Research on the bending strategy for an innovative, ressource efficient stator design

Due to new requirements regarding the efficiency of electrical machines it is necessary to steadily improve machine concepts or create new ones. Therefore, manufacturing technology has to be continuously improved, adapted or developed new. Forming technology offers an excellent opportunity to implement components for highly efficient electrical machines through its advantages regarding high productivity and high degree of material usage. This paper presents a new method for bending complete stacks of grain oriented electric sheets for use as radially laminated modules in an innovative machine concept with flux barriers. First, the principle of electric drives with flux barriers and the arrangement of the new radial lamination are explained. Then, practical preliminary studies concerning the bending of single sheets are performed. Based on this, the process and tooling for bending of pre-stacked sheets is developed and analysed. Accordingly, an increase in material utilisation of about 30% can be expected compared to classically designed stators. Furthermore, the use of the radially laminated stator principle increases the slot area by about 20% which makes it possible to insert more copper into the slot and thus increase the efficiency of the machine during operation. After validation of the process chain with a demonstrator motor and description of several manufacturing and quality improvements, finally, an outlook is given, and possible further research approaches are discussed.