Ernesto Tripodi

The Double-Sided Tubular Linear Induction Motor and Its Possible Use in the Electromagnetic Aircraft Launch System

In this paper, a double-sided stator tubular linear induction machine is presented, and its performance is discussed for possible use as a catapult in the electromagnetic acceleration of aircraft. Based on the use of the Fourier transform in the direction of the motion, a semianalytical model that is able to take into account the end effects due to the finite length of the stators is derived. The effectiveness of the model has been proven by comparison with a numerical analysis based on the finite-element method. The reported results obtained using the two methods show excellent agreement that makes the proposed model a valuable tool for a preliminary design of the device.

TUBULAR LINEAR INDUCTION MACHINE AS A FAST ACTUATOR: ANALYSIS AND DESIGN CRITERIA

In this paper, some design criteria for a Tubular Linear Induction Motor (TLIM) as a fast actuator are considered. The in∞uence of geometrical and physical parameters on the operating conditions of a TLIM are investigated by means a quasi-analytic model. The model is based on the application of the Fourier Transform both in space and in time. The Fourier transform in space is introduced to take into account the flnite length of the stator windings in the axial direction. The transient electrical response of the motor at standstill following the insertion of a three-phase system of voltage generators is performed by the Fourier transform in the time. Linear movements are very usual in mechanical engineering, especially in industrial robots, where linear speeds up to several meters per second are often required. These movements are usually obtained by using rotating motors in combination with rotation to translation mechanism. The resulting systems may have poor performance; in particular, an excessive time delay may prevent their use as fast actuators (1). The complexity of these systems can be overcome by using linear actuators. It is well known that tubular linear induction machines have the highest force to moving mass ratio when compared with other linear motors; this property makes these devices very attractive to be used as servo motors since they may have better performance in terms of reduction of delay times with respect to those of traditional systems. The simplest approach to model these linear motors is based on

Analysis and design criteria of a tubular linear induction motor for a possible use in the electro-magnetic aircraft launch system

In this paper a double stator tubular linear induction machine is presented and its performance are discussed for a possible use as a catapult in the electromagnetic acceleration of aircrafts. Based on the use of the Fourier transform in the direction of the motion, a semi analytical model that is able to take into account the end effects due to the finite length of the stators is derived. The effectiveness of the model has been proved by comparison with a numerical analysis based on the Finite Elements Method. The reported results obtained by the two methods shows an excellent agreement that makes the proposed model as a valuable tool for a preliminary design of the device.

Acceleration of electromagnetic launchers modeling by using graphic processing units

The solution of large and complex coupled electromechanical problems requires high performance computing resources. In the last years the use of Graphic Processing Units (GPUs) has gained increasing popularity in scientific computing because of their low cost and parallel architecture. In this paper the authors report the main results of the GPU approach to the parallelization of a research code for the electromagnetic launcher analysis. Programming a GPU - based environment poses a number of critical issues that have to be carefully addressed in order to fully exploit the potentiality of the system. Data have to be properly organized in order to fit the Single Instruction Multiple Data scheme; the data transfer between the host and the device, as well as the memory management of the GPU deserve accurate programming. Two examples of application of the parallelized code have been reported to show the performance improvements that can be obtained in the numerical analysis of both rail and induction launchers.

Travelling Wave Multipole Field Electromagnetic Launcher: An SOVP Analytical Model

The problem of the evaluation of eddy currents induced in a conductive cylinder is, here, reconsidered under the light of possible application in the electromagnetic launch context. In particular, we derive an analytical solution when the system is excited by a sinusoidal current flowing in a saddle coil moving in the axial direction. Subsequently, we consider an arrangement of such coils distributed in the axial and azimuth direction. When properly fed, they produce a travelling wave of flux distribution, which is able to exert a thrust force on the conductive cylinder. Since the governing vector field equation is not separable in the cylindrical coordinates, an approach based on the second-order vector potential formulation has been, here, adopted. Scalar field equations are obtained whose solutions are expressed in terms of Bessel functions.

Modeling of the Gyroscopic Stabilization in a Traveling-Wave Multipole Field Electromagnetic Launcher via an Analytical Approach

This paper presents an analytical model for the investigation of the gyroscopic stabilization of the launch package in induction-type coilguns. By a proper arrangement of coils and of their feeding currents, a traveling wave of flux density is produced, which is characterized by axial and azimuthal components of velocity. The resulting action exerted on a conductive cylinder has components in the same directions as the traveling wave. This produces a helical motion of the armature. Since the governing vector field equation is not separable in the cylindrical coordinate, an approach based on the second-order vector potential formulation has been adopted here.

Acceleration of Numerical Formulations by Using Graphic Processing Units and Its Application in Electromagnetic Launcher Modeling

The solution of large and complex coupled electromechanical problems requires high-performance computing resources. Over the past years, the use of graphic processing units (GPUs) in scientific computing has gained increasing popularity because of their low cost and parallel architecture. In this paper, the authors report the main results of a GPU approach for the parallelization of a research code for electromagnetic launcher analysis. Programming a GPU-based environment poses a number of critical issues that have to be carefully addressed in order to fully exploit system potential. Data have to be properly organized in order to fit the single-instruction multiple-data scheme; data transfer between the host and the device, as well as memory management of the GPU, deserves accurate programming. Two examples of application of the parallelized code have been reported to show the performance improvements that can be obtained in the numerical analysis of both rail and induction launchers.

A Self-Controlled Maglev System

This paper presents a MAGLEV system in which the magnetic suspension is assured by the repulsion of permanent magnets both on the guideway and on the vehicle. Due to the induced currents on a aluminum sheath surrounding the magnets on the guideway, the system intrinsic instability is overcome. The detailed structure of the proposed system is described and the main results of the simulations by means a FE code are reported.

Stabilization of a Permanent-Magnet MAGLEV System via Null-Flux Coils

In this paper, a passive permanent-magnet (PM)-based magnetic levitation system is presented and its stability is discussed. The suspension is assured by the repulsive force of properly shaped PMs placed on both the guideway and the vehicle. The interaction between the motional-induced currents on conductors attached to the guideway and the PMs on the armature produces a stabilization force. Two versions of the device are discussed. In the first, the stabilizing currents are the ones induced on a conductive sheet surrounding the guideway. In the second device, the stabilizing currents flow in an array of null-flux coils. Comparison of the performance of the two proposed systems are performed by a research code developed at the Department of Energy, System Territory and Construction Engineering.

Numerical Integration of Coupled Equations for High-Speed Electromechanical Devices

In this paper, a new approach for the numerical solution of coupled electromechanical problems is exploited with the aim of simulate electromagnetic devices with high-speed moving parts. The considered problem formulation rests on the low-frequency integral formulation of the Maxwells equations and the Newton-Euler rigid-body dynamic equations. The numerical integration of the coupled problem is discussed and developed with a two-step method. The method has been validated by comparison with experimental data (when available) and with results obtained by other numerical formulations. An example of application to a 2 degrees of freedom device based on permanent magnets is finally reported.