The history of the Department of Electrical Machines and Devices and the Professorship of Energy Conversion Engineering.

1901 - 1935

The Chair of Electrical Machines at the then Technical University of Munich was founded in 1901. Johann Ossanna, a senior engineer who was only 31 years old at the time, was appointed as the first chair holder. During his time at the chair, Ossanna was initially concerned with the electrification of mainline railroads. After the First World War, he took on, among other things, the long-distance transmission of large amounts of electrical energy.

Ossanna was born in South Tyrol in 1870 and studied at the Graz University of Technology. From there he moved to Siemens & Halske in Vienna. Ossanna became known for his work on the theory of the three-phase motor, published in 1899. Among other things, he extended the circular diagram of the asynchronous machine already given by Heyland in 1894 to include the power lines (Ossanna circular diagram).

Even before the First World War, Ossanna was appointed Privy Councillor. In 1921, the Technical University of Karlsruhe awarded him the title of "Dr.-Ing. E. h." and in 1942 he was elected a full member of the Mathematical-Natural Scientific Class of the Bavarian Academy of Science.

1935 - 1945

In 1935, Theodor Bödefeld succeeded him as ordinarius. During his time at the chair, he wrote, together with Heinrich Sequenz from Vienna, his well-known book "Elektrische Maschinen" (Electrical Machines).

Th. Bödefeld, born in 1898, studied at the Technical Universities of Darmstadt and Hanover. In 1922 he found employment at Maschinenfabrik Thyssen in Mülheim/Ruhr. In 1926 he moved to the Technical University of Karlsruhe as assistant to Prof. Rudolf Richter, where he wrote his doctoral thesis on the natural oscillation of the synchronous machine. In 1931 he became a professor at the Badisches Staatstechnikum in Karlsruhe.

After the Second World War, Bödefeld had to leave the chair again for political reasons. In 1947 he received a call to the Technical University of Istanbul, where he had already been a visiting professor from 1943 to 1944, but was refused permission to leave the country. In 1952 Bödefeld took over first the management of the calculation offices and later the technical management in the dynamo plant of Siemens-Schuckertwerke AG in Berlin-Siemensstadt. Th. Bödefeld died in 1959 at the age of 61.

1945 - 1946

After the reopening of the Technical University of Munich, J. Ossanna took over the chair again for a transitional period.

In 1952, J. Ossanna died at the age of 82.

1946 - 1955

Walter Seiz was appointed to the chair in 1946. He was always particularly interested in three-phase trailing machines.

Seiz was born in 1885 and studied in Karlsruhe. In 1912, he took over the calculation of three-phase commutator machines, in particular the Scherbius rule sets, at Brown-Boveri & Cie. in Baden. There he also completed a dissertation on "Theory of the Asynchronous Frequency Converter." In 1929 he was appointed to the chair of electrical machines at the Technical University in Danzig, where he remained until the end of the war.

1955 - 1971

W. Scheuring headed the chair from 1955 to 1971. In 1963/64, the Chair moved from the Electrotechnical Building in the inner courtyard of the TH to the new building in the northern area. In 1965, a new Chair of Electrical Drive and Power Plant Technology (Prof. G. Kessler) was founded, which took over the teaching and research field of electrical drive technology from the Chair of Electrical Machines and Devices.

1971 - 2000

After Prof. Scheuring's retirement, Hans-Werner Lorenzen was appointed to the chair in 1971. As a scientific employee of BBC AG (now ABB), he had been in charge of the entire field of medium and high-power electrical machines with regard to scientific and technical issues since 1965. Since 1968, as a department head at AG Brown Boveri Baden / Switzerland, he was initially concerned with small, synchronous as well as asynchronous rotary field drives, and finally, within the framework of scientific work, with asynchronous motors of medium power.

In continuation of a research activity from his industrial activities, Prof. Lorenzen establishes the long-standing and fruitful scientific engagement of the chair in the field of superconducting solenoids. In addition to a 300 kVA model synchronous generator with superconducting excitation winding, a magnetic energy storage system based on superconducting coils in toroidal arrangement (storage volume 1.4 MJ) is being developed. Another research focus is the investigation of traveling field linear machines: Based on the model of a homopolar excited synchronous linear motor built at the chair, essential statements on the operating behavior and possible applications of such converters are developed. For neurological research and diagnostics, the chair develops suitable torque transducers, which are used at the Klinikum rechts der Isar.

Medical technology is established as a central field of work: Based on a first prototype, which has proven itself in clinical use since 1993, a series of devices for magnetic stimulation, especially of peripheral nerves, is developed. The optimal design of the associated stimulation coils is also the subject of research. Therapeutic application of the system can, for example, effectively alleviate the symptoms of patients suffering from Parkinson's syndrome. In the case of centrally induced paralysis, lost movement patterns can be restored (e.g. the 'tweezer grip', which is demanding in terms of fine motor skills). In 1999, the development of an implantable blood pump will be started in cooperation with the German Heart Center. Of particular importance is a favorable efficiency of the small synchronous motor, in order to be able to feed the system efficiently from a battery.

The chair's participation in the interdisciplinary Collaborative Research Center 365, which aims to develop a new type of hybrid drive for road vehicles, leads to the development and investigation of innovative electromechanical converters as well as an electric drive train suitable for vehicles in the years 1993 - 2002.

Other key research topics have recently included the investigation of superconducting magnetic support bearings, the theoretical and metrological examination of the voltage stresses on large asynchronous motors during switching operations, and the in-depth analysis of special short-term energy storage systems in electrical supply networks.

Within the scope of numerous research contracts from large and medium-sized companies, the chair is involved in a wide range of different tasks in the field of electromechanical energy conversion. Examples are the work on a crankshaft starter generator for motor vehicles, the numerical calculation of the magnetic circuit of DC and synchronous machines or the investigation of double-layer capacitors with high power density.

Special emphasis of teaching is put on the dynamic behavior of asynchronous machines, on the digital simulation of machines and converter circuits as well as on the calculation of magnetic fields.

In the years 1987 - 1995 Prof. Lorenzen acts as 1st Vice President of the TU. Today, as an emeritus professor, he provides advice and support to the staff of the Department of Energy Conversion Technology.

2000 - 2002

In implementation of a decision by the university management, the Chair of Electrical Machines and Devices will be dissolved as of September 30, 2000. The background to this is a rededication concept which the university had drawn up for the establishment of a new Faculty of Economics and Social Sciences.

From now on, the department of electromechanical energy conversion will be represented by the independent department of 'Energy Conversion Technology', which Prof. Lorenzen, already emeritus, will initially head as provisional director.

2002 - today

On July 1, 2002, Hans-Georg Herzog took over as head of the department. Initially involved in the development of AC commutator motors for hand-held power tools, Prof. Herzog eventually worked as assistant to the board of management at Robert Bosch GmbH.