Brushless Wound Rotor Synchronous Machine Topology Using Concentrated Winding for Dual Speed Applications

Permanent magnet (PM) machines have broad applicability and a rapid output rise due to their good power factor, high efficiency, and power density. However, with the recent high cost, unavailability, and demagnetization issues of PMs, the wound rotor synchronous machine (WRSM) is a better substitute for permanent magnet machines for various applications in terms of price value and controllability. While the WRSM contains issues such as regular maintenance and replacement of brushes and slip rings, this paper introduces a brushless WRSM (BL-WRSM)with concentrated winding having 36 slots and 48 poles, which generates fundamental component and a dominant sub-harmonic component of magneto motive force (MMF). To achieve the brushless operation, the rotor has an additional winding called excitation winding that is connected with the main field winding via a rectifier. This additional winding is used to induce the electromotive force (EMF) by the sub-harmonic MMF component of the stator. The EMF is converted to DC by the rectifier and fed to the main field winding. This BL-WRSM has been developed for dual-speed applications such as washing machines. The machine has been tested for 46 rpm and 1370 rpm. The low-speed mode is for washing and the high-speed mode is for drying clothes. To validate the performance and feasibility, an outer rotor BL-WRSM is designed. The performance was compared with the conventional WRSM (C-WRSM). 2-D finite element analysis (FEA) simulation was conducted using ANSYS Electromagnetic.