is used as an analyzing tool to detect the broken rotor bars. Park's vector patterns in case of stator current and voltage are investigat...

The paper presents investigations carried out on the construction of slow-speed slotless permanent magnet wind generator. As rare earth magnet prices have been rising significantly during the last years, the possibilities of using other magnet materials in this generator have been investigated. In this paper we describe one possible solution using...

This paper presents the experimental study of induction generator broken rotor bars diagnostics. As induction generators are often used in renewable energy applications, such as wind and hydro power plants where they are also equipped with frequency converters, diagnostics of such machines is becoming more important. Tests are performed with an ind...

Due to their rugged build, simplicity and cost effective performance, induction motors are used in a vast number of industries, where they play a significant role in responsible operations, where faults and downtimes are either not desirable or even unthinkable. As different faults can affect the performance of the induction motors, among them brok...

During the past few decades there has been a continually increasing interest and investigation into fault detection and diagnostics of induction motors. There are various different diagnostic approaches and methods to detect faults in induction motors. Attention should be paid to the fact that as induction motors are often used in critical duty dri...

Analysis of both primary and secondary magnetic field of permanent magnet synchronous generator in the axial end zone of air-gap has been presented. The models for study of primary and secondary magnetic field by the method of conformal mapping and using the method of current images have been created and analysed. The influence of axial end effects...

This paper presents an analysis of tendencies in development and design of small-scale wind power applications on the basis of directly driven low-speed multipole permanent magnet synchronous generators. Analysis of primary magnetic field distribution and armature reaction in the conditions of surface-mounted radial magnetic flux permanent magnet s...

Tendencies in development of wind power industry including direct-drive small-scale wind power plants and generators have been analyzed. Synchronous generators with permanent magnet excitation for direct-drive wind power turbines are described. Primary magnetic field distribution and effect of armature reaction have been studied for design of a low...

This paper analyzes of toroidal winding permanent magnet axial-flux wind generator. Special attention is paid on peculiarities and output characteristics. The experimental generator has been designed and constructed on the base of this construction approach. Testing experimental generator allows to compare test result with simplified calculation me...

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