VP10-11 Quarter Sub-Harmonic-Based Self-Excited Brushless Wound Field Synchronous Machine Using Three-Layer Winding Configuration
Creators: Syed Sabir Hussain Bukhari
and Paavo Rasilo
Publisher: name: IEEE
Year: 2025

Wound field synchronous machines (WFSMs) have gained significant attention in recent years due to their lower manufacturing costs compared to permanent magnet machines [1]-[2]. However, these machines face a major drawback due to the use of brushes, slip rings, exciters, and pilot exciters for rotor field excitation. This paper introduces a novel quarter sub-harmonic-based self-excited brushless topology for WFSMs, utilizing a three-layer armature winding configuration. The armature winding in this design includes an 8-pole, double-layer main armature winding (ABC) and a 2-pole single-layer exciter winding (X) connected in series through a diode rectifier. When the inverter supplies three-phase currents (Iabc) to the main armature winding, it energizes the 2-pole exciter winding after rectification, simultaneously creating an 8-pole rotating magnetic field and a 2-pole pulsating magnetic field in the machine's air gap. The rotor of the machine features an 8-pole rotor field winding (F) and a 2-pole harmonic winding (H), both connected in series through a full-bridge diode rectifier. As the rotor rotates, the harmonic winding intercepts the pulsating 2-pole magnetic field, inducing harmonic current in it. This current is rectified to energize the rotor field winding, generating the rotor field. The electromagnetic interaction between the main stator and rotor fields produces torque. The proposed self-excited brushless WFSM topology is illustrated in Fig. 1(a). To validate the operation of the proposed topology, finite element analysis (FEA) is conducted in JMAG-Designer for an 8-pole, 48-slot machine model, as shown in Fig. 1(b). The machine is supplied with a current of 4A (peak) and analyzed at the rated speed of 900 rpm. The induced harmonic current and the rectified rotor field winding currents are presented in Fig. 2(a). Fig. 2(b) shows the output torque of the machine using the proposed brushless WFSM topology. These results demonstrate that an average torque of 8.55 Nm with a ripple of 25.59% is achieved. A detailed perfromance analysis of the proposed topology will be presented in the final paper.References: [1] S. S. H. Bukhari, J. Ikram, F. Wang, X. Yu, J. Imtiaz, J. Rodas, and J. -S. Ro, "Novel Self-Excited Brush-less Wound Field Vernier Machine Topology", in IEEE Access, vol. 10, pp. 97868-97878, 2022. [2] S. S. H. Bukhari, J. Yu, M. A. Shah, J. Rodas, M. Bajaj, and J. -S. Ro, “Novel Sub-Harmonic-Based Self-Excited Brushless Wound Rotor Synchronous Machine”, IEEE Canadian Journal of Electrical and Computer Engineering, vol. 45, no. 4, pp. 365-374, Fall 2022.
Wound field synchronous machines (WFSMs) have gained significant attention in recent years due to their lower manufacturing costs compared to permanent magnet machines [1]-[2]. However, these machines face a major drawback due to the use of brushes, slip rings, exciters, and pilot exciters for rotor field excitation. This paper introduces a novel quarter sub-harmonic-based self-excited brushless topology for WFSMs, utilizing a three-layer armature winding configuration. The armature winding in this design includes an 8-pole, double-layer main armature winding (ABC) and a 2-pole single-layer exciter winding (X) connected in series through a diode rectifier. When the inverter supplies three-phase currents (Iabc) to the main armature winding, it energizes the 2-pole exciter winding after rectification, simultaneously creating an 8-pole rotating magnetic field and a 2-pole pulsating magnetic field in the machine's air gap. The rotor of the machine features an 8-pole rotor field winding (F) and a 2-pole harmonic winding (H), both connected in series through a full-bridge diode rectifier. As the rotor rotates, the harmonic winding intercepts the pulsating 2-pole magnetic field, inducing harmonic current in it. This current is rectified to energize the rotor field winding, generating the rotor field. The electromagnetic interaction between the main stator and rotor fields produces torque. The proposed self-excited brushless WFSM topology is illustrated in Fig. 1(a). To validate the operation of the proposed topology, finite element analysis (FEA) is conducted in JMAG-Designer for an 8-pole, 48-slot machine model, as shown in Fig. 1(b). The machine is supplied with a current of 4A (peak) and analyzed at the rated speed of 900 rpm. The induced harmonic current and the rectified rotor field winding currents are presented in Fig. 2(a). Fig. 2(b) shows the output torque of the machine using the proposed brushless WFSM topology. These results demonstrate that an average torque of 8.55 Nm with a ripple of 25.59% is achieved. A detailed perfromance analysis of the proposed topology will be presented in the final paper.References: [1] S. S. H. Bukhari, J. Ikram, F. Wang, X. Yu, J. Imtiaz, J. Rodas, and J. -S. Ro, "Novel Self-Excited Brush-less Wound Field Vernier Machine Topology", in IEEE Access, vol. 10, pp. 97868-97878, 2022. [2] S. S. H. Bukhari, J. Yu, M. A. Shah, J. Rodas, M. Bajaj, and J. -S. Ro, “Novel Sub-Harmonic-Based Self-Excited Brushless Wound Rotor Synchronous Machine”, IEEE Canadian Journal of Electrical and Computer Engineering, vol. 45, no. 4, pp. 365-374, Fall 2022.