Sami Hlioui

Modification in Rotor Pole Geometry of Mutually Coupled Switched Reluctance Machine for Torque Ripple Mitigating

This paper presents a new method to minimize the torque ripple of a 3-phase, 6-slot, and 4-pole mutually coupled switched reluctance motor (MCSRM 6/4). The difference between a MCSRM and a classical SRM is their winding configuration. In a MCSRM, the mutual inductances are no longer neglectable when compared to self inductance. On the contrary, due to mutual inductances, the MCSRM can produce higher average torque than a classical SRM. A literature review is firstly performed to identify the source of high torque ripple level of a MCSRM. Then, the method using punching holes in rotor poles to modify the waveforms of flux as well as derivatives of inductances with respect to rotor position (dL/d and dM/d ) is proposed. Using the 2-D finite-element method (FEM), the influence of dimensions of punching hole on the electromagnetic performances (average torque and torque ripple) is analyzed. The two MCSRM are supplied by three-phase sine wave currents, and comparisons in terms of average torque and torque ripple versus RMS current density are also carried out. In order to make sure that the presence of punching holes does not cause mechanical problems, some mechanical studies are performed. Finally, experimental tests are also realized to validate numerical results obtained by 2-D FEM.

Comparison of Open Circuit Flux Control Capability of a Series Double Excitation Machine and a Parallel Double Excitation Machine

Double excitation synchronous machines combine permanent-magnet (PM) excitation with wound field excitation. The goal behind the principle of double excitation is to combine the advantages of PM-excited machines and wound field synchronous machines. These machines can constitute an energy-efficient solution for vehicle propulsion. This paper presents a comparison of the open circuit flux control capability of two structures of double excitation synchronous machines. First, a review of the state of the art of double excitation machines is presented. Then, the structures of these two machines are presented: one is a series double excitation synchronous machine and the other is a parallel double excitation synchronous machine. Finally, the open circuit flux control capabilities of both structures are compared.

3-D Formal Resolution of Maxwell Equations for the Computation of the No-Load Flux in an Axial Flux Permanent-Magnet Synchronous Machine

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.

A New Parallel Double Excitation Synchronous Machine

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.

Hybrid excitation synchronous permanent magnets synchronous machines optimally designed for hybrid and full electrical vehicle

In this paper, the performances of a hybrid excitation flux switching permanent magnets synchronous machine (HEFSSM) that have been optimally designed for a hybrid electric vehicle (HEV) application are shown. The different losses: copper losses and iron losses are computed for the European Normalized Driving Cycle (NEDC) by taking into account all operating points in the torque-speed plan. Finally, the optimization problem of such hybrid excitation machine for a given driving cycle is discussed.

Comparative study of Switched Reluctance Motors performances for two current distributions and excitation modes

This paper presents a 3-phase, 6-slot, and 4-pole Mutually Coupled Switched Reluctance Motor (MCSRM 6/4) with new current distribution. This kind of SRMs has both the merits of conventional SRMs and Fully Pitched SRMs, i.e. shorter end-windings and higher torque density. A comparison based on Finite Element Method (FEM) between conventional and mutually coupled SRMs, in terms of self flux-linkage and inductance per phase, mutual flux-linkage and inductance between phases, and output torque is realized. The conventional SRM is excited in unipolar mode, while the MCSRM is excited in bipolar overlapping mode. With a high coupling between phases for MCSRM, mutual inductances are employed to produce torque. Furthermore, the flux pathways are separated and distributed between phases, this leads to a less sensitivity to magnetic saturation. At high current density and high conduction angle, the MCSRM has a higher output torque and a lower torque ripple. Thus, comparing to conventional SRMs, the MCSRM is more outstanding for starter-generator applications (hybrid vehicles, aerospace) which needs high output torque.

PM and hybrid excitation synchronous machines: Performances comparison

In this paper, a new topology of hybrid excitation synchronous machine (HESM) is presented. This kind of machine is well suited for hybrid vehicle applications. First of all, a summary description of the HESM is presented. A simplified analytic study based on reluctant network is presented. It is validated by finite element analysis and experimental measurements. The mechanical performances of the presented HESM are compared to a conventional permanent magnet synchronous machine (PMSM) designed for the same application.

Overview of hybrid excitation synchronous machines technology

This paper describes the state of the art of hybrid excitation synchronous machines. Different hybrid excited synchronous structures from scientific and technical literature are described and analysed. Advantages and drawbacks of the different structures are discussed. Different method of classification of these structures will also be discussed. The contribution of the hybrid excitation principle for motoring and generating mode is detailed and the different models for the design of these structures are presented.

Three-Dimensional Analytical Modeling of a Permanent-Magnet Linear Actuator With Circular Magnets

We describe a 3-D analytical model based on formal resolution of Maxwells 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.

An Analytical Model for the Computation of No-Load Eddy-Current Losses in the Rotor of a Permanent Magnet Synchronous Machine

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 Maxwells 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 magnets finite length over the pole pitch, imposing that the total current over the magnets 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.