Dual-Mode Brushless Wound Rotor Synchronous Machine for High Starting Torque

This paper proposes a dual-mode brushless wound rotor synchronous machine (DBL-WRSM) for high starting torque. The proposed DBL-WRSM consists of two modes: induction and brushless (BL)-synchronous modes. First, the induction mode operates as a wound rotor induction machine (WRIM) to achieve a high starting torque. Second, the BL-synchronous mode operates as a brushless wound rotor synchronous machine (BL-WRSM) using the subharmonic of the stator magnetomotive force (MMF) in the steady state. To realize the dual-mode topology of the proposed machine, the stator is composed of two divided armature windings and two inverters that can produce subharmonics. The rotor has five switches that convert the rotor winding configuration between the two modes. To verify the proposed topology of DBL-WRSM, finite element analysis (FEA) was performed. Through the FEA results of the transient electromagnetic torque for the voltage source, it was confirmed that the proposed DBL-WRSM not only operates as a BL-WRSM in a steady state but also has a sufficiently high starting torque even under a full-load condition.