Movable Armature Research Articles

Simulation of the influence of parameters of disturbing vibration accelerations on the operation of a new two-channel transformer gravimeter

A new two-channel transformer gravimeter of an automated aviation gravimetric system was considered, the accuracy of which is higher than gravimeters known today. Its design was described. The influence of the parameters of disturbing vibrational accelerations on the operation of a new two-channel transformer gravimeter was simulated. The influence of frequencies and amplitudes of perturbing accelerations for the most unfavorable resonant cases on the operation of a two-channel transformer gravimeter was studied using a computer. After all, today there are no scientific, theoretical and practical works devoted to researching the possibility and expediency of using a two-channel transformer gravimeter as an AGS gravimeter. The transformer gravimeter contains a sensitive element consisting of a magnetic circuit, a movable armature, a primary excitation winding and a secondary output winding having two identical sections. Two sections of the secondary winding are connected in series-opposite, and the movable armature is connected to the motor, which, with a certain period, lowers the armature down and lifts it up along the magnetic circuit, and the motor is controlled by a switching device connected to the control voltage source, and the output signal from the secondary output winding is fed to the input of the output signal calculator, where an output signal is generated that is proportional to twice the value of the gravitational acceleration. A transformer gravimeter is a means of measuring the vertical component of the gravitational acceleration vector from an aircraft and can be used in the field of geodesy, geophysics, in particular, in the formation of reference gravimetric grids in hard-to-reach areas of the globe, as well as in aircraft and rocket building. The transformer gravimeter is part of the aviation gravimetric system placed on the aircraft.

Near-to-Zero Switching Synchronization Approach for DC Electromagnet Actuated Relays

This article puts forward an idea for dc electromagnetically (EM) actuated switching devices operation improvement by means of an electronic controller application. The idea is aimed at applying compensation for the movable armature inertia and the time required for coil (de)energization. Based on the results of the measurements of the tested contactors switching parameters, the most efficient (de)energizing conditions for “near–to–zero” synchronized switching (NZSS) method application were determined. The NZSS process realization approach operates on the principle of controlling the driving coil supply voltage delivery moment. By means of the same controller circuit, voltage-zero synchronized contacts making and current-zero synchronized contacts breaking operations were realized. The method was experimentally verified for various supply conditions and load parameters. Long-term tests confirm the suitability of the method for low-voltage (LV) EM actuated switching devices. The circuit was able to control various EM drives with no modification required for the structure in which it was used.

3-D Hybrid Analytical Prediction Model for Air-Cored Linear-Rotary Induction Machine

This article presents a 3-D hybrid analytical prediction model for an air-cored linear-rotary induction machine (LRIM) in which its columnar movable armature surfaced with the conductor. The analytical magnetic distributions in the conductor and air gap of the LRIM are predicted by employing a group of H-formulations in the conductor and the Laplacian equations with magnetic scalar potential (MSP) in the others in the Cartesian coordinate. The correctness of the magnetic field distributions and the eddy-current distributions is verified by the numerical computational results using the 3-D finite-element method (FEM).

Adaptive mechatronic mechanism information model

Defect-free machining of materials and products with a strictly organized anisotropic structure (polymer composite materials), with an uneven change in physical and mechanical properties throughout the volume (synthegran) or with high strength properties (artificially grown superhard ruby and leucosapphire crystals) is either impossible or not economically feasible on modern CNC technological machines. The reason for this is the lack of information about the power parameter, e.g., the machining force and torque. Therefore, the use of the developed adaptive mechatronic mechanism (AMM) module, which implements parametric stabili-zation of the power machining parameter in an open-loop control system, was an effective solution to this technological problem.An analysis of the issue state in the field of mechatronic and intelligent machines has shown that to date, mechatronics as a science sys-tematically combines mechanics, electronics,and informatics (computer science). Moreover, the term informatics indirectlyreflects another component of mechatronics –automation. In this regard, two main methods of automatic control are considered: by deviation in a closed system with feedbackand by disturbance in an open system without feedback on the controlled parameter.Examples of open-loop systems with disturbance control, in which the “disturbance compensation principle” is implemented, are given. This method cannot be replaced in the absence of sensors –sources of information about physical processes in technological machines for various purposes, for example, in machine tool building, biomedicine, nuclear and military technology. As a rule, in all these ma-chines there is a reciprocating movement of the working body (tool).The information model of the AMM module presented in the article reflects its main elements and characteristics, including driving forces (electromagnetic and electrodynamic), a ball-bearing screw mechanism, a fixed (unmovable) stator with a field winding and a movable armature with armature winding.The place of this article in the general system of scientific research on the formulated new scientific direction “Mechatronic and intelligent technologi-cal machines”is shown. This articleis an introduction to this scientific direction, when automatic regulation “by disturbance”is per-formed in a mechatronic machine, i.e., the principle of disturbance compensation is fulfilled.

