Armature Movement Research Articles

Analysis of Dynamic Parameters of the Switching-On Process of Electromagnetic Relays Powered by Harmonic Polluted Voltage Source

The article incorporates an analysis of the switching-on process of alternating current (AC), low-voltage (LV), and electromagnetic (EM) relays energized by harmonically polluted voltage sources. In the undertaken research, the dynamic parameters of relays actuated by electromagnetic drive were examined for shape and supply voltage waveform distortion levels as described by different THD factor values. During the research, diverse supplying voltages were delivered to drive electromagnet coils at a variety of phases so as to reflect the stochastic nature of the energizing procedure. The performed analysis allowed for determining the most influential and decisive factors dictating the basic parameter values of the switching-on process. As an outcome, time-related parameters of relay moving armature movement were obtained, and the frequency of disorder occurrences during the switching-on was examined. For experimentation needs, an experiment stand was developed, and dedicated software for measurement results analysis was elaborated. Based on the study results, EM relay switching-on operation reliability was evaluated in view of electric energy quality.

Three-dimensional magneto-thermo-mechanical coupling analysis with the influence of velocity skin effect

In this paper, the three-dimensional magnetic diffusion governing equations of an electromagnetic railgun are derived based on Maxwell’s equations and coupled with the energy equations. The finite element method is used to calculate the current density, temperature, and electromagnetic force distribution for armature velocities of 0, 200, 600, and 1200 m/s. The results show that there is a current concentration phenomenon on the rail’s inner surface and the trailing edge of the contact interface; the temperature rise of the rail along the moving direction of the armature tends to decrease, and ablation occurs at the corner of the moving armature’s trailing edge. An increase in the velocity of armature movement results in an increase in the electromagnetic forces on the armature and contact surface. This model can effectively represent the variation of each physical quantity with velocity and provide direction for the optimal design of the rail and armature.

Armature Electromagnetic Force Extrapolation Prediction Method for Electromagnetic Railgun at High Speed

The analysis and calculation of the armature electromagnetic force is the premise of studying the dynamic characteristics of the electromagnetic railgun. Aiming at the problem of the numerical solution “pseudo-oscillation” at high speed, an extrapolation prediction method of armature electromagnetic force based on the Deep Belief Network-Deep Neural Network (DBN-DNN) is proposed. Firstly, the electromagnetic field control equation and armature dynamics equation, considering the influence of armature movement, are given, and the finite element simulation model of the electromagnetic railgun is established to analyze the dynamic characteristics and numerical solution stability of the armature electromagnetic force. Then, based on the stable numerical simulation data under different armature conductivities, a DBN-DNN method is proposed to realize the extrapolation prediction of the armature electromagnetic force under the standard conductance. Finally, the extrapolation prediction performance of the proposed method is tested by two electromagnetic railgun cases. Additionally, we further propose the training strategy of DBN-DNN parameters from solving armature electromagnetic force at low conductivity to standard conductivity. The armature electromagnetic force extrapolation prediction method for the whole launch process from low speed to high speed provides a new idea for the dynamic characteristic analysis of the high-speed electromagnetic railgun.

Level‐set‐based method for designing novel brushed synchronous machines

AbstractNowadays, research on electromagnetic devices increasingly focuses on multiphysics three‐dimensional complex systems. However, this kind of simulations require huge computational resources and consequently very high CPU time. Ristagno et al. proposed a level‐set based method allowing meshing step savings in any iterative processes (as movement modeling or optimization processes). The level‐set method lies in implicit description of moving fronts as described in the study by Osher et al. (1988). Inspired by Räisänen et al., all physical parameters (material properties, supply or armature movement) are implemented by projection of mathematical functions. In this paper, the authors proposes to study and design a new kind of mechanical commutator for DC machines thanks to this coupled method. Indeed, there is a renewed interest in DC machines because they can be suitable for small mobilities. To be noted, small mobility concerns all kind of vehicles (2 wheels–4 wheels–autonomous vehicles such as drones) that have speeds below 50 km/h. However, specifications for traction applications are difficult to achieve for such a rustic machine and requires some modifications. That is why, inspired by usual synchronous machine, the commutator has been redesigned to obtain expected theoretically signal waveform. Furthermore, numerical coupled simulations have been used to design both machine and supply simultaneously. This work has led to the manufacture of a proof of concept and preliminary results are very promising.

