The Department of Theoretical Electrical Engineering was established in 1945 under the name Department of Electrical Theory and Measuring Electrical Engineering and it was the first electrical engineering department at the Institute and in Bulgaria.

The actual work of the Department began on 22.10.1945, when Prof. Mincho Petrov Zlatev was elected for Head of the Department. Prof. Zlatev graduated in 1931 at the High Technical School in Toulouse (France) in the field of electrical engineering. Later, in 1966 he received the degree Doctor of Science at the Politechnical Institute of Leningrad (USSR). He was a corresponding member of the French Academy of Science in Toulouse and an active member of other international associations and committees. He was Head of the Department till 01.09.1976. After Prof. Zlatev heads of the Department were:

Prof. Vesel Nikolaev Savov, 1976 - 1980 Рі.;

Prof. D.Sc. Sava Petrov Papazov, 1980 - 1984 Рі.;

Prof. D.Sc. Vladimir Ivanov Georgiev, 1984 - 1989 Рі.;

Prof. D.Sc. Samuil Leon Farhy,1989 - 1995 Рі.;

Assoc. Prof. Dr. Georgi Alexandrov Toshev, 1995-1999;

Assoc. Prof. Dr. Kostadin Georgiev Brandisky, 2000-2003;

Assoc. Prof. Dr. Snejana Dimitrova Terzieva , 2011-2021;

Prof. D.Sc Valeri Markov Mladenov, 2004-2011, 2021 -present.

The Maturing

In 1953 the Department was renamed into Department of Theoretical and Measuring Electrical Engineering. Primarily the lectures and the exercises were held in the building of BIAD at 108, Rakovsky Str. In September 1948 the Department was moved to 1, 19th February Str. and since 1969 it is situated in Darvenitsa. The lectures were on the disciplines Electrical Theory (later renamed Fundamentals of Electrical Engineering), Measuring Electrical Engineering and General Electrical Engineering. Several manuals were written at that time and the first educational labs were built.

The Development

As a result of the separation of the Departments of Measuring Electrical Engineering (1966) and General Electrical Engineering (1969) appeared  conditions for the concentration of closer scientific interests. The main educational and scientific activities were associated with the course Theoretical Engineering, which gave the new name of the department. The quality of teaching was improved. A lot of manuals and handbooks were published. The labs were reconstructed. Many of the lecturers defended dissertations and started investigations of more complex scientific problems. Different new research areas were successfully developed. In 1979 Prof. Sava Papazov defended his D. Sc. dissertation "Electromagnetic systems with optimal structure". This was the first D.Sc. dissertation, defended in Bulgaria from member of the Department. Three more dissertations followed: of Prof. Samuil Farhy - "Theoretical Problems in Analysis of Sophisticated Circuits with Concentrated Parameters" (1985), Prof. Liubomir Kolev - "Some Problems in Analysis of Linear and Non-linear Electrical Circuits" (1989) and Prof. Vladimir Georgiev - "Contributions to Analysis of Some Kinds of SC-circuits" (1995).
In the autumn of 1974 the Department was detached from the Faculty of Electrical Engineering and joined the Faculty of Automation.
In the end of the 70-es the main courses,  taught in the Department were basically modified, because of the publishing of the new manual in Theoretical Electrical Engineering. From that period dates the use of computing equipment in the teaching activities of the Department. This achievement was implemented by the department staff under the leadership of Prof. Sava Papazov and Prof. Vladimir Georgiev.  
Lecturers from the Department started teaching at the English and French Departments of Engineering.  Prof. D. Sc. Lubomir V. Kolev, Assoc. Prof. Dr. Simeon S. Vladov, Assoc. Prof. Dr. Valery M. Mladenov and Ass. Prof. Vesela D. Borshukova have lectures in English; Prof. D.Sc. Lubomir V. Kolev, Assoc. Prof. Dr. Nikolay A. Radev, Assoc. Prof. Dr. Milkana M. Bodurova, Assoc. Prof. Dr. Kancho P. Ivanov - in French.

At Present

At present the staff of the Department of Fundamentals of Theoretical Electrical Engineering counts 10 members. 9 of them have academic rank: 1 Professor with D.Sc. degree, 1 Professor with Ph. D. degree and 5 Associate Professors with Ph. D. degree. An essential course, taught by the lecturers of the Department is the course of Theoretical Electrical Engineering - part 1 and 2, for all students in different fields of engineering - at the Faculties of Electronic Engineering and Technology, Communication Engineering and Technology, Computer Science, Automation, Electrical Engineering and Transport. The Department also takes part in different number of courses at the Faculty of Foreign Language Learning, at the branches of the Technical University of Sofia and at the Autonomous Faculty.