Development of a new method of diagnostics electromagnetic drive power and commutation mechanisms

A new method for diagnosing power and switching electromagnetic mechanisms containing a control electromagnet and a movable armature is proposed. The movable element of the diagnosed electromagnetic mechanism (EMM) is irradiated with a high-frequency probing electromagnetic field and the reradiated electromagnetic field from it is recorded. The source of the probing field and the receiver of the re-radiated field is the EMM electromagnet winding. The probing electromagnetic field is formed by imposing on the low-frequency high-voltage operating voltage of the supply winding of the electromagnet EMM an additional high-frequency low-voltage voltage. The diagnostic parameter is determined by algorithmic processing of the measurement results of the magnitude of the voltage increment on the EMM winding, caused by exposure to a reradiated electromagnetic field, and the technical condition of the diagnosed electromagnetic mechanism is determined by the absolute value of the di-agnostic parameter. The method allows to diagnose the current state of the main functional units of the EMM and to control its operating modes as a whole.

Switching-On Operation of an Electromagnetic Relays Optimization Using a Phase Control Approach

The presented research activities deals with the idea of electromagnetically actuated switching devices switching- on process improvement by means of an electronic controller application. Based on the analysis of the results of the electromagnetic contactors dynamic at switching- on selection, the most efficient condition was determined. Making process improvement methods based on the principle of controlling the supply voltage phase were presented in this article: selected dynamic parameters at switching- on optimization in view of its parameters values minimization and intelligent compensation of the movable armature inertia using predictive control of the driving coil supply voltage. Experimental verification of the developed controller confirmed its applicability for various contactor types. Tested objects increased its ability for “near to zero,” switching- on operation realization and selected parameters optimization without the necessity of device construction modification.

Development of a high sensitive inductive movement sensor

Research on a contact induction displacement sensor over short distances is presented. A ferrite core with a winding and a movable armature is used as a sensor. There is an air gap between the core and the armature. To solve the problem of improving the accuracy of measurement, the sensor is included in the bridge measuring circuit, which is powered by high-frequency alternating current. To increase the sensitivity of the indicated sensor to movement, a differential circuit for its inclusion is proposed. Also, in order to increase sensitivity, the resonant mode of operation of the bridge measurement circuit is used. To maintain a constant voltage of the power generator, a phase-locked loop is used. As a result of the study of the induction displacement sensor, practical results were obtained with a maximum displacement of ±0.6 mm. The sensor has not been studied for large displacements, since with an increase in the indicated displacement, the nonlinearity of the displacement-current transformation appears. The maximum sensitivity of the differential sensor in the indicated range of movement 2.44 μA/μm is obtained without the use of a phase-locked loop. The use of a phase-locked-loop frequency adjustment system increased the sensitivity to 3.48 μA/μm. During the study, the dependence of the sensitivity of the sensor on the frequency of the power generator was determined, which allows to determine the optimal power frequency of the measuring bridge circuit. Studies have shown that the use of contact inductive meters have the prospect of application and reserves for improvement. And the use of differential inclusion of the sensor and the resonant mode of operation gives a significant increase in the sensitivity of the primary transducer at small displacements. An inexpensive sensor has been developed that will be useful for many applications where it is necessary to measure displacements and linear dimensions by contact methods

Analysis of design features of inductive electromagnetic current limiter

The design circuits of an electromagnetic short-circuit current limiter of inductive type with movable armature and moving core are considered. A comparative analysis of the design features of the electromagnetic current limiter with copper or superconducting winding is carried out. The operation principle of the electromagnetic short-circuit current limiter of inductive type with copper or superconducting winding is considered. The peculiarities of operation modes of the electromagnetic short-circuit current limiter of inductive type with copper or superconducting winding are analyzed. Using results of the mathematical modeling of the magnetic system of the electromagnetic short-circuit current limiter by the Finite Element Method in the FEMM software environment, the character of the distribution of the magnetic flux density in the nominal mode and in the current limiting mode is determined, which allows to determine the parameters of the current limiter and design features. In accordance with the design features of the electromagnetic short-circuit current limiter of inductive type, the sequence of calculation of the basic parameters of the magnetic system, taking into account the voltage drop factor, is given. The basic equations of the electric equilibrium of the voltage drop of the electromagnetic short-circuit current limiter of inductive type for nominal mode and short-circuit conditions are given. The use of the design circuit of the electromagnetic short-circuit current limiter with superconducting winding can provide energy-saving in nominal mode. The use of high-temperature superconducting wire due to increased critical parameters will ensure preservation of the superconducting state of the winding in short-circuit mode.

