@article{kokkonda_beddingfield_bhattacharya_carsten_varga_2023, title={A Novel Transformer Leakage Energy Recovery Active Clamp Control Technique for High Power AC/DC Flyback Converters}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131320}, abstractNote={A novel twin-pulse active clamp has been proposed for flyback converters that can efficiently recover the transformer leakage energy and route it to the output with reduced clamp current ratings and clamp capacitance compared to existing active clamp methods. This extends the application power range for ac/dc flyback converters by enabling a cost-effective leakage energy recovery method for high-power applications. In the case of a 2.5 kW flyback converter, the proposed clamp offers a potential reduction of the required clamp capacitance by 500x and the clamp current by more than 2x at the expense of a higher peak switch voltage stress when compared to an equivalent conventional active clamp. The operating principle and the design criteria for the proposed clamp method are discussed. Experimental results for a 2.5 kW ac/dc flyback converter prototype with the proposed clamp have been presented, validating the clamp operation. Its performance and efficiency improvement compared to a dissipative clamp with active discharge has also been evaluated over the entire operating region.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Kokkonda, Raj Kumar and Beddingfield, Richard and Bhattacharya, Subhashish and Carsten, Bruce and Varga, Bo}, year={2023}, pages={1238–1245} }
 @article{smith_beddingfield_grainger_2023, title={Power Flow Control for Decoupled Load Performance of Current-Fed Triple Active Bridge Converter}, volume={4}, ISSN={["2644-1314"]}, DOI={10.1109/OJPEL.2023.3266658}, abstractNote={This article presents a phase-shift control method for a converter containing a multi-winding transformer. The control strategy is developed from a power flow analysis of the converter and uses the derived power flow equations to supply constant power at a load port while the second load port experiences large load changes. This control method prevents the constant load port from experiencing transient behavior caused by magnetic coupling with the other load port. The approach is demonstrated with an experiment using a controller within a control hardware-in-the-loop set-up and then a full experimental setup within a lower power test bed. By using control to mitigate the effects of mutual flux within a multi-winding transformer, the load ports of the converter are effectively decoupled. The analytical procedure described in this article can also be applied to other converter topologies containing multi-winding transformers to achieve similar decoupled load performance, as demonstrated in the triple active bridge converter test bed.}, journal={IEEE OPEN JOURNAL OF POWER ELECTRONICS}, author={Smith, Zachary T. T. and Beddingfield, Richard B. B. and Grainger, Brandon M. M.}, year={2023}, pages={319–329} }
 @article{bracken_beddingfield_juds_andapally_grainger_ohodnicki_2023, title={Standardization of Core and Component Characterization at the Advanced Magnetics for Power and Energy Development Laboratory}, ISSN={["2473-7631"]}, DOI={10.1109/ITEC55900.2023.10187015}, abstractNote={Magnetic core and component characterization presents technical challenges, particularly with a focus on achieving higher frequency and voltage operation with advances in power electronics converters due to wide bandgap semiconductors. Accurate characterization plays a critical role in benchmarking the performance of existing core materials and construction for various component designs. In addition, characterization of fabricated components with application relevant excitation is critical for accurate assessment of technical figures of merit. Standardization of core and component characterization plays a foundational role in benchmarking and quantifying performance improvement of new magnetic materials, core constructions, and component designs. In this article, we discuss existing standards relevant for magnetic core characterization and several new standard development activities currently underway relevant for medium frequency and power applications. We also discuss the application of relevant measurements to selected magnetic core materials and components currently active within the Advanced Magnetics for Power and Energy Development (AMPED) Consortium. Example current transformer components are designed and tested as an example of standardized testing that is currently underway, to be expanded in the future to also include inductors and transformers amongst others.}, journal={2023 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE & EXPO, ITEC}, author={Bracken, Chris and Beddingfield, Richard and Juds, Mark A. and Andapally, Bharadwaj Reddy and Grainger, Brandon and Ohodnicki, Paul R., Jr.}, year={2023} }
