Johann Kolar - Academia.edu (original) (raw)
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Papers by Johann Kolar
2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL)
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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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IEEE Open Journal of the Industrial Electronics Society
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2017 IEEE Applied Power Electronics Conference and Exposition (APEC), 2017
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2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia), 2018
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2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019
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2021 IEEE 22nd Workshop on Control and Modelling of Power Electronics (COMPEL), 2021
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2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018
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2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018
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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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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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2016 IEEE Energy Conversion Congress and Exposition (ECCE), 2016
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IEEE Open Journal of Power Electronics, 2020
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Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248)
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2015 17th European Conference on Power Electronics and Applications (EPE'15 ECCE-Europe), 2015
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2014 16th European Conference on Power Electronics and Applications, 2014
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IEEE/ASME Transactions on Mechatronics, 2009
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IEEE Transactions on Industry Applications, 2009
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IEEE Transactions on Industry Applications, 2010
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IEEE Transactions on Industrial Electronics, 2014
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2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL)
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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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IEEE Open Journal of the Industrial Electronics Society
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2017 IEEE Applied Power Electronics Conference and Exposition (APEC), 2017
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2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia), 2018
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2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019
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2021 IEEE 22nd Workshop on Control and Modelling of Power Electronics (COMPEL), 2021
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2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018
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2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018
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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
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
2016 IEEE Energy Conversion Congress and Exposition (ECCE), 2016
Bookmarks Related papers MentionsView impact
IEEE Open Journal of Power Electronics, 2020
Bookmarks Related papers MentionsView impact
Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248)
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2015 17th European Conference on Power Electronics and Applications (EPE'15 ECCE-Europe), 2015
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2014 16th European Conference on Power Electronics and Applications, 2014
Bookmarks Related papers MentionsView impact
IEEE/ASME Transactions on Mechatronics, 2009
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industry Applications, 2009
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IEEE Transactions on Industry Applications, 2010
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IEEE Transactions on Industrial Electronics, 2014
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