Analysis of Current-Mode Controlled PWM DC/DC Converters Based on ESPM

Abstract

Current-mode control scheme has been widely used in practice because of its significant advantages. However, it is difficult to model and analyze current-mode controlled system due to double closed-loop being introduced and the non-dominant description of duty cycle. This chapter introduces the basic principles of current-mode control first, and then extends the ESPM to modeling and analysis of the closed-loop converters with current-mode control. Two methods for determining the duty cycle are presented, i.e., the accurate solution and the simplified solution of duty cycle. The former would be found wider applicability, as it does not need to satisfy the assumptions of small ripples and linear waveform with inductor current. The analytical periodic solutions, which can be helpful for better understanding the nonlinear operating mechanism of the circuit, are all confirmed to be more accurate by simulations.