Simplified Brushless Wound Field Synchronous Machine Topology Based on a Three-Phase Rectifier

Syed Sabir Hussain Bukhari,Jong-Suk Ro,Ghulam Jawad Sirewal,Hamza Ahmad

doi:10.1109/access.2021.3049561

Abstract

This paper proposes a novel simplified brushless wound field synchronous machine (BL-WFSM) topology based on an uncontrolled three-phase rectifier. The output of the rectifier is injected into the common point of the star-connected three-phase armature winding. This arrangement develops an armature MMF consisting of two components: the fundamental MMF, which is rotating in nature, and the harmonic pulsating magnetic field, which induces the harmonic current in the specially designed harmonic winding of the rotor. The induced harmonic current is rectified through the full-bridge rectifier, which excites the main rotor field to achieve brushless operation and produce torque while interacting with the main fundamental rotating field of the armature. The proposed brushless topology is simple as it involves a single three-phase rectifier which does not require any complicated control strategy. Furthermore, this topology is a cost-effective solution as compared to the conventional brushless WFSM topologies since it does not require any additional hardware component except for a typical rectifier. In addition, the performance of the proposed brushless topology is better than the existing three-phase rectifier-based brushless scheme in terms of efficiency, output torque, and torque ripple. The proposed simplified BL-WFSM topology is validated through 2-D finite element analysis (FEA) using JMAG-Designer 19.1 to obtain the output torque of the machine.

Highlights

Permanent magnet (PM) machines except for those using ferrite magnets are not a preferred choice for the electrical machine manufacturing industry, especially when considering the low-power density applications [1]
These results indicate that the output torque of the proposed machine is around 78.47% higher than the existing three-phase rectifier-based BL-wound field synchronous machine (WFSM) topology
A simplified brushless WFSM topology was proposed in this paper

Summary

INTRODUCTION

Permanent magnet (PM) machines except for those using ferrite magnets are not a preferred choice for the electrical machine manufacturing industry, especially when considering the low-power density applications [1]. The two-pole pulsating magnetic field induces a VOLUME 9, 2021 harmonic current in the harmonic winding of the rotor which is rectified to excite the main field winding to generate torque and achieve brushless operation. This topology offers several advantages over conventional BL-WFSM topologies such as simple machine structure, reduced drive size, low cost, reduced volume, and minimum control complications. This paper proposes a simplified brushless WFSM topology by employing an uncontrolled customary three-phase rectifier that injects the output current to the common point of the star-connected three-phase armature winding This arrangement generates a harmonic MMF in addition to the main armature MMF in the air gap of the machine. Unlike the existing three-phase rectifier-based topology, the proposed topology does not require any additional winding to be installed with the main armature winding in the stator slots of the machine, which makes it even simpler compared to the existing topology

OPERATING PRINCIPLE

Findings

CONCLUSION