Three-dimensional numerical simulation of multi-physical coupled environment during electromagnetic propulsion

Electromagnetic propulsion technology is a new propulsion technology which uses electromagnetic force to push objects into high or ultra-high speed. However, during propulsion, the armature and launch load are affected by harsh multi-physics environment. The coupled effect was often ignored or over idealized in previous numerical simulations, which leads to large errors between simulation and experiment. In this paper, a three-dimensional multi-physics coupling environment simulation model is established. The distribution of electromagnetic field, structure field and temperature field in armature from static to high speed are effectively calculated. Moreover, the coupled effect between physical fields and the influence of key parameters on the simulation results are revealed. In conclusion, this model can reproduce the physical field distribution of armature and rail during electromagnetic propulsion. The time-varying resistance and inductance and the velocity skin effect (VSE) are the key parameters affecting armature movement. This method reveals a feasible path for the simplification of multi-physical model and the mitigation of extreme environment.

Duality-Derived Models of High-Speed Electromagnetic Valves

The article analyzes a high-speed solenoid valve (HSV) whose core and moving armature are massive elements characterized by strong eddy currents, hysteresis, and saturation. The feedback control employed in obtaining a predetermined nonsinusoidal current in the core coil necessitates the use of a high-frequency pulsewidth modulation (PWM)-like voltage with parameters varying in a manner unknown in advance during the uninterrupted transient. In view of the known difficulties in using finite-element solvers, physical Cauer circuits are found to be a reliable engineering alternative. The use of the duality transformation is proposed to obtain a pure electric model of the core and armature. As a preliminary result, it is found that a threefold reduction in eddy-current loss is achieved by using the slotted core. The results obtained with the model are in a reasonable agreement with the experimental magnetizing current and the armature movement during successive valve operations.

Influence of Armature Movement Velocity on the Magnetic Field Distribution and Current Density Distribution in Railgun

In a railgun, the velocity of the armature has an important effect on the magnetic field distribution and current density distribution of the launch system. However, the calculation models established by scholars were mostly models under static conditions. They could not effectively reflect the velocity skin effect (VSE). This article uses the finite-element softwares COMSOL and LS-DYNA to establish a calculation model that considers the influence of the armature movement velocity on the magnetic field distribution and current density distribution. The calculation results show that when considering the armature movement, the magnetic field distribution of the rail side is very different from the static calculation result. Under the influence of the VSE, the current of the armature/rail (A/R) interface is mainly concentrated on the end of the armature's tail. When considering the armature movement, the values of maximum current density of the rail side doubled. Also, as the armature velocity increases, its range of influence also increases. However, it tends to saturate after reaching a certain velocity. Considering the influence of the armature velocity on the magnetic field distribution and current density distribution can make our results closer to the actual launch situation.

Influence of Breech Busbar on the Recoil Force of Railgun Launcher

The magnitude, distribution, and source of the recoil force play an important role in the launching precision and structural optimization design of the railgun. The breech busbar directly affects the electromagnetic field distribution of the railgun launcher (including armature, rails, and breech busbars), but the influence of the breech busbar on the recoil force of the launcher has not been considered in the previous studies. In this article, the recoil forces of the railgun launchers are studied by changing the structures of the breech busbars. 3-D finite element models of the launchers with flat-plate, swallow-tail, and disk-shaped busbars are established, respectively, and the busbars are fed through six coaxial cables. In the simulation models, the armatures’ movement directions are the positive direction of $Z$ -axis, and the directions of recoil forces are opposite to the armature movement directions. The electromagnetic forces’ distributions of the launchers are calculated by the numerical calculation method. The calculation results show that the breech busbars directly affect the magnitude and distribution of the recoil forces of the rails and the busbars. The $z$ -direction electromagnetic forces on the rails are opposite to the recoil forces, and they are the largest at the contact positions between the armatures and the rails. The electromagnetic forces of the rails can hinder the recoil of the launchers, and their effects on the recoil forces of the launchers cannot be ignored. The $z$ -direction electromagnetic forces on the busbars are in the same direction as the recoil forces, and the recoil forces of the launchers are mainly provided by the busbars. The ratios of the recoil forces to the armature thrust are 0.65, 0.42, and 0.94 for launchers with flat-plate, swallow-tail, and disk-shaped busbars, respectively. It is necessary to consider the influence of the breech busbar on the recoil force of the railgun launcher.

Electric converters of electromagnetic strike machine with battery power

At present, the application of pulse linear electromagnetic engines to drive strike machines for immersion of rod elements into the soil, strike drilling of shallow wells, dynamic probing of soils is recognized as quite effective. The pulse linear electromagnetic engine performs discrete consumption and conversion of electrical energy into mechanical work. Pulse dosing of a stream transmitted by the battery source to the pulse linear electromagnetic engine of the energy is provided by the electrical converter. The electric converters with the control of an electromagnetic strike machine as functions of time and armature movement, which form the unipolar supply pulses of voltage and current necessary for the normal operation of a pulse linear electromagnetic engine, are proposed. Electric converters are stable in operation, implement the necessary range of output parameters control determined by the technological process conditions, have noise immunity and automatic disconnection of power supply in emergency modes.

