Verlustoptimaler Betrieb einer elektrisch erregten Synchronmaschine für den Einsatz in Elektrofahrzeugen

In this thesis, it is investigated, how an electric vehicle drive based on a wound-field synchronous machine can be operated to obtain minimum losses across the entire operating range. Therefore, a prototype synchronous motor designed for application in an electric vehicle and a universal power electronic converter form the drive that is to be researched. To enable the extensive measurements needed for characterizing the drive, a test bench has been developed under special consideration of electromagnetic noise immunity. The electric behavior of the synchronous machine is described using the fundamental wave model in the rotor reference frame according to the two-axis theory. In order to also include saturation effects, the respective inductances are derived from the magnetization curve in dependence of a single magnetizing current. The model parameters are determined by numeric optimization to match with the measurements previously taken at certain operating points. The individual losses of the drive are obtained from measurements and are subsequently approximated as functions of currents and speed. Thereby an optimal combination of direct, quadrature and rotor currents can be found, for which these losses amount to a total minimum. The respective distribution of currents depends on the operating point and will be characterized. For its approximation or computation, several control methods and offline numeric optimization techniques as well as an online search algorithm are employed. All methods are evaluated with respect to resulting losses and implementation complexity and compared with each other. Finally, a quantitative estimate of the energy saving potential by application of optimized operation in an electric vehicle is given.