Dynamics Of Electromechanical System Research Articles

Nonlinear Actuation of Casimir Oscillators toward Chaos: Comparison of Topological Insulators and Metals

In the current study, we explore the sensitivity of the actuation dynamics of electromechanical systems on novel materials, e.g., Bi2Se3, which is a well-known 3D Topological Insulator (TI), and compare their response to metallic conductors, e.g., Au, that are currently used in devices. Bifurcation and phase portraits analysis in conservative systems suggest that the strong difference between the conduction states of Bi2Se3 and Au yields sufficiently weaker Casimir force to enhance stable operation. Furthermore, for nonconservative driven systems, the Melnikov function and Poincare portrait analysis probed the occurrence of chaotic behavior leading to increased risk for stiction. It was found that the presence of the TI enhanced stable operation against chaotic behavior over a significantly wider range of operation conditions in comparison to typical metallic conductors. Therefore, the use of TIs can allow sufficient surface conductance to apply electrostatic compensation of residual contact potentials and, at the same time, to yield sufficiently weak Casimir forces favoring long-term stable actuation dynamics against chaotic behavior.

Spectral Analysis of Output Voltages and Currents as a Criterion for Technical Diagnostics of Synchronous Generators of Ship Diesel Engine

Abstract Diesel generator sets (DGU) are very widely used in autonomous power supply systems. An example is marine power plants, diesel locomotives with electric power transmission, uninterruptible power supply units, etc. The power of ship DGUs reaches 2–6 or more MW in one unit. The number of units on ships can be different, but, as a rule, at least two. In this paper, we propose a method of monitoring the dynamic electromechanical system “diesel synchronous generator”. The method aims at using a synchronous generator machine as a multifunctional accurate and sensitive sensor for diagnostic parameters of the electromechanical system. The proposed method of technical diagnostics is based on continuous monitoring of non-uniformity of diesel torque, fluctuations in the instantaneous angular velocity and instantaneous angular acceleration of the diesel crankshaft. These data are the results of a spectral analysis of stator currents and voltages of a synchronous generator.

Управление нелинейной динамикой электромеханических систем

V.L. Kodkin, kodkina2@mail.ru, A.S. Anikin, anikinas@susu.ru, A.A. Baldenkov, baloo@mail.ru South Ural State University, Chelyabinsk, Russian Federation. Кодкин Владимир Львович, д-р техн. наук, профессор кафедры электропривода и автоматизации промышленных установок, Южно-Уральский государственный университет, г. Челябинск; kоdkinа2@mаil.ru. Аникин Александр Сергеевич, канд. техн. наук, доцент кафедры теоретических основ электротехники, Южно-Уральский государственный университет, г. Челябинск; аnikinаs@susu.m. Балденков Александр Александрович, аспирант кафедры автоматизированного электропривода, Южно-Уральский государственный университет, г. Челябинск; baloo@mail.ru.

Robust control for an electromagnetic actuator for a camless engine,

The increase of the effective efficiency of the internal combustion engines is important for the fuel consumption reduction and the CO2 emission reduction. The variable engine valve trains are important for the gas exchanges and influence directly the effective efficiency of the internal combustion engine. With the increased electrifications of the vehicles, variable valve train based on electricity driven actuators presents interest for investigation for gasoline engines for vehicular application.This article presents an innovative application of an electromagnetic actuator for a future variable engine valve train. The actuators are designed for small gasoline engine. The design of a high performing and dynamic electromechanical system leads to a nonlinear behavior of the actuator. The nonlinearities that have to be faced come from the magnetic laws and the mechanical friction. In the final control strategy, it is proposed to compensate them both with nonlinear feedforward actions and with a linear robust feedback controller, which is able to reject all what cannot be predicted. An experimental test bench is built for the correlation of the control model with experimental measures. Control strategies are developed and the performance indicators of the actuators are evaluated. The robust controller method uses CRONE system control methodology. The investigations show that very good dynamic performances of the controller are obtained.

