Name: Stanimir Stoyanov Valtchev 
Date & Place of Birth: 1951 in Lovetch, Bulgaria 
Nationality: Portuguese and Bulgarian 
E-mail: ssv @ 
Web Page: (other page)

I. Education

Ph.D. in Electrical and Computer Engineering, obtained from Instituto Superior Técnico – IST (Portugal), in collaboration with University of Technology – TU Delft (the Netherlands), defending the thesis: “Series Resonant Power Converter for Contactless Energy Transfer with Improved Efficiency”

Previous degrees in Electrical Engineering, obtained from Technical University of Sofia – TUS (Bulgaria). Received the Honour Award (together with an engraved wrist watch) for achieving the best academic result, 5.45 of SIX (curricular) and 6.00 of SIX for the MSc thesis: “Technology of semiconductor devices, applying solid BN wafers as in–situ dopant” (1974). Because of these achievements could start PhD studies without applying to the required national contest. This opportunity was lost because of the compulsory military service.

Secondary school degree from 19th school, Sofia, Bulgaria, class of mathematics, score 5.62 of SIX. 


1964                Member of the City Radioclub of Sofia: several amateur electronics constructions.

1969-1971       Involved in research activities during the university studies in the field of Radio techniques.

1973-1974       Involved (during studies) in semiconductor device technology development, paid a partial salary as a Researcher of the Scientific Research Division of TU Sofia.

1974                Project Engineer in the Institute of Medical Equipment (group of therapy apparata), designing automated bicycle ergometer for heart disease rehabilitation.

1974-1976       Military university and service, specializes in radars.

1976                Leads a project in the Institute of Medical Equipment, designing a cross field interference device for deep muscular and nervous disorders therapy.

1977                Admitted in the Power Electronics Laboratory at the Technical University – Sofia as а Research Engineer.

1978                Won a contest and was appointed for the position of Scientific Researcher 3rd Grade (equivalent then to the Teaching Assistant position) at TU Sofia. Worked on Research and Development projects:

Power supplies for High-Voltage CO2 lasers, highest precision, medical purposes, and for He–Ne lasers, portable, instrumentation purposes. Cooperation with the Factory of Lasers in Riazan, USSR.

DC–DC power converters (high switching frequency) and DC-AC UPS converters, 600 W, mobile, phase–shift regulation.

1979                Approved for the position of Scientific Researcher 2nd Grade (equivalent then to the position of Senior Assistant). Projects:

Experimenting on HF transistor converters, also super-resonant, up to 440 kHz (leader of the project). Wind generator, 2 kW induction heating equipment (leader of the project), etc.

1984-1986       Collaborated with the Laboratory for Manipulators and Robots of the same university, working on projects:

UPS converter 24VDC/220VAC, up to 5 kW with HF switching synthesis of the sine wave, Drives for DC motors as controlled brakes in Capacitor–Winding Machine,

Electronic trailer for measuring the road–tire cohesion for the Traffic Control Department of the Research Institute of Police,

Automatic infusion syringe for hospital purposes (project together with the Mechanical Engineering Faculty),

Portable equipment for measuring and recording of the sportsmen exerts during rowing (used later in other sports),

HF low noise power supply for multichannel portable data acquisition system for geophysical purposes, etc.

1986                Approved for the position of Scientific Researcher 1st Degree in the Laboratory for Manipulators and Robots. Appointed Assistant–Director of the Centre of Robotics (later became a new faculty).

1987                Research in TU Delft, the Netherlands, experimental 2 kW MOSFET power converter to verify the ideas (already had in Bulgaria) for efficient operation at super–resonant frequency. During the stay in the Netherlands participated in the NATO Advanced Study Institute "Demand–Side Management and Electricity End–Use Efficiency" in Povoa do Varzim, Portugal. In June 1987 appointed Universitair Docent in TU Delft.

1988-1991       Back in TU Sofia, being Principal Assistant Professor, main projects:

HF DC/DC 2.5 kW “booster” converter implemented in Super–Resonant mode with split inductances (15 output stages in parallel, sharing the load), tested successfully in the Power Supply Factory, Pernik.

Miniaturized 160 W HF power supply with a new amorphous iron wound core, power supplies for the public transport, etc.

1991-1992       Stay at TU Delft by TEMPUS individual grant. During planned by TEMPUS visit to Portugal held a seminar at the Technical University of Lisbon, Portugal on the Resonant Conversion operation, research on:

High frequency resonant converter, Multi-kilowatt super-resonant X–Ray generator single phase supplied, 100 kW, 150 kV.

1993                Research projects on power converters in TU Sofia – Bulgaria).

1994                Invited by colleagues from IST (TU–Lisbon) to the factory FRAEP to lead a project of HF high–efficiency soft–switching power supply 220VAC/40–60VDC/20A, with a power factor correction at the input. Invented and implemented original topology for a phase–shift regulated converter to achieve high efficiency (96%) at 250 kHz switching frequency. A version of the topology was presented at conferences, having received high appreciation. It is used in many students’ works, later on.

1995-1996       Contracted as a consultant of INESC and of enterprise TAPE for the area of Power Converters (Portugal).

1995-2000       Contracted as a consultant of the enterprise Signaal Special Products (then part of Holand Signaal, the Netherlands). Projects included resonant and “classical” power converters, also solar power and contactless power transfer (up to 97% efficiency in 15 kW contactless transfer was achieved).

2000-2002       Contracted again as a consultant of INESC (power supplies).

2000-2008       Researcher of Institute of Telecommunications (IT), in IST–Lisbon.

2008-…           Researcher of the Institute UNINOVA of FCT–UNL, Lisbon.
2009-…           Collaborates also with the “Energy Processing” group in TU Delft.




