Review of Fe-6.5 wt%Si high silicon steel—A promising soft magnetic material for sub-kHz application

To meet the growing need for energy efficiency in power electronics and electric machines, a number of new soft magnetic materials are being investigated. Among them, high silicon Fe-Si alloy has been recognized as a promising candidate for low-to-medium-frequency applications. Compared to the currently most widely used 3 wt% silicon steel, the steel containing 6.5 wt% Si possesses more favorable properties, including high electrical resistivity, good saturation magnetization, and near-zero magnetostriction. However, the high silicon content facilitates the formation of ordered phases, resulting in severe brittleness that prohibits mass production using the economical conventional processing methods. A number of new processing routes have been investigated and inspiring progress has been made. Prototypes of motors and transformers using high silicon steel have been demonstrated with improved efficiency and power density. If the processing cost and limitations of size and shape are properly addressed, high silicon steel is expected to be widely adopted by the industries. Among all the investigated processing techniques, rapid solidification appears to be the most cost-effective method for mass producing thin sheet of high silicon steel. This paper reviews the current state-of-the-art of the Fe-Si based soft magnetic materials including their history, structure, properties, processing, and applications

Soft Magnetic Materials

partially_open4partially_openFiorillo, F.; Bertotti, G.; Appino, C.; Pasquale, M.Fiorillo, F.; Bertotti, G.; Appino, Carlo; Pasquale, Massim

Additive manufacturing of soft magnets for electrical machines—a review

With growing interest in electrification from clean energy technologies, such as wind power and use of pure electric powertrains in various applications, the demand for next-generation, high-performance magnetic materials has risen significantly. Electrical machine design for these applications is facing challenges in terms of meeting very demanding metrics for power densities and conversion efficiencies, thereby motivating the exploration of advanced materials and manufacturing for the next generation of lightweight ultraefficient electric machines. Additive manufacturing (AM), a layer-by-layer three dimensional (3D) printing technology, opens up new venues of improvements for industrial manufacturing of electrical machines via near-net shape printing of complex geometries, reduction of parts count and production lead time, and conservation of expensive critical materials such as rare-earth magnets as well as nanocrystalline and amorphous soft magnetic composites, allowing their use in only critical regions required by desired properties of the printed parts. The magnetic, electrical, thermal, and mechanical properties of the magnetic materials are also greatly influenced by the selection of the AM method. Among the seven major American Standard Testing and Materials-defined standard modes of 3D printing, selective laser melting, fused deposition modeling, and binder jetting technology dominate the AM processing of soft magnetic materials and their integration in electrical machines. In this work, the state of the art in printability and performance characteristics of soft magnetic materials for electric machines is summarized and discussed. The prospects of soft magnetic materials selection in terms of price, printability, weight, and performance of the electrical machines are also discussed. This review highlights the current status of AM of large electrical machines, AM process selection guidelines, hybrid printing technologies, and the associated opportunities and challenges. An emphasis is put on multimaterial processing that is essential for electrical machines. Hybrid printing technologies that combine multiple AM processes with adequate automation and enable simultaneous multimaterials dispensing, real-time quality control, postprocessing, and surface finish with integrated subtractive computer numeric control machining are the requirements for progressing toward the end-user electrical machines

Магнитомягкие композиты на основе порошков железа для создания компонентов двухстаторного комбинированного электродвигателя