 @article{beddingfield_leary_noebe_nations_bowman_bhattacharya_2022, title={Calculation of Transformer Leakage Inductance by Simplified Flux Path Geometries}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947606}, abstractNote={Series inductance is a critical energy storage element in isolated power converters. Many have explored methods of estimating the total leakage inductance of transformers as an integrated series inductance without external inductors. However, this poses challenges with medium frequency converters and magnetic ribbon-based cores, e.g., metal amorphous nanocrystalline. The material's relatively high conductivity allows eddy currents to develop when magnetic flux intersects wide surfaces. These eddy currents result in significant additional losses that increase with increasing power flow. This paper presents a simplified and accurate method of estimating leakage flux while identifying separate leakage flux paths that correlate with the magnetic material surfaces. This enables an understanding the proportion of leakage flux that will contribute to extra losses. The methods presented are applicable to both leakage and fringing (around heterogeneous material interfaces) fluxes. This paper includes detailed FEA studies and 3D flux vector measurements matching the presented analytical models.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Beddingfield, Richard B. and Leary, Alex M. and Noebe, Ronald and Nations, Mark and Bowman, Randy and Bhattacharya, Subhashish}, year={2022} }
 @article{simizu_byerly_schneider_kim_nations_narasimhan_beddingfield_bhattachayara_mchenry_2021, title={Flux Switching Permanent Magnet Motor with Metal Amorphous Nanocomposite Soft Magnetic Material and Rare Earth Free Permanent Magnets}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9594971}, abstractNote={The power losses in high power-density motors due to high rotational speed and/or high pole counts may be reduced adopting metal amorphous nanocomposites (MANCs) featuring low power loss and a relatively high flux density ($\sim$1.3 T). We recently proposed a flux switching permanent magnet (FSPM) motor with a rating of 2.5 kW at 1400 Hz electrical speed that incorporates low loss (<3W/kg at 1 kHz) FeNi-based MANC with projected iron loss of about 5 W. The motor design allows use of rare earth-free permanent magnets. To incorporate MANCs, an axial flux motor with rotor and stator cores made from a wound ribbon has been developed. We performed 3-d FEA to optimize the design and built and tested a prototype showing that low loss MANC material can be used for motor applications with high magnetic switching frequency.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Simizu, Satoru and Byerly, Kevin and Schneider, Kyle and Kim, Heonyoung and Nations, Mark and Narasimhan, Sneha and Beddingfield, Richard and Bhattachayara, Subhashish and McHenry, Michael E.}, year={2021}, pages={3866–3872} }
 @article{zhu_pahl_fons_wong_bhattacharya_beddingfield_2021, title={Medium Voltage to Low Voltage Contactless Power Transformation for Data Centers}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595112}, abstractNote={Contactless power transfer (CPT) methods have widely been explored for many applications. An isolated wireless power link enables a touch-safe interface without electrically energized contacts eliminating any arc flash or electrocution hazard. The concept presented here will enable safe medium voltage distribution inside data centers eliminating low voltage distribution with bulky cables bringing voltages larger than 1kV directly to the server rack. This paper proposes high-efficiency single-stage contactless power conversion from medium voltage to low voltage for data center applications. The proposed solution is evaluated using a 10kW design example and verified by experimental tests. A plug-in contactless transformer is developed with customized nanocrystalline cores and 3D printed bobbins to improve the DC-to-DC efficiency and manufacturability. A high efficiency converter is developed to maintain a 48V output voltage with a IOOOV input voltage over a wide load range. The DC-to-DC efficiency and frequency modulation performance are analyzed.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Zhu, Guangqi and Pahl, Birger and Fons, Richard J. and Wong, Isaac and Bhattacharya, Subhashish and Beddingfield, Byron}, year={2021}, pages={5839–5844} }
