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Foto: Universität Paderborn

Prof. Dr.-Ing. Joachim Böcker

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Vita
Publikationen
Prof. Dr.-Ing. Joachim Böcker

Leistungselektronik und Elektrische Antriebstechnik (LEA)

Leiter - Professor

KET - Kompetenzzentrum für nachhaltige Energietechnik

Vorstand - Professor - Leistungselektronik und Elektrische Antriebstechnik

Institut für Industriemathematik

Vorstand - Professor

Telefon:
+49 5251 60-2209
Fax:
+49 5251 60-3443
Büro:
E4.317
Web:
Besucher:
Pohlweg 55
33098 Paderborn
Prof. Dr.-Ing. Joachim Böcker
2003 - heute

Professor für Leistungselektronik und Elektrische Antriebstechnik an der Universität Paderborn

2001 - 2003

Ingenieurbüro "böcker engineering"

1988 - 2001

AEG- und Daimler-Konzernforschung, Institut für Antriebstechnik und Leistungselektronik, Leiter der Gruppe Regelungstechnik

1988

Promotion an der TU Berlin

1982 - 1987

TU Berlin, Insitut für Mechanik, wissenschaftlicher Mitarbeiter

1982

Abschluss Dipl.-Ing. Elektrotechnik an der TU Berlin


Liste im Research Information System öffnen

2022

An Open-Source Transistor Database and Toolbox as an Unified Software Engineering Tool for Managing and Evaluating Power Transistors

N. Förster, P. Rehlaender, O. Wallscheid, F. Schafmeister, J. Böcker, in: Proc. 37th IEEE Applied Power Electronics Conference (APEC), IEEE, 2022


Robust Hysteresis Control for LLC Resonant Converters Using a Fully Isolated Measurement Scheme

L. Keuck, F. Schafmeister, J. Böcker, in: Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM), IEEE, 2022


Data-Driven Adaptive Torque Oscillation Compensation for Multi-Motor Drive Systems

A. Brosch, J. Rauhaus, O. Wallscheid, J. Böcker, D. Zimmer, IEEE Open Journal of Industry Applications (2022)

DOI


2021

Elektrische Antriebe – Regelung von Antriebssystemen

D. Schröder, J. Böcker, 5th ed., Springer Nature, 2021, pp. 1625

DOI


Frequency-Doubler Modulation for Reduced Junction Temperatures for LLC Resonant Converters Operated in Half-Bridge Configuration

P. Rehlaender, R. Unruh, L. Hankeln, F. Schafmeister, J. Böcker, in: 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe), 2021

LLC resonant converters are typically unsuitable to be applied for wide voltage-transfer ratio applications. With a full-bridge inverter, however, they can be operated in a variety of different modulations. Most notably, by permanently turning on one MOSFET and turning off the other MOSFET of the same bridge leg, the LLC can be operated in half-bridge configuration reducing the gain by a factor of two. The resonant capacitor is hereby charged to an average voltage of half the input voltage. In this modulation, however, the switch that is permanently turned on is stressed by the complete resonant current while exhibiting no switching losses. This paper proves that the frequency-doubler modulation can better balance the losses among all MOSFETs and should be the preferred mode of operation favored over the conventional half-bridge modulation. This paper analyzes the beneficial loss distribution, proposes an on-the-fly morphing modulation and discusses potential operating strategies to further reduce the junction temperature. Furthermore, it is shown that this modulation can also be altered to achieve the asymmetrical LLC operation. Experimental measurement results show that the modulation results in a substantial decrease of the maximum MOSFET temperature and shows that the converter can be smoothly transitioned during operation from full-bridge modulation to the frequency-doubler half-bridge operation and back.


Projekt Art-D Grids: Nachhaltige und stabile Microgrids in Afrika - eine Plattform für Forschung und Lehre für die Entwicklung

S. Krauter, J. Böcker, C. Freitag, B. Hehenkamp, U. Hilleringmann, K. Temmen, T. Klaus, N. Rohrer, S. Lehmann, in: Tagungsband des 36. PV-Symposiums, 18.-26 Mai 2021, Conexio, 2021, pp. 305-309


Common-Mode-Free Bidirectional Three-Phase PFC-Rectifier for Non-Isolated EV Charger

B. Strothmann, F. Schafmeister, J. Böcker, in: 2021 IEEE Applied Power Electronics Conference and Exposition (APEC), IEEE, 2021

DC-DC converters for on-board chargers (OBC) of electrical vehicles are usually galvanically isolated allowing modular single-phase PFC front-end solutions, but require transformers which are more bulky, costly and lossy than inductors of non-isolated DC-DCs. Furthermore, for vehicle-to-grid applications, bidirectional converters with transformers are generally more complex and have a higher count on semiconductor switches than transformerless solutions. However, when using non-isolated DC-DC converters within an OBC, the large common-mode (CM) capacitance comprising capacitive parasitics of the traction battery as well as explicit Y-capacitors connecting the high-voltage DC-system (HV-system) within specific HV-loads to ground has to be considered. For the PFC front-end stage, when supplied from the three-phase mains this means that generation of high-frequency and high-amplitude CM voltages, as it is common e.g. with the conventional six-switch full-bridge converter, has to be strictly avoided. For this reason, a modified topology is suggested leading to a different mode of operation and to a very low common-mode noise behaviour: The three-phase four-wire full-bridge PFC with split DC-link, whose midpoint is connected to the mains neutral provides very stable potentials at the DC-link rails and therefore it can be classified as Zero-CM-topology.For dedicated single-phase operation, as required for most OBC, an additional balancing leg may be added to the topology to reduce the required DC-link capacitance and allow non-electrolytic capacitors.The function of the bidirectional Zero-CM three-phase four-wire full-bridge PFC was verified by simulation and on an 11 kW-laboratory sample. The power factor is above 0.999 and an efficiency of 98 % is measured.


