다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Although the concept of variable-speed drives, based on utilization of multiphase machines, dates back to the late 1960s, it was not until the mid- to late 1990s that multiphase drives became serious contenders for various applications. These include electric ship propulsion, locomotive traction, electric and hybrid electric vehicles, ldquomore-electricrdquo aircraft, and high-power industrial applications. As a consequence, there has been a substantial increase in the interest for such drive systems worldwide, resulting in a huge volume of work published during the last ten years. An attempt is made in this paper to provide a brief review of the current state of the art in the area. After addressing the reasons for potential use of multiphase rather than three-phase drives and the available approaches to multiphase machine designs, various control schemes are surveyed. This is followed by a discussion of the multiphase voltage source inverter control. Various possibilities for the use of additional degrees of freedom that exist in multiphase machines are further elaborated. Finally, multiphase machine applications in electric energy generation are addressed.

Multiphase Electric Machines for Variable-Speed Applications

Large-scale deployment of intermittent renewable energy (namely wind energy and solar PV) may entail new challenges in power systems and more volatility in power prices in liberalized electricity markets. Energy storage can diminish this imbalance, relieving the grid congestion, and promoting distributed generation. The economic implications of grid-scale electrical energy storage technologies are however obscure for the experts, power grid operators, regulators, and power producers. A meticulous techno-economic or cost-benefit analysis of electricity storage systems requires consistent, updated cost data and a holistic cost analysis framework. To this end, this study critically examines the existing literature in the analysis of life cycle costs of utility-scale electricity storage systems, providing an updated database for the cost elements (capital costs, operational and maintenance costs, and replacement costs). Moreover, life cycle costs and levelized cost of electricity delivered by electrical energy storage is analyzed, employing Monte Carlo method to consider uncertainties. The examined energy storage technologies include pumped hydropower storage, compressed air energy storage (CAES), flywheel, electrochemical batteries (e.g. lead–acid, NaS, Li-ion, and Ni–Cd), flow batteries (e.g. vanadium-redox), superconducting magnetic energy storage, supercapacitors, and hydrogen energy storage (power to gas technologies). The results illustrate the economy of different storage systems for three main applications: bulk energy storage, T&D support services, and frequency regulation.

Electrical energy storage systems: A comparative life cycle cost analysis

Energy storage technologies and real life applications – A state of the art review

The electric vehicle (EV) technology addresses the issue of the reduction of carbon and greenhouse gas emissions. The concept of EVs focuses on the utilization of alternative energy resources. However, EV systems currently face challenges in energy storage systems (ESSs) with regard to their safety, size, cost, and overall management issues. In addition, hybridization of ESSs with advanced power electronic technologies has a significant influence on optimal power utilization to lead advanced EV technologies. This paper comprehensively reviews technologies of ESSs, its classifications, characteristics, constructions, electricity conversion, and evaluation processes with advantages and disadvantages for EV applications. Moreover, this paper discusses various classifications of ESS according to their energy formations, composition materials, and techniques on average power delivery over its capacity and overall efficiencies exhibited within their life expectancies. The rigorous review indicates that existing technologies for ESS can be used for EVs, but the optimum use of ESSs for efficient EV energy storage applications has not yet been achieved. This review highlights many factors, challenges, and problems for sustainable development of ESS technologies in next-generation EV applications. Thus, this review will widen the effort toward the development of economic and efficient ESSs with a longer lifetime for future EV uses.

Review of energy storage systems for electric vehicle applications: Issues and challenges

Cette these a pour objet le developpement d'outils de conception de machines polyphasees a poles lisses alimentees par onduleur de tension a modulation de largeur d'impulsion. Basee sur la decomposition multimachine de la machine polyphasee en une somme de machines fictives magnetiquement decouplees et mecaniquement couplees, l'approche adoptee consiste a etudier le probleme de l'adaptation convertisseur-machine en reportant les objectifs sur les machines fictives. Une representation matricielle du bobinage polyphase, le developpement d'un modele de calcul analytique du champ et l'introduction de la Transformee de Fourier Discrete permettent d'associer aux machines fictives un bobinage et une couche d'aimants. Les objectifs et contraintes lies a la reduction des courants arasites et a l'amelioration de la qualite du couple peuvent alors etre formules directement sur des grandeurs fictives, ce qui permet de deduire des demarches de conception optimale.

https://pastel.archives-ouvertes.fr/tel-00270448/document

Développement d'outils de conception de Machines polyphasées à aimants utilisant l'Approche multimachine.

