Mieczysław Ronkowski

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.

Modelling of electrical machines using the Modelica Bond-Graph Library

The paper presents the bond graphs approach to modelling electrical machines for controlled electromechanical systems applications. The bond graph models of electrical machines are based on the models of ideal couplings: transformer and electromechanical couplings, respectively. Using the couplings models as building blocks the models of electrical machines (brushed and brushless DC machines with permanent magnets, and synchronous machine) have been developed in terms of bond graphs. The models have been elaborated using the Modelica Bond-Graph Library and the DYMOLA package.

Design, modelling and analysis of a new type of piezoelectric motor. Multicell piezoelectric motor

This paper describes a new type of piezoelectric motor. The results, obtained in the field of piezoelectric motors, have pointed out that these motors have potentially high possibilities in the future special applications. The research work presents the design, simulations and parameters of the piezoelectric motor with three rotation-mode actuators. The motor is characterized by a high power, relative high speed and torque. The motor consist of stator with few (minimum 3) rotating mode actuators. The purpose of those efforts was to develop a new actuator dedicated for the embedded applications.

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.

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).

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

Nonlinear model of synchronous generator for autonomous electrical power systems analysis

This paper presents the nonlinear lookup table model for synchronous generator (SG) analysis. The saturation effects of the SG magnetic circuit have been considered. The saturated characteristic of the SG magnetic circuit are based on the open circuit saturation curve for magnetizing inductances. The model has been implemented into the Synopsys/Saber software using the MAST modelling language. To implement the no-load voltage characteristic of SG into the MAST model the table look-up tool has been used. Normal and fault operation of SG can be effectively studied. Developed model exhibits a network with the same number of external terminals as the real SG and represents its behaviour in terms of the electrical and mechanical variables as well. Accuracy and robustness of the nonlinear lookup table modelling approach has been confirmed by measurements performed on the 3 kVA synchronous generator.

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.