Model Predictive Control of Permanent Magnet Synchronous Motors in the Overmodulation Region Including Six-Step Operation

A. Brosch, O. Wallscheid, J. Böcker, IEEE Open Journal of Industry Applications (2021), 2, pp. 47–63

DOI


Temperature estimation of electric machines using a hybrid model of feed-forward neural and low-order lumped-parameter thermal networks

E.G. Gedlu, O. Wallscheid, J. Böcker, in: 2021 IEEE International Electric Machines & Drives Conference (IEMDC), 2021, pp. 1–8

DOI


Interleaved Single-Stage LLC Converter Design Utilizing Half- and Full-Bridge Configurations for Wide Voltage Transfer Ratio Applications

P. Rehlaender, F. Schafmeister, J. Böcker, IEEE Transactions on Power Electronics (2021), 36(9), pp. 10065-10080

DOI


Design and Analysis of a Regenerative Snubber for a 2.2 kW Active-Clamp Forward Converter with Low-Voltage Output

B. Korthauer, P. Rehlaender, F. Schafmeister, J. Böcker, in: 2021 IEEE Applied Power Electronics Conference and Exposition (APEC), IEEE, 2021

DOI


Alternating Asymmetrical Phase-Shift Modulation for Full-Bridge Converters with Balanced Switching Losses to Reduce Thermal Imbalances

P. Rehlaender, R. Unruh, F. Schafmeister, J. Böcker, in: 2021 IEEE Applied Power Electronics Conference and Exposition (APEC), IEEE, 2021

DOI


Adaptive Zero-Sequence Voltage Injection for Modular Solid-State Transformer to Compensate for Asymmetrical Fault Conditions

R. Unruh, J. Lange, F. Schafmeister, J. Böcker, in: 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe), IEEE, 2021

Modular solid-state transformers (SSTs) are a promising technology in converting power from a 10kV three-phase medium voltage to a lower DC-voltage in the range of 100…400V to provide pure DC power to applications such as electrolyzers for hydrogen generation, data centers with a DC power distribution and DC micro grids. Modular SSTs which can be interpreted as modular multilevel converters with an isolated DC-DC output stage per module, are designed with redundant modules to increase reliability. Usually, each of the three arms operates independently, and therefore, only a fixed number of faulty modules can be compensated in each arm, even if all modules are operational in the remaining two arms. With the proposed zero-sequence voltage injection, up to 100% more faulty modules can be compensated in an arm by employing the same hardware. In addition, module power imbalances are nearly eliminated by utilizing a fundamental frequency zero-sequence voltage. A dominant 3rd harmonic zero-sequence voltage injection in combination with the 5th, 7th and several higher order harmonics with adaptive (small) amplitudes minimize the required arm voltages at steady-state. For nominal operation or symmetrical faults, the proposed technique is equivalent to the well known Min-Max voltage injection, which already reduces the peak arm voltage by 13.4% compared to a constant star point potential. A statistical analysis proves, that the expected number of tolerable faulty modules of the 1MW SST increases by 12% without the need for additional hardware.


Single-Phase Operation of Common-Mode-Free Bidirectional Three-Phase PFC-Rectifier for Non-Isolated EV Charger with Minimized DC-Link

B. Strothmann, G. Book, F. Schafmeister, J. Böcker, in: PCIM Europe digital days 2021; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2021, pp. 1-8

In electric vehicles (EV) the large common-mode (CM) capacitance comprising capacitive parasitics of the traction battery as well as explicit Y-capacitors connecting within specific loads the high-voltage DC-system (HV-system) to ground, can cause issues when using non-isolated EV Chargers. One solution for a power factor correction (PFC) rectifier that is capable to operate with a non-isolated DC-DC converter, is the three-phase four-wire full-bridge PFC, with split DC-link, whose midpoint is connected to the mains neutral. Therefore, it provides very stable potentials at the DC-link rails and accordingly can be classified as Zero-CM topology, which facilitates a common-mode-free operation. When to be operated at a single-phase supply, which is a common requirement for On-board chargers (OBCs) this topology results in the voltage-doubler PFC (V2-PFC) being characterised by a comparably large DC-link voltage ripple at mains frequency. If the DC-link capacitance shall be minimized, for instance to avoid lifetime-limited electrolytic capacitors, two more circuits in addition to the original V2-PFC are proposed for keeping the common-mode-free operation: A balancing circuit (BC), that balances the voltages over the split capacitors and a ripple port (RP), that buffers the 100 Hz power pulsation of the mains. For both circuits the available two bridge legs of the three-phase topology in single-phase operation may be utilized. A 3.7 kW laboratory sample verifies the functionality of the additional circuits in conjunction with the V2-PFC and achieves an efficiency of 95 %.


