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.

This paper proposes a hybrid brushless wound-rotor synchronous machine (HB-WRSM) with an outer rotor topology that can operate as a permanent magnet synchronous machine (PMSM), as well as an HB-WRSM. In the first part, the existing brushless wound-rotor synchronous machine (BL-WRSM) is modified into a hybrid model by introducing permanent magnets (PMs) in the rotor pole faces to improve the magnetic field strength and other performance variables of the machine. In the second part, a centrifugal switch is introduced, which can change the machine operation from HB-WRSM to PMSM. The proposed machine uses an inner stator, outer rotor model with 36 stator slots and 48 poles, making the stator winding a concentrated winding. The HB-WRSM is utilized for dual-speed applications such as washing machines that run at low speed (46 rpm) and high speed (1370 rpm). For high speed, to have a better efficiency and less torque ripple, the machine is switched to PMSM mode using a centrifugal switch. The results are compared with the existing BL-WRSM. A 2D model is simulated using ANSYS Electromagnetics Suite to validate the machine model and performance.

This paper presents the design and performance analysis of a brushless wound rotor vernier machine (BLWRVM) for variable speed applications, particularly in the context of domestic appliances like automatic washing machines which have two cycles of operation: the wash cycle at low-speed and dry-cycle at high-speed. The proposed BLWRVM utilizes a different winding configuration that enhances the performance compared to the existing reference machine. The machine topology uses a dual winding setup on the stator, a 3-phase main ABC1 winding and a 1-phase additional A2 winding on the stator, specifically engineered to generate both fundamental and subharmonic components of MMF in the airgap of the machine. In order to achieve the brushless operation, the additional excitation winding is placed on the rotor which is connected through a rectifier to the field winding. The voltages are induced in this excitation winding using the MMF’s sub-harmonic component. These AC-induced voltages are rectified by a rotating rectifier placed on the rotor periphery and are then supplied to the main field winding. A 4-pole, 24-slot stator and 44-pole 44-slot outer rotor machine is designed. The fill factor of the machine’s stator slot was then increased to 35% and the rotor’s slot fill factor was increased to 30%. Furthermore, different skew angles of the rotor were analyzed to find the optimal skew angle that yields minimum torque ripple. The performance characteristics were compared with a reference BLWRVM. To validate the design a 2D-FEA was carried out to find out the performing characteristics of the proposed machine and reference machines using ANSYS Electromagnetic suite version 2022 R1.