الفهرس | Only 14 pages are availabe for public view |
Abstract Owing to growing concerns on energy utilization and environmental protection, research on electric vehicles and wind power generation has drawn much attention in the past few decades. As a key component of these applications, the development of electric machines has become an important research topic since the last century. The permanent-magnet brushless machines have dominated the industrial and domestic markets, for many years due to their outstanding performances when compared to their counterparts. However, the PM material takes disadvantages of relatively high cost, limited resource, and uncontrollable magnetic flux, which makes it become increasingly important to consider reduced or even no PM FSMs. Therefore, with the absence of PM materials, the advanced magnetless doubly salient brushless machines that provide great cost-effectiveness have become more popular recently. These machines are called “Flux Switching Machines”. The flux switching machine (FSM), or also called switched flux machine, falls into a family of machines with an excitation source in the stator. This machine operates on the principle that the EMF is generated from coupling of flux through coils by virtue of a salient rotor providing varying permeance along the air-gap. The flux switching machine has been actively studied over the past decades as it offers high efficiency and high-power density. The purpose of this thesis is to investigate the characteristics of existing magnetless flux switching machines, analyze their design philosophies and propose new topologies for various applications. Firstly, the background of magnetless machines and previous works conducted by other researchers are introduced. Based on the study of the existing works, the upcoming trend and the potential development are also reviewed. Secondly, a new three-phase inner rotor Flux Switching Generator (FSG) is investigated for two different rotors. Next, a novel structure with improved power-density, namely the dual-rotor three-phase FSM, is proposed for aircraft power generation and wind power generation. Then, all the key performances of the proposed machines are thoroughly analyzed by the finite element method (FEM), while the experimental setups have also been developed to verify the proposed concepts. Finally, a comparison between the inner-rotor and the dual-rotor topologies of FSMs is provided to show the potentials of each topology for modern industrial applications. |