multirate fuzzy control theory and its application in direct torque control study

Title: multirate fuzzy control theory and its application in direct torque control studyAuthor: Jiang LinDegree granted by: Southwest Jiaotong UniversityKeywords: nonlinear systems;; fuzzy systems;; TS fuzzy model;; input multi-sampling rate control;; output multirate control;; linear matrix inequality;; generalized eigenvalue minimization problem;; optimization of regional pole placement ;; disc pole configuration;; Lyapunov stability theory;; Riccati equation;; induction motor;; direct torque controlSummary:With modern microprocessors and related hardware rapid development of digital controller is widely used to control some, such as aircraft, robots, disk drives and other complex nonlinear systems and chaos. In particular, based on Takagi-Sugeno (TS) fuzzy Magnetic lifter model to study the nonlinear sampled-data control system has a number of research results, but these studies are mostly confined to a single sample rate control. However, in practice, for complex multi-input multi-output nonlinear system, a single sampling frequency for sampling and control is unrealistic, even impossible. Therefore, this article will multirate control theory and fuzzy control technology, the following aspects of the discussion and research:First, in order to obtain more accurate discrete nonlinear system model is proposed based on linear matrix inequality (LMI) technology, the global fuzzy system multirate discretization methods, the use of discrete technologies and systems to enhance the equivalence principle, by solving certain LMIs constrained generalized eigenvalue minimization problem (GEVP) to get the equivalent nonlinear systems with convex multi-cell nature of the multirate discrete TS fuzzy model.Second, the context of regional pole placement and quadratic optimal control is proposed based on optimization of regional pole placement of the input fuzzy optimal control of multirate methods to solve some of the Riccati equation to obtain the optimal fuzzy control law, closed-loop system stability by the Lyapunov stability theory to be guaranteed. When considering the input time-domain constraints and attenuation response, also proposed a method based on LMI constrained multi-objective multi-input multi-sampling rate of digital fuzzy control method. Sampling rate with a single fuzzy control systems, input multirate fuzzy control system to increase the number of valid input system, control system design to increase the redundancy, the system performance has been greatly improved.Furthermore, the proposed fuzzy observer and non-causal constraints of the output multirate feedback control method to avoid the output multirate http://www.999magnet.com/products/131-magnetic-lifter control system there is "causal constraints" problem, the poles of the closed-loop system in the appropriate disk configuration, the so that the closed-loop system has good dynamic and steady-state characteristics. By solving the LMIs to get some of the feedback control law and observation gain matrix. As the multirate controller time-varying characteristics, makes the output multirate fuzzy control system is far superior to the performance of a single sampling rate on the fuzzy control system. In particular, the appropriate weight to increase the number of output samples, using the output feedback control of multirate state feedback controller can be fully realized many of the features.Finally, for the adaptive flux observer in the low power state instability, we propose a flux rate of TS-type fuzzy observer, the observer gain matrix by some constant matrix through the combination of fuzzy membership functions into the nonlinear time-varying matrix, it can be run with the motor speed automatically changes with strong adaptability and robustness. Further based on the output multirate control theory, the stator voltage control cycle times of a stator current detection, output multirate proposed fuzzy observer, directly on the stator flux and rotor speed estimation, and implemented based on Multirate output fuzzy direct torque control system. Simulation results show that the transmission over the full speed range, stable operation under various conditions and at low speed dynamic and steady-state performance has been greatly improved.Degree Year: 2009