Novel Single Inverter-Controlled Brushless Wound Field Synchronous Machine Topology

Abstract

This paper proposes a novel brushless excitation topology for a three-phase synchronous machine based on a customary current-controlled voltage source inverter (VSI). The inverter employs a simple hysteresis-controller-based current control scheme that enables it to inject a three-phase armature current to the stator winding which contains a dc offset. This dc offset generates an additional air gap magneto-motive force (MMF). On the rotor side, an additional harmonic winding is mounted to harness the harmonic power from the air gap flux. Since a third harmonic flux is generated in this type of topology, the machine structure is also modified to accommodate the third harmonic rotor winding to have a voltage induced as the rotor rotates at synchronous speed. Specifically, four-pole armature and field winding patterns are used, whereas the harmonic winding is configured for a twelve-pole pattern. A diode rectifier is also mounted on the rotor between the harmonic and field windings. Therefore, the generated voltage on the harmonic winding feeds the current to the field winding for excitation. A 2D-finite element analysis (FEA) in JMAG-Designer was carried out for performance evaluation and verification of the topology. The simulation results are consistent with the proposed theory. The topology could reduce the cost and stator winding volume compared to a conventional brushless machine, with good potential for various applications.

Sub-harmonic-based Cost-effective Brushless Wound Rotor Synchronous Machine Topology

“…The main reason behind this approach is the rising price of rareearth metals used to develop high-performance-based PMs. In addition, PM machines require sophisticated flux-weakening strategies to achieve controllable speed and torque characteristics when they are used in electric vehicle (EV) and hybrid electric vehicle (HEV) applications [3], [4]. The classical brushless WRSM topologies involve additional exciters for the rotor field excitation, which make them expensive and bulky, and hence less practical to be adopted in several industrial applications.…”

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

“…Recently, the stable supply of rare-earth resources has become a challenge due to their rapid price fluctuations and environmental concerns associated with their mining and extraction [1][2][3][4][5]. Accordingly, researchers, these days, are actively investigating the nonrare-earth motors that can reduce or eliminate the usage of rare-earth permanent magnets (PMs) [6][7][8].…”

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.…”