System Identification and Fault Diagnosis of an Electromagnetic Actuator

The electromagnetic actuators are widely used in the industry due to their simple structure, force characteristics, and low manufacturing costs. However, from control point of view, they are nonlinear systems. In this brief, clustering-based system identification experiments as well as a piecewise mathematical model are described. Furthermore, a model-based fault detection and isolation of the actuator is presented, when the armature movement is sensed indirectly, by sensing only the armature current.

A TECHNIQUE OF EXPERIMENTAL INVESTIGATIONS OF LINEAR IMPULSE ELECTROMECHANICAL CONVERTERS

Purpose. Development of a technique of experimental studies linear pulse electromechanical converters parameters, which are used as shock-power devices and electromechanical accelerators, and comparing the experimental results with the calculated indices obtained using the mathematical model. Methodology. Method of experimental investigations of linear electromechanical converter is that the electrical parameters are recorded simultaneously (inductor winding current) and mechanical parameters characterizing the power and speed indicators of the joke with actuator. Power indicators are primarily important for shock-power devices, and high velocity - for electromechanical accelerators. Power indices were investigated using piezoelectric sensors, a system of strain sensors, pressure pulsation sensor and high-speed videorecording. Velocity indicators were investigated using a resistive movement sensor which allows to record character of the armature movement with actuating element in each moment. Results. The technique of experimental research, which is the simultaneous recording of electrical and mechanical power and velocity parameters of the linear electromechanical converter pulse, is developed. In the converter as a shock-power device power indicators are recorded using a piezoelectric transducer, strain sensors system, pressure pulsation sensor and high-speed video. The parameters of the inductor winding current pulse, the time lag of mechanical processes in relation to the time of occurrence of the inductor winding current, the average speed of the joke, the magnitude and momentum of electrodynamics forces acting on the plate strikes are experimentally determined. In the converter as an electromechanical accelerator velocity performance recorded using resistive displacement sensors. It is shown that electromechanical converter processes have complex spatial-temporal character. The experimental results are in good agreement with the calculated figures obtained by means of a mathematical model that describes the ultrafast electromagnetic, thermal and mechanical processes that occur when the yoke moves relative to the inductor. Originality. For the first time offered during experimental studies of impulse linear electromechanical converter to both to measure the electrical parameters, namely the inductor winding current, and mechanical parameters characterizing the power and velocity performance with yoke actuator. Practical value. The technique of experimental investigations the parameters of the linear pulse electromechanical converter that can be used to investigate the shock-power devices and electromechanical accelerators is proposed.

Measurement of Solid Armature’s In-Bore Velocity Using B-Dot Probes in a Series-Augmented Railguns

The waveform of solid armature displacement and velocity can be obtained by arranging B-dot probe arrays along the barrel of a series augmented railgun. The moment of armature arrival can be detected by an evident change in the differential signal from the B-dot probe while armature passes by. However, it is difficult or even impossible in a railgun to directly pick up the arrival moment, because both armature movement and rail current are responsible for the change of differential signal, especially in the series-augmented railgun where currents in both outer rails and connecting conductors are probably sensed by the B-dot probe. A ratio function (RF) has been introduced to eliminate the influence of current change, which is the ratio of the integral of differential signal to the current. The RF of the armature probe aimed at the armature current will reach a maximum at the moment of armature arrival, while the one at the rail current will reach the median. Three shots with identical initial conditions were conducted in a series-augmented railgun, each of which had adopted the armature probe, rail probe, and Velocity Interferometer System for Any Reflector, respectively. The good agreement between the displacement and velocity waveforms derived from B-dot probes indicated that the method and measurement were valid. The accuracy of the B-dot method is mainly affected by probe dimension and position, railgun current distribution, and electromagnetic noise.

Dynamic response of rails due to armature movement for electromagnetic railguns

An analytical model is proposed to investigate the dynamic behavior of rail under the effect of both the rail repulsive force and the armature contact force. The rail is modeled as a Bernoulli - Euler beam resting on a continuous elastic foundation with simply support at both ends of the rail. Numerical simulations are carried out using the analytical model at below, near and above the critical velocities respectively. The results show that the dynamic response of the rail under the effect of both the repulsive force and contact force is more intensive and complicated than the case in which only the repulsive force acted. The additional oscillations caused by the contact force may increase the possibility of electrical contact failure between the armature and the rails. For more detailed analysis, the analytical model is needed to take into account the varying elastic stiffness and damping effect of practical railgun structure.

