Theoretical analysis of the synchronous reactance influence on the speed regulation of PM motors

The paper summarizes the basic theoretical aspects concerning the speed regulation of surface mounted permanent magnet synchronous motors. In particular, the influence of the synchronous inductance is articulated considering the limitations imposed by the supply (maximum voltage and current) and the constraints for a specific variable-speed application. The study is conventionally approached, using the well-known single-phase equivalent circuit and the related steady-state vector diagrams. The involved key machine parameters are then discussed in term of sizing equations in order to predict the speed regulation capability since the initial electromagnetic design stage.