State of the Art of Magnetic Gears, their Design, and Characteristics with Respect to EV Application

This chapter briefly explains the advantage of using magnetic gears (MGs) for transportation applications. Usually, a traction EV unit consists of, besides the engine or motor, a mechanical gear. The drawbacks of using mechanical gears have been emphasized, especially with respect to high-speed motorization, where high transmission ratio can be reached only by connecting multiple gears in series. A magnetic gear is capable of overcoming these issues. The chapter presents a state of the art on the available MGs, with fixed or variable transmission ratio, pointing out their applicability. Next, the possible design approaches (harmonic, magnetic reluctance equivalent circuit, and vector potential) are introduced. Furthermore, the output performances (power and torque) of two types of studied MGs are evaluated, with emphasis on the main loss criteria: iron losses in all the active parts of the MG. Finally, the influence of several materials is observed by means of numerical computation in order to decide, based on specific configuration, the most suited variant for transportation and aeronautic applications

Investigation of novel multi-layer spoke-type ferrite interior permanent magnet machines

The permanent magnet synchronous machines have been attracting more and more attention due to the advantages of high torque density, outstanding efficiency and maturing technologies. Under the urges of mandatory energy efficiency requirements, they are considered as the most potential candidates to replace the comparatively low-efficient induction machines which dominate the industrial market. However, most of the high performance permanent magnet machines are based on high cost rare-earth materials. Thus, there will be huge demands for low-cost high-performance permanent magnet machines. Ferrite magnet is inexpensive and abundant in supply, and is considered as the most promising alternative to achieve the goal of low cost and high performance. In consideration of the low magnetic energy, this thesis explored the recent developments and possible ideas of ferrite machines, and proposed a novel multi-layer spoke-type interior permanent magnet configuration combining the advantages of flux focusing technique and multi-layer structure. With comparable material cost to induction machines, the proposed ferrite magnet design could deliver 27% higher power with 2-4% higher efficiency with exactly the same frame size. Based on the data base of International Energy Agency (IEA), electricity consumed by electric machines reached 7.1PWh in 2006 [1]. Considering that induction machines take up 90% of the overall industrial installation, the potential energy savings is enormous. This thesis contributes in five key aspects towards the investigation and design of low-cost high-performance ferrite permanent magnet machines. Firstly, accurate analytical models for the multi-layer configurations were developed with the consideration of spatial harmonics, and provided effective yet simple way for preliminary design. Secondly, the influence of key design parameters on performance of the multi-layer ferrite machines were comprehensively investigated, and optimal design could be carried out based on the insightful knowledge revealed. Thirdly, systematic investigation of the demagnetization mechanism was carried out, focusing on the three key factors: armature MMF, intrinsic coercivity and working temperature. Anti-demagnetization designs were presented accordingly to reduce the risk of performance degradation and guarantee the safe operation under various loading conditions. Then, comparative study was carried out with a commercial induction machine for verification of the superior performance of the proposed ferrite machine. Without loss of generality, the two machines had identical stator cores, same rotor diameter and stacking length. Under the operating condition of same stator copper loss, the results confirmed the superior performance of the ferrite machine in terms of torque density, power factor and efficiency. Lastly, mechanical design was discussed to reduce the cost of mass production, and the experimental effort on the prototype machine validates the advantageous performance as well as the analytical and FEA predictions

High performance and low-cost permanent magnet devices

In this thesis the investigation of the modelling, design and analysis of novel permanent magnet machine for cost sensitive applications is presented. More specifically, a novel technique of arranging Ferrite permanent magnets with low energy density to achieve high airgap flux densities like those encountered in devices equipped with high cost rare-earth permanent magnets, thus, achieving significant cost savings, without substantial change in performance. Consequently, a spoke-type rotor equipped with axially magnetized permanent magnets in addition to the conventional circumferential permanent magnets is proposed, in order to increase the flux focusing and the airgap flux density

A Novel Rotor Topology for High-Performance Fractional Slot Concentrated Winding Interior Permanent Magnet Machine

This article presents a finite-element-based, multiobjective design optimization study of the fractional-slot, concentrated wound, permanent magnet synchronous machine (FSCW PMSM). Design objectives included maximization of efficiency, minimization of cost and low ripple without sacrificing torque density and wide constant power speed range. A large-scale optimization study revealed that while a V-type rotor provides high torque density, a spoke-type rotor has the benefit of low torque ripple. Quest for a design that can combine the goodness of both V-and spoke type rotors for an FSCW stator has led to a novel interior permanent magnet rotor topology referred here as Y-type. The goals of achieving maximum efficiency, minimum cost and wide CPSR were also accomplished in the proposed Y-type FSCW IPMSM. For experimental verification purpose, three fully optimized rotors-V-, spoke-and Y-type were constructed for a 12-slot/10-pole FSCW stator. Extensive experimental tests were conducted on three machines for a detailed comparison study. It will be shown that the proposed Y-type FSCW IPMSM outperforms both V and spoke-type configurations. A scaled-up version of the Y-type FSCW IPMSM shown to have satisfied many of the Freeedomcar 2020 targets, which is promising for application in electric vehicles