Dynamic Modes of Electromechanical Systems under Parametrical Disturbances

The results of a theoretical and experimental investigation of the influence of damping and pitch plays on the dynamics of electromechanical systems in the zones of main, harmonic, and subharmonic resonances under parametrical disturbances are presented. Design models of electromechanical systems taking into account spring linkages, pitch plays, mechanical damping, and inconstancy of a gear ratio and reduction radius are proposed. The equations and structural schematics describing the movement of electromechanical systems under consideration in the initial values and adopted system of generalized parameters and relative units are presented. The electric drive is described by a linear mechanical characteristic taking into account the electromagnetic inertia of power circuits. The problems of linearization of electromechanical systems under parametric disturbances are considered, and the zone parameters are revealed under which it is possible. The analytical relationships for determining the optimum parameters of electric drive and the estimation of resonant amplitudes of oscillations of the elastic torque are obtained. Results of analysis of the influence of pitch-play formation on the oscillations in the zones of main and subharmonic resonances are presented. Features of these oscillations related to the magnitude of average load of transmissions and the direction of change in the frequency of parametric disturbances are considered. The reliability of theoretical regulations and conclusions of the article are confirmed by the results of industrial experience in the use of various circuits of a reduction-gear electric drive of rotation of an excavator under parametric disturbances caused by a gear wheel meshing with the gear ring.

Nonlinear Dynamics of Electro-mechanical System Composed of Two Pendulums and Rotating Hub

Dynamics of a structure composed of two pendulums attached to a rotating rigid hub is analysed in the paper. The system is rotating in a horizontal plane so the gravity force does not influence its motion. Both pendulums are treated as lumped masses fixed at the ends of stiff and massless rods connected to the hub by flapping hinges. Three possible variants of the excitation are considered: (a) an ideal energy source, where torque is given by a defined harmonic function (b) a simplified limited power supply, where torque is given by an arbitrary defined function or (c) a non-ideal energy source, where DC output characteristic of limited power is taken into account.

Teaching Reform and Thinking of the Course Electro-Mechanical Systems Dynamics Based on Higher Engineering Education Mode

Electro-mechanical system dynamics is a professional course of integrated post-graduate, it combined with basic theory and practical applications, it belongs to cross - disciplinary of mechanics and mechanical engineering, it not only has the highly abstract and exact science of basic theory , but also has the extensiveness and depth of the practical application.For graduate students’ strong interest and desire involved in taking part in the actual subject actively, electro-mechanical system dynamics course content and teaching model are reformed, case teaching method is introduced, assessment methods are innovated, enable students to master the problem-solving approach and apply it to their own research projects.At the same time，it also guides the students to discover and ask new questions from the actual phenomenon and achieves good results in the practice of the process in training research - oriented students.

PWM interface for piezoelectric energy harvesting

A wideband electric interface based on pulse width modulation (PWM) for a piezoelectric energy harvester is investigated. The switching interfaces are used to increase the output power of energy harvesting devices for a wide frequency range. It is shown that the energy harvesting technique can effectively enable harvested power to be the maximum possible value for a dynamic electromechanical system for all excitation frequencies. The proposed wideband interface is composed of a full-bridge converter with PWM modulation. The piezoelectric voltage is adaptive to the vibration. In the final experiment, the PWM interface harvested more energy in the case of multi-frequency vibration.

The Control Simulation Analysis of MATLAB-Based High-Precision Numerical Control Welding Positioner

Based on electromechanical system dynamics model of 3-axis NC positioned, together with the general nonlinear decoupling control theory, the decoupling control method of NC 3-axis positioned is proposed in this paper. In order to control each axis and the simulation of the decoupling control, the Simulink platform of MATLAB soft is used to build a electromechanical system simulation model for NC positioned. The results show that the proposed nonlinear decoupling feedback control method is effective and applicable.

Conceptual Design of Hybrid-Driven Precision Press

In this paper, a novel precision press is proposed, which is to combine the motion of a large constant speed motor with a small servomotor via a two-DOF mechanism, where, the constant speed motor provides main torque and motion requirements, while the servomotor contributes to modulations on this motion. The forward kinematic optimal design, electromechanical system dynamics modeling and simulation of this new mechanical press system have been presented here. The simple analysis of theoretical feasibility of the hybrid-driven press is investigated.

