In this paper we presented the study of a dual excitation synchronous machine designed for dual electrical or full electrical vehicle application. This machine combines two excitation flux sources: permanent magnets and DC excitation coils that are situated in the stator and the rotor is fully passive. For the studied application, the considered driving cycle was presented and it was shown that the required performances are highly variables. We presented with details the Dual Excitation Synchronous Machine Flux Switching (DEFSSM) for witch control parameters were optimized in order to optimize power losses for each operating point of the considered driving cycle.