Modern road vehicles are more and more often being equipped with electric actuators. These are intended to play critical roles in passengers comfort and safety. Among the electrified components onboard road vehicles, one can distinguish electric power steering (EPS) systems, which have been the subject of intensive investigations covering both design and control aspects. The abilities of several AC motor topologies to fulfil the EPS systems’ requirements have been assessed by a large scientific community in both academia and industry. The present work was aimed at the prediction of the electromagnetic features of the flux-switching permanent magnet machines (FSPMMs), with an emphasis on the air gap flux density. The latter was firstly formulated while neglecting the slotting effect at both sides of the air gap. Then, stator and rotor permeance functions, taking into account the slotting effect and the PM flux concentrating arrangement, were incorporated into the derived flux density spatial repartition. Moreover, the accuracy of the latter was improved through two dedicated correction functions that take into account the rotor position and the magnetic saturation. The last part of the paper presents a simple approach to enhance the developed torque of FSPMMs in an attempt to meet the EPS requirements.

The article is aimed at an investigation of the no- and on-load features of surface-mounted permanent magnet synchronous machines (SMPMSMs) equipped with irregular pole shapes, with emphasis on the air gap flux density. The latter is predicted considering the resolution of the governing equations based on the magnetic potential vector formulated within the PM segments. The superposition of the resulting flux densities yields the one of the total pole. The proposed model involves appropriate geometrical parameters that makes it possible the application of the developed approach to any pole shape irregularity. SMPMSMs equipped with bread-loaf and sinusoidal with and without harmonics PMs are investigated using the developed approach and their features are compared. The obtained results are validated by finite element analysis. An experimental validation is carried out considering a prototype equipped with bread-loaf magnets.

This paper deals with the winding arrangement of multi-phase fractional-slot permanent magnet (PM) synchronous machines (FSPMSMs), with emphasis on the enhancement of their open-circuit fault-tolerance capability. FSPMSMs are reputed by their attractive intrinsic fault-tolerance capability, which increases with the number of phases. Of particular interest is the open-circuit fault-tolerance capability, which could be significantly enhanced through the parallel connection of the coils or suitable combinations of the coils of each phase. Nevertheless, such an arrangement of the armature winding is applicable to a limited set of slot-pole combinations. The present work proposes a design approach that extends the slot-pole combinations to candidates that are characterized by a star of slots including three phasors per phase and per winding period. It has the merit of improving the tolerance against open-circuit faults along with an increase in the winding factor of multi-phase machines. Special attention is paid to characterization of the coil asymmetry required for the phase parallel arrangement. A case study, aimed at a finite element analysis (FEA)-based investigation of the open-circuit fault-tolerance of a five-phase FSPMSM, is treated in order to validate the analytical prediction.

The paper is aimed at a simple analytical approach to predict the no- and on-load features of fractional-slot permanent magnet synchronous machines (FSPMSMs). The proposed approach is based on the combination of: (i) a formulation of the no-load air gap flux density based on the resolution of the Maxwell equations, and (ii) the magnetic equivalent circuit (MEC) of the stator. The resulting compound analytical model is iteratively solved using a Newton-Raphson algorithm where the stator MEC incorporates position-dependent magneto-motive force (MMF) sources yielded by the no-load air gap flux density formulation along with those due to the armature magnetic reaction. Prior to do so, a comparison, based on the tradeoff accuracy/CPU time, of three stator MEC networks is carried out. Following the MEC selection, the proposed approach is applied to three case studies which differ by their slot per pole and per phase number and by the permanent magnet arrangement, leading to the prediction of their no- and on-load features. The obtained analytical results are validated by finite element analysis.

The paper is aimed at an analytical approach dedicated to the investigation of the effects of the pole shoe geometry on the no-load flux features of inner permanent magnet tubular-linear synchronous machines (IPM T-LSMs). It considers the most common geometries: (i) rectangular pole shoes, and (ii) trapezoidal pole shoes. The proposed approach combines two analytical models which are the magnetic equivalent circuit (MEC) and the permeance function. First, a basic MEC of an elementary part of the machine is considered to predict a preliminary air gap flux density trapezoidal waveform. Then, the accuracy of the proposed approach is enhanced by the incorporation of a mover permeance function that accounts for the PM spoke-type arrangement. The proposed approach is applied to the investigation of the impact of the mover pole shoe shape on the air gap flux density. The developed pole shoe sizing procedure makes it possible the selection of an IPM T-LSM with an appropriate mover geometry for which an investigation of the no- and on-load features is carried out by finite element analysis. The prototyping of the selected topology enables the experimental validation of the back-EMF and the load characteristic.

The paper deals with an approach to reduce the detent force of double-sided flat linear permanent magnet synchronous machines (PMSMs). The study is initiated by a finite element analysis (FEA)-based investigation of the detent and normal forces of a conventional concept with aligned PM rows mounted on both mover sides. It is found that while it exhibits a quasi-null normal force, the concept is penalized by a huge detent force. An attempt to reduce such a drawback consisting in shifting the PM rows is proposed. Its effectiveness in reducing the detent force is demonstrated by FEA. However, it leads to a remarkable increase of the normal force. In order to minimize this latter, a second design approach consisting in a unilateral extension of both sides of the stator magnetic circuit, is proposed. It is shown that selecting 50% for both PM shift-to-the pole pitch and stator extension length facing the air gap-to-the pole pitch ratios yields acceptable peak-to-peak values of the detent and normal forces. The force production of the resulting machine is then evaluated and compared to the conventional concept one. In spite of the minimization of the force ripple, its mean value is limited to 50%. An approach consisting in a reconfiguration based on the star of slots of the armature in both stator sides, is proposed and assessed by FEA. As a result, an increase of the mean force as well as a reduction of the force ripple are gained.