Damian Mazur

The effect of strong parasitic synchronous and asynchronous torques in induction machine with rotor eccentricity

Parasitic torque harmonics and stator current harmonics to rotational speed of the asynchronous motor are presented in this paper. To calculate these relationships a 2.5D finite element model has been used. The rotor bar skew has been simulated with the division of the electric machine into so called elementary machines having straight, but shifted against each other, rotor bars. The obtained results on both 2D and 3D graphs are presented to the rotational speed of the electric motor. Parameters for each particular harmonics have been found with these graphs. These graphs help to identify the origins of these harmonics as the co-action of the MMF of the stator current and the magnetic induction from the rotor in the airgap. Particular attention has been payed to how iron saturation influences these harmonics. The harmonics under study (in quantity of 18) has been taken under consideration, because they exhibited their presence in the above mentioned graphs as the functions of speed. Their origin has been also indicated on the graphs made as an extension of the Kluszczynski analytic/graphic diagrams.

Operation of the switched reluctance motor at continuous conduction of phase current

Continuous conduction of the phase current in the switched reluctance motors has been discussed in this paper. An SRM mathematic model has been presented as well, and the conditions to occur when the continuous conducting has been specified. Simulation research results as well as experimental data has been presented. Comparison was made and conclusions were drawn

Inverters operation in rigid and autonomous grid

Purpose – The aim of this paper is to develop the method of optimal control of the three‐phase inverter system for autonomous and power grid operation. The presented method will also allow the cooperation of several inverters creating an autonomous network. This system should also be able to reduce demanded higher harmonics in power voltage according to the list of numbers of these harmonics. In this article the authors describe a system that is used to create a symmetrical three‐phase voltage. The supply power is taken from the renewal source. The inverter system as well as cooperation of several such systems to create an autonomous network is under consideration. The generated three‐phase voltage should be symmetrical even when the RL load is not symmetrical or else it changes in impulse. Cooperation of the system with the autonomous network is also under consideration. The task is to supply the set current of the basic harmonic to the power grid and possibly to reduce voltage higher harmonics on output...

Voltages in the Shaft of the Induction Motor in 3D FEM Formulation

A 3D model reflecting entire internal structure of the asynchronous machine using finite elements method, has been presented here. Nodal finite elements have been used to approximate scalar potential and edge finite elements to approximate vector magnetic potential. This model includes both the skew of the rotor bars as well cross current flowing through the rotor iron laminates. The three-phase stator winding is supplied with four-lead mains voltage. The axial flux was calculated by integration of the vector potential around the shaft of the machine. Making isolation between I a mine worse in the area of tooth stator, was leading to the voltage in the rotor shaft, this voltage was used for diagnostics. Plots were calculated following the switching on the machine at various speeds. Bar as well as ring fractures were simulated. The simulation results have been confirmed by the theoretical anticipations.

Simulating and Measurements of the Stator Currents and Torque in Induction Motors with Rotor Eccentricity

A multislice, 2.5 dimensional model was used to calculate the state variables waveforms of the asynchronous machine. In this model, a magnetic field is calculated, in orthogonal to the machines axis, two-dimensional intersections with the use of the finite element method. The wavelet transform was used to visualize the waveforms harmonic components. The performed analysis showed that the wavelet transform can be successfully used in the analysis of the asynchronous machines waveforms, as an alternative to the short time Fourier transform

The Analysis of Wind Turbine with Horizontal Rotation Axis with the Use of Numerical Fluid Mechanics

The analysis of horizontal rotation axis wind turbine of type H-rotor is presented in this article. The calculation has been made using a 3D model of horizontal rotation axis turbine for three wind flow speeds: 5, 10, 15 m/s, with the stable rotational speed of the rotor of 200 rotations per minute. The analysis of wind turbines requires building a 3D calculation model. The building of such a model is very time-consuming and the calculations involving numerical fluid mechanics require substantial calculation power. The article presents 3D CAD model of horizontal rotation axis wind turbine in ANSYS calculation environment, discrete net, and boundary conditions and the results of calculating horizontal rotation axis wind turbine with the use of numeric fluid mechanics.

Electric energy production in a wind farm - the statistical analysis of measurement results using the time series

The paper presents an analysis of the results of electric energy production in a wind farm. A statistical analysis of the measurement results were performed using the STATISTICA program. The article presents time series on the forecast of electric energy production and actually sold electric energy produced in a wind farm. The analysis was based on data coming from a real wind farm - located in Subcarpathion region.

Autotransformer rectifier circuits with parallel connection without the use of IPT chokes - review

When using many rectifying devices, higher harmonic components of currents absorbed by them from the grid become significantly important. They can cause very harmful phenomena connected with grid voltage drop, glimmering of lights or significant power losses. The presented 18 pulse rectifier circuits enable to lower the content of higher harmonics of the grid currents. When considering leakage inductance of autotransformers and supplying grid these rectifier circuits may be classified to the ‘clean power’ circuit type. Due to instability of ITP type chokes and their vulnerability to magnetic circuits saturation it was decided to resign from their application. Different 18 pulse rectifier circuits were analyzed and diode currents waveforms were calculated and their characteristic parameters were presented. These results may simplify the process of designing such circuits.

Rectifier circuits with magnetically non-coupled chokes

When using many rectifying devices, higher harmonic components of currents absorbed by them from the grid become significantly important. They can cause very harmful phenomena connected with grid power outages, glimmering of lights or significant heat losses. The 18 pulse rectifier circuits presented in the article enable to lower the content of higher harmonics of the current absorbed from a grid. When considering appropriate values of leakage inductance of chokes and the supplying grid these rectifier circuits may be classified to the ‘clean power’ circuit type. Due to instability of ITP type chokes and their vulnerability to magnetic circuits saturation it was decided to resign from their application. Autotransformer or ZSBT chokes were replaced with magnetically non-coupled chokes. These presented results may simplify the process of designing such circuits.

Cascade complex systems — Global modeling using neural networks

In the paper global modeling of complex systems is discussed. Complex systems consists of several sub-systems connected in series. To modeling the complex system a global model is created. Thus, the global model of the complex system consists of simple models, which are connected to the corresponding structure. In the process of modeling the complex system needs a global quality criterion. As the global quality criterion was adopted a weighted sum of the quality criteria of simple models. For simple models as a quality criterion was adopted the sum of squared errors. The global quality criterion includes weighting factors that determine the participation of the quality criterion of individual simple models. Thus, the global quality criterion of the global model to a certain extent depends on the choice of the weighting factors in the global quality criterion. The investigation of influence of these weighting factors on the quality of the global model of the complex system is discussed. The investigation is examined by a complex system which is composed from three nonlinear simple plants connected in series. As the global model of the complex system multilayer feed forward neural networks are used.