Nonlinear Modelling and Control of PWM DC-DC Buck-Boost Converter for CCM

In this paper, a nonlinear model of inverting pulse-width-modulated buck-boost converter for continuous conduction mode is introduced based on the large-signal averaging technique. The simulation of the nonlinear buck-boost model is performed in MATLAB/SIMULINK and compared with the corresponding circuit in SaberRD simulator for validation purpose. Additionally, a nonlinear control scheme of cascaded proportional-integral sliding-mode current controller is designed. The equivalent control law, existence, and stability conditions are introduced. The simulation results show that the proposed control system enhances the regulation performance, removes the steady-state error, and provides robust tracking against large disturbances.