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Hybrid excited synchronous machines (HESMs) combine permanent-magnet (PM) excitation and wound field (WF) excitation. The goal of hybrid excitation is to combine the advantages of PM excited machines and WF synchronous machines. HESM have been identified as one of the emerging technologies for modern energy conversion systems. They have been the subject of many review articles. The principle of hybrid excitation allows solving many drawbacks related to PM electric machines operation: flux weakening, energy efficiency, and PMs price fluctuation. It helps to introduce an additional degree of freedom in the design of synchronous machines, and allows therefore an easier adaptation of PM synchronous machines to a wider applications scope. To this additional degree corresponds the possibility of adjusting the contribution of the two magnetic field sources: PM and WF. The use of this technology for electric traction has been the subject of many scientific and technical contributions. In this contribution, the emphasis will be put on the use of these machines as generators in transportation applications and renewable energy applications. The design and operation of three particular structures will be presented. Two of them have been designed as generators for transportation applications, and the third one has been designed as generator for renewable energy conversion. All of them are flux switching hybrid excited synchronous machines (FSHESM). [ABSTRACT FROM AUTHOR]

The aim of this study is to analyze the vibration behavior of a five-phase flux switching machine in order to detect and discriminate full and partial open-phase faults. To achieve our goal, radial magnetic stress was calculated by two magnetic models. The first magnetic model, presented in this paper, is obtained by finite element analysis (FE) and the second one by permeance network analysis (PN) of the studied electrical machine. Stator radial accelerations were evaluated coupling each of the two magnetic models with an analytical mechanical model. The results of two multiphysics models are compared with experimental results, in order to validate them. Experimental measurements are performed under healthy and faulty conditions, at fixed rotational speed. For faulty conditions, full open-phase and partial open-phase fault of the stator winding were analyzed. [ABSTRACT FROM AUTHOR]

This paper presents performance improvements of a double excitation synchronous motor by using a reluctance network (RN). The distinguishing feature of the double excitation principle is to use permanent magnets with high energy, while air-gap flux is flexibly controlled by field windings. Therefore, the first contribution of this paper focuses on maximizing air-gap flux range control. Second, an approach for torque ripple reduction is proposed by directly modifying air-gap flux according to the instantaneous torque profile. The achieved resultant torque stays almost constant for a case study. The validity of the RN method is examined by comparisons with 3-D finite element and experimental results for several machines. [ABSTRACT FROM AUTHOR]

This paper deals with the fault tolerance of a five-phase flux switching machine. Short-circuit currents calculation considering inductances variation is developed. Machine behavior (torque quality, copper losses, and homopolar current) under a single short-circuit phase fault, two consecutive and nonconsecutive phases short-circuited, is simulated with a two-dimensional finite elements (2-D FE) model and validated experimentally. Then, a new method is developed to improve its performances in faulty mode, by reconfiguring reference currents. In fact, an accurate torque model is established and then used in a genetic algorithm to optimize reference currents in faulty mode. In this approach of reference currents computation, the used algorithm has multiobjectives and multiconstraints, thereby allowing choosing the appropriate fault-tolerant current solution according to our application. The torque model is considered to be more accurate and closer to the 2-D FE results in both healthy and faulty modes. Then, a comparison of machine performances in healthy, degraded, and reconfigured modes is presented. Experimental results corroborate the analysis. [ABSTRACT FROM AUTHOR]

In this paper, an analytical method for the computation of the electromagnetic field in the airgap of an inset permanent magnet synchronous machine is proposed. The originality lies in the fact that both the stator and rotor saliencies have been taken into account in the analytical procedure. The purpose in to compute both quickly and accurately the magnetic fluxes and instantaneous torque of the machine, in order to minimize torque ripples in an optimal predesign process. It is shown that the instantaneous torque is in good agreement with finite element results, for a shorter computation time. The model presented here can be used when the 2-D approximation of the machine is valid, which is the case for most of machines' topologies. [ABSTRACT FROM AUTHOR]

