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The purpose of this study is to propose an analytical model with consideration of the permeability of soft-magnetic materials, which can predict the magnetic field distribution more accurately and facilitate the initial design and parameter optimization of the machine.

This paper proposes an analytical model of stator yokeless radial flux dual rotor permanent magnet synchronous machine (SYRFDR-PMSM) with the consideration of magnetic saturation of soft-magnetic material. The analytical model of SYRFDR-PMSM is divided into seven regions along the radial direction according to the different excitation source and magnetic medium, and the iron permeability in each region is considered based on the Maxwell–Fourier method and Cauchy’s product theorem. The magnetic vector potential of each region is obtained by the Laplace’s or Poisson’s equation, and the magnetic field solution is determined using the boundary conditions of adjacent regions.

The inner and outer air-gap flux density, flux linkage, output torque, etc., of SYRFDR-PMSM are predicted by analytical model, resulting in good agreement with that of finite element model. Additionally, the SYRFDR-PMSM prototype is manufactured and the correctness of analytical model is further verified by experiments on no-load back electromotive force and current–torque curve. Reasonable design of the slot opening width and pole arc coefficient can improve the average output torque and reduce output torque ripple.

The analytical model proposed in this paper assumes that the permeability of soft-magnetic material is a fixed value. However, the actual iron’s permeability varies nonlinearly; thus, the prediction results of the analytical model will have some deviations from the actual machine.

The main contribution of this paper is to propose an accurate magnetic field analytical model of SYRFDR-PMSM. It takes into account the permeability of soft-magnetic material and slot opening, which can quickly and accurately predict the electromagnetic performance of SYRFDR-PMSM. It can provide assistance for the initial design and optimization of SYRFDR-PMSM.

Modeling electric machines is one of the powerful approaches for analyzing their performance. A dynamic model and a steady-state model are introduced for each electric machine. Permanent magnet induction machine (PMIM) is a dual-rotor electric machine, which has various advantages such as high-power factor and low magnetizing current. Studying PMIM and its modeling might be valuable. The purpose of this paper is to introduce a simple and accurate method for dynamic and steady-state modeling of PMIM.

In this paper, arbitrary dqo reference frame is used to model PMIM. First, three-phase dynamic equations of stator and rotors are introduced. Then, they are transferred to an arbitrary reference frame. The voltage and magnetic flux equations aligned at dqo axes are obtained. These equations give the dynamic model. To investigate the results, PMIM simulation is performed according to obtained dynamic equations. Simulation results verify the analytic calculations.

In this paper, dynamic equations of PMIM are obtained. These equations are used to determine dynamic equivalent circuits of PMIM. Steady-state equations and one phase equivalent circuit of the PMIM using phasor relations are also extracted.

PMIM equations along dqo axes and their dynamic and steady-state equivalent circuits are determined. These equations and the equivalent circuits can be transformed to different reference frames and analyzed easily.

This paper aims to propose an improved two-dimensional hybrid analytical method (HAM) in Cartesian coordinates, based on the exact subdomain technique and the magnetic equivalent circuit (MEC).

The magnetic field solution is obtained by coupling an exact analytical model (AM), calculated in all regions having relative permeability equal to unity, with a MEC, using a nodal-mesh formulation (i.e. Kirchhoff’s current law) in ferromagnetic regions. The AM and MEC are connected in both axes (x, y) of the (non-)periodicity direction (i.e. in the interface between the tooth regions and all its adjacent regions as slots and/or air-gap). To provide accuracy solutions, the current density distribution in slot regions is modeled by using Maxwell’s equations instead of the MEC characterized by an equivalent magnetomotive force (MMF) located in slots, teeth and yokes.

It is found that whatever the iron core relative permeability, the developed HAM gives accurate results for no- and on-load conditions. The finite-element analysis demonstrates excellent results of the developed technique.

The main objective of this paper is to make a direct coupling between the AM and MEC in both directions (i.e. x- and y-edges). The current density distribution is modeled by using Maxwell’s equations instead of the MEC and characterized by an MMF.

The purpose of this paper is to propose a two-dimensional (2-D) hybrid analytical model (HAM) in polar coordinates, combining a 2-D exact subdomain (SD) technique and magnetic equivalent circuit (MEC), for the magnetic field calculation in electrical machines at no-load and on-load conditions.

In this paper, the proposed technique is applied to dual-rotor permanent magnet (PM) synchronous machines. The magnetic field is computed by coupling an exact analytical model (AM), based on the formal resolution of Maxwell’s equations applied in subdomains, in regions at unitary relative permeability with a MEC, using a nodal-mesh formulation (i.e. Kirchhoff's current law), in ferromagnetic regions. The AM and MEC are connected in both directions (i.e. r- and theta-edges) of the (non-)periodicity direction (i.e. in the interface between teeth regions and all its adjacent regions as slots and/or air-gap). To provide accurate solutions, the current density distribution in slot regions is modeled by using Maxwell’s equations instead to MEC and characterized by an equivalent magnetomotive force (MMF) located in the slots, teeth and yoke.

It is found that whatever the iron core relative permeability, the developed HAM gives accurate results for both no-load and on-load conditions. Finite element analysis demonstrates the excellent results of the developed technique.

The main objective of this paper is to achieve a direct coupling between the AM and MEC in both directions (i.e. r- and theta-edges). The current density distribution is modeled by using Maxwell’s equations instead to MEC and characterized by an MMF.

The purpose of this paper is to investigate the use of hybrid‐excitation solutions, using contemporaneously permanent magnets and field coils, for DC machines intended to operate as the core of high‐reliability drives in critical applications supplied by batteries (e.g. fire‐extinguishing pumps, smoke blowers, etc.) where a roughly constant speed is required and a minimal use of electronic devices is prescribed to improve overall dependability.

