High-Efficient Self-Excited Brushless Wound Rotor Synchronous Machine Topology

This article proposes a new armature winding configuration to implement the sub-harmonic field excitation method for brushless operation in wound rotor synchronous machines (WRSMs). The proposed configuration combines single- and double-layer winding arrangements to generate a fundamental and a suitable magnitude of sub-harmonic magnetomotive force (MMF) components in the machine’s airgap. The fundamental MMF creates the main stator field, while the sub-harmonic MMF component induces a harmonic current in rotor’s harmonic winding. This current is rectified through a serially connected full-bridge diode rectifier, which excites the rotor field winding to achieve brushless operation. The proposed brushless WRSM topology is validated using a two-dimensional finite element analysis, for an eight-pole, forty-eight-slot machine model developed in JMAG-Designer version 22.2. Its performance is compared to that of a conventional dual-armature winding-based brushless WRSM topology. Results show that the proposed brushless WRSM topology achieves lower torque ripple, reduced losses and higher efficiency than the conventional topology due to its single-winding configuration.