In this paper, an analytical method for the calculation of the electromagnetic field in the airgap of a permanent-magnet synchronous machine is developed, so as to compute the torque of the machine. Such a work is applicable to different machine topologies (even for salient rotor ones), when a two dimensional approximation of the structure is possible. This analytical model can be useful in an optimization task. In the first part, the analytical method of the field computation is explained in detail, both for the magnet's field, and for the armature reaction field. The results are compared to finite elements analysis. [ABSTRACT FROM AUTHOR]

The aim of this paper is to assess the efficacy of non-conformal meshing in mesh-based generated reluctance network modeling. A representative semi-numerical example is introduced to demonstrate the possibilities and accuracy offered by a non-conformal meshing. In a conformal mesh, two reluctance block elements share the same branch. This makes the computation faster and more accurate but is not convenient for motion processing or mesh relaxation and it does not solve the air-gap modeling problem (rotor/stator connectivity). To solve this, different approaches are used. The interpolation approach developed in this paper aims to render motion processing independent of discretization. This approach is also applied to couple different meshes (spatial discretization) and makes it possible to connect a lumped parameter model to a meshed one. The model is divided into independent zones that are connected via the interpolation coupling. Several reluctance network (RN) non-conformal meshes are presented and global quantities are compared to a fine-meshed finite-element model. Magnetic saturation is considered in the iron parts. Comparisons are provided under open-circuit and on-load configurations for flux linkage and force. The main advantage is to overcome the limitations of generic RN for which the movement modeling requires remeshing at each position. The drawbacks of the method are the increased number of variables (additional interface nodes) and a certain loss of accuracy due to the interpolation function order. [ABSTRACT FROM AUTHOR]

This aim of this paper is to assess the efficacy of mesh-based generated reluctance network (MGRN) modeling for the performance evaluation of a permanent magnet linear machine under load conditions. In the previous publications related to the use of this modeling technique, only approach implementation under an open-circuit performance has been assessed. The MGRN approach is based on the discretization of the geometry using elementary reluctance blocks (reluctance elements). This modeling technique has been implemented in a software tool that allows the automated processing of an arbitrary geometry providing a gain in model development durations. Validation of the MGRN model has been realized by comparison with a finite element analysis (FEA). Comparisons showed that both local and global quantities evaluated by MGRN and FEA are in excellent agreement. [ABSTRACT FROM AUTHOR]

In [1], an error in Fig. 2 in Section II-B is corrected. In the original figure, Fig. 2(b) was exactly the same as Fig. 2(a). The correction is shown here. [ABSTRACT FROM AUTHOR]

This paper describes an analytical model for computing the rotor eddy-current losses in the case of permanent magnet synchronous machines, based on a formal resolution of Maxwell’s equations. We focus on the computation of the eddy currents in the machine magnets, in which the diffusion equation is analytically solved, using an accurate electromagnetic model of the stator slotting. The model originality lies in its capacity of taking into account both the diffusion phenomenon and the magnet’s finite length over the pole pitch, imposing that the total current over the magnet’s surface should be zero at each instant. This important problem is studied by solving a Fredholm integral equation. A validation using a 2-D time-stepping finite-element model is also performed, and the obtained losses are shown to be in good agreement with those given by the analytical method, for a shorter computation time. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to compare performances of two configurations of an embedded Claw Pole Alternator (CPA) where the excitation winding is transferred to the stator side. These configurations are: the Simple Excited Automotive Alternator (SE2A) and the Hybrid Excited Automotive Alternator (HE2A). Performed study is based on test at no-load and under load operation regimes, using Magnetic Equivalent Circuit (MEC) models validated experimentally. It has been found that the hybrid Excited claw pole alternator provides higher performances, due to the increase of leakage flux through the integration of permanent magnets between adjacent rotor claws. [ABSTRACT FROM AUTHOR]

