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Papers by Johann Kolar

Research paper thumbnail of Optimal Design of Highly Efficient and Highly Compact PCB Winding Inductors

2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL)

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Research paper thumbnail of A Simplified Hard-Switching Loss Model for Fast-Switching Three-Level T-Type SiC Bridge-Legs

Electronics

Hard-switching losses in three-level T-type (3LTT) bridge-legs cannot be directly estimated from ... more Hard-switching losses in three-level T-type (3LTT) bridge-legs cannot be directly estimated from datasheet energy loss curves, which are given for symmetric two-level half-bridge configurations only. The commutations in a 3LTT bridge-leg occur between semiconductors with different blocking voltages and/or current ratings, and involve a third semiconductor device in the switching transition, which contributes additional capacitive losses. This paper, therefore, describes a simplifed approach to estimate a lower bound for the hard-switching losses of 3LTT bridge-legs (note that the approach is applicable to other three-level topolgies as well). In view of the very fast switching speeds of wide-bandgap semiconductors, the model neglects voltage/current overlap losses and considers only the dominating charge-related loss contributions (semiconductor output capacitances, body diode reverse-recovery charge), thus requiring minimal information from datasheets. A direct experimental verific...

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Research paper thumbnail of Highly Dynamic Eddy-Current-Based Sealed Magnetic Bearing Position Measurement With Temperature Drift Correction - “Seeing Through Conductive Walls”

IEEE Open Journal of the Industrial Electronics Society

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Research paper thumbnail of Comparative evaluation of IPT resonant circuit topologies for wireless power supplies of implantable mechanical circulatory support systems

2017 IEEE Applied Power Electronics Conference and Exposition (APEC), 2017

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Research paper thumbnail of Comparative Evaluation of Y-Inverter against Three-Phase Two-Stage Buck-Boost DC-AC Converter Systems

2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia), 2018

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Research paper thumbnail of New 40kV / 300kVA Quasi-2-Level Operated 5-Level Flying Capacitor SiC “Super-Switch” IPM

2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019

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Research paper thumbnail of New Third-Harmonic Injection Modulation Reducing the DC-Link Energy Buffer Requirement of Phase-Modular Three-Phase Isolated PFC AC/DC Converter Systems

2021 IEEE 22nd Workshop on Control and Modelling of Power Electronics (COMPEL), 2021

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Research paper thumbnail of Towards a 99.5% Efficient All-Silicon Three-Phase Seven-Level Hybrid Active Neutral Point Clamped Inverter

2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018

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Research paper thumbnail of New PCB Winding ”Snake-Core” Matrix Transformer for Ultra-Compact Wide DC Input Voltage Range Hybrid B+DCM Resonant Server Power Supply

2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018

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Research paper thumbnail of Swiss competence center on energy research FURIES - Overview and contributions in the area of power electronics and SmartGrids

2019 21st European Conference on Power Electronics and Applications (EPE '19 ECCE Europe), 2019

This paper introduces a special session on results of the Swiss competence center on energy resea... more This paper introduces a special session on results of the Swiss competence center on energy research FURIES that has been established in coordination with the Swiss Energy strategy 2050 with the specific aim to develop, promote and deploy power grid-related innovative solutions toward the implementation of the Swiss Energy Strategy 2050. This contribution will report on activities within WP 3, “AC/DC multi-terminal grids and power electronics”. This WP includes three subtasks with contributions from the major Swiss technical universities: Multi-terminal HVDC system design, fault detection and clearing in multi-terminal HVDC, enabling component and converter technologies and applications. The spectrum of the center's activities is briefly introduced and as an illustrative example, the contributions of the SCCER FURIES in relation with HVDC grids are summarized. These contributions include: new high power DC testing methods and laboratories, new DC breaker principles and fault loc...

