Original optimization procedures of halbach permanent magnet segmented array

This paper presents a direct design and optimization procedures of an arbitrary PM Halbach Segmented Array. The direct design is based on the ideal PM Halbach definition. The arc width, magnitude and orientation of polarization of each segment are taken as optimization variables after calculation of PM thickness. A new optimization procedure based on integration of Least Square Method inside the well-known Sequential Quadratic Programming method is proposed to improve the optimization results and to reduce time computation

Technical support study to OUA/IBAR-PARC. Synthesis report

The report is composed of four main chapters: An introduction concerning the zoosanitary situation in sub-Sahara Africa, and an estimation of the economic impact of improvements in animal health. A detailed review of the actors in the livestock sector ant the tools available for intervention in the control of Rinderpest and other major diseases. In a third chapter, technical strateties are proposed for the prospective program. This focuses on disease surveillance and national systems of epidemiological surveillance with support for the laboratories and research (Rinderpest, CBPP). Proposals for geographical strategies of Rinderpest and CBPP control adapted to different geo-epidemiological contexts make up the last chapter of this report. (Résumé d'auteur

Experimental Study of Iron Losses Generated by a Uniform Rotating Field

This paper introduces a mock-up with a solid iron cylinder rotating in a fixed excitation frame powered by dc current. A uniform field is created in the rotating cylinder, which is driven by an external motor. The braking torque is measured, allowing the study of iron losses generated by a uniform rotating field. The aim is to advance toward a vector iron loss model that takes into account different magnetization directions and their interdependency. The eddy current losses are the dominant loss source in the mock-up, rendering it easier to model. A standard eddy currents model is proposed. It models well the losses at low and medium magnetic flux density, but lower losses are measured near saturation levels. This could be due to the high thickness to radius ratio changing the eddy current paths near the edges of the rotor, which can be later analyzed by a full 3-D finite-element method analysis. A 2-D finite-element method simulation is performed, which estimates the magnetic flux heterogeneity in the rotor. Several lessons are drawn from this mock-up, which prepares a second version with a higher speed and a longer laminated stack rotor. A higher air gap will decrease the voltage fluctuation in the primary winding, a smaller angular opening of the excitation frame will improve the uniformity of the flux in the rotor

Modeling quasi-static magnetic hysteresis: a new implementation of the play model based on experimental asymmetrical B(H) loops

This paper relates a new model of quasi-static magnetic hysteresis based on the Play model hysterons, which builds the magnetic field density B from the magnetic field H. In the original model, H is discretized into temporal values H(t m ), which is itself modeled by a hysteron chain of m sub-values. B is then reconstructed from these sub-values through a function experimentally determined by measuring B(H) centered cycles, using a constraint optimization method. The new proposed method is to measure asymmetrical B(H) loops, which give additional equations leading to a fully determined linear square invertible system. The asymmetrical B(H) loop is included in a bigger symmetrical loop with a magnetic flux density turnaround in order to be regulatable

3D magnetic field model of a permanent magnet ironless axial flux motor with additively manufactured non-active parts

A simulation model of an ironless Axial-Flux Permanent-Magnet (AFPM) machines is presented. Indeed as accurate analytical methods do not yet exist for ironless AFPM, 3D Finite Element Analysis (FEA) is required at each time of an operating point. The purpose of this article is to show that for any operating point of the motor, the torque can be calculated from the distribution of the axial magnetic flux density obtained from only one 3D FEA. The proposed simulation model is validated by using a prototype of an AFPM ironless whose non-active parts are additively manufactured. This first step through the 3D printing technology is simplified by the use of cylindrical magnets and plastic mechanical supports

Magnetic field continuity conditions in finite-element analysis

This paper deals with the magnetic field continuity conditions in finite-element analysis. Our study is based on numerical and analytical models. Different known finite-element codes, based on 2-D nodal finite element or 3-D edge element, are used to analyze the magnetic field in a linear motor-like device. The use of an analytical model gives interesting insight on interface errors problems in finite-element analysi

Lumped Parameter Thermal Model of Permanent Magnet Synchronous Machines

This paper describes a thermal equivalent circuit of Liquid Cooling Totally Enclosed Permanent Magnet Synchronous Machines (LCTE-PMSMs). Conductive heat transfer in all directions is taken into account. Specific care has been taken to represent them by equivalent circuit. The conductive heat transfer in heterogeneous media like slots and the convective heat transfer in the airgap and the end-winding are studied

SPECTRAL CLUSTERING BASED PARCELLATION OF FETAL BRAIN MRI

Many neuroimaging studies are based on the idea that there are distinct brain regions that are functionally or micro-anatomically homogeneous. Obtaining such regions in an au-tomatic way is a challenging task for fetal data due to the lack of strong and consistent anatomical features at the early stages of brain development. In this paper we propose the use of an automatic approach for parcellating fetal cerebral hemi-spheric surfaces into K regions via spectral clustering. Unlike previous methods, our technique has the crucial advantage of only relying on intrinsic geometrical properties of the corti-cal surface and thus being unsupervised. Results on a data-set of fetal brain MRI acquired in utero demonstrated a convinc-ing parcellation reproducibility of the cortical surfaces across fetuses with varying gestational ages and folding magnitude

Joint Design of Halbach Segmented Array and Distributed Stator Winding

In the past, designers develop analytical models that are useful to size rapidly surface mounted permanent magnet synchronous motor with sinusoidal waves and a high specific power. In order to ensure the assumptions of sinusoidal waves, a joint design of the stator winding and the rotor is presented. First, an Halbach permanent magnet array is optimized to obtain the desired airgap magnetic flux density wave. Then, in order to obtain a surface current density wave consistent with the desired wave, the conductor distribution along the stator bore is determined