ABSTRACT
The desirability for new induction machines that possess the combined advantages of the well-established wound-rotor and squirrel-cage induction machines have motivated considerable research interests in the development of dual-stator induction machines. Although extensive literature survey has revealed considerable advancements in the design architecture of dual-stator winding induction machine, it is yet to attain maturity from the standpoints of optimized active material utilization, efficiency and harmonic attenuation. In pursuit of some of these critical issues, this research is primarily aimed at developing a pragmatic approach of re-designing a standard three phase induction machine into an improved dual-stator winding induction machine (DSWIM) and of its practical implementation. More specifically, a methodology which encompasses realizing a dual stator winding machine prototype based on hybrid analytical and genetic algorithm (GA) optimization as well as establishing the machine performance characteristic indices, and its experimental validations. A paramount consideration is the comprehensive characterization of such improved dual-stator winding induction machine. The adoption of DSWIM housing similar pole ratios, as opposed to dissimilar pole ratios widely studied in the literature, is to permit full winding utilization and maximization of its output power capability. In this dissertation detailed mathematical modelling, based on Park's equations in d-q-0 arbitrary reference frame, to underpin simulation of the dual stator winding in MATLAB environment and application of finite element technique to stator field distribution mapping to enable computation of machine inductances have been developed and successfully implemented. All the leading DSWIM design parameters based on the classical design and GA optimization technique are presented and comprehensively discussed. The proposed theoretical computations of dual stator winding inductances are shown to be superior to the existing technique based winding function approach. As a major goal accomplished, a prototype implementation of the DSWIM equipped with 8/8 similar pole ratio has been satisfactorily realized in the laboratory as a demonstration of the practicability of the proposed design concept. This has enabled an elaborate experimental setup which facilitated accurate measurements of fundamental parameters of the proposed dual stator winding induction machine as well as in-depth operational performance evaluations comprising its steady state and dynamic drive capabilities. Of noteworthy is the GA optimization with respect to the similar pole ratio DSWIM stator winding re-design that revealed its optimum efficiency and power factor (p.f) values respectively to be 93.43% compared with 87% and 88.02% compared with 80% for standard 3-? induction machine of the same rating. The significance of the improvement in DSWIM efficiency and power factor achieved is central to the actualization of the prime goal of this research work and capable of driving future research directions. The DSWIM housing similar pole ratios has, to the best of our knowledge, remained largely unexplored. The importanceof the proposed DSWIM design consideration has also envisaged its potential application to exploiting maximum power harvest from wind turbines operating in low wind regimes prevalent in the tropical region.