LLC Converter in Capacitive Operation Utilizing ZCS for IGBTs – Theory, Concept and Verification of a 2 kW DC-DC Converter for EVs

D. Urbaneck, P. Rehlaender, J. Böcker, F. Schafmeister, in: 2021 IEEE Applied Power Electronics Conference and Exposition (APEC), 2021

LLC resonant converters typically employ power MOSFETs in their inverter stage. The generally weak reverse recovery behaviour of the intrinsic body diodes of those MOSFETs causes significant turn-on losses when being forced to hard commutations. Continuous operation in this way will lead to self-destruction of the transistors. Consequently, zero-voltage switching (ZVS) is essential in a MOSFET-based inverter stage. To ensure ZVS, the LLC converter is operated in the inductive region. On the contrary, IGBTs show dominant turn-off losses and are therefore conventionally not applied in LLC converters typically requiring high switching frequencies to achieve low output voltages. However, if the LLC converter is intentionally designed for capacitive operation, zero-current switching (ZCS) is enabled and thus robust and cost-efficient IGBTs can be applied in the inverter stage. The aim of this work is to investigate the use IGBTs in the inverter of an LLC converter. The theory behind the capacitive operated LLC is derived using a switched simulation model and compared with the fundamental harmonic approximation (FHA). The results prove FHA to be useless for practical converter design. Instead, a stress value analysis based on switched model simulations is proposed to the design a capacitive operated LLC utilizing ZCS. A 2 kW prototype for on-board EV applications was built to verify the theory and design approach. The prototype confirms the derived theory and thus the deployment of IGBTs in the inverter stage of LLC resonant converters. Synchronous rectification turns out to require a specific control solution, but if given the resulting efficiency in the most critical operation point exceeds the value of a MOSFET-based (inductive operated) LLC-design of an identical application. Therefore, this concept should be further developed.


Accurate Torque Control for Induction Motors by Utilizing a Globally Optimized Flux Observer

M. Stender, O. Wallscheid, J. Böcker, IEEE Transactions on Power Electronics (2021), 36(11), pp. 13261-13274

DOI


Accurate Torque Estimation for Induction Motors by Utilizing a Hybrid Machine Learning Approach

M. Stender, O. Wallscheid, J. Böcker, in: 2021 IEEE 19th International Power Electronics and Motion Control Conference (PEMC), IEEE, 2021

DOI


Combined Electrical-Thermal Gray-Box Model and Parameter Identification of an Induction Motor

M. Stender, O. Wallscheid, J. Böcker, in: IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, IEEE, 2021

DOI


Gray-Box Loss Model for Induction Motor Drives

M. Stender, O. Wallscheid, J. Böcker, in: 2021 IEEE 19th International Power Electronics and Motion Control Conference (PEMC), IEEE, 2021

DOI



Data-Driven Permanent Magnet Temperature Estimation in Synchronous Motors with Supervised Machine Learning: A Benchmark

W. Kirchgässner, O. Wallscheid, J. Böcker, IEEE Transactions on Energy Conversion (2021), 36(3), pp. 2059 - 2067

DOI


Thermal Neural Networks: Lumped-Parameter Thermal Modeling With State-Space Machine Learning

W. Kirchgässner, O. Wallscheid, J. Böcker, arXiv preprint arXiv:2103.16323 (2021)


Torque and Inductances Estimation for Finite Model Predictive Control of Highly Utilized Permanent Magnet Synchronous Motors

A. Brosch, O. Wallscheid, J. Böcker, IEEE Transactions on Industrial Informatics (2021)

DOI


Comparison of unidirectional Three- and Four-Wire based Boost PFC-Rectifier Topologies for Non-Isolated Three-Phase EV On-Board Chargers under Common-Mode Aspects

M. Hagemeyer, P. Wallmeier, F. Schafmeister, J. Böcker, in: Proc. 36th IEEE Applied Power Electronics Conference (APEC), IEEE, 2021, pp. 569 - 576


Projekt Art-D Grids: Nachhaltige und stabile Microgrids in Afrika - eine Plattform für Forschung und Lehre für die Entwicklung

S. Krauter, J. Böcker, C. Freitag, B. Hehenkamp, U. Hilleringmann, K. Temmen, T. Klaus, N. Rohrer, S. Lehmann, in: Tagungsband 36. PV-Symposium / BIPV-Forum 18-26. Mai 2021, 2021


2020

Analysis of the Magnetic Skin Effekt in Motors and Inductors

J. Böcker, in: 2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), IEEE, 2020

DOI


Estimating Electric Motor Temperatures with Deep Residual Machine Learning

W. Kirchgässner, O. Wallscheid, J. Böcker, IEEE Transactions on Power Electronics (2020), 36(7), pp. 7480-7488

DOI


Evaluation of MMCs for High-Power Low-Voltage DC-Applications in Combination with the Module LLC-Design

R. Unruh, F. Schafmeister, J. Böcker, in: 2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe), IEEE, 2020

In this paper, a full-bridge modular multilevel converter (MMC) and two half-bridge-based MMCs are evaluated for high-current low-voltage e.g. 100 - 400V DC-applications such as electrolysis, arc welding or datacenters with DC-power distribution. Usually, modular multilevel converters are used in high-voltage DC-applications (HVDC) in the multiple kV-range, but to meet the needs of a high-current demand at low output voltage levels, the modular converter concept requires adaptations. In the proposed concept, the MMC is used to step-down the three-phase medium-voltage of 10kV, and provide up to 1 MW to the load. Therefore, each module is extended by an LLC resonant converter to adapt to the specific electrolyzers DC-voltage range of 142 - 220V and to provide galvanic isolation. The six-arm MMC converter with half-bridge modules can be simplified and optimized by removing three arms, and thus halving the number of modules. In addition, the module voltage ripple and capacitor losses are decreased by 22% and 30% respectively. By rearranging the components of the half-bridge MMC to build a MMC consisting of grid-side full-bridge modules, the voltage ripple is further reduced by 78% and capacitor losses by 64%, while ensuring identical costs and volume for all MMCs. Finally, the LLC resonant converter is designed for the most efficient full-bridge MMC. The LLC can not operate at resonance with a fixed nominal module voltage of 770V because the output voltage is varying between 142 - 220V. By decreasing the module voltage down to 600V, additional points of operation can be operated in resonance, and the remaining are closer to resonance. The option to decrease the module voltage down to 600V, increases the number of required modules per arm from 12 to 15, which requires to balance the losses of the LLCs and the grid-side stages.


