High-Efficient Brushless Wound Rotor Synchronous Machine Topology Based on Sub-Harmonic Field-Excitation Technique

Abstract

This paper presents a new high-efficient three-phase brushless wound rotor synchronous machine (BL-WRSM) based on a sub-harmonic field excitation technique. In the proposed machine topology, the stator is equipped with two different three-phase windings: (1) main armature winding, and (2) additional armature winding. The main armature winding is based on a 4-pole winding configuration, whereas the additional armature winding is based on a 2-pole winding configuration. Both windings are supplied current from two different inverters, i.e., inverter-1, inverter-2, and simultaneously. Inverter-1 provides the regular input current to the main armature winding, whereas inverter-2 provides a three-phase current of low magnitude to the 2-pole additional armature winding. This generates an additional sub-harmonic component of MMF in the airgap beside the fundamental MMF. On the other side, the rotor is equipped with (1) harmonic, and (2) field windings. These windings are electrically coupled via a rectifier. The fundamental component of MMF produces the main rotating magnetic field, whereas the sub-harmonic MMF gets induced in the harmonic winding to produce harmonic current. This current is rectified to give DC to the rotor field winding to attain brushless operation. To authenticate the operation and analyze its performance, the proposed BL-WRSM topology is supported using 2-D finite element analysis (FEA) in JMAG-Designer. Later on, the performance of the proposed brushless topology is compared with the customary BL-WRSM topology to verify its high efficiency, high output torque, low torque ripple, and low unbalanced radial force on the rotor.

A Novel Sub-Harmonic Synchronous Machine Using Three-Layer Winding Topology

“…Furthermore, three advanced brushless field excitation methods were developed in recent times: harmonic, inductive, and capacitive power transfer [9]. Few major research investigations were done to discover the feasibility of higher-order harmonic and sub-harmonic MMF components to provide adequate power to the WFSM field winding [11][12][13][14][15][16][17]. Higher-order harmonics that are generated from the 3-phase stator MMF were used for a brushless set-up encountering additional harmonic losses [11].…”

“…Nonetheless, a cost-effective scheme for a BL-WRSM using sub-harmonic excitation has been proposed in [16]. Moreover, another dual inverter 4 pole BL-WRSM machine based on the sub-harmonic excitation method presented in [17].…”

Brushless Wound Rotor Synchronous Machine Based on a Consequent-Pole Rotor Structure with Better Torque Attributes

“…Researchers have made various efforts to develop simpler, cost-effective, and more convenient excitation methods for the rotor field of WRSMs as compared to the traditional field excitation techniques which involve brushes, sliprings, exciters, and pilot exciters regardless of the power rating of the machine [16][17][18][19][20][21].…”

“…In this method, a subharmonic component of MMF is commonly generated and employed for the brushless operation of WRSMs through a specific armature winding arrangement [19,20]. e second category uses a time harmonic-based method to generate stator MMF [21]. In this method, a third harmonic MMF is usually produced and engaged for the brushless operation of WRSMs.…”

Cost-Effective Scheme for a Brushless Wound Rotor Synchronous Machine

“…Many excitation schemes have been proposed to improve the excitation systems of brushless synchronous machines over the past century, which are briefly summarized here. One of the solutions proposed for brushless excitation is the integration of the exciter into the main machine [2][3][4][5]. This removes the need for the brush-slip-ring assembly required to excite the field winding of a WRSM.…”