Effect of nonlinear friction on the dynamics of electromechanical systems

A two-mass model of the electromechanical system (EMS) is proposed in which a new composition of the mechanical subsystem is provided. The transfer function of the system taking into account loads on the shaft of an actuating motor and an object and nonlinearity of the friction function are obtained. Frequency characteristics are determined that clearly show that the accurate values of the viscous friction factors have to be known to assess qualitative indicators of systems and wires

Electromechanical coupled dynamical modeling of high speed motorized spindle’s motor-spindle subsystem

Based on that high speed motorized spindle system has characteristics of the complex electromechanical system, the view of electromechanical coupling analyses on high speed motorized spindle is put forward. Coupling phenomena of several physical processes and parameters multidimensional coupling that exist in the high speed motorized spindle system are extracted and summed up. Global coupling relation block diagram of high speed motorized spindle system is given. The configuration and coupling situation of high speed motorized spindle's motor-spindle subsystem are analyzed. The coupling relation block diagram of the subsystem is gained and the physical model of the subsystem is also set up. Founded on the electromechanical system dynamics theory and the variational principle, voltage equation and mechanical movement equation are built up by Lagrange equation. Simultaneous equations of voltage equation and mechanical movement equation are the mathematical model of the subsystem. So the dynamical equation of the subsystem is educed, which provides the theoretical basis for further research on the electromechanical coupled dynamical performance of high speed motorized spindle system.

Structronics and Actuation of Hybrid Electrostrictive/Piezoelectric Thin Shells

Certain ferroelectric materials possess dual electrostrictive and piezoelectric characteristics, depending on their specific Curie temperatures. The nonlinear electro-mechanical effect of electrostrictive materials provides stronger actuation performance as compared with that of piezoelectric materials. Due to the complexity of the generic ferroelectric actuators, micro-electromechanics, structure-electronic (structronic) coupling and control characteristics of hybrid electrostrictive/piezoelectric dynamic systems deserve an in-depth investigation. In this study, dynamic electro-mechanical system equations and boundary conditions of hybrid electrostrictive/piezoelectric double-curvature shell continua are derived using the energy-based Hamilton’s principle, elasticity theory, electrostrictive/piezoelectric constitutive relations, and Gibb’s free energy function. These governing equations clearly reveal the coupling of electrostrictive, piezoelectric, and elastic fields and characteristics change triggered by the Curie temperature. The electric terms are used to manipulate and to control the static/dynamic behavior of hybrid electrostrictive/piezoelectric shells. To apply the hybrid shell system equations to other geometries, simplification procedures using two Lamé parameters and two radii of curvature are demonstrated in two cases: A hybrid electrostrictive/piezoelectric conical shell and a hybrid electrostrictive/piezoelectric toroidal shell. Following the same procedures, one can apply the generic system equations to other common geometries, e.g., beams, arches, plates, rings, cylindrical shells, spherical shells, etc., or specific materials, e.g., electrostrictive or piezoelectric, and further evaluate their electromechanical characteristics and actuation/control effectiveness.

Adaptive tracking control of an induction motor with robustness to parametric uncertainty

The paper presents an adaptive tracking controller for an induction motor driving a load. Using nonlinear models of the motor and load, an asymptotic stability (AS) result for the rotor position/velocity tracking error is obtained. The control is capable of handling parametric uncertainty throughout the entire electromechanical system dynamics. The control requires full state feedback (i.e. rotor position, velocity, stator currents, and rotor flux). Simulation results are used to evaluate the effectiveness of the proposed controller.

Solution of the singularly perturbed stability problem

The singularly perturbed problem of the stability /1/ of solutions of a system of differential equations with derivatives multiplied by various powers of small parameters is considered. The effect of small parameters on the system dynamics is examined and the conditions under which the stability problem for the original system can be reduced to the analysis of a truncated system in special cases are determined. The general approach, based on separation of motions combined with methods of stability theory, enables the permissibility of idealizations /2/ in problems of mechanics to be examined (with a mathematically rigorous construction /3/ of simplified models as comparison systems for solving singularly perturbed problems) and enables estimates of the allowed parameter values to be obtained. The regular method used in this paper avoids a number of difficulties that arise in applied problems of mechanics, while generalizing existing results and producing a number of new results. The analysis focuses on problems of the dynamics of electromechanical systems in special critical cases.

Stability and stabilisation of doubly-fed single-frame cascade induction machines

This paper presents a theoretical and experimental study of the dynamic performance of a doubly-fed single-frame cascade induction machine which can operate synchronously from rest over a wide speed range. The dynamic electromechanical-system equations are developed and theoretical performance boundaries for stable operation are found and compared with experimental results. The nature of its instability and an easily implemented feedback control which stabilises its operation are both described. It is shown that the machine can be operated as a stable variable-speed brushless machine with controllable dynamic response. Its mechanical construction is potentially only a little more complicated than that of a squirrel-cage induction machine.