Dual Interleaved 3.6 kW LLC Converter Operating in Half-Bridge, Full-Bridge and Phase-Shift Mode as a Single-Stage Architecture of an Automotive On-Board DC-DC Converter

P. Rehlaender, S. Tikhonov, F. Schafmeister, J. Böcker, in: 2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe), IEEE, 2020

DOI


Data-Driven Recursive Least Squares Estimation for Model Predictive Current Control of Permanent Magnet Synchronous Motors

A. Brosch, S. Hanke, O. Wallscheid, J. Böcker, IEEE Transactions on Power Electronics (2020), pp. 2179-2190

DOI


1-MW Full-Bridge MMC for High-Current Low-Voltage (100V-400V) DC-Applications

R. Unruh, F. Schafmeister, N. Fröhleke, J. Böcker, in: PCIM Europe digital days 2020; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2020

A full-bridge modular multilevel converter (MMC) is compared to a half-bridge-based MMC for high-current low-voltage DC-applications such as electrolysis, arc welding or datacenters with DC-power distribution. Usually, modular multilevel converters are used in high-voltage DC-applications (HVDC) in the multiple kV-range, but to meet the needs of a high-current demand at low output voltage levels, the modular converter concept requires adaptations. In the proposed concept, the MMC is used to step-down the three-phase medium-voltage of 10 kV. Therefore, each module is extended by an LLC resonant converter to adapt to the specific electrolyzers DC-voltage range of 142-220V and to provide galvanic isolation. The proposed MMC converter with full-bridge modules uses half the number of modules compared to a half-bridge-based MMC while reducing the voltage ripple by 78% and capacitor losses by 64% by rearranging the same components to ensure identical costs and volume. For additional reliability, a new robust algorithm for balancing conduction losses during the bypass phase is presented.


11kW, 70kHz LLC Converter Design with Adaptive Input Voltage for 98% Efficiency in an MMC

R. Unruh, F. Schafmeister, J. Böcker, in: 2020 IEEE 21st Workshop on Control and Modeling for Power Electronics (COMPEL), IEEE, 2020

Although there are numerous design methodologies for the LLC resonant converter, they often do not consider the possibility of input voltage adjustment. In the proposed concept, a modular multi-level converter (MMC) is used to step-down the three-phase medium voltage of 10 kV, and provide up to 1 MW of pure DC power to the load consisting of electrolyzers for hydrogen generation. Therefore, each module is extended by an LLC resonant converter to adapt to the specific electrolyzers DC voltage range of 142...220 V and to provide galvanic isolation. In order to achieve a high efficiency for a wide range of load conditions, the input voltage of the LLC converter is adjusted between 600 V and 770 V while operating at resonance or close to resonance. The parameters of the 11kW LLC resonant converter with an integrated leakage inductance are systematically optimized to maximize the efficiency for all loads while achieving zero-voltage switching. For a fast estimation of eddy current losses, a new method is proposed, which uses a single FEM simulation to fit newly developed loss equations. The calculated average efficiency is 97.8%. The prototype of the LLC converter reaches a peak efficiency of over 98% at resonance at half load which is similar to the precalculated value.


Emulation of Microgrids for Research and Validation of Control and Operation Strategies

K.S.C. Stille, D. Weber, J. Lange, T. Vogt, O. Wallscheid, J. Böcker, in: 2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), IEEE, 2020

DOI


Heat dissipation strategies for silicon carbide power SMDs and their use in different applications

B. Strothmann, T. Piepenbrock, F. Schafmeister, J. Böcker, in: PCIM Europe digital days 2020; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2020, pp. 1-7

Heat dissipation is a limiting factor in the performance of many power electronic components. Especially in the TO-263-7 package, which is used for several SiC-MOSFETs, the heat transfer must take place through the cross section of the printed circuit board (PCB) to the heatsink at the bottom side. Most commonly, thermal vias are used to form this path in a perpendicular direction through all PCB-layers. In a given soft- and hard switched example applications with the use of C3M0065090J SiC-MOSFETs, this conventional approach limited the component’s maximum heat dissipation to approx. 13 W. A recent alternative approach are massive copper blocks (”pedestals”) being integrated in PCBs and reaching from their top- to the bottom-side in relevant footprint areas under SMD-housed power semiconductors. Pedestals allowing to increase the heat dissipation in the given case to even 36 W. This step is achieved due to the clearly superior heat spreading capability of that massive thermal connection between SiC-MOSFET and heatsink. For the hard switched example application the number of switch-elements can be halved to one, by using the pedestal instead of thermal vias. Independently of optimizing the heat transfer path, the up-front avoidance of losses helps to stay within existing heat dissipation limits, of course. The dominant conduction losses of the mentioned soft-switched example application could be halved by changing to SiC-MOSFET types with significant lowered RDSon. By using pedestals and changing to SiC-MOSFETs with lowered RDSon, the number of switch-elements can also be halved for the soft switched application.


