Gérard Vinsard

An approach to optimize winding design in linear induction motors

A method which mixes analytical and numerical approaches is developed to avoid finite elements computations in moving media. An optimization of a linear induction motor (LIM) is performed using two criteria: the efficiency; and the ratio of the thrust to the heat losses. Specific windings can be designed for LIMs which allow a significant improvement in their performance.

2-D adaptive mesh with movement

Adaptive meshes of electrical machines have to take into account the movement of the rotor. To combine accuracy and fast computation, nodes are added and canceled for any variation of the rotor position.

Mesh improvement in 2-D eddy-current problems

A mesh improvement technique in 2-D eddy-current problems is proposed. This technique uses an a posteriori error estimator issued from a local solution in the conducting region.

Generating rotor geometries by using a genetic method

The rotor of a synchronous variable reluctance machine is shaped by using genetic methods. In order to decrease the number of genes, macro-operators are tested.

An analysis of the rotational forces in the secondary of an electromagnetic pump

An analysis of the force density in the secondary of a linear induction motor is proposed. The Hodge-Helmholtz decomposition is applied, from which the force density is the sum of rotational and gradient terms, and the numerical details for the effective computation are done. An interpretation of the decomposition, useful for the case of a pumping application, is provided.

On the optimization of linear induction devices

ContentsAn analytical and numerical method is developed to optimize linear induction motor supply with respect to criteria such as the efficiency or the force. The analysis uses a classical finite elements calculation in the motionless region; the boundary between the rail and the air-gap requires a special statement. Given a set of constraints, the optimal currents can be found by the Raleigh quotient.ÜbersichtEs wurde ein analytisches und numerisches Verfahren zur Optimierung linearer Induktionsmotoren bezüglich der Kriterien Wirkungsgrad und Vortriebskraft entwickelt. Die Analyse verwendet die klassische Methode der finiten Elemente für ruhenden Bereich; lediglich die Berandung zwischen Reaktionsschiene und Luftspalt erfordert eine gesonderte Beschreibung. Bei vorgegebenen Nebenbedingungen lassen sich die optimalen Stromwerte mittels des Quotienten von Raleigh ermitteln.

Mixing by chaotic advection in a magneto-hydrodynamic driven flow

A new device containing three circular electrodes and where very small quantities of a weakly electrically conductive liquid are propelled and mixed by chaotic advection is designed and constructed. The liquid, a copper sulfate solution, is propelled by the Lorentz body force, i.e., a magnetic field perpendicular to an electrical current. When the potentials of the electrodes are constant and the Lorentz force is small enough so that at the free surface the vertical velocity is practically zero, the flow field exhibits there a saddle point when the three circular electrodes are not in a concentric position. By modulating the electrical potential between the electrodes, the position of the saddle point changes. This slowly varying system is far from integrable and exhibits large-scale chaos, the non-integrability is due to the slow continuous modulation of the position of the saddle stagnation point and the two streamlines stagnating on it. Dye advection experiments are compared successfully to a numerical...

Equilibrium shape of a liquid metal subject to electromagnetic forces

The equilibrium shape of a conductive liquid metal submitted to electromagnetic forces is computed in the axisymmetric geometry and a comparison with experiments is performed. Meshing techniques are used to spare computation time.

Rotating Motion in Salt Water With Laplace Forces

A Laplace force density in salt water due to a magnet and a constant current generates a rotating motion and then distorts the free surface. The coupling problem between electromagnetism and mechanics is modeled with a special attention to the fluid flow problem.

Analytical modelling of a thin liquid metal layer submitted to an ac magnetic field

A cylindrical thin liquid metal layer is submitted to a uniform ac magnetic field. When the intensity of the electromagnetic field exceeds a critical value, an opening in the liquid is shaped from outside to inside. At a given intensity of the electromagnetic field, this opening is in a frozen state, that is, the liquid metal layer reaches a new equilibrium shape. In this paper, we show that this equilibrium corresponds to a minimum of the total energy of the system. This total energy is equal to the sum of the magnetic energy and the mechanical energy. The magnetic energy is computed by assuming that the induced eddy current flowing through the liquid metal layer is concentrated in the cross-section Sc equal to the product of the skin depth and the thickness of the layer. This assumption leads us to study an equivalent electrical circuit.The mechanical energy is composed of the potential energy and the surface energy.