There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

Multilevel inverter technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy control. This paper presents the most important topologies like diode-clamped inverter (neutral-point clamped), capacitor-clamped (flying capacitor), and cascaded multicell with separate DC sources. Emerging topologies like asymmetric hybrid cells and soft-switched multilevel inverters are also discussed. This paper also presents the most relevant control and modulation methods developed for this family of converters: multilevel sinusoidal pulsewidth modulation, multilevel selective harmonic elimination, and space-vector modulation. Special attention is dedicated to the latest and more relevant applications of these converters such as laminators, conveyor belts, and unified power-flow controllers. The need of an active front end at the input side for those inverters supplying regenerative loads is also discussed, and the circuit topology options are also presented. Finally, the peripherally developing areas such as high-voltage high-power devices and optical sensors and other opportunities for future development are addressed.

Multilevel inverters: a survey of topologies, controls, and applications

Multilevel converters have been under research and development for more than three decades and have found successful industrial application. However, this is still a technology under development, and many new contributions and new commercial topologies have been reported in the last few years. The aim of this paper is to group and review these recent contributions, in order to establish the current state of the art and trends of the technology, to provide readers with a comprehensive and insightful review of where multilevel converter technology stands and is heading. This paper first presents a brief overview of well-established multilevel converters strongly oriented to their current state in industrial applications to then center the discussion on the new converters that have made their way into the industry. In addition, new promising topologies are discussed. Recent advances made in modulation and control of multilevel converters are also addressed. A great part of this paper is devoted to show nontraditional applications powered by multilevel converters and how multilevel converters are becoming an enabling technology in many industrial sectors. Finally, some future trends and challenges in the further development of this technology are discussed to motivate future contributions that address open problems and explore new possibilities.

/pdf/recent-advances-and-industrial-applications-of-multilevel-26fluutoc9.pdf

Recent Advances and Industrial Applications of Multilevel Converters

http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

Vorrichtung zur nachbildung der phasenströme eines dreiphasen-dreipunkt-pulsgleichrichtersystems

Case Study: Wireless Voltage Probe for Accurate Voltage Measurement on High and Transient Reference Voltages

This paper presents a constrained optimization and calorimetric experimental analysis of low torque (2.2 mNm) axial flux permanent magnet motors with small active rotor surface area (1.4 cm2) with the aim to drive an implantable blood pump to support patients with a Fontan circulation. Till today, no such treatment option is clinically available, despite the urgent need. For a previously presented implantable blood pump concept, in this paper now the corresponding motors are optimized concerning efficiency and power density, where e.g. the optimal permanent magnet and back-iron height of the rotor or the optimal pole pair number and tooth height of the stator are determined. Afterwards, the different motor prototypes are realized, tested and compared to each other. Besides the implant size also the generated motor losses are very crucial, since the local temperature increase of the blood and surrounding tissue must always be kept below 2 °C. However, as will be shown in this paper, due to the fact that the low torque of the motors cannot be separated from the test-bench bearing friction with conventional torque sensors, a sophisticated calorimetric test bench to accurately measure the motor losses is needed.

Optimization and Calorimetric Analysis of Axial Flux Permanent Magnet Motor for Implantable Blood Pump Assisting the Fontan Circulation

A non-contact power generator includes: a magnet disposed at a distance to a main surface of a moving body that moves in one direction and the opposite direction, and the magnet generating a magnetic flux passing the main surface; a coil being separated from a surface of the magnet that faces away from the main surface, the coil being linked with the magnetic flux from the magnet; and a magnetic flux guide member disposed in a part of a magnetic path of the magnetic flux linked with the coil. The magnet is moved along the shaft in the moving direction of the moving body at a speed lower than the speed of the moving body by a reaction force acting on the magnet on a basis of eddy currents generated in the main surface in such a direction as to hinder a change of the magnetic flux from the magnet.

Non-contact power generator

Bidirectional, bipolar switches up to now consisted of a combination of known power semiconductor switches - such as IGBTs and diodes - in differenttopologies; novel power semiconductor switches - such as reverse blocking or reverse conducting IGBTs - permit to simplify these circuits. The approach of this paper is to dene equally sized components incorporating the different topologies and semiconductors. It is thus possible to directly compare those various bidirectional, bipolar switches. An assessment of their properties is given with respect to the operational conditions in the sparse matrix converter.

/pdf/comparison-of-different-bidirectional-bipolar-switches-for-qhsw7ue9pb.pdf

Johann W. Kolar

Papers

Vorrichtung zur nachbildung der phasenströme eines dreiphasen-dreipunkt-pulsgleichrichtersystems

Case Study: Wireless Voltage Probe for Accurate Voltage Measurement on High and Transient Reference Voltages

Optimization and Calorimetric Analysis of Axial Flux Permanent Magnet Motor for Implantable Blood Pump Assisting the Fontan Circulation

Non-contact power generator

Comparison of different Bidirectional Bipolar Switches for use in Sparse Matrix Converters