Electromechanical Switching Devices Research Articles

Run-to-Run Adaptive Nonlinear Feedforward Control of Electromechanical Switching Devices

Feedforward control can greatly improve the response time and control accuracy of any mechatronic system. However, in order to compensate for the effects of modeling errors or disturbances, it is imperative that this type of control works in conjunction with some form of feedback. In this paper, we present a new adaptive feedforward control scheme for electromechanical systems in which real-time measurements or estimates of the position and its derivatives are not technically or economically feasible. This is the case, for example, of commercial electromechanical switching devices such as solenoid actuators. Our proposal consists of two blocks: on the one hand, a feedforward controller based on differential flatness theory; on the other, an iterative adaptation law that exploits the repetitive operation of these devices to modify the controller parameters cycle by cycle. As shown, this law can be fed with any available measurement of the system, with the only requirement that it can be processed and converted into an indicator of the performance of any given operation. Simulated and experimental results show that our proposal is effective in dealing with a long-standing control problem in electromechanics: the soft-landing control of electromechanical switching devices.

Visualization and Characterization of Cumulative Arc Erosion Behavior Using 2-D Microscopic Images

The electrical arc erosion behavior extremely limits the lifespan of electromechanical switching devices. Observation of the gradual evolution of arc erosion is highly beneficial for to understand the arc ignition and the contact degradation. In this article, the erosion of contact materials is simulated and visualized in situ with the recorded 2-D microscopic images. A novel method for erosion area identification is proposed with the combination of difference image method and mathematical morphology operations. The variation in erosion area as a function of switching current cycles is demonstrated, and the center of erosion zone that migrates continuously during the endurance experiment is determined. Finally, not only three types of arc erosion regimes (centralized arc erosion, separated arc erosion, and commutated arc erosion) are revealed, but also the associated occurrence probabilities during 1000 cycles are provided.

Structure and electronic properties of single-walled C3N nanotubes

Abstract One-dimensional nanotubes have become an indispensable ideal candidate material for nano-device applications due to their excellent and unique electronic, mechanical, and thermal properties. By the first-principles method of density functional theory, we have theoretically investigated the structural stability, electronic properties, carrier mobility, and Poisson's ratio of C3N single-walled nanotubes (C3NSWNT). We find that C3NSWNT is stable and the ground state of the system is non-magnetic. The electronic properties and carrier mobilities of C3NSWNT can be adjusted by diameter and edge engineering. The electron mobility of (n,n) armchair C3NSWNT (A-C3NSWNT) is lower than that of (n,0) zigzag C3NSWNT (Z-C3NSWNT), but the hole mobility of (n,n) A-C3NSWNT is higher than that of (n,0) Z-C3NSWNT. Moreover, both A-C3NSWNT and Z-C3NSWNT can transfer from semiconductor to metal by tuning the electric field, and Z-C3NSWNT is more sensitive to the applied electric field than A-C3NSWNT due to smaller energy gap. But only A-C3NSWNT can transfer from semiconductor to metal by tuning strain, and be more suitable to the application in nano electromechanical switching devices. These research results may provide some theoretical support for the potential application and development of nanoelectronic devices based on C3NSWNT.

PECULIARITIES OF CALCULATING STATIONARY HEATING OF WINDINGS OPERATING IN COMPLEX FORCED CONTROL SYSTEMS

General description of the research topic. A technique and an algorithm for calculating the thermal field of electromagnets operating in complex forced systems proposed by authors are considered. The widespread use of such devices in electromechanical switching devices allows not only to increase their speed but also significantly reduce the size, mass and energy losses, which indicates the relevance of this topic. The mathematical model of heating the windings of forced electromagnets proposed by the authors is a system of 1D differential equations of stationary heat transfer in a cylindrical coordinate system, supplemented by equations of electrical and magnetic circuits. This model allows to take into account the ripple of the currents in the windings and the losses in the magnetic core due to these ripples, contains certain signs of scientific novelty and represents the goal of the paper. The algorithm developed by the authors for calculating the thermal field of electromagnets operating in forced control systems is a complex iterative cycle. Its implementation is greatly simplified by using the Maple computing environment which allows to realize complicated and cumbersome mathematical transformations, automates the process of computations, and obtain results of numerical simulation in a convenient tabular and/or graphic form, which indicates the practical significance of this works. The results of comparison of computation results with experimental data presented in the paper indicate the adequacy of the model and algorithm proposed.