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Research paper thumbnail of 4D-Interleaving of Isolated ISOP Multi-Cell Converter Systems for Single Phase AC/DC Conversion

The multi-cell converter approach allows to break the performance barriers of conventional system... more The multi-cell converter approach allows to break the performance barriers of conventional systems by leveraging the advantages of using multiple interleaved low voltage and/or low current converter cells. In this digest, a fourth dimension of interleaving is proposed which considers the time dependent degrees of freedom in the control of the entire multi-cell converter system. This new control concept is based on the possibility to decouple the operation of the series connected input stages from the parallel connected output stages by using the energy storage capability of the DC-link capacitors. This digest shows how the 4D-interleaving concept improves the system performance such as the efficiency which will be demonstrated with measurement results on a hardware prototype system in the final paper.

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Research paper thumbnail of Full-ZVS modulation for all-SiC ISOP-type isolated front end (IFE) solid-state transformer

2016 IEEE Energy Conversion Congress and Exposition (ECCE), 2016

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Research paper thumbnail of Electrical and Thermal Characterization of an Inductor-Based ANPC-Type Buck Converter in 14 nm CMOS Technology for Microprocessor Applications

IEEE Open Journal of Power Electronics, 2020

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Research paper thumbnail of New web-based interactive e-learning in power electronics and electrical machines

Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248)

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Research paper thumbnail of A fast method for the calculation of foil winding losses

2015 17th European Conference on Power Electronics and Applications (EPE'15 ECCE-Europe), 2015

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Research paper thumbnail of Impact of PV string shading conditions on panel voltage equalizing converters and optimization of a single converter system with overcurrent protection

2014 16th European Conference on Power Electronics and Applications, 2014

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Research paper thumbnail of Megaspeed Drive Systems: Pushing Beyond 1 Million r/min

IEEE/ASME Transactions on Mechatronics, 2009

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Research paper thumbnail of Comparative Evaluation of Polyphase Bearingless Slice Motors for Fluid-Handling Applications

IEEE Transactions on Industry Applications, 2009

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Research paper thumbnail of Modulation Concepts for the Control of a Two-Phase Bearingless Slice Motor Utilizing Three-Phase Power Modules

IEEE Transactions on Industry Applications, 2010

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Research paper thumbnail of Slotless Bearingless Disk Drive for High-Speed and High-Purity Applications

IEEE Transactions on Industrial Electronics, 2014

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Research paper thumbnail of Optimal Design of Highly Efficient and Highly Compact PCB Winding Inductors

2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL)

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Simplified Hard-Switching Loss Model for Fast-Switching Three-Level T-Type SiC Bridge-Legs

Electronics

Hard-switching losses in three-level T-type (3LTT) bridge-legs cannot be directly estimated from ... more Hard-switching losses in three-level T-type (3LTT) bridge-legs cannot be directly estimated from datasheet energy loss curves, which are given for symmetric two-level half-bridge configurations only. The commutations in a 3LTT bridge-leg occur between semiconductors with different blocking voltages and/or current ratings, and involve a third semiconductor device in the switching transition, which contributes additional capacitive losses. This paper, therefore, describes a simplifed approach to estimate a lower bound for the hard-switching losses of 3LTT bridge-legs (note that the approach is applicable to other three-level topolgies as well). In view of the very fast switching speeds of wide-bandgap semiconductors, the model neglects voltage/current overlap losses and considers only the dominating charge-related loss contributions (semiconductor output capacitances, body diode reverse-recovery charge), thus requiring minimal information from datasheets. A direct experimental verific...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Highly Dynamic Eddy-Current-Based Sealed Magnetic Bearing Position Measurement With Temperature Drift Correction - “Seeing Through Conductive Walls”

IEEE Open Journal of the Industrial Electronics Society

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparative evaluation of IPT resonant circuit topologies for wireless power supplies of implantable mechanical circulatory support systems

2017 IEEE Applied Power Electronics Conference and Exposition (APEC), 2017

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparative Evaluation of Y-Inverter against Three-Phase Two-Stage Buck-Boost DC-AC Converter Systems

2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia), 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of New 40kV / 300kVA Quasi-2-Level Operated 5-Level Flying Capacitor SiC “Super-Switch” IPM