ELECTROMECHANICAL PROCESSES IN A LINEAR PULSE-INDUCTION ELECTROMECHANICAL CONVERTER WITH A MOVABLE INDUCTOR AND TWO ARMATURES

Purpose. The purpose of the paper is to determine the influence of the height of the mobile and stationary disk electrically conductive armatures covering the movable inductor on the electromechanical processes of linear pulsed-induction electromechanical converter (LPIEC). Methodology. With the help of the developed mathematical model that describes electromechanical and thermal processes of LPIEC, the influence of the heights of the armatures on electromechanical processes, the values of the electrodynamic forces acting on the inductor and armature, and the moving speed of the movable armature (MA) is established. Results. It is shown that if the height of the stationary armature (SA) is twice the height of the MA, then the inductor at the initial instant of time is acted upon by electrodynamics forces pressing it to the SA, and the displacement of the inductor begins with a delay of 0.35 ms. If the height of the MA is twice the height of the SA, then the electrodynamics forces act on the inductor at the initial instant of time, repelling it from the SA, and its movement begins with a delay of 0.1 ms. If the heights of the SA and the MA are equal, then until the time 0.15 ms on the inductor, the electrodynamics forces practically do not act and the inductor moving relative to the SA begins with a delay of 0.25 ms. Originality. The effect of the geometric parameters of the SA and MA on the velocity of the inductor moving relative to the SA, MA relative to the inductor and the MA relative to the SA is established. It has been established that the highest velocity of the MA relative to the SA develops the lowest MA, and the height of the SA does not affect it practically. However, with the increase in the height of the MA, the effect of SA begins to affect. In this case, it is expedient to select the height of the SA to be 0.4-0.42 of the height of the inductor. Practical value. It is shown that as the weight of the actuating element increases, the currents in the active elements of the LPIEC increase, the induction velocities of the inductor relative to the SA and the MA decrease relative to the inductor. At the same time, the maximum the electrodynamic forces values acting on the inductor decrease, and the armatures increase. Moreover, the maximum the electrodynamic forces acting on the MA are less than similar forces acting on the SA.

INVESTIGATION OF THERMAL PROCESSES IN A LINEAR PULSE-INDUCTION ELECTROMECHANICAL CONVERTER OF CYCLIC ACTION

Purpose. Investigation of the influence of the intensity of cooling of active elements and the period of succession of power pulses on the thermal processes of linear pulse-induction electromechanical converter (LPIEC) operating in a cyclic mode. Methodology. The electromechanical and energy processes of LPIEC, which arise during the direct course of the working cycle, are investigated. It is shown that by the end of the operating cycle, a significant part of the energy is stored in the capacitive energy storage device, and is also converted into thermal energy of the armature and inductor. With a significant number of operating cycles, an unacceptably high temperature rise of LPIEC active elements occurs. To solve this problem, intensive cooling of the winding of the inductor, the movable armature or both of them, as well as an increase in the pulse repetition period are used. It has been experimentally established that when the LPIEC is operating in a cyclic mode, the inductor winding with a steel frame blown with air is heated more slowly than the winding with an insulating frame. The experimental dependences with an accuracy of 6 % coincide with the calculated results. A constructive scheme of the LPIEC of cyclic action with intensive cooling of the stationary winding of the inductor has been developed. Results. A mathematical model of the LPIEC of cyclic action is developed, taking into account a complex of interrelated electromechanical and thermal processes. The solutions of its equations are represented in a recurrent form. The electromechanical and energy processes of LPIEC, which arise during the direct course of the working cycle, are investigated. It is shown that for a considerable number of operating cycles, unacceptably high temperature excesses of active elements of the LPIEC are observed. It is shown that intensive cooling of the winding of the inductor, the movable armature or both of them, and also the increase in the pulse repetition period ensure the temperature stabilization of the LPIEC. Measurements of the temperature on the surface of the winding of the inductor LPIEC during cyclic operation are carried out. A constructive scheme of the LPIEC of cyclic action with intensive cooling of the stationary winding of the inductor has been developed. Originality. A mathematical model of the LPIEC of cyclic action is developed, taking into account a complex of interrelated electromechanical and thermal processes. The solutions of its equations are represented in a recurrent form. It is shown that by the end of the working cycle a significant part of the energy is converted into thermal energy of the armature and inductor. It is determined that for a significant number of operating cycles, unacceptably high temperature excesses of active elements of the LPIEC are observed. It is shown that intense cooling of active elements, as well as an increase in the pulse repetition period, ensure the temperature stabilization of the LPIEC. A design scheme of the LPIEC with intensive cooling of the stationary winding of the inductor has been developed. Practical value. It is shown that by thermal cooling of at least one of the active elements and by increasing the pulse repetition period, the temperature stabilization of the LPIEC is ensured. A constructive scheme of the LPIEC of cyclic action with intensive cooling of the stationary winding of the inductor has been developed.

