Stability in nonlinear switched systems and design of switched controller for a brushless direct current motor drive

The main purpose of this thesis is to show the performance difference between un-switching and switching modelling, control design for nonlinear systems and it is also testing, researching modern control methods, stability and stabilization for continuous and discrete time switching non-linear systems. In this context, BLDCM is the model system which is preferred for the nonlinear switched system. After the literature review, mathematical preliminary and stability proofs are presented, two applications are given for continuous time systems and discrete time systems. In these applications, the following are briefly given: First application, a switched adaptive controller is proposed to control the phase currents in BLDCM drives. After deriving the error dynamics, the conduction and commutation periods of the drive is taken into account separately, and two different controllers are designed for each operation region of the current loop of BLDCM drives. All the system constants in the mathematical model of the drive are considered uncertain, and adaptation rules are derived for these unknown parameters. The stability of the closed-loop system is shown by a common Lyapunov function, and the convergence of the current error to zero is stated by means of LaSalle-Yoshizawa theorem. Unlike the first application, in the second application, a switching control design with commutation delay compensation is proposed to control the torque output and to reduce commutation torque ripple in uncertain BLDCM drives. Finally, for each application, a various numerical simulations are performed for different working conditions to test the viability of the proposed controller.