Johann W. Kolar

Bio: Johann W. Kolar is an academic researcher from ETH Zurich. The author has contributed to research in topics: Rectifier & Three-phase. The author has an hindex of 97, co-authored 965 publications receiving 36902 citations. Previous affiliations of Johann W. Kolar include Alstom & Infineon Technologies.

Electrical power converter having a dual buck power stage and main switching stage and method for controlling such an electrical power converter

Abstract: An electrical power converter includes a dual buck power stage with a first half bridge and second half bridge. Each of the half bridges is arranged between a first common node and a second common node. Each of the half bridges comprises an upper switching element and a lower switching element. The upper switching element is configured to switch a current between the first common node and a respective first or second bridge midpoint. The lower switching element is configured to switch a current between the respective first or second bridge midpoint and the second common node. The first and second bridge midpoints are connected to a summing node via respective first and second dual buck inductors. A main switching stage is arranged to supply, through a main stage inductor and through a main output line, a main stage current to the summing node.

Eddy-Current Linear-Rotary Position Sensor for an Implantable Total Artificial Heart

Abstract: This paper presents an eddy-current linear-rotary position sensor for ShuttlePump, an implantable total artificial heart based on a linear-rotary actuator. The sensor is obtained by extending a commercially available rotary position sensor with appropriate data processing by also capturing the information about the linear position. In fact, with changing linear distance of the target, the amplitudes of the sine and cosine sensor outputs change. Furthermore, the commercial IC serving as interface for the rotary sensor adjusts its excitation frequency due to the changing coupling between the sensor and the linearly moving target. Hence, there are two options to additionally measure the linear position, which are analyzed theoretically with finite element simulations, validated experimentally and compared in terms of achievable sensitivity, bandwidth and linearity. Both options allow to reach z-resolutions below the required 100 $\mu m$ and a $\varphi-$ accuracy in the 5° range while meeting the specified 100 Hz bandwidth requirement and can hence be used for feedback position control of ShuttlePump.

New Concept for Current-Impressed WPT to Multiple Independent Stainless-Steel-Enclosed Linear Actuator Sliders

Abstract: Linear actuators (LAs) in pharmaceutical or chem-ical industries must be encapsulated into stainless steel (SS) enclosures to comply with extreme purity standards and facilitate thorough cleaning and disinfection. Therefore, advantageously wireless power transfer (WPT) should be used to supply the sliding part of such actuators, with the primary winding extended to cover the entire LA stroke, such that hard-to-clean cable car-rier assemblies can be eliminated. Typically multiple independent sliders and/or tool carriages must then be supplied from the same primary winding, resulting in a multi-receiver WPT system. However, providing power with a voltage-impressed method to such a system is challenging due to the voltage sharing among the receivers. Therefore, this paper proposes a novel current-impressed method suitable for multi-receiver WPT systems. The proposed method is thoroughly analyzed, optimized, verified by circuit simulations, and compared against a conventional current-impressed approach. As a result, the proposed method facilitates overload capability and has higher efficiency. The exemplary system is designed for two 100 W tool carriages and 72 V DC input and output voltages.

Control input driving method for e.g. Zener diode, involves galvanically decoupling input by transformer, and switching on and off of input by transformer transmission of bipolar voltage impulses from control unit as clock signal source

Abstract: The method involves galvanically decoupling a control input by using a transformer (T1). The control input is switched on and off by transformer transmission of bipolar voltage impulses from a control unit (V1) i.e. application-specific integrated circuit, as a clock signal source. A switching element (S1) is connected with a secondary side of the transformer. The secondary side of the transformer has two reversely poled windings that are connected in series. The voltage impulses are shorter than switch on or switch off time of the controlled switching element. An independent claim is also included for a method for operating a high-intensity discharge lamp.

Guideline for a Simplified Differential-Mode

Abstract: The design of electromagnetic interference (EMI) input filters, needed for switched power converters to fulfill the regulatory standards, is typically associated with high develop- ment effort. This paper presents a guideline for a simplified differential-mode (DM) filter design. First, a procedure to estimate the required filter attenuation based on the total input rms current using only a few equations is given. Second, a volume optimization of the needed DM filter based on the previously calculated filter attenuation and volumetric component parameters is introduced. It is shown that a minimal volume can be found for a certain optimal number of filter stages. The considerations are exemplified for two single-phase power factor correction converters operated in continuous and discontinuous conduction modes, respectively. Finally, EMI measurements done with a 300-W power converter prototype prove the proposed filter design method. Index Terms—Design guideline, electromagnetic compatibil- ity, electromagnetic interference (EMI), noise estimation, volume optimization.

I and i

Abstract: 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 …

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

Abstract: 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.

Recent Advances and Industrial Applications of Multilevel Converters

Abstract: 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.