A 3,6 kW Single-Stage LLC Converter Operating in Half-Bridge, Full-Bridge and Phase-Shift Mode for Automotive Onboard DC-DC Conversion

P. Rehlaender, T. Grote, S. Tikhonov, S. Mario, F. Schafmeister, J. Böcker, in: PCIM Europe digital days 2020, 2020

Automotive DC-DC converters linking the traction battery to the auxiliary battery are characterized by the wide input and output voltage ranges resulting from the varying state-of-charge of the traction and auxiliary battery. The wide voltage transfer ratio needs to be covered for the entire load range conventionally requiring two-stage converter architectures. Considering a less complex single-stage solution potentially enabling cost and weight advantages, traditional LLC converters are unsuitable topologies since it results in a too wide operating frequency range. Most alternative topology candidates show comparable difficulties. To overcome this issue, the gain range of the LLC with full-bridge inverter can be extended by operation in half-bridge mode for low voltage transfer ratios. Phase-shift operation is utilized for intermediate gains and low loads. This paper describes a detailed design methodology for the resonant tank. The experimental results with a peak efficiency of 96.5 % and a power density of 2.1 kW/l prove the proposed concept.


Two-Stage Automotive DC-DC Converter Design with Wide Voltage-Transfer Range Utilizing Asymmetric LLC Operation

T. Rüschenbaum, P. Rehlaender, P. Ha, T. Grote, F. Schafmeister, J. Böcker, in: PCIM Europe digital days 2020, 2020

An onboard DC-DC converter connects the high voltage traction battery to the low voltage auxiliary battery of an EV. It has to provide power across a wide range of input and output voltages. This paper presents the design and evaluation of an economical two-stage converter concept consisting of a first-stage boost converter and a second-stage LLC converter. While for low input voltages, the boost converter can supply the second-stage LLC with the optimum bulk voltage, for high input voltages, the boost converter is turned off and the LLC regulates the output voltage on its own. Whereas this is unproblematic for high output currents, for low loads high switching frequencies become necessary. For this purpose, the LLC needs to be designed for a wide gain range. Traditionally, this is achieved through a small magnetizing inductance resulting in increased conduction losses. If an asymmetric duty cycle operation is used to cover the low gains at low output current, the LLC can be optimized for a better efficiency. A prototype design proves that the asymmetric duty cycle operation is feasible to achieve a wide gain range at a high efficiency whereas the conventional design achieves very poor efficiencies.


LLC Converter Design in Capacitive Operation utilizes ZCS for IGBTs – a Concept Study for a 2.2 kW Automotive DC-DC Stage

D. Urbaneck, P. Rehlaender, F. Schafmeister, J. Böcker, in: PCIM Europe digital days 2020, 2020

LLC resonant converters generally employ MOSFETs in the inverter stage, which can be of half-bridge (HB) or full-bridge (FB) type. The generally weak intrinsic (body) diodes of the MOSFETs cause turn-on losses when being forced to hard current commutations finally leading to the components self-destruction when operated constantly in this way. Consequently, zero-voltage switching (ZVS) operation is more or less essential in a silicon (Si) MOSFET-based HB or FB. To ensure ZVS, the LLC is operated in the inductive region, i.e. with lagging resonant current. On the contrary, IGBTs show dominant turn-off losses and therefore are conventionally not applied in LLCs typically requiring high switching frequencies to achieve low output voltages. Yet, if the LLC is intentionally designed for the capacitive region, i. e. operation with leading current, zero-current switching (ZCS) enabling IGBTs in the inverter stage can be ensured. This paper explores in detail the LLC in the capacitive operating region and gives design considerations for a capacitive LLC utilizing both robust and cost-efficient IGBTs for an exemplary 2.2 kW automotive on-board DC-DC converter application. The results of a loss analysis show that the LLC resonant converter can be operated well in the capacitive region. In the given case, significantly lower overall and 30 % lower inverter stage losses are achieved in the thermally relevant worst-case comparison with an inductive LLC based on Si MOSFETs.


Comparison of Gray-Box and Black-Box Two-Level Three-Phase Inverter Models for Electrical Drives

M. Stender, O. Wallscheid, J. Böcker, IEEE Transactions on Industrial Electronics (2020), 68(9), pp. 8646-8656

DOI


Accurate Torque Estimation for Induction Motors by Utilizing Globally Optimized Flux Observers

M. Stender, O. Wallscheid, J. Böcker, in: 2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), IEEE, 2020

DOI


Permanent magnet synchronous machine temperature estimation using low-order lumped-parameter thermal network with extended iron loss model

E.G. Gedlu, O. Wallscheid, J. Böcker, in: The 10th International Conference on Power Electronics, Machines and Drives (PEMD 2020), 2020, pp. 937–942


Practical Implementation and Verification of Simple-to-Implement Digital Current Observer for Half-Bridge Topologies

M.E. Ahmmad, F. Schafmeister, J. Böcker, in: Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM digital days), IEEE, 2020


Data Set Description: Identifying the Physics Behind an Electric Motor–Data-Driven Learning of the Electrical Behavior (Part II)

S. Hanke, O. Wallscheid, J. Böcker, arXiv preprint arXiv:2003.06268 (2020)


Data-Driven Permanent Magnet Temperature Estimation in Synchronous Motors with Supervised Machine Learning

W. Kirchgässner, O. Wallscheid, J. Böcker, arXiv preprint arXiv:2001.06246 (2020)



2019

Speed Estimation in Induction Machines at all Speed Ranges Using Sensing Windings