Durability and Reliability of Electro-Mechanical Relays for Oil and Gas

AbstractElectro-mechanical relays (EMRs) are widely used in variety of manufacturing industries including oil and gas. One of their applications in the oil and gas industry is in the design of downhole logging wireline and measurement-while-drilling/logging-while-drilling (MWD/LWD) instruments such as magnetic resonance instruments, formation testing instruments, cement bond tools, etc.EMRs are mainly electrically operated switches that multiplex high-powered circuits using a low-power signal. Typically, EMRs consist of one or two wire coils wrapped around magnetic cores, a movable armature, and a set of contact(s) that reside inside a sealed vacuum compartment.The structural durability and reliability of EMRs has been the subject of research for many years, and these characteristics are considered a prime reliability concerns in the oil and gas industry. Their poor reliability has been documented by their several inherent failure modes, e.g., limited life expectancy due to shock, vibration, temperature and moisture, thermal stresses caused by soldering, contact wear, contact bouncing, and contact arcing/welding.This paper presents results from a reliability study and an engineering assessment to determine the applicability and functionality of EMRs in electromagnetic-acoustic sensors. The discussion includes steps to improve and minimize the risk.

The method for detecting defects in movable armature of the signalling relay

Despite significant progress in the development of microelectronic rail automatic systems observed in recent decades, relay-contact devices are still widely used in railway signalling systems, that are fundamental to the safe operation of railways and must perform predictably and reliably.Thus, signalling relays used for safety-critical or safety-related applications in railway signalling systems should be properly maintained and tested to ensure their performing safely and reliably throughout their expected service life.With the purpose of developing a method for detecting defects in movable armature of the signalling relay, the time dependences of transient currents during relays switching have been investigated for relay in various technical conditions: in operable condition, as well as with artificially created defects (bends) of contact springs. The measured data have been analyzed in the time and frequency domain using the wavelet transform modifications (CWT, DWT, DWPT).The analysis of the transient currents was carried out using segmentation of the current characteristics of the relay. The relay transient current at first and third segments which corresponded to unmovable anchor state, increase with time during relay switch-on approximately as the exponential function.The time constants of the relay current were calculated by approximating the measured current-time dependences at the first segment of the current curve by exponential function.The presence of defects in the movable armature of the relay had practically no effect on the values of calculated time constants.However, these values strongly depended on the technical condition of the relay magnetic circuit and the relay coil, as well as on the voltage applied to the coil terminals. This behavior of the relay time constant on the first segment of the relay current characteristic makes it possible to use this parameter to monitor the technical state of the electromagnetic relay system.Defects of the armature and contact springs led to the appearance of additional features at the second segment of the relay transient current, which corresponded to the movement of the armature. The magnitude of these features on the current curve depended on the value of bending of the relay's contact spring. The width and appearance time of the features at the second segment of the current-switching curve correspond to the non-simultaneous switching of the relay contacts. To determine the amplitude (energy) of these features (peaks) on transient current curve, their duration and the times of appearance, the wavelet transform was used. The results of investigations confirmed the possibility of determining the defects of the relay movable armature by using wavelet analysis of the second segment of the relay transient current characteristic.

