Publications

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1974
Eng. Stanimir Valtchev, Top MSc Graduate of the year 1974, Award and Engraved Wrist-Watch, Valtchev, Stanimir , September, (1974) Abstract
Eng. Stanimir Valtchev, Top MSc Graduate of the year 1974, Specialized in Technology of Electronic Equipment and Integrated Circuits
1978
Experimental Research of the Boron Nitride Diffusion, Valtchev, Stanimir , Elektropromishlenost i Priborostroene, (1978) Abstract
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Experimental Research of the Boron Nitride Diffusion, , Elektropromishlenost i Priborostroene, (1978) Abstract
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Experimental Research of the Boron Nitride Diffusion, Atanasov, Alexander, Valtchev Ivan, Kolevska Dobrinka, and Valtchev Stanimir , Elektropromishlenost i Priborostroene (now: Elektrotechnica & Elektronica), January, Number 1, p.31–35, (1978) Website
1980
Power supply for 2 kW ? 25 kV CO2 gas laser, Valtchev, Stanimir , September, (1980) Abstract
International project (1251?78 and 1252?78) in which the Technical University of Sofia (S.Valtchev, N.Stefanov) has sucessfully acomplished the task of constructing and implementing in production a high precision (0.01% regulation) power supply for a cirurgical laser tool (1977-1980). The construction involved a vacuum tube cascaded with MOS-FET to obtain very high quality current source necessary for the stable characteristics of the gas discharge in the laser tube.
1983
Control System for Power Converter of DC to Sinusoidal AC Voltage, Natchev, Branimir, and Valtchev Stanimir , National Conference (with international participation) of Power Electronics SILEKTRON?83, (1983)
Driver Circuit for Power Transistor Switches, Natchev, Branimir, and Valtchev Stanimir , National Conference (with international participation) of Power Electronics SILEKTRON?83, (1983)
Power Converter of DC to Sinusoidal AC Voltage for Robotic Purposes, Vasilev, Vasil, Natchev Branimir, and Valtchev Stanimir , Scientific Session VMEI?83, Section Robotics, (1983)
1984
PWM Servosystem for DC Motors Control, Vasilev, Vasil, and Valtchev Stanimir , Scientific and Technological Conference "Industrial Robots?84", (1984)
1986
An Electronic System for Rowers' Propulsion Motion Activities Studies, , Problems of the Fitness, (1986) Abstract
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An Electronic System for Rowers{'} Propulsion Motion Activities Studies, Valtchev, Stanimir , Problems of the Fitness, (1986) Abstract
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An Electronic System for Rowers' Propulsion Motion Activities Studies, Vasilev, Vasil, Batchev Vihren, Milev Mihail, Valtchev Stanimir, and Tatzov Alexander , Problems of the Physical Culture and Sport (now: "Sport and Science Magazine"), February, Number 2, p.13–17, (1986) Website
Power Transistor Pulse Generator for Technological Purposes, Valtchev, Stanimir, Krustev Georgi, and Popov Evgeni , Jubileum Scientific Session of VMEI?Gabrovo, Power Electronics Section, October, (1986)
1988
Behavior of the Series Resonant Energy Converter at Frequencies Differing from the Resonant One, Valtchev, Stanimir, and Krustev Georgi , The Day of the Radio Conference, May, (1988)
Experimental Results of the MOS Transistor Series Resonant Energy Converter Exploration, Valtchev, Stanimir, and Krustev Georgi , The Day of the Radio Conference, May, (1988)
1989
Equipment for Measuring the Road–Tyre Cohesion, Valtchev, Stanimir , 6th National Congress of Mechanics, Varna, (1989) Abstract
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Some Properties of the Transistor Series Resonant Power Convertors, Valtchev, Stanimir , The Day of the Radio Conference, 5–6 May 1989, Sofia, (1989) Abstract
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Some Properties of the Transistor Series Resonant Power Convertors, , The Day of the Radio Conference, 5–6 May 1989, Sofia, (1989) Abstract
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Some Properties of the Transistor Series Resonant Power Convertors, Valtchev, Stanimir , The Day of the Radio Conference, May, (1989)
Equipment for Measuring the Road?Tyre Cohesion, Tatzov, Alexander, Dimitrov D., Borisov T., Botchev R., Pashov P., Petrov P., Petrov D., and Valtchev Stanimir , 6th National Congress of Mechanics, September, (1989)
1990
Efficient Resonant Power Conversion, Valtchev, Stanimir, and Klaassens Ben J. , IEEE Transactions on Industrial Electronics, Volume 37, Number 6, p.490–495, (1990) AbstractWebsite
The DC analysis of a series-resonant converter operating above resonant frequency is presented. The results are used to analyze the current form factor and its effect on the efficiency. The selection of the switching frequency to maximize the efficiency is considered. The derived expressions are generalized and can be applied to calculations in any of the switching modes for a series-resonant circuit. For switching frequencies higher than the resonant frequency, an area of more efficient operation is indicated which will aid in the design of this class of converters and power supplies. It is pointed out that (especially for power MOSFETs where ohmic losses dominate) it is more attractive to select switching frequencies that are higher than the resonant frequency because of the possibility of nondissipative snubbers. Slowing down the rise of the gate voltage and, hence, the slow decrease of ON resistance during turn-on is also not a drawback to high-frequency switching. Because of this safer operation, the standard intrinsic diode of the power MOSFET could be used at high frequencies instead of the more expensive FREDFET
Efficient Resonant Power Conversion, Valtchev, SS, and Klaassens JB , IEEE Transactions on Industrial Electronics, Volume 37, Number 6, p.490-495, (1990) Abstract
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High Efficiency Resonant Power Conversion, Valtchev, Stanimir, and Klaassens Ben J. , 1st USSR Conference (with international participation) of Power Electronics Systems and Low?Power Converters Equipment (SES i UMPT), (1990)
High Efficiency Resonant Power Conversion, Valtchev, Stanimir , 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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Some Regulation Characteristics of Pulse–Width Modulated Series Resonant Power Conversion, Valtchev, Stanimir , 6th Conference PEMC{'}90, pp. 83–87, Budapest, (1990) Abstract
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