An experimental prototype of electric motor on permanent (FeNdB) magnets with switchable magnetic flux with two sectioned stators and a rotor using SMC material based on encapsulated metal powders has been developed. The method of manufacture of magnetic cores by powder metallurgy method on the basis of magnetically soft encapsulated titanium dioxide composites has been developed, including computer modeling of magnetic cores components, creation of tooling for their manufacture by pressing and selection of technological modes of pressing. Press set for manufacturing stator components by pressing in the form of a mold was made of hardened 5XHB steel. With its use magnetic components for twostator combined electric motor are pressed. The main electromagnetic characteristics of the components were measured with an express magnetometer. Complex studies showed that the magnetic components have sufficient strength and the necessary electromagnetic characteristics to create a two-stator combined electric motor of this type. An experimental sample of electric motor with maximum power of 15 kW was created on the basis of manufactured magnetic components. Advantages of composite material over electrical steel and other soft magnetic alloys allow providing their wider application in electric machines in order to increase specific power at high speed of rotation with less losses.Разработан экспериментальный образец электродвигателя с переключаемым магнитным потоком с двумя секционированными статорами и ротором на постоянных (FeNdB) магнитах с применением SMC-материала на основе капсулированных металлических порошков. Создана методика изготовления магнитопроводов на основемагнитомягких капсулированных диоксидом титана композитов методом порошковой металлургии, включающая в себя компьютерное моделирование компонентов магнитопроводов, создание оснастки для их изготовления методом прессования и выбор технологических режимов прессования. Оснастка для компонентов статора методом прессования в виде пресс-формы изготовлена из закаленной стали 5ХHB. С ее применением спрессованы магнитныекомпоненты для двухстаторного комбинированного электродвигателя. Основные электромагнитные характеристики компонентов измерены с помощью экспресс-магнетометра. Комплексные исследования показали, что магнитные компоненты обладают достаточной прочностью и необходимыми электромагнитными характеристиками длясоздания двухстаторного комбинированного данного типа электродвигателя. На основе изготовленных магнитных компонентов создан экспериментальный образец электродвигателя с максимальной расчетной мощностью 15 кВт. Преимущества композиционного материала перед электротехнической сталью и другими магнитомягкими сплавами позволяют обеспечить более широкое их применение в электрических машинах с целью повышения удельной мощности при высокой скорости вращения с меньшими потерями

Modular Medium-Voltage Grid-Connected Converter with Improved Switching Techniques for Solar Photovoltaic Systems

© 1982-2012 IEEE. The high-frequency common magnetic-link made of amorphous material, as a replacement for common dc-link, has been gaining considerable interest for the development of solar photovoltaic medium-voltage converters. Even though the common magnetic-link can almost maintain identical voltages at the secondary terminals, the power conversion system loses its modularity. Moreover, the development of high-capacity high-frequency inverter and power limit of the common magnetic-link due to leakage inductance are the main challenging issues. In this regard, a new concept of identical modular magnetic-links is proposed for high-power transmission and isolation between the low and the high voltage sides. Third harmonic injected sixty degree bus clamping pulse width modulation and third harmonic injected thirty degree bus clamping pulse width modulation techniques are proposed which show better frequency spectra as well as reduced switching loss. In this paper, precise loss estimation method is used to calculate switching and conduction losses of a modular multilevel cascaded converter. To ensure the feasibility of the new concepts, a reduced size of 5 kVA rating, three-phase, five-level, 1.2 kV converter is designed with two 2.5 kVA identical high-frequency magnetic-links using Metglas magnetic alloy-based cores

Materials Used in High-Speed Electrical Machines

The high-speed electrical machines are widely used in different industries, such as machine tools, aerospace engineering, autonomous power engineering, etc. This chapter devoted to materials used in high-speed electrical machines with high-coercitivity permanent magnets (HCPMs). It is considered to be materials of rotor sleeve, shaft, stator magnetic core, and permanent magnet. Material selection methods are presented. In addition, mechanical strength calculation of the rotor sleeve is shown. The obtained results can be used in the design of high-speed electrical machines with high-coercivity permanent magnets and in their future development

