Variable-speed, sub-harmonically excited BL-WRSM avoiding unbalanced radial force

Different topologies for brushless wound rotor synchronous machines (BL-WRSMs) have been proposed recently. This paper proposes a new model for the existing sub-harmonically excited BL-WRSM to eliminate the unbalanced radial force presented in the initial model. The initial and proposed models are analyzed using a two-dimensional finite element method. Furthermore, a variable-speed analysis for the BL-WRSM is conducted by altering the stator input current. Finally, a prototype of the proposed model is built and tested at the rated speed, to compare its performance with that of the conventional WRSM. Simulation and experimental results validate the proposed BL-WRSM’s operation.