Penalty Method Involving Electric Sliding Contact Problem

Basing on governing Maxwell and energy equation of rail gun considering armature movement in two dimension, The total domain to be solved is divided into two subdomains: moving (armature) part and static (rail) part, finite element formulations of two subdomains are built independently, then using the interface condition of two subdomains, formulations are connected by coupled equation which is derived out by penalty method. Shifted physical quantity is used to simulate movement. The final magnetic-thermal coupled fields finite element formulations of rail gun are established by these methods. Numerical calculation results compared by theoretical and other numerical results verify that penalty method is an effective way to deal with electric sliding contact problem associating with Shifted physical quantity method.

Inductance Gradient Variation With Time and Armature Sliding Along the Rails

The inductance gradient is one of the important parameters on the design and evaluation of railgun performance. The size, shape, and material of rails have effects on the inductance gradient. In 2-D analysis, the length of rails assumed to be infinite and then the effect of the armature ignored and a constant inductance gradient is obtained. In 3-D simulations, with assuming a fixed position for the armature (usually in the middle of rail), the inductance gradient can be determined. However, with the moving of the armature along rail length and the increasing of the current path, the applied force on the projectile will be different when it is constant and in the middle of the structure. Therefore, inductance gradient in the structure length will be changed. In this paper, with considering a railgun with copper rails with 1-m length, according to the input current and the resultant force of the aluminum armature in the rail length it was displaced in every step, the inductance gradient was determined. The results show that the amount of inductance gradient is not constant and will be increased with armature movement toward the muzzle.

Transient modelling of a linear induction launcher-type coil gun with two-dimensional cylindrical finite-difference time domain method

Two-dimensional (2D) simulation of a linear induction launcher-type coil gun is performed by the cylindrical finite-difference time domain (FDTD) method. Maxwell's equations in cylindrical coordinates are used to formulate the problem. Circular symmetry is assumed for reducing the 3D problem to a 2D one. A singularity that appeared at r=0 is extracted by using the integral formulation of the FDTD method. A special quasi-static approximation of the FDTD method is applied in the cylindrical problem space which is terminated with the second-order Mur absorbing boundary condition. The armature movement in the FDTD method is treated by the quasi-steady-state method. An experimental model was built, and the muzzle velocity was measured for comparison with the calculated value. Good agreement was obtained.

Using genetic algorithm for the optimization of electromagnetic devices

Stochastic methods offer a certain robustness quality to optimization process. In this paper, the genetic algorithm, based on the computer simulation of the natural evolution, is used for the shape optimization of an electromagnetic actuator. The framework is modeled by a 2D finite element method allowing the computation of the magnetic force. The aim is to obtain a desired force profile considering the armature movement.

Movement simulation of voltage excited electromagnetic field in non-linear electromagnetic device supplied with capacitor

Deals with the coupled field‐circuit simulation of the dynamic state of electromagnetic system with capacitors. Mathematical model of the dynamic phenomena includes: equation of transient electromagnetic field in non‐linear conducting and moving medium, equation of the converter electric circuit and the equation of mechanical motion. The two different methods of grid remeshing according to the armature movement have been proposed. System designed for the ground penetrator of comet landing module has been investigated.

A new algorithm for coupled solutions of electric, magnetic and mechanical systems in dynamic simulation of solenoid actuators

An algorithm is presented for the simultaneous solutions of the coupled electric, magnetic, and mechanical problems in the dynamic simulation of a solenoid actuator. The transient nonlinear field in the coupled problem is analyzed using the finite-element (FE) method, which considers the effects of saturation, eddy current, and armature movement in the actuator. The nonlinear electronic circuit is represented by equivalent circuit equations that are coupled to the FE equations and are solved simultaneously with them in an iterative manner. Dynamic responses of the solenoid actuator predicted by using this algorithm agree closely with experimental results. The advantage of this method is that its principle is applicable to general types of power electronic devices. With suitable modifications, it can be used to simulate the dynamic responses of power-electronic-controlled electric machines.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis and synthesis of an electromagnet used for circuit breaker operation

A particular type of electromagnet, used for circuit breaker operation, is described. The transient state is simulated in order to determine the coil current and the response time of the electromagnet. The simulation is based upon a step by step integration of the electrical circuits' equations and the armature movement. The circuit parameters are determined by interpolation on the "characteristic matrix" of the system which is previously computed with the FLUX2D package. A simulation of the transient state is performed using a grid of static computations. A preliminary optimization approach is performed in order to obtain an acceptable reliability and a minimum breaking time.