Adaptive nonlinear control of the flyback switch mode power supplies

Abstract

Modern control approaches are completely studied in standard DC-DC buck and boost converters. However, industrial switching power supplies haven't been investigated precisely using nonlinear control systems. This issue is related to more complex state-space model of these converters. In this paper, adaptive nonlinear control of isolated flyback switching power supplies is studied using Lyapunov stability analysis. In spite of large variations in load and line, proposed closed-loop system is able to stabilize and regulate output state variable of the flyback converter in different operational conditions without steady-state error. Considering presence of Right Half Plan Zero (RHPZ) in transfer function of the isolated flyback switching power supply, proposed controller employs the double-loop cascaded structure which includes a separate voltage loop to improve steady-state and dynamic responses. Estimated values of the system uncertain parameters are employed for implementation of the controller and hence fast dynamic response can be obtained during system startup and parameters changes. Finally designed isolated flyback chopper is simulated in MATLAB/Simulink in different operating points to investigate accuracy of the proposed controller.