M.T. Joy, J. Böcker, in: 2018 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), IEEE, 2019

DOI


Empirical Evaluation of Exponentially Weighted Moving Averages for Simple Linear Thermal Modeling of Permanent Magnet Synchronous Machines

W. Kirchgässner, O. Wallscheid, J. Böcker, in: 2019 IEEE 28th International Symposium on Industrial Electronics (ISIE), 2019

DOI


Deep Residual Convolutional and Recurrent Neural Networks for Temperature Estimation in Permanent Magnet Synchronous Motors

W. Kirchgässner, O. Wallscheid, J. Böcker, in: 2019 IEEE International Electric Machines & Drives Conference (IEMDC), 2019

DOI


Common Mode Analysis of Non-Isolated Three-Phase EV-Charger for Bi-Directional Vehicle-to-Grid Operation

B. Strothmann, F. Schafmeister, J. Böcker, in: PCIM Europe 2019; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2019, pp. 1-7

For future Vehicle-to-Grid (V2G) applications, the six-switch full-bridge is often used as AC-DC front-end converter of a three-phase EV-charger. In many publications, the common mode (CM) noise is not taken into account. However, this must not be neglected considering the large effective capacitance, of up to 3 muF, as allowed by new standards. In this paper, different modulation techniques are investigated, related to their CM-noise. Based on electric circuit simulations, CM-filters are estimated, and the CM-currents are investigated. Accordingly, the conventional six-switch full-bridge is practically difficult to use in non-isolated chargers, because the resulting CM-currents and/or the required EMI-filter become too large, even if CM-Voltage optimized modulation techniques are used.


Pareto Design and Switching Frequencies for SiC MOSFETs Applied in an 11 kW Buck Converter for EV-Charging

B. Strothmann, F. Schafmeister, J. Böcker, in: 2019 IEEE Applied Power Electronics Conference and Exposition (APEC), IEEE, 2019

Utilisation of SiC semiconductors' fast switching speeds and high switching frequencies as a consequent are often in discussion. But which switching frequency is really optimal in terms of converter volume, losses and costs? Based on the example of a buck converter, this question is investigated, and a tool for loss calculation and design is described in this paper. A Pareto optimization of the converter is performed where the switching frequency is one of several design parameters. The buck converter can be realized by multiple rails interleaved, and several switches can be placed in parallel. Considered converter modes are continuous conduction mode, that allows hard-switching, ZVS, and incomplete ZVS depending on the switching frequency. Based on Pareto optimizations, a design is selected, and a laboratory sample of 5.5 kW for application in an EV battery charger is built up. Efficiencies of 99.5 % are achieved with switching frequencies of around 100 kHz.



MMC-Topology for High-Current and Low-Voltage Applications with Minimal Number of Submodules, Reduced Switching and Capacitor Losses

R. Unruh, F. Schafmeister, N. Fröhleke, J. Böcker, in: PCIM Europe 2019; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, VDE, 2019

Due to recent developments in MMCs, they are used in many medium-voltage and high-power applications today, but efficient and modular solutions for high-power at low-voltage such as for electrolysis are still required. The proposed Y-MMC converts the grid AC-voltage into a DC-voltages, and an LLC converter is connected to each submodule capacitor to provide the required current to the DC-load. This paper proposes a topology that uses only half the number of submodules and moreover to reduce the effective switching frequency by a third, while preserving the same THD und output power of an YY-MMC.


Development of a Black-Box Two-Level IGBT Three-Phase Inverter Compensation Scheme for Electrical Drives

M. Stender, O. Wallscheid, J. Böcker, in: 2019 IEEE 28th International Symposium on Industrial Electronics (ISIE), IEEE, 2019

DOI


Finite-control-set model predictive control for a permanent magnet synchronous motor application with online least squares system identification

S. Hanke, S. Peitz, O. Wallscheid, J. Böcker, M. Dellnitz, in: 2019 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE), 2019, pp. 1–6


Stator flux-based field-oriented position-sensorless control of permanent magnet synchronous motors with limited parameter knowledge

O. Wallscheid, M.S. Shafiq, J. Böcker, in: 2019 IEEE 28th International Symposium on Industrial Electronics (ISIE), 2019, pp. 402–407


Hierarchical model predictive speed and current control of an induction machine drive with moving-horizon load torque estimator

O. Wallscheid, E.F.B. Ngoumtsa, J. Böcker, in: 2019 IEEE International Electric Machines & Drives Conference (IEMDC), 2019, pp. 2188–2195


Continuous-control-set model predictive control with integrated modulator in permanent magnet synchronous motor applications

S. Hanke, O. Wallscheid, J. Böcker, in: 2019 IEEE International Electric Machines & Drives Conference (IEMDC), 2019, pp. 2210–2216


Improved Fusion of Permanent Magnet Temperature Estimation Techniques for Synchronous Motors Using a Kalman Filter

D.E.E. Gaona, O. Wallscheid, J. Böcker, IEEE Transactions on Industrial Electronics (2019)


Computer-Aided Design and Optimization of an Integrated Transformer with Distributed Air Gap and Leakage Path for an LLC Resonant Converter

L. Keuck, F. Schafmeister, J. Böcker, in: Proc. 34th IEEE Applied Power Electronics Conference (APEC), IEEE, 2019, pp. 1415 - 1422


Computer-Aided Design and Optimization of an Integrated Transformer with Distributed Air Gap and Leakage Path for LLC Resonant Converter