Permanent Magnet Vernier Machine: A Review

Permanent magnet vernier machines (PMVMs) gained a lot of interest over the past couple of decades. This is mainly due to their high torque density enabled by the magnetic gearing effect. This study will provide a thorough review of recent advances in PMVMs. This review will cover the principle of operation and nature of magnetic gearing in PMVMs, and a better understanding of novel PMVM topologies using different winding configuration as well as different modulation poles and rotor structures. Detailed discussions on the choice of gear ratio, slot-pole combinations, design optimisation and role of advanced materials in PMVMs will be presented. This will provide an update on the current state-of-the art as well as future areas of research. Furthermore, the power factor issue, fault tolerance as well as cost reduction will be discussed highlighting the gap between the current state-of-the art and what is needed in practical applications

Magnetic Gears and Magnetically Geared Electrical Machines with Reduced Rare-Earth Materials

This thesis covers a new emerging class of electrical machines, namely, Magnetic Gears (MGs) and Magnetically Geared Machines (MGMs). This particular kind of gears/machines are able of either scaling up or down the revolution-per-minute to meet various load profiles as in the case of mechanical gearboxes. Mechanical gearboxes have historically dominated various applications due to their relatively high torque density. However, mechanical gearboxes require physical contact between the rotational components, whereas MGs and MGMs accomplish fundamentally the same function via a contactless mechanism. This physical isolation between the rotational components lead to several advantages in a favor of MGs and MGMs over mechanical gearboxes. Although MGs and MGMs can potentially provide a solution for some of the practical issues of mechanical gears, MGs and MGMs have two major challenges that researchers have been trying to address. Those challenges are the high usage of rare-earth Permeant Magnet (PM) materials and the relatively complex mechanical structure of MGs and MGMs both of which are a consequence of the multi-airgap design. As in any engineering field, materials play a significant role and present a trad-off between the performance and cost. In addition to the previous trad-off, the concern with rare-earth PM materials is sustainability as well as price fluctuations. Current research in electrical machines demonstrate real initiatives to reduce the cost of electrical machines by reducing/eliminating the PM rare-earth content while attempting to maintain a competitive electromagnetic performance. Most advanced electrical machines use Dy-NdFeB PM with high energy product at elevated temperatures. Dysprosium (Dy) is one of heavy rare-earth elements and the key source of the price volatility. As a consequence, this thesis aims to address foregoing PM material challenges and investigate the electromagnetic performance of designs that blend different PM types in the context of MGs and MGMs. In addition, practical designs will be proposed in order to reduce the complexity related to the nature of MGs and MGMs

Photo-degradation of renewable biopolymer blended with thermoplastic high density polyethylene (HDPE)

High Density Polyethylene (HDPE) is one type of thermoplastic with varies applications but non-biodegradable material while biopolymer (BP) is environmentally friendly and degradable materials. However, BP has poor mechanical characteristics and restrict their capacity for varying in applications. Therefore, in this study, HDPE was blended with BP in liquid and particle form to produce BPL/ BPP. The composition ratio of BP blended with HDPE were 5, 10, 15, 20, 25 and 30% wt/wt of BP. These BP, HDPE, BPL/ BPP with different percentages of loading then were exposed to different UV exposure (250h, 500h, 750h, 1000h, 2000h, and 3000h) to identify the photo-degradation process. The formation of functional group of urethane linkages and other absorption peak was identified by using Fourier Transform Infrared Spectroscopy (FTIR). Norrish I and Norrish II reaction was taking place that produced ketone, amide group and carboxylic acid when increase in UV irradiation exposure that identified the photo-degradation process occurs in BPL/ BPP. By increasing percentages of BP loading, Melt Flow Index (MFI) shows decreasing in results indicate good flowability and improved its processability. Dynamic Mechanical Analysis (DMA) also shows a single peak of Tg indicated miscibility blending of BPL and BPP in all percentages of loading. BPL and BPP show higher tensile stress and hardness results as compared to BP. This is revealed the new blended polymer enhanced the mechanical properties of BP itself. Meanwhile, Scanning Electron Microscope (SEM) of BP shows brittle fracture morphology while HDPE shows ductile fracture and BPL or BPP show ductile to brittle morphological structure due to increasing in percentages of BP loading. Ultimately, BPL30-3000h, spider-web-like structure appeared while for BPP30-3000h, revealed a fine lamellar type of structure. Hence, BPL/ BPP successfully produced, and photo-degradation process occur and having good mechanical properties as compared to single materials itself (BP or HDPE)

Optimisation de la Conception du Moteur Synchrone à Excitation Hybride pour Véhicules Électriques à Haut Performance

