Imen Abdennadher

Design of a Single-Stator Dual-Rotor Permanent-Magnet Machine

We present a new integrated electromechanical set for automotive hybrid propulsion systems. It consists of two concentric permanent-magnet (PM) machines with inner and outer surface-mounted PM rotors, and a stator sandwiched between the two rotors, yielding a so-called ldquosingle-stator dual-rotor PM machinerdquo. The stator magnetic circuit consists of two concentric parts decoupled by a nonmagnetic ring. In an earlier topology, distributed windings were used in both stators. We substitute concentrated windings to extend the flux weakening range. We discuss our investigation of the magnetomotive force (MMF) spatial profile and of the torque production capability of this dedicated concentrated winding surface-mounted PM machine.

MEC-Based Modeling and Sizing of a Tubular Linear PM Synchronous Machine

Linear machines are currently considered as viable candidates for direct-drive wave and free-piston energy converters. This paper is devoted to an approach based on a magnetic equivalent circuit (MEC), which is also called lumped circuit, dedicated to the modeling and sizing of a tubular linear permanent-magnet synchronous machine (T-LPMSM). The proposed approach considers, in a first step, the cancelation of the end-effect phenomenon. To do so, a dedicated design procedure, consisting in achieving a

Concentrated winding PM machines: a pre‐design approach

2\pi/3

Analytical Prediction of the No-Load Operation Features of Tubular-Linear Permanent Magnet Synchronous Machines

-shift between the armature phase flux linkages by selecting a fractional ratio of the stator pole pitch to the mover one and balancing the amplitudes of the phase flux linkages by extending the stator magnetic circuit with teeth of appropriate dimensions, is firmly applied on two basic T-LPMSM topologies using a dedicated MEC. Then, an investigation of the influent sizing parameters on the force production capability of the initial concept is carried out. The MEC-based prediction of the force requires the incorporation of the mover displacement, yielding the so-called “position varying MEC” on one hand and the armature magnetic reaction on the other hand. The finite-element analysis of the armature phase flux linkages and the developed force enable the validation of the results yielded by the established MECs.

An approach to reduce the cogging force in tubular linear PM synchronous machines

Purpose – The purpose of this paper is to discuss the design of concentrated winding permanent magnet (PM) machines dedicated to propulsion applications considering both surface‐mounted and flux‐concentrating arrangements of the PMs.Design/methodology/approach – Following the selection of a suitable distribution of the concentrated winding, a derivation of the machine inductances is carried out in order to highlight the increase in the flux‐weakening range gained through the substitution of distributed windings by concentrated ones. Then, mmf and finite element analysis are carried out in order to investigate the air gap flux density and the torque production capability of both surface‐mounted and flux‐concentrating PM machines.Findings – The paper finds that, although both machines provide almost the same average torque, the surface‐mounted PM machine offers lower torque ripple with respect to the flux‐concentrating arrangement: a crucial benefit in electric and hybrid propulsion systems.Research limitat...

Feature Investigation of a T-LPMSM Following the Selection of Its Slot-Pole Combination

This paper is aimed at an analytical approach to predict the no-load operation features of tubular-linear permanent magnet synchronous machines (T-LPMSMs). These are currently considered as viable candidates for wave energy conversion. The developed approach is based on the derivation of the air-gap flux density, considering both the first- and second-type modified Bessel functions of appropriate orders. Following its formulation, the air-gap flux density is applied for the prediction of the no-load operation features, with a focus on the cogging force, the phase flux linkages, and the back electromotive forces. A case study is treated considering three axial arrangements of a T-LPMSM, such as the case of an infinite length machine, the case of a finite length machine, and the case of a finite length machine enabling a quasi-cancellation of the end effect. A comparison between the analytically predicted features and those numerically computed by a 2-D finite-element analysis has led to good agreement.

Prediction of the air gap flux density distribution of a T-LSM with quasi-Halbach magnetized PMs: Application to the cogging force minimization

The paper is aimed at an approach to reduce the cogging force in tubular linear permanent magnet synchronous machines (T-LPMSMs). An analytic prediction of the air gap flux density distribution is developed in a first step, considering the case of slottless machine and the case where the slotting effect is taken into consideration. The established model enables, thanks to a simple formulation, the assessment of the cogging force assuming an “infinite” length machine. Then, the influence of the end effect on the cogging force is investigated in the case of the real machine. The study is extended to a cogging force reduction approach devoted to a quasi-cancellation of the end effect. It consists in a two-step procedure, such that: (i) achieving a 2π/3-shift between the armature winding flux linkages by arranging the ratio of the stator pole pitch to the mover one, and (ii) balancing the amplitudes of these flux linkages by extending the stator magnetic circuit with teeth of appropriate dimensions. The cogging force prediction of the T-LPMSM following the quasi-cancellation of its end effect highlights the effectiveness of the proposed approach.

A design approach to reduce the end effect in linear tubular PM machines

This paper investigates the no-load and the on-load behavior of a fractional-slot tubular-linear permanent magnet synchronous machine (T-LPMSM). The study is initiated by the selection of the machine slot-pole combination. To do so, a formulation of the air gap flux density, based on the solution of the magnetic potential vector equation in the air gap and in the PM regions, is derived. The electromagnetic model allows the prediction of the phase back electromotive forces (EMFs) and of the cogging force. The effect of the slot-pole combination on these features is then considered to the aim of the optimal selection of the slot per pole and per phase. A case study considering the optimized slot per pole and per phase number is treated where the analytically predicted no-load features are validated by finite element analysis (FEA). The investigation is extended to the on-load characteristic which is predicted by FEA and is validated by experiments.

No-load Features of T-LSMs With Quasi-Halbach Magnets: Application to Free Piston Engines

The paper is aimed at a dual sizing-based approach to minimize the cogging force of a tubular linear synchronous machine (T-LSM) with quasi-Halbach magnetized PMs in the mover. The study is initiated by the prediction of the spatial repartition of the no-load air gap flux density. Then, a formulation of the cogging force, based on the predicted spatial repartition of the no-load air gap flux density, is developed, considering (i) the case of an “infinite” length machine and (ii) the case of a finite length one. A case study, corresponding to an initial concept, is treated with a focus on the prediction of its spatial repartition of the no-load air gap flux density and its cogging force. With this done, the study is extended to a first cogging force reduction procedure considering the case of an “infinite” length machine. It consists in the investigation of the effects of two influent sizing parameters on the cogging force, that enables the identification of a pre-optimized concept. The cogging force of this latter is then predicted in the case of a finite length machine. The study is achieved by a second cogging force reduction procedure, consisting in a quasi-cancellation of the end effect. The prediction of the cogging force of the optimized T-LSM with quasi-Halbach magnetized PMs has clearly demonstrated the effectiveness of the proposed dual sizing-based approach.

Designing energy efficient Smart Buildings in ubiquitous environments

The paper is aimed at a design approach dedicated to the reduction of the longitudinal end effect in a linear tubular permanent magnet machine. The proposed approach consists in a two-step procedure, such that: (i) achieving a 2π/3-shift between the armature winding flux linkages by arranging the ratio of the stator pole pitch to the mover one, and (ii) balancing the amplitudes of these flux linkages by extending the stator magnetic circuit with teeth of appropriate dimensions. A magnetic equivalent circuit (MEC) of the linear PM machine is established taking into account the proposed approach. A FEA-based investigation of the flux linkage validates the MEC results.