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The paper presents a model for coupling electromagnetic and thermal phenomena in an induction motor. The thermal analysis is done using an equivalent thermal network whose losses are determined from a complex finite element analysis of the magnetic field. The electromagnetic model includes both saturation and space harmonics. To show the validity of the proposed method, a test bench is realized so predicted and measured temperatures are compared. Index Terms--Eddy currents, finite element methods, induction machines, thermal models.

The authors present a method to obtain steady state performances of induction motors including space harmonics and saturation. The principle of the method consists on a spectral decomposition of the source field in the air gap, to compute each elementary problem corresponding to a harmonic order and then to use superposition to determine the total field. The saturation is included in an average sense using effective reluctivities. Computations are compared to experiments. Index Terms--Eddy currents, finite element methods, induction motors, moving bodies.

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. Index Terms--Finite-element methods, induction heating, magnetohydrodynamics (MHD), mesh generation, metals.

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. Index terms - Conducting liquids, Electromagnetic forces, Electromagnetic induction, linear motor, pumps.

A method of approximation of the magnetostatic functional is investigated. It can be used for motors with a complex geometry such as the doubly salient switched reluctance machine with many teeth. This approximation allows to simplify the meshing and then reduces the number of nodes. The obtained results are acceptable for the fluxes (less than 5%) and not so good for the torque (less than 25%). However this method Can be used as a pre-processor for a geometrical optimization. Index terms - magnetostatics, stepper motors, approximation methods, reluctance 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 is performed using two criteria: the efficiency and the ratio of the thrust to the heat losses. Specific windings can be designed for linear induction motors which allow a significant improvement in their performances.

A coupled electromagnetic-circuit model that allows any time dependence of the terminal voltage is described in the context of the capacitor motor. This model, called the first harmonic method, is an approximation of the full time step model. Practical results and comparisons with the experiment are provided.

The applications such as the optimal control of the SRM require a fast lumped state model, which is widely studied in the literature. The method used to obtain the inductances from the FE field computation, in the saturated case, is known as the energy perturbation method. We suggest here both an improvement of this method and a strategy for building an adaptative map of the coenergy, which are required by the lumped model.

A method allowing the effective computation of the steady state of the electromagnetic field in induction motors is detailed. This method needs no time steps and use short CPU time. We analyze its accuracy and robustness and test it on an actual motor. A comparison with another method of computation - the complex magnetodynamic - is provided.

This paper is devoted to the optimization of solid rotors for high speed applications, using a boundary integral method. The method is applied to two examples: a slotted asynchronous rotor and a salient reluctant synchronous one. The starting under constant voltage is especially studied in both cases. An important part of the paper deals with the asynchronous motor. An idealized stator generates a sinusoidally distributed tangential flux density, so that the optimization concerns only the rotor slotting. At constant permeability, the boundary integral method proves to be very fast and efficient for an approximate designing of a slotted rotor.

We present the first data from the THEMIS Search Coil Magnetometers (SCM), taken between March and June 2007 while the THEMIS constellation apogee moved from the duskside toward the dawnside. Data reduction, especially the SCM calibration method and spurious noise reduction process, is described. The signatures of magnetic fluctuations in key magnetospheric regions such as the bow shock, the magnetopause and the magnetotail during a substorm, are described. We also discuss the role that magnetic fluctuations could play in plasma transport, acceleration and heating. [ABSTRACT FROM AUTHOR]

THEMIS instruments incorporate a tri-axial Search Coil Magnetometer (SCM) designed to measure the magnetic components of waves associated with substorm breakup and expansion. The three search coil antennas cover the same frequency bandwidth, from 0.1 Hz to 4 kHz, in the ULF/ELF frequency range. They extend, with appropriate Noise Equivalent Magnetic Induction (NEMI) and sufficient overlap, the measurements of the fluxgate magnetometers. The NEMI of the searchcoil antennas and associated pre-amplifiers is smaller than 0.76 pT $/\sqrt{\mathrm{Hz}}$ at 10 Hz. The analog signals produced by the searchcoils and associated preamplifiers are digitized and processed inside the Digital Field Box (DFB) and the Instrument Data Processing Unit (IDPU), together with data from the Electric Field Instrument (EFI). Searchcoil telemetry includes waveform transmission, FFT processed data, and data from a filter bank. The frequency range covered depends on the available telemetry. The searchcoils and their three axis structures have been precisely calibrated in a calibration facility, and the calibration of the transfer function is checked on board, usually once per orbit. The tri-axial searchcoils implemented on the five THEMIS spacecraft are working nominally. [ABSTRACT FROM AUTHOR]

In the present paper, the authors implement a steady state finite element analysis of the heat field inside an induction motor. The tested machine is a standard squirrel cage asynchronous motor of Totally Enclosed Fan Cooled "TEFC" design. The thermal calculation is done in a 2D radial view that represents an angular space of 12.857 ° (rotor tooth pitch) of the considered machine. To validate the proposed thermal model, the temperature measurements at different points within the motor were obtained using 16 sensors (CTN thermistors) placed inside the test motor. The simulated temperatures so obtained are in good agreement with the measured ones, and the 2D study seems to be appropriate to characterize the heating of the active parts of the machine. [ABSTRACT FROM AUTHOR]