Novel Self-Excited Brush-Less Wound Field Vernier Machine Topology

To realize the brush-less operation for wound field vernier machines (WFVMs), a novel self-excited topology is proposed in this paper which involves a four-pole main armature winding and a two-pole excitation winding connected in series using an uncontrolled rectifier. Upon supplying current from a single current-controlled voltage source inverter (VSI), this procedure results in four-pole and two-pole magnetomotive force (MMF) components in the airgap. The four-pole MMF produces the main stator field while the two-pole MMF component develops a sub-harmonic field in the airgap. The rotor is altered to house a forty-four-pole rotor field and two-pole harmonic windings. The two-pole harmonic field is employed to induce a current in the harmonic winding, which is rectified by means of a full-bridge diode rectifier to energize the rotor field winding and realize brush-less operation for WFVM. Two-dimensional finite element analysis (2-D FEA) is implemented in JMAG-Designer to confirm the operation of the proposed WFVM topology and attain the electromagnetic performance for a four-pole, twenty-four-slot outer-rotor vernier machine.