Study of Pole Changing of a Hybrid Excited Synchronous Machine with Stator Cage Winding

The hybrid excited synchronous machine with stator cage winding is investigated as an alternative traction drive for electric vehicles. Due to the structure of this electric machine it has several advantages and aspects, which could be beneficial. One aspect is the pole changing capability. This could be used to reduce the core losses since these depend on the frequency and therefore on the pole pair number, leading to a better efficiency. Especially in electric vehicles efficiency is important, which is the reason for the investigation. Therefor the performance maps are calculated based on response surfaces in order to avoid computational expensive optimization using finite element analysis. These maps illustrate the loss reduction and efficiency increase for partial load region. Since the operation point of the electric machine varies significantly in automotive application, it is of interest to consider a representative range. For this, standardized driving cycles are utilized and the operation points are calculated using a longitudinal vehicle model. These operation points and the performance maps as look up tables are then used as input for calculating the energy consumption. The results demonstrate that a beneficial use of pole changing is possible.