Investigation the Effect of B Dot Probe Positions in 500kJ Pulsed Power Supply System using MATLAB Simulation

In a rail gun a small sensing coil named B dot probe is kept over the path of armature which generates the signal from an induced voltage based on faraday's law. The output signal which is generated from the B dot probes consist of a positive and negative elements. The zero-crossing point in the output signal is hypothetical to be the time of passage for the centroid of the armature current, and the zero-crossing times from different probes kept along the length of the rails are on the whole employed to find out the velocity of the projectile. Pulsed power supply system has got a significant role in rail gun system as it gives an enormous electrical energy in a short duration of time to accelerate the movable armature with higher velocity. Pulsed power supply system which is generally capacitor based are the most well-known form of pulsed power supplies system used in rail gun investigation for the past several years. In India for surface fire support, 500-kJ capacitor module pulsed power system design which is capable to accelerate the projectile with a velocity of 1km/s to 1.5km/s, is currently under investigation. In this paper an effort is made to design a 500kJ PPS using MATLAB in order to predetermine the gun parameters such as acceleration of the projectile, muzzle velocity, peak current, current at exit, and also effective barrel length. In general the capacitors are grouped into modules and they are triggered at different time to get desired parameters of rail gun. In this work the capacitors are grouped in five modules and modules are triggered by using projectile positions and projectile position is being identified by using B dot probes positions.

A New Model of Electromechanical Relays for Predicting the Motion and Electromagnetic Dynamics

In this paper, a novel multiphysics and nonlinear model for electromechanical relays is presented. The electromagnetic dynamics is analyzed by calculating the total reluctance of the magnetic equivalent circuit (MEC), which is composed of a fixed length iron core and an angular air gap. Magnetic saturation and angular dependency of the reluctance are considered in the analysis. Then, an energy balance over the electromagnetic components of the system is used to obtain the torque which drives the movable armature. A planar mechanism of four rigid bodies, including spring-damping torques that restrict the motion and model the contact bounces that occur in the switchings, is proposed to explain the dynamics of the movable components. Experimental tests show the accuracy of the model in both the electromagnetic and the mechanical parts.

Mechanical Analysis of Power Electromagnetic Contactors

This paper presents an analysis of the drive mechanism of an AC three-phase electromagnetic contactor. One of the key-feature of the drive mechanism is the strength characteristic, which has been established from experimental tests. A good correlation between strength torque characteristic and the mechanical characteristics of the drive coil for different voltage supply (from 1.1 to 0.7 of rated voltage) has been observed. The recorded oscillograms of the time evolution of the trip of the movable armature, allow to obtain the connection time and the disconnection time of the contactor. Also, the drive coil has been supplied with variable voltage (from 1.1 to 0.7 of rated voltage). The connection and disconnection times are important parameters related to the contactor behaviour from mechanical point of view.

Mechanical Analysis of Power Electromagnetic Contactors

This paper presents an analysis of the drive mechanism of an AC three-phase electromagnetic contactor. One of the keyfeature of the drive mechanism is the strength characteristic, which has been established from experimental tests. A good correlation between strength torque characteristic and the mechanical characteristics of the drive coil for different voltage supply (from 1.1 to 0.7 of rated voltage) has been observed. The recorded oscillograms of the time evolution of the trip of the movable armature, allow to obtain the connection time and the disconnection time of the contactor. Also, the drive coil has been supplied with variable voltage (from 1.1 to 0.7 of rated voltage). The connection and disconnection times are important parameters related to the contactor behaviour from mechanical point of view. Keywords: Electromagnetic Contactor, Drive Mechanism, Trip Characteristic.

Study on the Air Damping of the Movable Armature

The distance of air gap is much larger than the mean free path of gas molecules for MEMS devices with small vibration. The nonlinear Reynolds equation can be transformed into linear Reynolds Eq. based on this condition and under certain assumptions. Then the mathematical model of damping of the movable armature is established with the linear Renault equation. The damping characteristics of the movable armature are studied based on the damping force mathematical model. The relation of damping coefficient and the dimensions of movable armature, the dimensions of air gap are analyzed. The research in this paper provides references for the design and analysis of the damping coefficient of the MEMS devices with small vibration.

The permeance in magnetic circuits

The field distribution of a magnetic circuit, and the forces acting on a movable armature, is always possible to solve when all permeances and their derivatives are known. An airgap can be seen as an ideal permeance surrounded by fringe and edge permeances, and accurate formulas have been found by conformal mapping. A suitable computer program is indicated.