 @article{beddingfield_samanta_nations_wong_ohodnicki_bhattacharya_2020, title={Analysis and Design Considerations of a Contactless Magnetic Plug for Charging Electric Vehicles Directly From the Medium-Voltage DC Grid With Arc Flash Mitigation}, volume={1}, url={https://doi.org/10.1109/JESTIE.2020.2999589}, DOI={10.1109/JESTIE.2020.2999589}, abstractNote={Electric vehicle charging has shifted to higher voltages to achieve higher power for more rapid charging capabilities. This article provides a contactless magnetic plug solution that enables medium-voltage grid connections for electric vehicle charging to achieve 3.5-<inline-formula><tex-math notation="LaTeX">$\text{kV}_{\rm DC}$</tex-math></inline-formula>-to-400-<inline-formula><tex-math notation="LaTeX">$\text{V}_{\rm DC}$</tex-math></inline-formula>, 150-kW rapid charging capabilities. This novel magnetic plug improves upon existing electric vehicle charging solutions by guaranteeing safe operation and connection through galvanic and physical separation from the medium-voltage side. It achieves this with a gap and barrier in the transformer core. We introduce a unique asymmetry in the core to localize parasitic capacitance, fully separating the medium- and low-voltage regions. This approach eliminates arcing risk and allows rapid charging capabilities to be delivered to the general public. This gapped core constitutes the plug action of our proposed charging system. We present solutions for the unique challenges of this solution through a detailed analysis of the magnetic design. We confirm this analysis in finite-element analysis and experimentation. The solution is verified through a scaled laboratory prototype of 20 kW, 1 <inline-formula><tex-math notation="LaTeX">$\text{kV}_{\rm DC}$</tex-math></inline-formula> to 50 <inline-formula><tex-math notation="LaTeX">$\text{V}_{\rm DC}$</tex-math></inline-formula> that is representative of the proposed 150-kW design. We demonstrate safe, arc-free, disconnection in included active content, a new solution for high-power electric vehicle rapid charging.}, number={1}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Beddingfield, Richard B. and Samanta, Suvendu and Nations, Mark S. and Wong, Isaac and Ohodnicki, Paul R. and Bhattacharya, Subhashish}, year={2020}, month={Jul}, pages={3–13} }
 @article{lu_buric_byerly_moon_nazmunnahar_simizu_leary_beddingfield_sun_zandhuis_et al._2019, title={Real-Time Monitoring of Temperature Rises of Energized Transformer Cores With Distributed Optical Fiber Sensors}, volume={34}, ISSN={["1937-4208"]}, DOI={10.1109/TPWRD.2019.2912866}, abstractNote={Real-time temperature mapping that solves local overheating problems is important for obtaining an optimized thermal design for high-efficiency power transformers. Internal temperature monitoring of operating power transformers can also be leveraged for asset monitoring applications targeting at fault detection enabling condition-based maintenance. Transformers present a variety of challenging sensing environments such as high levels of electromagnetic interference and limited space for conventional sensors to operate. Immersion of power transformers in insulation oils for thermal management during operation and the presence of relatively large and time-varying electrical and occasional magnetic fields make sensing technologies requiring electrical wires or active power at sensing locations highly undesirable. In this work, we investigate thermal response of a standard telecom fiber instrumented on compact transformer cores by using an optical frequency-domain reflectometry scheme. Correlation between conventional temperature sensing methods and fiber-optic sensing results as well as tradeoffs between spatial resolution and temperature measurement accuracy is discussed and spatially resolved real-time monitoring of temperatures in energized transformers is experimentally demonstrated.}, number={4}, journal={IEEE TRANSACTIONS ON POWER DELIVERY}, author={Lu, Ping and Buric, Michael P. and Byerly, Kevin and Moon, Seung Ryul and Nazmunnahar, Mst and Simizu, Satoru and Leary, Alex M. and Beddingfield, Richard Byron and Sun, Chenhu and Zandhuis, Paul and et al.}, year={2019}, month={Aug}, pages={1588–1598} }
