Unified control of a buck converter for wide load range applications

A new discrete time state feedback controller is presented, which allows high bandwidth voltage control of a buck converter for any load condition whether it operates in discontinuous conduction mode (DCM), continuous conduction mode (CCM) or in the boundary of these regions. This makes the buck converter applicable for a wide range of applications. For the control design process two large signal models are developed, which represent the buck converter´s discrete time dynamics in CCM and DCM. A simple PI regulator is used for the voltage control of the converter. The operation mode is detected and the voltage controller is connected in cascade to a current controller in CCM or to a nonlinear state feedback decoupling structure in DCM. In this work, the modeling and design of the proposed control topology are introduced and its performance is demonstrated in simulation and experiment.