2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019

Bookmarks Related papers MentionsView impact

Research paper thumbnail of New Third-Harmonic Injection Modulation Reducing the DC-Link Energy Buffer Requirement of Phase-Modular Three-Phase Isolated PFC AC/DC Converter Systems

2021 IEEE 22nd Workshop on Control and Modelling of Power Electronics (COMPEL), 2021

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Towards a 99.5% Efficient All-Silicon Three-Phase Seven-Level Hybrid Active Neutral Point Clamped Inverter

2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of New PCB Winding ”Snake-Core” Matrix Transformer for Ultra-Compact Wide DC Input Voltage Range Hybrid B+DCM Resonant Server Power Supply

2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Swiss competence center on energy research FURIES - Overview and contributions in the area of power electronics and SmartGrids

2019 21st European Conference on Power Electronics and Applications (EPE '19 ECCE Europe), 2019

This paper introduces a special session on results of the Swiss competence center on energy resea... more This paper introduces a special session on results of the Swiss competence center on energy research FURIES that has been established in coordination with the Swiss Energy strategy 2050 with the specific aim to develop, promote and deploy power grid-related innovative solutions toward the implementation of the Swiss Energy Strategy 2050. This contribution will report on activities within WP 3, “AC/DC multi-terminal grids and power electronics”. This WP includes three subtasks with contributions from the major Swiss technical universities: Multi-terminal HVDC system design, fault detection and clearing in multi-terminal HVDC, enabling component and converter technologies and applications. The spectrum of the center's activities is briefly introduced and as an illustrative example, the contributions of the SCCER FURIES in relation with HVDC grids are summarized. These contributions include: new high power DC testing methods and laboratories, new DC breaker principles and fault loc...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of 4D-Interleaving of Isolated ISOP Multi-Cell Converter Systems for Single Phase AC/DC Conversion

The multi-cell converter approach allows to break the performance barriers of conventional system... more The multi-cell converter approach allows to break the performance barriers of conventional systems by leveraging the advantages of using multiple interleaved low voltage and/or low current converter cells. In this digest, a fourth dimension of interleaving is proposed which considers the time dependent degrees of freedom in the control of the entire multi-cell converter system. This new control concept is based on the possibility to decouple the operation of the series connected input stages from the parallel connected output stages by using the energy storage capability of the DC-link capacitors. This digest shows how the 4D-interleaving concept improves the system performance such as the efficiency which will be demonstrated with measurement results on a hardware prototype system in the final paper.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Full-ZVS modulation for all-SiC ISOP-type isolated front end (IFE) solid-state transformer

2016 IEEE Energy Conversion Congress and Exposition (ECCE), 2016

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Electrical and Thermal Characterization of an Inductor-Based ANPC-Type Buck Converter in 14 nm CMOS Technology for Microprocessor Applications

IEEE Open Journal of Power Electronics, 2020

Bookmarks Related papers MentionsView impact

Research paper thumbnail of New web-based interactive e-learning in power electronics and electrical machines

Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248)

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A fast method for the calculation of foil winding losses

2015 17th European Conference on Power Electronics and Applications (EPE'15 ECCE-Europe), 2015

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Impact of PV string shading conditions on panel voltage equalizing converters and optimization of a single converter system with overcurrent protection

2014 16th European Conference on Power Electronics and Applications, 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Megaspeed Drive Systems: Pushing Beyond 1 Million r/min

IEEE/ASME Transactions on Mechatronics, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparative Evaluation of Polyphase Bearingless Slice Motors for Fluid-Handling Applications

IEEE Transactions on Industry Applications, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Modulation Concepts for the Control of a Two-Phase Bearingless Slice Motor Utilizing Three-Phase Power Modules

IEEE Transactions on Industry Applications, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Slotless Bearingless Disk Drive for High-Speed and High-Purity Applications

IEEE Transactions on Industrial Electronics, 2014

Bookmarks Related papers MentionsView impact

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