Nonlinear System Decoupling Theory And Their Application In Motor Systems

In late 20^th century, differential geometry theory was widely used in research of nonlinear system. Geometric theory of nonlinear system was formed and some key theory problems of general nonlinear system were made, such as structure decomposition, exact linearization and noninteracting control and so on. During this period, with higher and higher precision requirement of industrial control systems, the decoupling method via nonlinear system linearization couldn't satisfy demanding of high-precision control, moreover, nonlinear decoupling research about practical industrial objects is not adequate. In other hand, singular system, a class of important systems in engineering application, has attracted a lot of attentions. Compared with research on linear singular systems, however, the development of nonlinear singular systems is slow and there exist a few researches to be focused on especially in fundamental theory.The thesis mainly adopts differential geometry theory as research method. Input- output decoupling control of induction motor, decoupling control of linear induction motor, disturbance decoupling of the nonlinear singular system without relative degree are discussed. The main contributions are as following:(1) Status equations of the induction motor are built, and a coordinate change with help of relative degree of the nonlinear system is introduced such that the control system can be expressed in a simple form. By means of the simple form, the feedback control law is constructed in which the control system can be realized input-output decoupling. Velocity and flux regulators are given.(2) In nonlinear decoupling applications, the research field of differential geometry methods is widened so that the decoupling problems about the linear induction motor are discussed. Via nonlinear coordinate transformation, the complex coupling system is decomposed into a set of simple forms. In addition, feedback control laws are introduced such that the motor system can be described by mutually independent velocity and flux subsystems. Velocity and flux regulators are designed.(3) Decoupling problems of nonlinear singular systems without the relative degree are considered. New disturbance decoupling algorithm is developed, and the coordinate transformation is introduced via this algorithm such that the systems assume a set of simple form, and the feedback control law is constructed assuring the system decoupling.