APPLICATION OF THE COMPUTING ENVIRONMENT MAPLE TO THE CALCULATION OF THE DYNAMICS OF THE ELECTROMAGNETS IN THE COMPLICATED SYSTEMS OF FORCED CONTROL

General description of the research topic. The authors propose a technique for calculating the dynamics of electromagnets operating in complex forced systems. Such forced electromagnets are widely used in electromechanical switching devices, in particular in vacuum contactors, to reduce their size, energy consumption and to increase speed, which indicates the relevance of this topic. A mathematical model of the dynamics of a forced electromagnetic system, which takes into account the peculiarities of behavior in transients of its individual elements – the mechanical system, the magnetic and electrical circuits, taking into account the interaction of the electromagnet with a control device when the apparatus is activated, contains certain signs of scientific novelty and is the purpose of the paper. The technique of calculating the dynamics of forced electromagnets uses the computing environment Maple. The calculation is based on a mathematical model, which is a system of nonlinear differential equations of the magnetic and electric circuits, supplemented by the equations of motion of the elements of a mechanical system. The use of the computing environment Maple, applied here to automatically perform the mathematical transformations, allows avoiding the complicated processes of choosing the numerical integration method, programming of complex and cumbersome equations and numerical integration procedures, to obtain results of calculations in convenient tabular and/or graphic form. This specifically indicates the practical significance of this work. The results of the comparison of calculations with previously published experimental data presented in the paper indicate the high efficiency of the proposed models and techniques.

Isolation of Single-Wired Transition-Metal Monochalcogenides by Carbon Nanotubes.

The successful isolation of single layers from two-dimensional (2D) van der Waals (vdW)-layered materials has opened new frontiers in condensed matter physics and materials science. Their discovery and unique properties laid the foundation for exploring 1D counterparts. However, the isolation of 1D vdW-wired materials has thus far remained a challenge, and effective techniques are demanded. Here we report the facile synthesis of isolated transition-metal monochalcogenide MoTe nanowires by using carbon nanotubes (CNTs) as molds. Individual nanowires are perfectly separated by CNTs with a minimal interaction, enabling detailed characterization of the single wires. Transmission electron microscopy revealed unusual torsional motion of MoTe nanowires inside CNTs. Confinement of 1D vdW-wired materials to the nanotest tubes might open up possibilities for exploring unprecedented properties of the nanowires and their potential applications such as electromechanical switching devices.

Визначальні фактори зносостійкості контактів електромеханічних комутаційних апаратів

The article imposed the influencing factors to the performance of the contacts of electromechanical switching devices and conditions for enhancing their durability. Made the attempt to generalize and systematize the impact of these factors on the durability and functionality of contacts switching devices with a view to finding new opportunities for improving the performance of electric aparatus through the development and application of new contact materials, improving the design of contacting and extinguishing systems and others.

Pre-Conditioning Automotive Relay Contacts to Increase Their Resistance to Dynamic Welding

Electromechanical switching devices such as relays may be surprisingly forgiving to occasional, but temporary, electrical stress beyond specification. Consequently delayed openings due to welded contacts on the order of milliseconds usually have been unnoticed and hence have not been reason for concern. However, as electrical systems of vehicles are getting smarter and more and more diagnostic routines are being implemented, even such short delay times may be translated as errors. Pre-conditioning contact surfaces has been explored as a measure to increase the welding resistance and eliminate contact opening delays. The 20-A-class relay investigated has been optimized to break occasional current peaks up to 80 ADC.

Effects of different loads on the surface of silver metal oxide contacts for general-purpose relays

Silver metal oxides have become very popular as contact materials in electromechanical switching devices due to their high resistance to erosion and contact welding. Initially, these materials were developed for contactors and circuit breakers. Investigations on silver metal oxide contacts for general-purpose relays were conducted in order to gain an insight into the effects and failure mechanism of such contacts under specific loads, such as resistive and inrush current loads. It will be shown that contact failures may be influenced by very thin silver layers on the surface of silver metal oxide materials and the behavior of these layers at thermal stress. The silver layers are a result of the mechanical treatment in the production of rivets and the following riveting process. The results support the development of new silver metal oxide materials for general-purpose relay applications.

