Grzegorz Kostro

Nonlinear equivalent circuit model of a traction transformer for winding internal fault diagnostic purposes

The paper presents the development of an equivalent circuit model of a traction transformer intended for studies into the diagnostics of interturn faults. The model accounts for the nonlinear B-H characteristic of the transformer core. The derivation of the model is based on the Lagranges energy method. The values of model parameters were evaluated by means of 3D finite element model computations. The simulation studies based on the proposed equivalent circuit suggest that interturn faults can be detected by evaluating transformer losses.

Identification of the mechanical properties of the skin by electromechanical impedance analysis of resonant piezoelectric actuator

This paper is devoted to the analysis and verification of developed piezoelectric sensor/actuator for measuring the mechanical properties of soft tissues, especially human skin. The key element of the measurement structure is an electromechanical system that uses both the reverse piezoelectric effect (vibration generation - stimulation of the tissues in the appropriate frequency range) and direct piezoelectric effect (system response registration). By analyzing the response of the piezoelectric sensor/actuator - an electromechanical signature of the tested tissue, it is possible to identify a series of mechanical quantities describing the tested object, such as stiffness, viscosity, Youngs modulus. An analytical approach is shown in order to establish a link between the electromechanical equivalent circuit obtained for a resonance frequency of the actuator and the calculations based on the Hertzs contact mechanics theory. A finite element method analysis is then presented in order to assess the performance of the chosen topology of piezoelectric sensor/actuator. Finally, the proposed method of impedance characterization is verified experimentally by a prototype of piezoelectric bimorph sensor/actuator.

Comparative analysis of salient and non-salient pole brushless synchronous generator for application in autonomous electric power system

This paper presents a comparative study of two types of brushless synchronous generator for application in autonomous electric power systems (e.g. airplane power grid). Commercially used salient pole and a prototype non-salient pole high speed multi-pole brushless synchronous generator (BSG) have been presented. Comparative analysis of both types of the generator has been performed. Chosen simulation (using FEM and circuit models) and measurement results have been presented.

A wide-band modeling of DC-DC two-transistor flyback converter.

This paper presents results on wide-band modeling of DC-DC flyback converter. The model of converter is composed of detailed models of transformer, transistors, diodes and tracks. Parameter identification methods are based on manufacturer data sheet and externally measurable characteristics and parameters. The templates of models are written in the MAST and implemented for simulation in the SABER simulator. Validation of simulation results has been based on experimental results of the 120/5V DC-DC two-transistor flyback converter.

Low speed permanent magnet synchronous generator for vertical axis wind turbine

The paper presents design process and tests of a prototype low speed permanent magnet synchronous generator (PMSG) dedicated for the innovative vertical-axis wind turbine. The rated data of the designed generator are following: power − 15 kVA, voltage − 400 V (Y), rotation speed − 93.75 rpm. The design assumptions, chosen results of the design process and experimental tests of the prototype PMSG are presented. The considered PMSG can be used in low-power wind plants applied for vessels (ships, yachts) and stationary prosumers power installations. The whole project realization (concept, design, engineering documentation, building and testing) of the prototype low-speed PMSG was commissioned by company ALU ECO Sp. o.o. Gdansk, and co-financed by the Polish Agency for Enterprise Development (PAED).

Five-Phase Squirrel-Cage Motor. Construction and Drive Properties

This paper presents the simulation and experimental results of a five-phase squirrel-cage induction motor. The new machine has been designed to operate in a drive system with third harmonic rotor flux injection in order to improve the motor torque utilization. The motor structure, the mathematical model as well as the laboratory prototype have been described. The motor speed-torque characteristics and transients are elaborated Furthermore, the start-up possibility in the case of one or two stator winding faults has been shown as well. The idea of a closed loop speed control with increased load torque is presented.

A new prototype of piezoelectric bending resonant transducer for analysis of soft tissues properties

A new prototype of piezoelectric bending resonant transducer for analysis of soft tissues properties

Synchronous generator model taking into account the non-uniform saturation of the pole shoes

For the evaluation of modern electric power systems with regard to their behavior, weight, and reliability a novel modeling and simulation tools have been developed. The paper presents circuit model of synchronous generator taking into account both the non-sinusoidal distribution of the stator and rotor winding, and non-uniform saturation of the pole shoes. This model is suitable for simulation of both salient and no-salient pole generators. Winding function approach is used to define the self and mutual inductance which has enabled to take into account the non-sinusoidal distribution of stator and rotor windings. The equivalent airgap length distribution function is used to model the shape of the salient pole rotor and non-uniform saturation of the pole shoe. Simulation and experimental tests were carried out to validate this modeling method. The developed model can be used to analyze an autonomous power systems, in which a single generator has a significant impact on the power quality.