Carole Henaux

Visual Evidence of Magnetic Shielding With the PPS-Flex Hall Thruster

Magnetic shielding (MS) of insulating walls in a Hall thruster (HT) drastically reduces the damaging ion bombardment, therefore significantly increasing the thruster operational lifetime, as demonstrated in recent work. In essence MS rests on preventing the field line from intersecting the wall in the discharge chamber downstream section. We show here that such a topology can be attained with the newly developed PPS-flex HT. The latter is a unique prototype that offers a wide range of magnetic configurations through a combination of 22 coils with a sophisticated magnetic circuit that propagates the flux.

A New Concept of Modular Permanent Magnet and Soft Magnetic Compound Motor Dedicated to Widespread Application

This paper deals with the design and test of a permanent-magnet machine based on a novel modular stator concept. The manufacturing and recycling costs are minimized thanks to the use of composite magnetic materials (plastic bonded magnets, soft magnetic composites). The main properties of composite magnetic materials, from a magnetic and mechanical point of view, are briefly presented in the first part of this paper. After focusing on their thermal properties by detailing a thermal experimental study, the proposed concept of a modular permanent-magnet machine is described. Experimental characterization of the realized prototype, in static and dynamic operating modes, demonstrates its advantages compared with conventional structures.

Synchronous reluctance machine flux barrier design based on the flux line patterns in a solid rotor

The paper focuses on the synchronous reluctance machine rotor design. The rotors shape in this machine should maximize the flux passing in the d axis while minimizing the flux in its q axis. This can be achieved by designing the rotor to respect the natural flow of the flux in the d axis in order to reduce the magnetic resistance while increasing the insulation in the q axis. The proposed design method in this paper is based on determining the analytical equation of the flux lines through a solid rotor. The analytical equation will allow the definition of the optimal curvature of the flux barriers. In a second phase, the width of the flux barriers is determined on the basis of the flux preservation theory in every flux segment. A comparison study using a finite elements simulation will allow us to validate the proposed approach.

A global approach for the study of forces developed by a tubular linear moving magnet

A global approach for the study of forces developed by a tubular linear moving magnet actuator for a low speed and high force application is described. We used here an easy analytical approach made with the Amperes law to give the field distribution done by permanent magnets in the airgap. In order to calculate the effort developed by the moving part we used the Laplace force which takes into account the field distribution calculated previously and the current distribution on the stator. The results are validated extensively by comparison with finite element analysis. The analytical field solutions allow the prediction of the thrust force. This facilitates the characterization of tubular machine topologies and provides a basis for comparative studies, design optimization, and machine dynamic modeling.

Topology Optimization for Magnetic Circuits Dedicated to Electric Propulsion

In this paper, we present a method to solve inverse problems of electromagnetic circuit design, which are formulated as a topology optimization problem. Indeed, by imposing the magnetic field inside a region, we search the best material distribution into variable domains. To perform this, we minimize the quadratic error between the prescribed magnetic field and the one computed by a finite element method (FEM). A dedicated software was developed in MATLAB using fmincon routine and FEM Magnetics (FEMM) software; this code is named

TORQUE RIPPLE REDUCTION IN A SYNRM AT A CONSTANT AVERAGE TORQUE BY MEANS OF CURRENT HARMONICS INJECTION

{\rm ATOP}^{\rm TO}

Magnetic Field Continuity Conditions in Finite-Element Analysis

for algorithm to optimization propulsion using topology optimization. To perform the first derivative of the objective function, we implemented an adjoint variable method. Indeed, this approach makes it possible to provide the derivative by only two uses of the finite element tool. Nevertheless, the problem is discrete because we take only two possibilities: with or without material. Thus, the solid isotropic material with penalization method was used to penalize intermediate values to have discrete solutions. Some numerical experiments with 40 and 800 variables concerning circuit designs validated our approach. This represents a first study to design a Hall effect thruster.

Synchronous motor winding segmentation for parallel interleaved inverters

This paper studies the impact of current harmonics on the synchronous reluctance machine’s average torque and torque ripple. The electromagnetic model of a general m-phase synchronous reluctance machine which integrates the inductance and current harmonics is developed. This model shows that there exist two mechanisms that generate an average torque with a non-zero average value: the proper contribution of the current harmonics and the interaction between them. This model is then used in the case of a 2-phase synchronous reluctance machine with a common transversally laminated anisotropic rotor. This machine design shows negligible inductance harmonics with respect to its fundamental value. Therefore, it has been found that the interaction between the 3rd and 5th current harmonics generates a torque equivalent to the torque generated by the fundamental current component. A locus of the current harmonic components that deliver a constant torque is determined. Furthermore, we have found that, on this locus, the machine torque ripple decreases significantly. Experimental data validate the developed theoretical work and show that at the same torque, the torque ripple is reduced from 20% to 4%.

Comparison, with an Analytical Optimization Process, of Two Synchronous Halbach Permanent Magnet Machines, for a Direct Drive Stick Application

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 analysis.

A tool to help to design windings of permanent magnet synchronous machines

This paper deals with a new concept of winding segmentation of permanent-magnet synchronous machines originally presented in a recently published patent. Called, in this paper, the coupled star winding, this new segmentation winding allows reducing total loss and current ripples when fed by an interleaved parallel inverters. This segmentation method can potentially integrate the functionality of magnetically coupled inductors.