A high‐reliability hybrid‐excitation DC motor, initially designed basing on theoretical considerations, is then analyzed using purposely developed 2D and 3D finite element method (FEM) electromagnetic models under static, dynamic, healthy, and faulty conditions.

The simulation results confirm that properly designed drives employing hybrid‐excitation DC motors may constitute an effective solution for applications requiring a very high reliability under DC supply with limited speed regulation capability.

The methodology employed exhibits the usual limits concerning the accuracy of FEM analysis: hysteresis is neglected, 2D simulations neglect axial component of fields, in 2D dynamic analysis the electrically discontinuous laminated cores are modeled as orthotropic continuous parts, commutator operation is approximated by means of a position‐dependent resistors network, and the excitation current provided by choppers is approximately considered as constant.

Hybrid excitation DC motors, which may be easily manufactured using existing facilities and mature technologies, might provide an interesting solution for emergency drives requiring minimal regulation capabilities and very high reliability under direct DC supply.

Hybrid excitation is not much investigated in the literature especially for DC motors, although such solution may result potentially interesting especially when a limited flux adjustment capability is required.

The purpose of this paper is to investigate the magnetic forces generated by a 12 slot/10 pole concentrated winding PM machines, considering a comparative study between two topologies: a surface mounted permanent magnet (SPM) machine and an interior PM (IPM) machine.

Following a description of the main characteristics of the concentrated winding permanent magnet machines (CWPMMs) under comparison, an investigation of the magnetic forces developed by both machines under study is carried out using finite element analysis (FEA).

A 2D FEA-based investigation has highlighted that the SPM machine develops higher magnetic forces than the IPM one. However, and following a 3D FEA, it has been found that the distribution of the magnetic forces along the air gap of the SPM machine is almost homogenous while it is concentrated in two opposite positions in the air gap of the IPM machine.

This work has treated almost all features of the machines under comparison, except the power losses. These should be investigated with emphasis on the PM eddy current losses is so far as the harmonic content of the armature air gap MMF is high.

The list of the selection criteria of CWPMMs should be extended to the magnetic force cancellation in order to fulfill the requirements of many applications such as the automotive ones.

The paper proposes a combined electromagnetic-mechanical approach to investigate the magnetic forces generated by CWPMMs using 2D and 3D FEA.

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.

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.

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.

The research should be extended to the comparison of the obtained results related to the torque production capability with experimental measurements.

An increase in the efficiency associated with the extension of the flux‐weakening range and a reduction of the volume make the concentrated winding PM machines interesting candidates, especially in large‐scale production applications such as the automotive industry.

The paper proposes an approach to design and performance investigation of concentrated winding PM machines considering both surface‐mounted and flux‐concentrating arrangements of the PMs.

The purpose of this paper is to an analytical approach-based prediction of the eddy current loss in the PMs of a concentrated winding machine equipped with 12 slots in the stator and ten poles in the rotor.

The investigation of the PM eddy current loss has been carried out using an analytical model and a 2D time-stepped transient finite element analysis (FEA).

It has been found, in the case of the treated machine, that just the subharmonic of rank 1 and the harmonic of rank 7 have significant contributions to the eddy current loss in the PMs.

A shift between the results yielded by the developed analytical model and those computed by FEA has been noticed. This limitation is mainly due to the slotting effect which has been omitted in the analytical model.

Fractional slot PM machines are currently given an increasing attention in automotive applications. The prediction of their iron loss in an attempt to rethink their design represents a crucial efficiency benefit.

The analytical prediction of the eddy current loss in each PM then in all PMs and their validation by FEA represent the major contribution of this work.

The purpose of this paper is to propose an approach to improve the torque production capability of fractional slot permanent magnet machines.

Following an analytical formulation of the electromagnetic torque, two optimization criteria are selected: the maximization of the average torque and the minimization of the torque ripple. For the sake of a simple analysis, the proposed approach assumes that the effects of the machine circumferential and radial parameters, on the torque production capability, are almost decoupled, so that their sizing optimization could be carried out separately.

The torque production capability of the optimized machine has been confirmed by finite element analysis, which confirms the appropriateness of the proposed sizing approach.

The obtained results should be validated by experiments carried out on a prototype.

The proposed approach has been carried out thanks to the introduction of the torque average value and ripple amplitude iso‐2D curves for circumferential parameters and iso‐3D surfaces for radial ones.

This paper deals with the analysis, the modeling, the control and the fault‐tolerance capability of a three‐switch inverter (TSI, also known delta‐inverter) fed fractional‐slot six‐phase brushless DC motor (BDCM) drive.

Following the presentation of the advantages of multi‐phase fractional‐slot brushless machines and the possibility of their association to TSI, the analysis of the operating sequences as well as the modeling of a TSI fed six‐phase BDCM drive are developed. Then, a dedicated control strategy of such a drive is synthesized. Finally, a case study is simulated considering both transient behaviour during the start‐up of the BDCM as well as a steady‐state one under healthy and faulty operations.

It has been found that the 60‐electrical degree shift between the six phases of the BDCM makes it simple to achieve its operating sequences with its armature fed by a TSI, considering a suitable anti‐parallel connection of the six phases.

Crucial cost benefits associated with improved compactness, reliability, and fault‐tolerance capability could be gained thanks to the integration of TSI fed six‐phase BDCM drives in large‐scale production industries, such as the automotive one.

The paper proposes an analysis of the operating sequences as well as the fault‐tolerance capability of TSI fed six‐phase BDCM drives.