 @inproceedings{samanta_wong_beddingfield_bhattacharya_zhu_pahl_2019, title={Supplying Medium Voltage to Data-center Racks Directly Using SiC-Based Converter}, url={https://doi.org/10.1109/WiPDA46397.2019.8998837}, DOI={10.1109/WiPDA46397.2019.8998837}, abstractNote={With the increase in size of data centers and cloud computing, its power demand is also rising sharply. Traditionally, this power distribution is achieved at about 400VDC which is inconvenient because it requires very bulky conductor to prevent high copper loss. In this paper, a new power distribution architecture for data centers is reported where direct medium voltage distribution to data-center racks are achieved with SiC based inverter. The safety issues raised due to bringing medium voltage to the racks are addressed with contactless power transfer technology. The rectifier circuit handles a high current at 48V, and synchronous rectification would be suitable to boost the efficiency. In this paper, a GaN based synchronous rectification is studied. This proposed converter circuit is analyzed and simulated in PowerSim 11. A 3kW experimental setup is developed in the lab to verify the analysis and simulation performances of the converter, where the input is 1000V and the output is 48V.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, publisher={IEEE}, author={Samanta, Suvendu and Wong, Isaac and Beddingfield, Richard and Bhattacharya, Subhashish and Zhu, Guangqi and Pahl, Birger}, year={2019}, month={Oct}, pages={85–92} }
 @article{beddingfield_bhattacharya_byerly_simizu_leary_mchenry_ohodnicki_2018, title={Thermal profile shaping and loss impacts of strain annealing on magnetic ribbon cores}, volume={33}, ISSN={["2044-5326"]}, url={https://doi.org/10.1557/jmr.2018.157}, DOI={10.1557/jmr.2018.157}, abstractNote={Abstract}, number={15}, journal={JOURNAL OF MATERIALS RESEARCH}, publisher={Cambridge University Press (CUP)}, author={Beddingfield, Richard and Bhattacharya, Subhashish and Byerly, Kevin and Simizu, Satoru and Leary, Alex and McHenry, Mike and Ohodnicki, Paul}, year={2018}, month={Aug}, pages={2189–2206} }
 @inproceedings{beddingfield_storelli_bhattacharya_2017, title={A novel dual voltage source converter for magnetic material characterization with trapezoidal excitation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020117541&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930922}, abstractNote={A magnetic core testbed is intended to provide a variety of induction curves to fully characterize a magnetic material. Off the shelf solutions are prohibitively expensive and limited in testing range for research purposes. Mainly, high voltages and/ or currents and the ability to create a variety of induction profiles, beyond sinusoidal, is needed for full core characterization. This paper establishes the need for a novel magnetic core testing apparatus to explore high frequency trapezoidal excitation. Then a solution is presented using a novel dual voltage source converter circuit. The authors validate the topology in simulation and present a laboratory prototype. Specifically, the induction profile seen in many dual active bridges is of immediate interest and generated with this approach.}, booktitle={2017 thirty second annual ieee applied power electronics conference and exposition (apec)}, author={Beddingfield, R. and Storelli, D. and Bhattacharya, S.}, year={2017}, pages={1659–1666} }
 @inproceedings{beddingfield_storelli_bhattacharya_2017, title={Active elimination of DC bias flux in series DC active filter coupling transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020036855&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930897}, abstractNote={The Medium-voltage DC amplifier is a thyristor based power converter with a series DC active filter that provides a highly controllable and responsive platform to establish a high power dc bus. Having bulk power flow through the thyristor converter offers an economical and high power density solution over PWM converters. By designing the system to meet standards requested by the US Navy for the Next Generation Intelligent Power System, this paper will show a platform applicable to many high power DC microgrid fields. In particular, there are promising applications in mobile mining equipment, electric aircraft and ships. This paper proposes a novel control technique to actively mitigate the DC flux that is generated by the load current. This control approach yields significant reductions in the core volume and required transformer turns. The proposed solutions will be evaluated in a 4 kVA 400 VDC laboratory scale test-bed.}, booktitle={2017 thirty second annual ieee applied power electronics conference and exposition (apec)}, author={Beddingfield, R. and Storelli, D. and Bhattacharya, S.}, year={2017}, pages={1498–1505} }