This paper presents two short-circuit fault models of a hybrid excitation flux switching permanent magnet machine, i.e., excitation phase short-circuit and interturn short-circuit in excitation windings. Two-dimensional finite element (FE) method is used to calculate the major parameters, such as armature and excitation inductances, which are not only functions of rotor position, but also of armature and excitation currents. Moreover, in case of short-circuits, the variations of armature and excitation currents are often significant. This in turn leads to an important change in winding inductances. Therefore, in order to precisely predict machine performance under short-circuit conditions, the use of inductances versus rotor position and RMS currents is essential. With the obtained FE results, two MATLAB/Simulink-based models are established. Then, the previously mentioned short-circuits have been studied and their influences on electromagnetic performances, such as armature and excitation currents, speed and torque, armature and excitation copper losses, stator and rotor core iron losses, as well as permanent magnet (PM) eddy current losses are analyzed. Experiments have been carried out to validate the simulations. [ABSTRACT FROM PUBLISHER]

A general approach to magnetic losses in soft magnetic composites (SMC) is discussed. It is applied to exciting conditions typical of applications, where the induction waveform is most frequently nonsinusoidal. The standard predicting approach, based on the statistical theory of losses (STL) and the related concept of loss separation, is extended to the case of granular heterogeneous materials. As a starting point, the classical loss component is calculated, taking into account that in small enough samples the measured loss is independent of the specimen cross-sectional area, because of negligible grain-to-grain (macroscopic) eddy currents. The loss separation is then performed under the conventional sinusoidal induction regime and the STL is used to identify a limited set of parameters, associated with the prediction of the excess loss, by which the energy loss under distorted induction can be predicted. Significant predicting examples are provided, regarding two different SMCs, where the induction waveform is either triangular or distorted by introduction of a third harmonic component. [ABSTRACT FROM AUTHOR]

This paper presents a 3-D analytical model of an axial flux permanent-magnet synchronous machine, based on formal resolution of Maxwell equations. This method requires much less computation time than conventional 3-D finite elements, and is therefore suitable for optimization purposes. In a first part, the mathematical procedure used to compute the machine no-load flux is described in detail. This method is 3-D, and then takes into account the radial edge effects of the machine, as well as the curvature effects by a resolution in cylindrical coordinates. Moreover, the originality of this method lies in the fact that it is totally analytical. The obtained results are verified using 3-D finite elements, and compared with simpler analytical models of axial flux machines, taken from the literature. This work puts in evidence the advantages of the proposed model. In particular, it is shown that the radial edge effects are important for a correct estimation of the no-load flux. On the contrary, the curvature effects are a second-order phenomenon. [ABSTRACT FROM PUBLISHER]

This paper presents 3-D finite-element analysis of a new double excitation synchronous machine. It is shown that the machine has true field regulation capability. The principle of operation and design aspects of this new machine are presented in the paper. Comparison of 3-D FEA with an experimental study done on a prototype having a different rotor structure is also investigated. [ABSTRACT FROM PUBLISHER]

This study presents a fault-electromagnetic-thermal model of a fault-tolerant dual-star flux-switching permanent magnet motor. The analytical results in terms of phase currents, rotor velocity and output torque are firstly calculated by a Simulink-MATLAB-based fault (short-circuit) model. Then, the fault and normal phase currents are used in the motor 2D finite element method (FEM) model to calculate the copper and iron losses. As the main heat sources in electrical machines, the obtained copper and iron losses are used in the lumped parameter (LP) and the 3D FEM thermal models to calculate the temperatures of different machine components. Finally, the variation of temperatures of the machine in the presence of faults can be predicted. The results obtained by the LP and the 3D FEM models are also validated by experimental tests. A good agreement has been observed among the analytical, numerical and experimental results. In order to realise the 3D FEM model of the doubly salient rotating machine, a method to transform the salient rotor into a non-salient one have been proposed. Some methods are also proposed to enhance the performance of the cooling system and decrease the maximum temperature of the machine. [ABSTRACT FROM AUTHOR]