Convertisseurs à bobine variable pour applications de transport durables

Abstract: Power electronics converters are key components and enable efficient conversion and management of electrical energy in a wide range of applications. For vehicular use, there is an inevitable need to improve their performance and reducing their size. This is particularly important in case of powertrain DC-DC converters as they are required to have improved performance while respecting the specifications, characteristics and stringent space limitations. These objectives define research targets and a particular progress is essential in the field of passive components, semiconductor devices, converter topologies and control. At the current state of technologies, the passive components particularly the power inductors are dominant components which affect the overall volume, cost and performance of power electronic converters. Considering the aforementioned critical aspects, this thesis proposes a variable inductor (VI) concept in order to reduce the weight and size power inductors which are traditionally bulky and have fairly limited operating range. By modulating the permeability of the magnetic material, this concept enhances the current handling capability of power inductors, controls the current ripples, reduces the magnetic and switching losses, as well as the stresses applied to switching devices. Furthermore, it enables the use of smaller cores which leads to the reduction of mass and volume allowing improvements in the converter operation and its overall performance. However, to integrate it into powertrain DC-DC converters, it is fundamental, to question the design of the component itself, the selection of suitable magnetic core materials, and the control of current in the auxiliary winding and saturation management of magnetic cores. This thesis systematically addresses these different research challenges. A particular attention is paid to the experimental study of a VI prototype to demonstrate the concept on a small-scale in order to explore its viability. Subsequently a detailed characterization was developed using finite element analysis to determine the intrinsic functionality of the passive component. Furthermore, this thesis proposed an RMS current based VI design to reduce oversizing of power inductors for electric vehicles application. In this methodology, the selection of a suitable magnetic core material is a crucial step to assure smaller and efficient converters. Hence, this thesis proposes a simplified approach based on weighted property method (WPM) for an appropriate selection of magnetic core in accordance to the needs of the user. Furthermore, to validate the integration of this concept in DC-DC converter topology used in the powertrain of electrified vehicles, an affine parameterization method is used to design the control parameters and a simple management strategy is proposed to enable dynamic control of the VI. The converter control and the proposed strategy are evaluated through simulations of a complete powertrain of a three-wheel recreational vehicle. The small-scale experimental and simulations, and full-scale simulations have demonstrated an interesting capacity of the VI for improving the performance of DC-DC converters for electrified vehicles and manage the saturation of the magnetic core while reducing the size and weight of magnetic components.Les convertisseurs d’électroniques de puissance sont des composants clés de la conversion et gestion efficace de l’énergie électrique dans une large gamme d’applications. Pour des utilisations véhiculaires, il est inévitablement nécessaire d’améliorer leurs performances et de réduire leur taille. Ceci est particulièrement important dans le cas des convertisseurs à courant continu (CC) de la chaine de traction où des performances améliorées en réponse à une large gamme de variations de charge sont recherchées tout en respectant les spécificités, caractéristiques et limitation d’espace nécessaires aux véhicules électrifiés. Ces objectifs définissent une cible de recherche et en particulier des progrès sont essentiels dans le domaine des composants passifs, des dispositifs semi-conducteurs, des topologies des convertisseurs et leurs commandes pour généraliser l’utilisation de véhicules électriques. Les composants passifs, en particulier les inductances de puissance, sont des composants dominants qui affectent le volume global, le coût et les performances de ces convertisseurs d’électroniques de puissance. Compte tenu de ces aspects, cette thèse propose un concept de bobine variable afin de réduire le poids et la taille des inductances de puissance qui sont traditionnellement encombrantes et ont une gamme de fonctionnement assez limitée. En modulant la perméabilité du matériau magnétique, ce concept améliore la capacité de gestion du courant des bobines de puissance, contrôle les ondulations du courant et réduit les pertes magnétiques et par commutation, bien comme les contraintes appliquées aux dispositifs de commutation. En outre, il permet l’utilisation de noyaux plus petits, ce qui entraîne une réduction de masse et de volume, en permettant une amélioration du fonctionnement du convertisseur et de ses performances globales. Cependant, pour l’intégrer aux convertisseurs CC-CC utilisés dans la chaine de traction, il est fondamental de se questionner sur la conception du composant lui-même, la sélection du matériau magnétique, la commande du courant de l’enroulement auxiliaire et la gestion de la saturation du noyau magnétique. Cette thèse aborde de manière systématique ces différents défis de recherche. Une attention particulière est accordée à l’étude expérimentale d’un prototype de bobine variable pour faire la preuve de concept à petite échelle afin d’explorer sa viabilité. Par la suite, une large caractérisation par éléments finis a été développée pour déterminer le fonctionnement intrinsèque de ce composant passif. De plus, cette thèse propose une méthode systématique de design de bobine variable basée sur le courant RMS pour réduire le surdimensionnement traditionnellement associer aux inductances de puissance pour des applications véhiculaires. Dans cette méthodologie, la sélection appropriée du matériau pour le noyau magnétique est une étape cruciale pour garantir des convertisseurs plus petits et efficaces, donc une démarche de sélection simplifiée basée sur la méthode des propriétés pondérées pour le choix de noyau magnétique approprié au besoin de l’application a été mis au point. De plus, pour valider l’intégration de ce concept dans une topologie de convertisseur CC-CC traditionnellement utilisée dans la chaine de traction des véhicules électrifiés, une méthode de synthèse affine a été utilisée pour définir les paramètres des contrôleurs de courant et une stratégie de gestion de la saturation du noyau a été proposée pour permettre le contrôle dynamique de la bobine variable. La commande du convertisseur et la stratégie ont été évaluées par simulation d’une chaine de traction complète d’un véhicule récréatif réel. Les résultats expérimentaux à petite échelle et simulations à pleine échelle ont démontrés des capacités intéressantes de cette bobine variable pour l’amélioration des performances des convertisseurs CC-CC, ayant la capacité de gestion de la saturation du noyau magnétique tout en réduisant la taille et le poids de ces composants passifs, dans le but de son utilisation dans la chaine de traction des véhicules électrifiés