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Mudrov, M., A. Zyuzev, N. Konstantin, S. Valtchev, and S. Valtchev, "Hardware-in-The-loop system numerical methods evaluation based on brush DC-motor model", Proceedings - 2017 International Conference on Optimization of Electrical and Electronic Equipment, OPTIM 2017 and 2017 Intl Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2017, United States, Institute of Electrical and Electronics Engineers Inc., pp. 428–433, 7, 2017. Abstract

Hardware-in-The-loop (HiL) systems nowadays become popular. During the HiL creation process it is important to select a proper numerical method because the accuracy of the process simulation, in case of the HiL, depends on the correct numerical approach selection. That is why it is important to evaluate the most popular numerical approaches. The {"}Sequential{"} Euler (solves equations step-by-step), the Forward Euler (the most popular method for HiL creators), and the Second-order Adams-Bashforth approach are under consideration. A mathematical model based on the DC-motor with independent excitation is selected as a basis for the experimental numerical calculation. In consequence, recommendations for the numerical method selection are given, based on the obtained results.

Valtchev, S., "High Efficiency Resonant Power Conversion", High Efficiency Resonant Power Conversion, April, 1992. Abstract
Mode of operation and area of rnhanced efficiency for series-resonant converters is presented. Frequency control on voltage source DC-DC converters is discussed and other principles of control are introduced. Optimum modes of operation for power transistor resonant converters are also considered. For even better efficiency a resonant current shaping is discussed.
Valtchev, S., and B. J. Klaassens, "High Efficiency Resonant Power Conversion", 1st USSR Conference (with international participation) of Power Electronics Systems and Low?Power Converters Equipment (SES i UMPT), 1990.
Valtchev, S., "High Efficiency Resonant Power Conversion", 1st USSR Conference (with international participation) of Power Electronics Systems and Low–Power Converters Equipment (SES i UMPT), Alma–Ata, USSR, 1990. Abstract
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Valtchev, S., "High frequency wireless energy for improving the EV autonomy", International Symposium on Electric Vehicle and 4-th Annual Conference of Polish Society for Environment Friendly Vehicles, 2012. Abstract
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Valtchev, {S. S. }, and DEE Group Author, "High frequency wireless energy for improving the EV autonomy", International Symposium on Electric Vehicle and 4-th Annual Conference of Polish Society for Environment Friendly Vehicles, pp. 6, 1, 2012. Abstract

There have been many and very significant advances in the Wireless Power Transfer, resulting up to now in flexible and safe battery charging eliminating the necessity of power cables. The relatively low frequencies (tens of kilohertz) applied for those {"}classical{"} chargers are already well developed. A {"}new{"} technology appeared now that makes possible to apply a strong magnetic resonant coupling. Similar experiments were applied by N. Tesla more than a hundred years ago but now the researchers are capable to reach much higher frequencies. To achieve the necessary high level of magnetic field coupling it is essential to allow high levels of electric current intensity inside the resonant loops. In this article the achievement of highest magnetic field is analysed and experimented. Some results are discussed based on the choice of the resonant loop type and construction. The applications in the on-line energy supply for the EV are one of the aimed goals. The other goal may be the future more efficient induction machine.

, "High frequency wireless energy for improving the EV autonomy", International Symposium on Electric Vehicle and 4-th Annual Conference of Polish Society for Environment Friendly Vehicles, 2012. Abstract
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Valtchev, S., "High Level Education Through Research Training Networks: A Potential Strategy To Build Knowledge In EV/HEV", International Symposium on Electric Vehicles ISEV2011, keynote speech, Beijing, 2011. Abstract
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Valtchev, {S. S. }, {J. J. } Pamies-Teixeira, and DEE Group Author, High Level Education Through Research Training Networks: A Potential StrategyTo Build Knowledge In EV/HEV, , vol. NA, 1, 2011. Abstract
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Pina, J., C. Caracaleanu, A. Gonçalves, P. Pereira, S. Valtchev, M. Neves, and A. Rodrigues, "High Performance, Environment Friendly, Modular and Fault Tolerant Renewable Energy Microgrid", 12th International Energy Conference & Exhibition (ENERGEX2007), 2007.
Valtchev, S., "HV DC as the Next Generation Telecom Power Supply", Symposium INTELEC{'}95, 2013. Abstract
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, "HV DC as the Next Generation Telecom Power Supply", Symposium INTELEC'95, 2013. Abstract
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