Since 1970, the ever-growing concerns of human community for the life-threatening environmental changes have pushed the policy makers to decarbonize those sectors with high energy demands, including the transportation industry. Optimal designs of Electric Vehicles (EVs) can contribute to today’s exigent car market, and take the leading role for future sustainable transportation of human and goods. At the heart of electromechanical energy conversion lays the electrical machines, which have attracted lots of interests and efforts for efficiency increase and cost reduction. In this thesis, a methodology is proposed and implemented to design and optimize the cost and efficiency of a Hybrid Excitation Synchronous Machine (HESM) for a given vehicle and a desired driving cycle. Hybridization in the excitation system can combine the favorable qualities of high-torque at low-speed with superior overloading capability, exceptional flux weakening and extended Constant Power Speed Range (CPSR), high efficiency, and flexible controllability in motoring and generation modes. With HESM technology, we can also shift from the rare-earth magnets towards the cheap ferrite magnets and guaranty the supply for motor industry. The designed HESM in this work responds to three requirements of the vehicle, namely, the maximum cruising speed, acceleration time, and gradeability, with the least or null overdesign in the drivetrain. At the same time, it will have the maximum global efficiency over the driving cycle, and the minimum cost for the material. The optimization is conducted at either of the component and system levels. The optimization at component-level is developed based on the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). A new formulation for the objective functions is proposed, which deals with the design optimization and cost minimization, simultaneously. To maximize the efficiency, a system-level search is conducted to find the optimum HESM with the highest global efficiency over a given driving cycle. Due to the 3D direction of magnetic flux in the selected HESM topology, the Finite Element Analysis (FEA) was very time- and process-consuming. To be able to evaluate the objective functions during the optimization, a new model has been developed based on a 3D Magnetic Equivalent Circuit (MEC) network. This model predicts well the non-linearity of magnetic materials, as compared with the FEA simulations. At last, the final optimized HESM is evaluated by the virtue of FEA technique.Depuis 1970, les préoccupations de l’humanité envers les changements climatiques ont poussé les chercheurs à faire des études approfondies pour optimiser les machines électriques pour avoir des véhicules électriques plus performants et moins énergivores. La conception optimale de véhicules électriques (EV) peut contribuer pour un marché automobile plus exigeant et jouer un rôle principal pour le futur du transport durable des biens et des personnes. Les machines électriques se trouvent au cœur de la conversion d'énergie électromécanique, qui ont suscité beaucoup d'intérêts et d’efforts pour augmenter leur rendement et réduire leur coût. Cette thèse propose une méthodologie et une mise en œuvre pour minimiser le coût et maximiser l’efficacité d’une machine synchrone à excitation hybride (HESM) pour un véhicule donné et un cycle de conduite sélectionné. L'hybridation du système d’excitation peut combiner les qualités favorables comme un couple élevé à basse vitesse avec une capacité de surcharge supérieure, un défluxage exceptionnelle et une plage de vitesse prolongée de puissance constante (CPSR), une efficacité élevée et une contrôlabilité flexible dans les modes de traction et de freinage régénératif. Avec la technologie HESM, nous pouvons également passer des aimants de terres rares aux aimants en ferrite bon marché, et garantir l’approvisionnement pour l’industrie automobile. Le HESM conçu dans ce travail répond à trois exigences du véhicule : la vitesse de croisière maximale, le temps d’accélération et la capacité de monter une pente, avec un surdimensionnement minimal ou nulle de la chaîne de traction. Une optimisation multiniveau avec une interaction entre la vision composant et la vision système est proposée et validée. L’optimisation au niveau du composant est développée sur la base de l’algorithme génétique de tri non dominé (NSGA-II). Une nouvelle formulation pour les fonctions objectives est proposée pour l’optimisation simultanée de la conception de la machine et de la minimisation de son coût. Après avoir optimisés onze HESM au niveau du composant, pour maximiser l’efficacité, une optimisation au niveau du système est réalisée pour trouver le HESM optimal avec le plus haut rendement global sur le cycle de conduite donné. Une validation de la conception finale de la HESM présente un meilleur rendement global sur le cycle de conduite de 18,65% en relation à une machine synchrone à excitation séparée équivalente et 15,8% en relation à une à aiment permanent. En raison de la direction 3D du flux magnétique dans la topologie HESM sélectionnée, l’analyse par éléments finis (FEA) prenait beaucoup de temps et de ressources computationnelles. Afin d’évaluer les fonctions objectives lors de l’optimisation, un nouveau modèle a été développé basé sur un réseau de circuits magnétiques équivalents 3D (MEC). Ce modèle prédit bien la non-linéarité des matériaux magnétiques, par rapport aux simulations FEA. Enfin, le HESM optimisé final est évalué grâce à la technique FEA

Design and Application of Electrical Machines

Electrical machines are one of the most important components of the industrial world. They are at the heart of the new industrial revolution, brought forth by the development of electromobility and renewable energy systems. Electric motors must meet the most stringent requirements of reliability, availability, and high efficiency in order, among other things, to match the useful lifetime of power electronics in complex system applications and compete in the market under ever-increasing pressure to deliver the highest performance criteria. Today, thanks to the application of highly efficient numerical algorithms running on high-performance computers, it is possible to design electric machines and very complex drive systems faster and at a lower cost. At the same time, progress in the field of material science and technology enables the development of increasingly complex motor designs and topologies. The purpose of this Special Issue is to contribute to this development of electric machines. The publication of this collection of scientific articles, dedicated to the topic of electric machine design and application, contributes to the dissemination of the above information among professionals dealing with electrical machines