Design optimization of double excitation synchronous machines in railway traction

Classical electrical machines such as asynchronous and permanent magnet synchronous machines have been widely applied in traction applications and particularly in railway traction. This thesis, however, evaluate the contribution of a special class of synchronous machine called textbf{D}ouble textbf{E}xcitation textbf{S}ynchronous textbf{M}achine (DESM) for the railway traction. Double excitation term indicates that the field flux of the machine is created by two sources: excitation windings and permanent magnets. The degree of freedom provided by the excitation windings provides the opportunity to work on the energy efficiency improvement target. This thesis will try to answer the question whether DESM is more advantageous over classical machines in a specific driving cycle and in addition, in which cases a DESM performs better.Recent studies have merely optimized the individual components, the major drawback of this approach is that the combination of the best individuals does not necessarily form a best system. In order to achieve more realistic results, a multi-physic models taking into account nonlinear characteristic and various disciplines such as electromagnetic, thermal, mechanical and power electronics will be developed.