Eddy Currents in Windings of Switched Reluctance Machines
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Beschreibung
Within this work a switched reluctance traction drive was investigated at the Institute for Power Electronics and Electrical Drives (ISEA) in Aachen. Three different winding geometries were applied to the prototype machine. Measurements resulted in distinct differences of machine efficiency (88.5 %, 90.5 %, 93.4 %), obviously originated in different eddy current losses. The publication of Klauz is the first and only known work in which eddy currents in switched reluctance machines were calculated by finite element simulations. The average copper losses of a low voltage machine with four turns per coil were found to vary by over 600 % between the different conductors. Klauz’ results confirm clearly the need to consider eddy current losses in the design process of new machine designs. However, the presented simulation models need to be built manually for each investigated geometry. Thus, a variation of the winding geometry implies an unreasonable effort. Moreover, solely single pulse operation was investigated. The main objective of this thesis lies in the development of a universal simulation process for switched reluctance machines that includes eddy current losses and allows the operation with different control structures like hysteresis control, single pulse operation or pulse width modulation (PWM). An important aspect is the development of a tool for fully automated generation of finite element models with adjustable winding geometry. This is a key requirement to allow design optimization based on geometry variation. The inclusion of converter losses, iron losses, friction losses and end-effects completes the simulation model. As a result, the new simulation tool allows to predict performance and efficiency of new machine designs very accurately.
Since the focus of the thesis lies on the determination of winding eddy currents, the fundamentals of analytic eddy current loss calculation are presented in detail. It is assumed that the reader of this work is familiar with the functional principle of switched reluctance drives and that terms like flux-linkage characteristic or turn-on and turn-off angle are known. A comprehensive introduction to switched reluctance drives and their controls can be found in. Furthermore, it is referred to the script of De Doncker and to the theses of Inderka and Fuengwarodsakul.
Autor*in
Christian Carstensen
Themen in »Eddy Currents in Windings of Switched Reluctance Machines«
Finite-Elemente-Methode Geschaltete Reluktanzmaschine Kupferverlust Wirbelstrom Wirkungsgrad