@article{etemadrezaei_lukic_2016, title={Coated-Strand Litz Wire for Multi-Megahertz Frequency Applications}, volume={52}, ISSN={["1941-0069"]}, DOI={10.1109/tmag.2016.2550425}, abstractNote={Substantial induced eddy-current losses and the need for skin-depth-size strands leave litz wire out as an option for inductive applications at multi-megahertz frequencies. To address this, we analyze and minimize the litz-wire eddy-current losses by adding a coating layer to each strand while keeping the wire dimensions and packing factor constant. The skin and proximity effects of isolated and in-bundle coated strands are studied for various coating properties and dimensions. A new method is proposed for calculation of proximity losses inside coated-strand litz wire, which enables simple systematic approach for proximity loss and ac resistance (Rac) determination. Three types of pure copper (Cu), silver-coated copper (Ag/Cu), and nickel-coated copper (Ni/Cu) strands are studied in isolation and inside a litz wire. The litz wires associated with these strands are fabricated and their power dissipations are measured. Analytical results followed by finite-element modeling and experimental results show 26% reduction in Ni/Cu litz wire Rac, and 3% reduction in Ag/Cu litz wire Rac at 13.56 MHz compared with same-size Cu litz wire.}, number={8}, journal={IEEE TRANSACTIONS ON MAGNETICS}, author={Etemadrezaei, Mohammad and Lukic, Srdjan M.}, year={2016}, month={Aug} }
 @article{etemadrezaei_lukic_2016, title={Multilayer Tubular Conductor for High Q-Factor Wireless Power Transfer System Resonators}, volume={52}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2016.2574772}, abstractNote={In this paper, we investigate multilayer tubular conductor for multi-MHz Wireless Power Transfer systems high-Q (quality factor) resonators. The conductor layers' thicknesses and current sharing between them are optimized at 13.56 MHz, showing significant reduction in conductor ac resistance RAC. Capacitive ballast is used as a practical method for current sharing between layers and operation of coil near resonance. A two-layer conductor is designed, fabricated, and characterized at 27.93 MHz, showing 18.1% and 12.8% reduction in RAC, compared with an identical conductor without capacitive ballast and a same size solid conductor, respectively.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={IEEE}, author={Etemadrezaei, Mohammad and Lukic, Srdjan M.}, year={2016}, pages={4170–4178} }
 @inproceedings{etemadrezaei_lukic_2015, title={Multi-layer tubular conductor for high Q-factor wireless power transfer system resonators}, DOI={10.1109/ecce.2015.7310096}, abstractNote={In this paper we investigate multi-layer tubular conductor for multi-MHz Wireless Power Transfer (WPT) systems high-Q (quality factor) resonators. The conductor layers thickness and current sharing between them are optimized at 13.56 MHz, showing significant reduction in conductor AC resistance (RAC). Capacitive ballast is used as a practical method for current sharing between layers and operation of coil near resonance. A two-layer conductor is designed, fabricated and characterized showing 18.1% reduction in RAC at 27.93 MHz using capacitive ballast.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Etemadrezaei, M. and Lukic, Srdjan}, year={2015}, pages={3111–3118} }
 @inproceedings{etemadrezaei_lukic_2012, title={Equivalent complex permeability and conductivity of litz wire in wireless power transfer systems}, DOI={10.1109/ecce.2012.6342286}, abstractNote={In this paper the skin and proximity effect losses for Litz wire winding used in wireless power transfer system is calculated using exact 2-D method. Based on those losses the equivalent complex permeability and conductivity are calculated for each strand in the bundle. Due to specific properties of Litz wire, the whole bundle is homogenized using isotropic complex permeability and conductivity and is simulated numerically in Finite Element (FE) verifying the analytical and experimental results.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Etemadrezaei, M. and Lukic, S. M.}, year={2012}, pages={3833–3840} }