L. Keuck, F. Schafmeister, J. Böcker, H. Jungwirth, M. Schmidhuber, in: Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM), IEEE, 2019


Novel Current Measurement Concept for Half Bridge Topologies based on simple-to-implement Digital Current Observer

M.E. Ahmad, F. Schafmeister, J. Böcker, in: Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM), IEEE, 2019


LCC Resonant Converter for Piezoelectric Transducers with Phase Shift Control

S. Bolte, F. Schafmeister, J. Böcker, in: Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM), IEEE, 2019


Bidirectional Resonant Converter with Integrated Magnetics for On-Board Chargers

S. Bolte, F. Schafmeister, J. Böcker, in: Proc. IEEE International Symposium on Industrial Electronics (ISIE), IEEE, 2019, pp. 770 - 774


Interleaved Active Clamp Forward Converters as Single Stage On-Board DC-DC Converters for EVs – an Accurate Model and Design Considerations

P. Rehlaender, T. Grote, F. Schafmeister, J. Böcker, in: Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM), IEEE, 2019


A PCB-Integrated Winding Using a Litz Structure for a Wireless Charging Coil

P. Rehlaender, T. Grote, S. Tikhonov, H. Njiende, F. Schafmeister, J. Böcker, P. Thiemann, in: Proc. 21st European Conference on Power Electronics and Applications (EPE-ECCE Europe), EPE, 2019, pp. 1 - 9


Analytical Topology Comparison for a Single-Stage On-Board EV-Battery Converter

P. Rehlaender, T. Grote, F. Schafmeister, J. Böcker, in: Proc. IEEE International Symposium on Industrial Electronics (ISIE), IEEE, 2019, pp. 2477 - 2482


2018

Consideration on primary control reserve provision by industrial microgrids in grid-coupled operation

T. Vogt, J. Badeda, J. Böcker, D.U. Sauer, in: 2017 IEEE 12th International Conference on Power Electronics and Drive Systems (PEDS), IEEE, 2018

DOI


Gopinath-observer for flux estimation of an induction machine drive system

O. Buchholz, J. Böcker, in: 2017 IEEE Southern Power Electronics Conference (SPEC), IEEE, 2018

DOI


Online-Identification of the Machine Parameters of an Induction Motor Drive

O. Buchholz, J. Böcker, in: 2018 IEEE 27th International Symposium on Industrial Electronics (ISIE), IEEE, 2018

DOI


Gopinath-observer for flux estimation of an induction machine drive system

O. Buchholz, J. Böcker, in: 2017 IEEE Southern Power Electronics Conference (SPEC), IEEE, 2018

DOI


Consideration on primary control reserve provision by industrial microgrids in grid-coupled operation

T. Vogt, J. Badeda, J. Böcker, D.U. Sauer, in: 2017 IEEE 12th International Conference on Power Electronics and Drive Systems (PEDS), IEEE, 2018

DOI


Sensorless Control of Induction Motor Drives Using Additional Windings on the Stator

M.T. Joy, J. Böcker, in: 2018 IEEE 9th International Symposium on Sensorless Control for Electrical Drives (SLED), IEEE, 2018

DOI


GaN Buck Converter in CCM with Optimized High Frequency Inductors

S. Bolte, N. Fröhleke, J. Böcker, in: PCIM Europe 2018; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2018, pp. 1-6


Energy Management for a Nano-CHP Unit and an Electrical Storage System in a Residential Application

D. Weber, K.S.C. Stille, O. Wallscheid, J. Böcker, in: 2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), IEEE, 2018

DOI


Lifetime Extension of Photovoltaic Modules by Influencing the Module Temperature Using Phase Change Material

D. Weber, M.I. Rafsan Jani, M. Grabo, O. Wallscheid, T. Klaus, S. Krauter, J. Böcker, in: World Conference on Photovoltaic Energy Conversion (WCPEC-7), 45th IEEE PVSC, 28th PVSEC, 34th EU PVSEC., 2018

DOI


Improving torque and speed estimation accuracy by conjoint parameter identification and unscented Kalman filter design for induction machines

O. Wallscheid, M. Schenke, J. Böcker, in: 2018 21st International Conference on Electrical Machines and Systems (ICEMS), 2018, pp. 1181–1186


Lifetime Extension of Photovoltaic Modules by Influencing the Module Temperature Using Phase Change Material

D. Weber, M.I.R. Jani, M. Grabo, O. Wallscheid, J. Böcker, T. Klaus, S. Krauter, in: 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC)(A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC), 2018, pp. 0784–0789


A combined approach to identify induction machine parameters and to design an extended kalman filter for speed and torque estimation

O. Wallscheid, M. Schenke, J. Böcker, in: 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC), 2018, pp. 793–799


Online-Identification of the Induction Machine Parameters Using the Extended Kalman Filter

O. Buchholz, J. Böcker, J. Bonifacio, in: 2018 XIII International Conference on Electrical Machines (ICEM), IEEE, 2018

DOI


Speed Estimation in Induction Motors Using Additional Windings

M.T.. Joy, J. Böcker, in: 2018 20th European Conference on Power Electronics and Applications (EPE’18 ECCE Europe), 2018, pp. P.1-P.10


Adaptive Frequency Control of DC-DC-Converters for Maximum Efficiency Using Artificial Neural Network

L. Keuck, A. Munir, F. Schafmeister, J. Böcker, in: Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM), IEEE, 2018


Switching Loss Characterization of Wide Band-Gap Devices by an Indirect Identification Methodology