This paper proposes a simple and effective scheme for Direct Torque Control (DTC) of Brushless DC Motor. Unlike the traditional DTC where both the torque and flux must to be employed in order to deliver the switching table for the inverter, the proposed DTC scheme utilizes only the torque information. By considering the particular operating principle of the motor, the instantaneous torque can be estimated only by using back EMF ratio in an unified differential equation. The simulation results have shown the good performance of the proposed scheme. It can be seen thus a very suitable technique for EV drives which need fast and precise torque response.

/pdf/five-phase-version-of-12slots-8poles-three-phase-synchronous-4rj0u0sty7.pdf

Five-Phase Version of 12Slots/8Poles Three-Phase Synchronous Machine for Marine-Propulsion

On a shipboard electric power system, in steady-state operations, the electric grid disturbances due to powerfull periodic pulsed loads are estimated by the voltage and frequency modulations. Energy Storage System (ESS) with fast discharge ability allows to reduce the stress on the grid components and to meet the design standard requirements. This paper focuses on the sizing and simulation of a supercapacitor ESS (SC ESS). Regarding the chosen topology, the SC bank is directly connected to the grid converter (without DC bus stage) because reliability, efficiency and ability to ensure other functions (as voltage sag mitigations) are expected. Regarding the SC ESS management, the DC voltage is controlled at any time and SC ESS charge and discharge are ordered by stepping the reference DC voltage to minimal value or maximal value. Furthermore SC ESS charge/discharge cycle is synchronized with the pulsed load with a smooth time advance in order to compensate the lower power rise of the ESS in comparison with the one of the pulsed load. The results obtained with the shipgrid simulator are convincing: the frequency modulation is significantly reduced (by more three times) and becomes compliant with the standard requirement. Regarding the generator side, the governor torque variations are strongly mitigated.

/pdf/study-of-a-supercapacitor-energy-storage-system-designed-to-4jjawmxb7m.pdf

Study of a supercapacitor Energy Storage System designed to reduce frequency modulation on shipboard electric power system

This paper investigates the adaptation of the magnet shape for a low speed surface-mounted PM synchronous machine. For the considered marine propulsion application, the reduction of the ripple torques is of critical importance which explains the choice of a five-phase winding. From a multi-machine modelling of the five-phase machine, a reference back-emf spectrum is determined as design objective. To fulfill this requirement, it is decided to adapt the magnet shape. To perform this task, an analytical air gap field computation is developed and validated by using a finite element analysis software (FEMM). A particular trapezoid magnet shape is then determined for the case study. In comparison with the initial rotor made with fully pole-pitch magnets, the new magnet shape almost eliminates the pulsating torque. Furthermore, the average torque to magnet volume is improved which can be considered as a better use of the magnet material.

Study of a particular magnet shape for a five-phase surface-mounted PM machine

In this chapter, a hybrid Diesel/MCT/Battery system for power supply and power management on a small island is studied. The power variation of marine current turbine (MCT) related to the tidal phenomenon is considered. A semidiurnal tide causes the seawater to rise and fall with a period about 12 h, thus resulting large variations of the MCT output power on a daily basis. On the other hand, the electricity demand from the grid side (or load side) has its own pattern during each day. Large differences between the power produced from the renewable sources and the power demanded from the grid/load side could cause power unbalance problem. This chapter proposes using Vanadium Redox flow Battery (VRB) energy storage system to manage the total available power of the hybrid MCT/battery/diesel system and to follow the grid/load demand on a daily basis. The MCT-dominated power supply case and the case when diesel generators as the main supply source are investigated, respectively. The battery modeling and control with appropriate activating rules of the diesel generator are presented in this chapter. At the end of this chapter, some insights for future MCT farm operation for hybrid island power supply will be discussed.

Franck Scuiller

Papers

Développement d'outils de conception de Machines polyphasées à aimants utilisant l'Approche multimachine.

Five-Phase Version of 12Slots/8Poles Three-Phase Synchronous Machine for Marine-Propulsion

Study of a supercapacitor Energy Storage System designed to reduce frequency modulation on shipboard electric power system

Study of a particular magnet shape for a five-phase surface-mounted PM machine

Hybrid Diesel/MCT/Battery Electricity Power Supply System for Power Management in Small Islanded Sites: Case Study for the Ouessant French Island