| The technique of vector space decomposition modeling and control of multiphase induction machines is presented in the research reported in this thesis. By vector space decomposition, the analytical modeling and control of a multiphase induction machine are accomplished in orthogonal subspaces and the dynamics of the electromechanical energy conversion related and the non-electromechanical energy conversion related machine variables are thereby totally decoupled.; Multi-dimensional current regulation schemes have been developed to limit a special kind of zero sequence current associated with voltage source inverter fed multiphase induction machines. The concept of multi-dimensional current regulation not only solves the problem of multi-phase current regulation, but also makes the problem conceptually clear. That is, the torque control of induction machine with arbitrary phase numbers can always be performed on a d-q plane, and any current components other than d-q will be controlled on the planes orthogonal to the d-q to minimize stator {dollar}rm Isp{lcub}2{rcub}R{dollar} loss if the efficiency of the machine is a major concern, or to improve torque capability under unbalanced operation.; In addition to having high power rating, the multiphase winding structure provides a multiphase induction machine with capabilities of starting and running even with one or more of its stator excitation sets failed. However, when operated with such a structurally unbalanced condition, the dynamic properties of the machine will change drastically from its balanced operation condition. Using the concept of vector space decomposition, techniques of modeling and field oriented control of machine with structural unbalance have also been developed. Instead of using the conventional symmetrical component method, the proposed technique is established on the basis of the asymmetrical winding structure directly and therefore provides a precise, physically insightful tool to the modeling and control of induction machine with various types of structural unbalance. |