This paper presents copper and iron loss models of a classical switched reluctance motor (SRM) and a mutually coupled switched reluctance motor (MCSRM). The iron losses in different parts of machines are then detailed. Based on the power losses model, a lumped parameter (LP) transient thermal model during driving cycles is performed, the analytical results are validated by the finite-element (FE) transient thermal model. Special attention has been paid to model the salient rotor and a method to transform the salient rotor into a nonsalient one has been proposed. A comparison between the maximum temperatures obtained by using different heat source (average power losses or instantaneous power losses during driving cycles) is given. The experimental tests are also realized to verify the analytical and numerical results. [ABSTRACT FROM PUBLISHER]

We describe an exact 2-D analytical model for predicting the open circuit magnetic field in idealized structures of wound field and series hybrid excitation permanent-magnet synchronous machines. This technique can be used for either internal or external rotor radial-field machine topologies. It involves analytical solution of Maxwell's equations in stator and rotor slots and annular air-gap/magnet regions. We compare results from this analytical model to corresponding finite-element analyses. We then use it to estimate the cogging torque, induced back-electromotive force, and to study the effects of rotor skewing. [ABSTRACT FROM PUBLISHER]

We describe a 3-D analytical model based on formal resolution of Maxwell's equations of a permanent-magnet linear actuator, with circular-shaped magnets. We present all details of the 3-D analytical calculation for the no-load flux and then compare results obtained by this model to those obtained by 3-D finite-element analysis. The comparisons show a good agreement between the two models and so validate our analytical model. Unlike 3-D finite-element analyses, which are time consuming, the analytical models that we present in this paper are suitable for an optimization process of such a structure. [ABSTRACT FROM AUTHOR]

Abstract: Sinusoidal motor''s mathematical models are usually obtained using classical d–q transformation in the case of salient pole synchronous motors having sinusoidal field distribution. In this paper, a new inverse modelling for synchronous motors is presented. This modelling is derived from the properties of constant torque curves in the Concordia''s reference frame. It takes into account the non-sinusoidal field distribution; EMF, self and mutual inductances having non-sinusoidal variations with respect to the angular rotor position. Both copper losses and torque ripples are minimized by adapted currents waveforms calculated from this model. Experimental evaluation was carried out on a DSP-controlled PMSM drive platform. Test results obtained demonstrate the effectiveness of the proposed method in reducing torque ripple. [Copyright &y& Elsevier]

We present novel results on magnetic losses in soft magnetic composites (SMCs) excited with rotating field. Soft composites are very promising in electrical engineering applications, where new topologies of electrical machines with two- and three-dimensional induction loci are increasingly found. An experimental characterization of industrial SMC products has, therefore, been carried out, up to the kilohertz range, under alternating and circular flux loci, making use of a specifically designed and optimized loss measuring setup. The obtained results have been analyzed for all kinds of excitation, according to the loss separation concept, with the emphasis being placed on the relationship between the rotational and the alternating loss components. In particular, it is found that the ratio between the rotational and the alternating losses is, for any given peak induction, independent of frequency. [ABSTRACT FROM AUTHOR]

We report and discuss significant results on the magnetic losses and their frequency dependence insoft magnetic composites. Two types of bonded Fe-based materials have been characterized atdifferent inductions from dc to 10 kHz and analyzed by extending the concept of loss separation and the related statistical theory to the case of heterogeneous materials. Starting from the experimental evidence of eddy current confinement inside the individual particles, the classical losscomponent is calculated for given particle size distribution. Taking then into account thecontribution of the experimentally determined quasistatic (hysteresis) loss, the excess losscomponent is obtained and quantitatively assessed. Its behavior shows that the dynamichomogenization of the magnetization process with frequency, a landmark feature of magnetic laminations, is restrained in these materials. This results into a partial offset of the loss advantage offered by the eddy current confinement. [ABSTRACT FROM AUTHOR]