L. Keuck, N. Jabbar, F. Schafmeister, J. Böcker, in: Proc. 20th European Conference on Power Electronics and Applications (EPE-ECCE Europe), EPE, 2018, pp. 1 - 10


Coupled Inductor Design for Interleaved High-Current DC-DC Converters

M. Hagemeyer, F. Schafmeister, J. Böcker, in: Proc. International Conference on Electrical Machines and Systems (ICEMS), Korea IEE & IEE Japan, 2018, pp. 2316 - 2321


Koopman Operator-Based Finite-Control-Set Model Predictive Control for Electrical Drives

S. Hanke, S. Peitz, O. Wallscheid, S. Klus, J. Böcker, M. Dellnitz, arXiv preprint arXiv:1804.00854 (2018)


Design of a flywheel energy storage system for high current pulsating loads

M. Hagemeyer, N. Fröhleke, J. Böcker, B. Rödder, L. Aßmann, B. Völkel, in: 2017 IEEE 12th International Conference on Power Electronics and Drive Systems (PEDS), IEEE, 2018

DOI


2017

Model-based control structure for high-speed permanent magnet synchronous drives

K. Peter, F. Mink, J. Böcker, in: 2017 IEEE International Electric Machines and Drives Conference (IEMDC), IEEE, 2017

DOI


Investigation of long short-term memory networks to temperature prediction for permanent magnet synchronous motors

O. Wallscheid, W. Kirchgässner, J. Böcker, in: 2017 International Joint Conference on Neural Networks (IJCNN), 2017

DOI


Wassergekühltes On-Board-Ladegerät mit optimiertem Kühlkanal

S. Bolte, C. Henkenius, J. Böcker, E. Kenig, A. Zibart, H. Figge, wt Werkstattstechnik online (2017), 107(5), pp. 381ff

Für On-Board-Ladegeräte sind brückenlose netzfreundliche Gleichrichter in Kombination mit einem Resonanzkonverter empfehlenswert. Auf diese Weise lassen sich Verluste minimieren und es wird eine hohe Leistungsdichte erreicht. Darüber hinaus wurde der Kühlungskreislauf des Ladegeräts durch CFD (Computational Fluid Dynamics, rechnergestützte Flüssigkeitsdynamik)-Simulationen des Kühlkanals optimiert, um einen bestmöglichen Wärmeübergang bei geringem Druckabfall zu erzielen.


Water-cooled on-board charger with optimized cooling channel

S. Bolte, C. Henkenius, J. Böcker, A. Zibart, E. Kenig, H. Figge, in: 2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), IEEE, 2017

DOI


Calorimetric measurements with compensating temperature control

S. Bolte, L. Keuck, J.K. Afridi, N. Fröhleke, J. Böcker, in: 2017 IEEE 26th International Symposium on Industrial Electronics (ISIE), IEEE, 2017

DOI


An iterative compensation method for production tolerances in electric drive systems

M. Ott, A. Gülec, J. Böcker, in: 2017 IEEE International Electric Machines and Drives Conference (IEMDC), IEEE, 2017

DOI


Winding concepts for high frequency inductors with reduced DC resistance

S. Bolte, J.K. Afridi, J. Böcker, in: 2017 IEEE International Telecommunications Energy Conference (INTELEC), IEEE, 2017

DOI


Calorimetric Measurement of Wide Bandgap Semiconductors Switching Losses

S. Bolte, L. Wohlrab, J.K. Afridi, N. Fröhleke, J. Böcker, in: PCIM Europe 2017; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2017, pp. 1-6


Glocal identification methods for low-order lumped parameter thermal networks used in permanent magnet synchronous motors

D. Gaona, O. Wallscheid, J. Böcker, in: 2017 IEEE 12th International Conference on Power Electronics and Drive Systems (PEDS), 2017, pp. 1–126


Sensitivity analysis of a permanent magnet temperature observer for PM synchronous machines using the monte carlo method

D. Gaona, O. Wallscheid, J. Böcker, in: 2017 IEEE 12th International Conference on Power Electronics and Drive Systems (PEDS), 2017, pp. 599–606


A direct model predictive torque control approach to meet torque and loss objectives simultaneously in permanent magnet synchronous motor applications

S. Hanke, O. Wallscheid, J. Böcker, in: 2017 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE), 2017, pp. 101–106


Observing the Permanent Magnet Temperature of Synchronous Motors Based on Electrical Fundamental Wave Model Quantities

O. Wallscheid, A. Specht, J. Böcker, IEEE Transactions on Industrial Electronics (2017), 64(5), pp. 3921–3929


Fusion of a lumped-parameter thermal network and speed-dependent flux observer for PM temperature estimation in synchronous machines

D. Gaona, O. Wallscheid, J. Böcker, in: 2017 IEEE Southern Power Electronics Conference (SPEC), 2017, pp. 1–6


Investigation of Long Short-Term Memorys to Temperature Prediction for Permanent Magnet Synchronous Motors

O. Wallscheid, W. Kirchgässner, J. Böcker, in: IEEE International Joint Conference on Neural Networks (IJCNN 2017), 2017


Fusion of direct and indirect temperature estimation techniques for permanent magnet synchronous motors

O. Wallscheid, J. Böcker, in: 2017 IEEE International Electric Machines and Drives Conference (IEMDC), 2017, pp. 1–8


Derating of automotive drive systems using model predictive control

O. Wallscheid, J. Böcker, in: 2017 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE), 2017, pp. 31–36


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