 @inproceedings{beddingfield_bhattacharya_2017, title={Multi-parameter magnetic material characterization for high power medium frequency converters}, booktitle={Tms 2017 146th annual meeting & exhibition supplemental proceedings}, author={Beddingfield, R. and Bhattacharya, S.}, year={2017}, pages={693–708} }
 @inproceedings{cho_han_beddingfield_ha_bhattacharya_2016, title={Seamless black start and reconnection of LCL-filtered solid state transformer based on droop control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015434753&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855416}, abstractNote={The solid state transformer (SST) is an emerging technology that can replace conventional passive transformers and actively manage renewable energy resources, energy storage devices, and loads. In this paper, a seamless black start control strategy is proposed for an SST-based smart grid system that has fault ride-through capability when it is islanded from the grid. Also, a method is developed to achieve smooth reconnection to the grid after a fault is cleared. The main component of the proposed control strategy is control of the high-voltage side converter of the SST (HV SST), which is based on a combination of droop control and an LCL filter. A single-loop controller for the capacitor voltage of the LCL filter is proposed, and simple criteria for setting compensator gains are provided. A low-voltage scaled SST system is introduced, and the controllers of the converters within the system are described. The proposed control strategy has been tested in simulation and experimentally on a low-voltage scaled testbed.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Cho, Y. and Han, Y. and Beddingfield, R. B. and Ha, J. I. and Bhattacharya, S.}, year={2016} }
 @inproceedings{beddingfield_de_mirzae_bhattacharya_2015, title={Design methodology of series DC coupling transformer in a medium-voltage DC amplifier system}, volume={2015-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937857830&partnerID=MN8TOARS}, DOI={10.1109/apec.2015.7104350}, abstractNote={The medium-voltage dc amplifier is a controllable dc source for the purpose of testing medium-voltage dc system technologies for shipboard applications. In a medium-voltage dc amplifier system, a dc active filter with a series dc coupling transformer is an integral component of the system required for both steady-state and dynamic voltage injection. This paper describes the design aspects and methodology for the series dc coupling transformer in such a system. The design of the transformer is one of the most critical aspects of this system as it has to withstand large continuous dc current offset without saturating. Based on system performance requirements, design criteria for the transformer is defined and two transformer designs based on two Iron-based magnetic materials are evaluated for a 12 kVA, 300 Vdc laboratory-scale amplifier test bed. An optimal design methodology is also proposed in this paper. Various design compromises have been studied and reported. The practical transformer design considerations and feasibility study for a medium-voltage dc amplifier system are given.}, number={May}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Beddingfield, R. and De, A. K. and Mirzae, H. and Bhattacharya, S.}, year={2015}, pages={183–190} }
 @inproceedings{beddingfield_davis_mirzaee_bhattacharya_2015, title={Investigation of series DC active filter and hybrid AC active filter performance in medium voltage DC amplfier}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84945919142&partnerID=MN8TOARS}, DOI={10.1109/ests.2015.7157880}, abstractNote={To further improve energy management, the US navy is exploring medium-voltage DC as the power supply of choice for next generation integrated power systems (NGIPS). Using the mature technology of multi-pulse thyristor bridge rectifiers, viable topologies are proposed that meet power density expectations. However, due to the non-linear ripple associated with thyristor commutations in such active front-ends (AFEs), a high bandwidth series AC active filter is used to smooth out the current harmonics. Similarly, a high bandwidth hybrid DC active filter is used for DC bus smoothing and improved dynamic performance. This paper will investigate the combined performance and consequential interactions of both active filters.}, booktitle={2015 IEEE Electric Ship Technologies Symposium (ESTS)}, author={Beddingfield, R. and Davis, A. and Mirzaee, H. and Bhattacharya, S.}, year={2015}, pages={161–166} }