1977–1986      Teaching the laboratory classes in Power Supplies Equipment, being appointed Teaching Assistant in part-time regime (this position is allowed to full–time Scientific Researchers).

1987                Appointed Universitair Docent (Assistant Professor) in TU Delft (starting June 1987).

1988                By the contest opened in the same time in Bulgaria (announced already in 1986), received the position of Principal Assistant Professor at the Department of Power Electronics (TU Sofia).

1989                Granted a definitive position (tenure) as a Principal Assistant Professor in TU Sofia.

1977–1994      Supervisor of the graduation theses of more than 50 engineers, many of whom foreigners (began supervising theses as External Supervisor at the time when was still working at the Institute for Medical Equipment). Took part in the jury of many more graduation theses.

1977–1988      Taught more than 500 students of practical and laboratory classes.

1988–1994      Teaching mainly theoretical classes of Power Supply Equipment. Lectured (theory) and examined (orally) more than 700 students.

1989–1994      Appointed as responsible for two subjects, part of a New Master of Science Program:

Modern Power Transistor Converters (4th year students),

Switched–Mode Power Supplies (postgraduate students).

1989–1991      Participated in creating of the new Faculty of Industrial Engineering (where all subjects are taught in English) in cooperation with the Brunel West London University and TU Sofia.



1987–1988      Assigned the position of Universitair Docent (i.e. Assistant Professor) at TU Delft, the Netherlands, in the Laboratory of Power Electronics.

1987–1992      Advisor and co–advisor of MSc. students.

2009                Collaborated also by substituting in lecturing (during a short stay)




1995–1996      Lecturing four subjects of the course FUNDETEC (European qualification program in Electrical Engineering and Electronics ).


1995–2003      Lecturing (theory and practice) of the subject: Automation and Control (1st semester of the 4th year Mechatronics Engineering).

1996–2003      Lecturing (theory and practice) of the subject: Electrical Measurements (2nd semester of the 3rd year Mechatronics Engineering) and the subject Instrumentation (2nd semester of the 3rd year Mechatronics Engineering).

1997–2003      Lecturing (theory) of the subjects: Electronics I (1st semester of the 3rd year Mechatronics Engineering) and Electronics II (2nd semester of the 3rd yearMechatronics Engineering).

2000–2003      Lecturing (theory and practice) of the subjects: Power Electronics I (1st semester of the 4th year Mechatronics Engineering) and Power Electronics II (2ndsemester of the 4th year Mechatronics Engineering).

2002–2003      Lecturing (theory) of the subjects: Theoretical Electrotechnics I (1st semester of the 3rd year Mechatronics Engineering) and Theoretical Electrotechnics II (2nd semester of the 3rd year Mechatronics Engineering).

1995–2003      Supervised more than 10 final projects of students.



1996–2002      Lecturing (as Invited Auxiliary Professor, theory and practice) of the subjects: Power Electronics I (2nd semester of the 3rd year Industrial Electrical Engineering) and Power Electronics II (1st semester of the 4th year Industrial Electrical Engineering).

1997–2002      Lecturing (theory and practice) of: Numerical Methods (2nd semester of the 3rd year Industrial Electrical Engineering).

1998–2002      Lecturing (theory and practice) of: Electronics of Regulation and Commanding (1st semester of the 4th year Industrial Electrical Engineering).

1996–2002      Supervised final projects of more than 15 students.



2000–2001      Lecturing (practice) of: Power Electronics (1st semester of the 5th year Electrical and Computer Engineering – branch: Control and Robotics). This work was done as educational support to IST (in substitution of the PhD study fees due to IST).

2000–2008      Co–supervised final projects of at least 7 students.



2002–…          Lecturing (theory and practice) of: Power Electronics in Actuators (2nd semester of the 4th year Master Course in Electrical and Computer Engineering).

2002–…          Lecturing (practice) of: Theoretical Electrotechnics (1st semester of the 2nd year Master Course in Electrical and Computer Engineering).

2002–…          Lecturing (theory and practice) of: Instrumentation and Electrical Measurements (2nd semester of the 3rd year Master Course in Electrical and Computer Engineering).

2008–…          Lecturing (theory and practice) of Instrumentation and Monitoring (3rd sem.) of the new Master Course in Renewable Energy.

2008-…           Lecturing (theory and practice) of Power Electronics (4th sem.) of the new Master Course in Renewable Energy.

2002–…          Supervised theses of 9 MSc students and supervises 7 more.



1986–1987      Assistant Director of the Center of Robotics. This Center later became the Faculty of Robotics at TU Sofia – Bulgaria.

1990–1994      Deputy Dean for the Foreign Students at TU Sofia (position related to the whole university, responsible for the educational problems of the foreign students, post–graduates and PhD students).



Efficient energy conversion, e.g. soft–switching techniques, super-resonant operation, etc.

Drives and actuators, energy transfer (also contactless), energy harvesting from solar, thermal, mechanical and other renewable sources of energy, microminiaturized power converters.

Electric vehicle: battery management, energy management and transfer (also contactless), etc.



IEEE (M., 1991, SENIOR MEMBER, 2008),

Power Electronics Society of IEEE (since 1991),

Industrial Electronics Society of IEEE (since 1993),



1960…            From the school, for results at the Math Olympiads, dedicated books and diplomas.

1974                From TU Sofia, for being top of the class (MSc Graduation).

1997                                From IEEE, “Meritorious Paper Award” for article published in 1996, diploma.



Bulgarian, fluency: oral and written (school diplomas)

Russian, fluency: oral and written (school and university diplomas)

English, fluency: oral and written (school, university and other diplomas)

Dutch, fluency: oral and written (three levels Dutch language diplomas)

Portuguese, fluency: oral and written (no specific course)


Other language courses taken (weaken knowledge):

French, 1960

Czech, 1970

German, 1977–78