Nanoelectromechanical switches with vertically aligned carbon nanotubes

Electromechanical switching devices have been fabricated successfully employing vertically grown multiwalled carbon nanotubes (MWCNTs) from the prepatterned catalyst dots on the patterned device electrodes. The devices show various interesting switching characteristics depending on the length and the number of MWCNTs used. The device design not only simplifies the fabrication process, but also improves the integration density greatly. The device has a great potential in realizing technically viable nanoelectromechanical systems, such as switch, memory, fingers, or grippers.

An overview of today's thick-film technology

How thick-film systems are used in all facets of today's electronic industry, starting with their initial application in the computer and defense industries, is described. As the state of the art grew, composition suppliers broadened their lines, developing new higher performance materials to meet changing and more sophisticated packaging requirements. The present technology offers advantages of simple processing, fast and inexpensive tooling systems, economy, quick tumaround time between need and prototype, using wider tolerance active devices, high reliability, and multilevel circuit capabilities. As a result, virtually all sectors of today's electrical and electronics industries are turning to solid-state systems which utilize thick-film hybrid microcircuitry. Consumer and automotive electronic uses are exhibiting the highest rate of new thick-film circuitry adoption at the present time. Industrial usage for high power, measuring and control systems, is also increasing rapidly, and thick-film hybrid circuits are strong candidates to replace electromechanical switching devices. The use of. hybrid microcircuits is forecasted to double or triple current usage on a worldwide basis by 1975. In the future, thick films are expected to play an ever increasing role in the packaging of semicpnductor devices because of their low production cost and high performance advantages.

Electromechanical switching devices: reliability, life and the relevance of circuit design : A. G. Leighton, Radio Electron. Engr., February (1966), p. 99

As the role of computational models has increased, the accuracy of computational results has been of great concern to engineering decision-makers. To address a growing concern about the predictive capability of the computational models, this paper proposes a hierarchical model calibration procedure with a statistical model calibration technique. The procedure consists of two activities: (1) calibration planning (top-down) and (2) calibration execution (bottom-up). In the calibration planning activity, engineers define either physics-of-failure (PoF) mechanisms or system performances of interest. Then, an engineered system can be decomposed into subsystems or components of which computational models are better understood in terms of PoF mechanisms or system performances of interest. The calibration planning activity identifies vital tests and predictive models along with both known and unknown model input variable(s). The calibration execution activity takes a bottom-up approach, which systematically improves the predictive capability of the computational models from the lowest level to the highest using the statistical calibration technique. This technique compares the observed test results with the predicted results from the computational model. A likelihood function is used for the comparison metric. In the statistical calibration, an optimization technique is integrated with the eigenvector dimension reduction (EDR) method to maximize the likelihood function while determining the unknown model variables. As the predictive capability of a computational model at a lower hierarchy level is improved, this enhanced model can be fused into the model at a higher hierarchical level. The calibration execution activity is then continued for the model at the higher hierarchical level. A cellular phone is used to demonstrate the hierarchical calibration framework of the computational models presented in this paper. It is concluded that the proposed hierarchical model calibration can effectively enhance the ability of the computational model to predict the system reliability of the cellular phone system.

Electromechanical switching devices—Reliability, life and the relevance of circuit design

The design and method of manufacture of an electromechanical switching device will largely determine its inherent reliability, but its actual reliability, when incorporated in a complex circuit, will be very dependent on its mode of use. It is the purpose of this paper to stress those aspects affecting reliability which are within the orbit of influence of the user. While general factors affecting the reliability of the main types of electromechanical switching devices are discussed, emphasis is placed on the performance of electrical contacts and the ways in which improved performance can be obtained.

Electromechanical switching devices: reliability, life and the relevance of circuit design

Electromechanical switching devices are grouped broadly into two classes: those which can be used to choose a specific set of contacts from a considerable number of selections, e.g. rotary switches, and those which when operated or released will establish or break the same set of contacts, e.g. relays. Both groups of devices are discussed in considerable detail from the point of view of reliability, and suggestions for maintenance organization are given. A variety of quenching techniques to minimize damage to the contacts are described. Some aspects affecting circuit design are also treated.

The examination of electric contacts by the plastic replica method

ELECTROMECHANICAL switching devices, typified by the relay, are used by millions in the communications industry and have been developed to a high degree of perfection and specialization. Their reliability is such that only a few failures per billion contact operations are expected under telephone operating conditions. The use of twin contacts of noble metals, improved contact actuation, erosion control, and cleaner operating environments all have contributed to this perfection.