An adaptive external ramp control of the peak current controlled Buck converters for high control bandwidth and wide operation range

Buck converters for wide operation range are frequently seen in various applications. In many cases it is preferable to use one fixed compensator to fit the wide operation range. In this paper, an adaptive ramp control scheme is applied to peak current mode (PCM) controlled Buck converters for wide operation range. The control bandwidth of the PCM buck converter is improved by adaptively adjusting the external ramp. This paper revisits the small signal model of the PCM control and analyzes the relationship between the external ramp and the system dynamics. Based on the analysis, the proposed adaptive external ramp for PCM is developed to achieve high control bandwidth for wide operation range buck converters. Assuming one single fixed compensator design, the proposed control scheme can increase the control bandwidth significantly compared to fixed external ramp design. Faster transient response is verified with experimental results.