Comparative Study of Direct Duty Ratio Control DDRC and Current Programed Mode CPM for Synchronous Buck Converter

Abstract

This paper presents a comparative study between Direct Duty Cycle Control (DDCC) and Current Programed Mode (CPM) control for synchronous Buck

converter. Frist, a model of Buck converter is presented using both moving average and small-signal model around the point of load. Then, the control laws are designed for both DDCC and CPM methods. The CPM control law is designed using the artificial ramp compensation approach to ensure both the performance and the stability when the duty cycle is larger than 50%. The study shows that the CPM loop simplifies the voltage loop design, limits the instantaneous peak current, and makes the implantation of control law simpler and less costly. The simulation results have shown the superiority of CPM control in both transient response and reference tracking, and in attenuating input voltage variations with ensuring stability when duty cycle is larger than 50%.